LIETUVOS AGRARINIŲ IR MIŠKŲ MOKSLŲ CENTRAS ALEKSANDRO STULGINSKIO UNIVERSITETAS

Adas Marčiulynas

Netikrojo eglinio skydamario (Physokermes piceae Schrank.) biologija ir reikšmė paprastosios eglės

(Picea abies (L.) H. Karst.) medžių būklei Lietuvoje

Daktaro disertacijos santrauka

Žemės ūkio mokslų sritis, Miškotyros mokslo kryptis (04 A)

Girionys, 2016

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Disertacija rengta 2011–2015 metais Lietuvos agrarinių ir miškų mokslų centre (LAMMC)

pagal Lietuvos Respublikos švietimo ir mokslo ministro 2012 m. vasario 24 d. įsakymu Nr.

V-327 suteiktą doktorantūros teisę Aleksandro Stulginskio universitetui su Lietuvos

agrarinių ir miškų mokslų centru.

Mokslinis vadovas

Prof. habil. dr. Rimantas Rakauskas (Vilniaus universitetas, Biomedicinos mokslai,

Zoologija, 05 B)

Disertacija ginama Aleksandro Stulginskio Universiteto ir Lietuvos agrarinių ir miškų

mokslų centro, Žemės ūkio srities, Miškotyros mokslo krypties taryboje:

Pirmininkas

Dr. Virgilijus Baliuckas (Lietuvos agrarinių ir miškų mokslų centras, Žemės ūkio mokslai,

Miškotyra, 04 A)

Nariai:

Prof. dr. Vitas Marozas (Aleksandro Stulginskio universitetas, Žemės ūkio mokslai,

Miškotyra, 04 A)

Prof. habil. dr. Jonas Rimantas Stonis (Lietuvos edukologijos universitetas, Biomedicinos

mokslai, Zoologija 05 B)

Dr. Iveta Varnagirytė-Kabašinskienė (Lietuvos agrarinių ir miškų mokslų centras, Žemės

ūkio mokslai, Miškotyra, 04 A)

Dr. Katarzyna Golan (Gyvybės mokslų universitetas, Biomedicinos mokslai, Zoologija 05 B)

Disertacija bus ginama viešame Miškotyros mokslų krypties tarybos posėdyje

2016 m. kovo 2 d., 13 val. Aleksandro Stulginskio universiteto centrinių rūmų

posėdžių salėje (217 kab.) Studentų g. 11, Akademijos mstl., Kauno r.

Disertacijos santrauka išsiuntinėta 2016 m. vasario 1 d.

Disertaciją galima peržiūrėti Lietuvos nacionalinėje Martyno Mažvydo, Aleksandro

Stulginskio universiteto ir Lietuvos agrarinių ir miškų mokslų centro filialo Miškų instituto

bibliotekose.

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INTRODUCTION Norway spruce (Picea abies (L.) Karst.) is one of the most common tree species in

Lithuania (Navasaitis et al., 2003), composing 0.43 million ha of forest stands (20.8% of the total forest area), which mainly occurred in western, northern and central part of a country, constituting a total growing stock of 82 million m3 (State Forest Service, 2014).

Norway spruce is sensitive to wind damages while needles and young shoots may suffer from the late spring frosts, from long periods of drought and often are damaged by pests or diseases. In Lithuania, the most important insect pest is the spruce bark beetle (Ips typographus L.) which causes damages annually.

During recent years, intense damages in spruce stands were caused by the spruce bud scale (Physokermes piceae Schrank.)(Coccidae, Hemiptera). For example, in 2010, the spruce bud scale damaged 7,700 ha of spruce stands most of which were clear felled by sanitary cutting (State Forest Service, 2012).

Usually, the spruce bud scale insects develop in parks on ornamental plants. It appears that the insect prefers weakened trees growing in open, well illuminated sites (Žiogas, 1997; Belova et al., 2000; Turguter and Ulgenturk, 2006). In countries, which are geographically situated south of Lithuania, the spruce bud scale is common and well recognized tree pest. Therefore, its biology, phenology and natural enemies were widely studied and phenology recorded (Schmutterer, 1956; Novak, 1974; Turguter and Ulgenturk, 2006; Graora et al., 2012). However, environmental conditions in southern and central European countries such as Turkey, Germany or Serbia are considerably different than those are in Lithuania, showing the need for local phenological observations, and studies on biology and natural enemies of this pest insect.

The spruce bud scale is able to attack spruces of various age including young forest stands (State Forest Service, 2012). The insect damages different species of spruce (Picea spp.) by sucking sap of the needles and of young shoots, and not only weakens the trees by causing premature yellowing and needle cast, dieback of small branches and tops but also creates conditions for the parasitic fungus Rhizosphaera kalkhoffii infections, which, through the wounds, infects needles, buds and twigs (Ben-Dov and Hodgson, 1997; Menkis et al., 2015). In addition, at the feeding sites of P. piceae, the needles are coated with honeydew, on which the sooty mold gets established and prevents photosynthesis and respiration processes and further weakens already damaged trees. Although it appears that ecology of P. piceae and of several fungal taxa is closely associated, the impact of P. piceae on fungal diversity and community composition remains largerly unclear.

Reports suggest that in different European countries the invasion of the spruce bud scale arose due to change in climatic conditions. Germany’s scientist suggested that the main reason for the spread of the spruce bud scale was the unusually dry and warm weather conditions in the spring and early summer of 2002 and 2003, which influenced the spread of the pest insect in spruce stands in 2004 (Forster and Meier, 2005). A study in Sweden showed that in this

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country the spread of the pest was determined by health status of trees which were weakened following the prevailing droughts in 2006 and 2008-2009 as well as in June of 2010 (McCarthy and Skovsgaard, 2011). However, in these countries, the tree species composition, stocking level, site and forest type of the spruce stands which were damaged by the pest was not examined.

Damages caused by the spruce bud scale and associated pathogenic fungi are obvious; however, it is not known how different intensity of damage affects tree respiration and photosynthesis, and to which extent it contributes to loss of needles and shoots in a tree.

Due to activity of the spruce bud scale, some increment of the tree diameter decreases. In support, Swedish foresters provided evidence that severe damage of this pest influenced significantly the current-year radial increment of the tree (Mc Carthy and Skovsgaard, 2011). Despite that there is still no data on the reduction or recovery processes of the radial increment in the spruce stands damaged by different intensity.

Study aim To examine biology of the spruce bud scale (Physokermes piceae Schrank.) and to

evaluate its effect on the health of Norway spruce in Lithuania.

The main objectives 1. To assess biology and phenology of the spruce bud scale under the environmental

conditions present in Lithuania; 2. To investigate community of natural enemies of the spruce bud scale and to evaluate their

abundance in spruce stands damaged by the pest; 3. To determine distribution and abundance of the spruce bud scale in damaged (during

2010) Norway spruce stands in Lithuania; 4. To asses fungal diversity colonizing needles of Norway spruce in stands damaged by the

spruce bud scale; 5. To evaluate losses caused by the spruce bud scale to the Norway spruce.

Relevance of the subject In recent years, Lithuanian foresters are concerned about the incidences of the spruce

bud scale (Physokermes piceae), which was previously quite rare and did not cause serious damage. Until recently, higher abundance of the spruce bud scale was only on spruce trees growing in parks or in other urban greeneries. Until 2009, Norway spruce stands were rarely damaged, and therefore the pest did not cause economic losses for the country's forests. Following environmental conditions which favored development of this Norway spruce pest in 2008, in 2009 the mass outbreaks and spread of the spruce bud scale occurred in 174 ha of forest stands.

In 2010, a significantly expansion of the spruce bud scale to new Norway spruce stands was observed resulting in 7,652 ha area in 39 forest enterprises. 997 ha of damaged stands following

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outbreaks of the spruce bud scale were adicated by using various types of sanitary measures and 258 ha of these were clear felled despite that these stands were of young age. Due to high activity of the spruce bud scale, the planting of spruce were stopped in the areas of its outbreaks, instead planting deciduous or coniferous trees with deciduous in admixture. Often the clear felled are as were left to natural regeneration.

After a cold winter of 2010, damages increased because at the feeding sites of P. piceae, the needles were coated with honeydew, on which the sooty mold got established and prevented photosynthesis and respiration processes. Because of the disruption of these processes, the spruce was unprepared for the winter and also suffered from so-called winter drought when trees lack water for evaporation. Moreover, radial and height increment was reduced and the needles of the following year became shorter.

The visual symptoms of damage following the spruce bud scale attacks result in the mature and mid-age Norway spruce stands becoming darker in color (due tithe activity of the fungi causing sooty mold), needles falling pre-maturely, tree crowns becoming defoliated, the trees showing decline, and the increment decreasing.

Weakened trees are often attacked by the bark beetles, which are among the most common and most damage causing insects of coniferous trees. The spruce bud scale is also dangerous because it can damage both young as well as mature Norway spruce stands. However, there is no information about species composition, stocking level, site type of the spruce stands damaged by the pests. Soil properties in Norway spruce stands damaged by the spruce bud scale were widely analyzed only by the Latvian scientists but not considered elsewhere.

So far available information about distribution and damages of the spruce bud scale in the Baltic countries is very limited. There are only a few scientific publications in which the damage of the pest to spruce stands is discussed. As in Lithuania the spruce bud scale began to spread only in recent year, there is no research on this pest damage to the growth of spruce needles and shoots, and its effect on the reduction of radial growth. Moreover, there is no research which involved identification of the spruce bud scale associations with the fungi. The relevance of this research is obvious, especially in this period, when due to the climate changes we can expect more frequent and stronger invasions of the new tree pests.

Scientific novelty One of the first studies on biology, phenology and entomophages of the spruce

bud scale were performed in 1956 in Germany (Schmutterer et al., 1956), and later, because of the increasing damages to the spruce stands, it was also studied in other European countries (Schwenke, 1972; Turguter and Ulgenturk, 2006). In Lithuania, such studies as

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also mentioned above, were new, and these allowed establish phonological table of spruce bud scale corresponding to the climatic conditions present in Lithuania, and also for the first time identified insects parasitic to the spruce bud scale.

In many European countries, the pest caused serious damage to the Norway spruce stands, which were clear felled by sanitary cuttings; however there is not much data about damage to remaining living trees. Although the current-year changes in Norway spruce needles and shoots are apparent, due to damage caused by pest, so far information on tree radial growth was only available from Sweden after damages of Physokermes inopinatus. This thesis includes comprehensive studies on losses of spruce assimilation apparatus weight as a result of P. piceae attacks, which is new not only for Lithuania, but also for Europe.

The spruce bud scale in different development all stages of its life is feeding on different parts of crown of Norway spruce. In summer, larvae of the spruce bud scale are feeding on spruce needles, thereby causing wounds through which the pathogens can infect the plant. In spring, when trees are growing intensively, a female of scale insects are feeding on new needles and shoots by sucking their nutrients and at the same time releasing sweet excretions similar to honey, called honeydew. Secreted honeydew is rapidly colonized by a fungal species causing sooty mold. However, to date more detailed information on diversity of fungal species associated with the spruce bud scale and colonizing needles and shoots of Norway’s spruce coated with honeydew is scarce. Such information is of practical importance and would allow evaluate impact of these fungal species on the health tree needles and shoots damaged by the spruce bud scale.

It is known that the spruce bud scale often invades stands of Norway spruce of different ages growing in moist drained forest soils. However, the tree species composition, stocking level and site richness indicators of these stands was not examined before. Furthermore, characteristics of damaged spruce stand present in different forest types were not previously described. The studies of the present doctoral work covered larger part of the Lithuanian Norway spruce stands that were damaged by the spruce bud scale in 2010, which allowed accurately characterize forest stands that under favorable conditions can be vulnerable to the invasion of these pests.

Proved statements

1. In Lithuania, the spruce bud scale (Physokermes piceae) have natural enemies and sufficient abundance of them can regulate effectively the population of spruce bud scale;

2. The spruce bud scale usually damage pure Norway spruce (Picea abies)stands growing on dry forest sites and soils of low fertilization;

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3. Activity of the spruce bud scale and its excretion of the honeydew creates suitable conditions for the distribution of pathogenic fungi on shoots and needles of Norway spruce;

4. The complex interaction between the spruce bud scale and sooty mold fungi negatively affects the sanitary condition and radial growth of Norway spruce trees and causes looses of assimilation apparatus. Approval of the dissertation The results of the performed research have been published in two scientific

articles; both in journals with an impact factor (included into Thomson Reuters Web of Science database). The work was presented at two international conferences.

Volume and structure of the work The doctoral dissertation consists of introduction, literature review, research methods,

study results and discussion sections, conclusions, references and list of publications. The results are set out in 6 sections. The list of references includes 184 sources. The doctoral dissertation contains 88 pages, including 14 tables and 37 figures, and at the end two annexes.

1. MATERIALS AND METHODS 1.1. Determination of the species of the spruce bud scale and its

biology, phenology and parasitism During the field assessment of the insects, part of the samples was used for species

identification. DNA of adult female of scale insects was extracted directly using Dneasy Blood & Tissue kit (Qiagen). For species identification of the spruce bud scale, fragments of mitochondrial COI DNA was amplified using primers PcoF1 (CCT TCA ACT AAT CAT AAA AAT ATY AG) (Park et al., 2010) and HCO-2198 (TAA ACT TCA GGG TGA CCA AAA AAT CA) (Folmer et al., 1994).

Determination of biology, phenology and parasitism of the spruce bud scale was carried out between 2012 and 2014. For the study, a naturally growing Norway spruce stand with the dense under story of spruce was selected in Dubrava forest enterprise, in 112 block and 13 plot of Vaišvydava forest district. Number of the healthy, parasitized or damaged insects in different phases of development was recorded during detailed examinations. During microscopy observations were examined: the general appearance and size of the bud scale females, the oviposition size as well as number of eggs in the oviposition, the appearance of the pest larvae and various parameters of shoots. Records of the bud scale were carried out by model branches method in 2013 and in 2014, according to the adopted methodologies (Vasseur and Schwester, 1957; Žiogas, 2006).

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1.2. Determining stands suitability for the reproduction of the spruce bud scale and its distribution in Norway spruce stands in Lithuania

The study sites were selected in three different regions of Lithuania, i.e. Central, Western and Northern. In order to accurately determine the cause of massive outbreaks in each region, the following forest enterprises were selected, which were characterized by most extensive outbreaks of spruce bud scale in 2010: in Central Lithuania were: Dubrava EE, Jonava and Kaišiadorys forest enterprise; in Western: Kazlų Rūda and Šakiai forest enterprises; and in Northern: Biržai, Rokiškis and Kupiškis forest enterprises. The degree of damages caused by the spruce bud scale was obtained from the selected forest enterprises. According to the forest management database, healthy stands, damaged by different intensity of the spruce bud scale and dead stands were classified based on forest types, site, species composition, stocking level, age, and other parameters. This allowed to determine which stands of Norway spruce were most damaged by the pest. After relationship was established between intensity of damage and different parameters of a stand, as well as their growing conditions, the stands potentially most succeptible to outbreaks of the spruce bud scale were identified.

1.3. Determining diversity and occurrence of fungi in needles and shoots damaged and undamaged by the spruce bud scale

This study included ten study sites representing five visually undamaged and five heavily damaged 40–50-year-old pure P. abies stands in Lithuania. In 2012-2013 all outbreaks of the spruce bud scale were ceased, therefore all research plots were established in planted seed orchards of Norway spruce (Picea abies) (Fig.1.). During the evaluation process, viable populations of the spruce bud scale were determining in selected stands.

Figure 1. Map of Lithuania showing study sites, in which damaged and undamaged

needles/shoots of Picea abies were sampled.

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In each stand, ten lateral shoots with needles were sampled from 5 damaged and 5 undamaged trees. By this, 100 shoots were sampled in each forest stand resulting in 500 altogether.

DNA isolation and amplification. Fungal DNA was extracted using the standard CTAB protocol. The polymerase chain reaction (PCR) were performed using ITS rDNA primers fITS 9 (5‘-GAACGCAGCRAAIIGYGA3‘) (Ihrmark et al., 2012) and ITS4 (5‘-TCCTCCGCTTATTGATATGC-3‘) (White et al., 1990). Construction of the sequencing library and sequencing using a 316 chip as a part of the larger sample were carried out by NGI SciLifeLab (Uppsala, Sweden).

1.4. Methods for evaluating damage of spruce bud scale and of fungi

causing sooty mold to Norway spruce stands The study was carried out in stands of two maturity groups, VI-VII age (maturing)

and I-IV age (young) classes of Norway spruce stands, in which the mass damages of the spruce bud scale were recorded. Both damaged and undamaged (control) stands of the scale insects were growing in a typical spruce forest sites. Plots were selected in three different regions of Lithuania: Southwest (SW) Lithuania - Jurbarkas (8 plots), Šakiai (8 plots), Kazlų Rūda (6 plots); Middle Lithuania (M) - Dubrava EE (7 plots), Kaišiadorys (8 plots), Jonava (8 plots); and in North Lithuania (N) - Biržai (8 plots), Rokiškis (8 plots) and Kupiškis ( 8 plots) forest enterprises. 27 and 24 research plots were selected in damaged maturing and in young stands, respectively. 9 plots in undamaged stands were also selected.

Evaluation of sanitary condition of the trees. In 2013, in the selected research plots the sanitary condition of the trees was examined. In each research plot, a sanitary condition was evaluated in 30 randomly selected spruce trees: determined using a category of damaged trees (Воронцов et al., 1991).

In order to assess lost weight of spruce assimilation apparatus in a period and after period of damages of spruce bud scale and its associated fungi, five trees were randomly selected in each research plot and on each tree three branches with terminal shoots of 5 years old (2009-2013) were collected. The length of each terminal shoot was measured at 0.5 cm accuracy. The shoots were dried at 105° C temperature. Dried needles (N= 100) were removed from each terminal shoot and weighted (g) with 0.002 g accuracy (Mikšys ir Urbaitis, 2013).

Dendrochronology research methods (Stravinskienė, 1994) were used in order to determine the dynamics of spruce radial growth before, during and after damages of the scale insects. For the measurements of annual radial growth (width of the tree ring), evaluation of the tree ring structure and for the data storage on a computer the Win Dendro and Lignostation dendrochronology equipment (measuring accuracy 0.001 mm) were used.

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For the consistent evaluation of the Norway spruce radial growth, the variance component analysis was done using combined linear statistic model:

where ijlmy - is an observation of the mth tree from the ith forest enterprise, µ -

is the overall mean, iu - is the fixed effect of the ithforest enterprise, d - is the fixed effect

of the forest site hydrotop as a covariate, s - is the fixed effect of thestandstocking level as

a covariate, a - is the fixed effect of the stand age as a covariate, jium )( - is the random

effect of the jth year in the i forest enterprise, liup )( - l is the random effect of the stand

damage in the i forest enterprise, jliump )( - is the random effect of interaction of the jth year

and l stand damage in the i forest enterprise, ijlmε - is the random residual.

Between the stands damaged in 2009-2013 periods, both in young stands of spruce, as well as in maturing stands, the significance of the Kolmogorov-Smirnov test was established (Smirnov, 1948).

2. RESULTS AND DISCUSSION

2.1. Identification of the spruce bud scale species by COI DNA

sequences method Polymerase chain reaction (PCR) is a method which is increasingly used in

molecular biology and following DNA sequencing allows species identification. Identifying species of scale insects or in determination of their phylogenetic relations, the mitochondrial DNA sequences can be used. One of the most commonly used fragments of mitochondrial DNA is COI.

There were 540 nucleotides in the COI sequence alignment, of which 294 were variable and 252 parsimony informative while 42 were singletons. Average nucleotide composition was T – 38.6%, C – 14.7%, A – 40.5% and G – 6.2%. Distance analysis showed that within group p-distances for P. piceae were 3.36%, while for other analyzed species of Coccidae they were lower and ranged from 0 to 1.37%. The only exception was Parthenolecanium corni (9.63%). Details are given in Table 1.

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Table 1. Within group p-distances for analyzed species of Coccidae (%). n/c denotes cases in which it was not possible to estimate evolutionary distances.

Species p-distances (%) Species p-distances

(%) Ceroplastes ceriferus (n=7) 1.10 Drepanococcus chiton n/c Ceroplastes floridensis (n=2) 0.19 Ericerus pela (n=2) 0 Ceroplastes japonicus (n=6) 0.33 Milviscutulus magnifera n/c Ceroplastes kunmingensis n/c Neolecanium cornuparvum (n=3) 0 Ceroplastes pseudoceriferus (n=2) 0.56 Neosaissetia tropicalis n/c Ceroplastes rubens (n=4) 1.05 Paralecanium expansum n/c Ceroplastes rusci n/c Paralecanium frenchii n/c Ceroplastes sp. n/c Parthenolecanium corni (n=2) 9.63 Coccidae sp. 1 n/c Physokermes piceae (n=4) 3.36 Coccidae sp. 2 n/c Protopulvinaria pyriformis n/c Coccidae sp. 3 n/c Pulvinaria psidii n/c Coccus formicarii (n=5) 1.37 Pulvinaria sp. n/c Coccus hesperidum (n=5) 1.07 Saissetia coffeae n/c Coccus longulus n/c Saissetia miranda n/c Coccus pseudomagnoliarum n/c Saissetia sp. 1 n/c Coccus viridis (n=2) 0 Toumeyella parvicornis n/c

Distance analysis of P. piceae samples revealed that three isolates (505-507) represent different haplotypes of the same species (values of p-distances lower than 0.5%), while isolate 508 definitely belong to another species (Table 2). Most likely it was Physokermes hemicryphus, which is found in Lithuania and in neighborhood countries, and does not cause significant damages to spruce.

Table 2. Pair wise p-distances for analyzed samples of Physokermes piceae (%). Sample 1 Sample 2 p-distances (%)

Isolate 505 CO Isolate 507 CO 0.19 Isolate 506 CO Isolate 507 CO 0.37 Isolate 505 CO Isolate 508 CO 6.48 Isolate 506 CO Isolate 508 CO 6.67 Isolate 507 CO Isolate 508 CO 6.30

Species delimitation. To confirm the identity of different isolates of P. piceae,

species delimitation procedure according to the method of Pons et al. (2006) was performed, using the GMYC model. Using the single-threshold GMYC model, 34 (CI = 29-35) putative species were inferred. In most cases, there was a good correspondence between morphological species description and genetic clusters inferred by the GMYC species delimitation method. The exceptions were Ceroplastes ceriferus, Coccus formicarii and P. piceae. According to this method the results confirmed the previous results, that three out of four (505-507) samples were attributed as one species, while one sample (508) – as another (Fig. 2). Therefore, in the phenology studies of the spruce bud scale, was decided to select individuals (P. piceae) with average parameters only, in order avoid errors by mixing two species of insects.

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Figure 2. Phylogenetic tree of the Coccidae genus species based on partial COI-sequence

after Bayesian analysis (shown in branches aposterioric probability). On the scale substituents per one sequence site.

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2.2. Studies on morphology, biology and phenology of the spruce bud scale After biological and phenological records of spruce bud scale, which was done for the

first time in Lithuania, the developmental stages of this serious spruce pest was determined. Following observations, the feeding time of these pests was clarified, and this feeding resulted in shortened tree needles and shoots. The time period during which the scale females intensively secrete the honeydew, which covered spruce needles, and which fungal species causing sooty mold was determined. Equally, the average temperatures at which the insects begin to feed after wintering, the beginning of female fertilization, as well as larvae hatching, and moult was determined. These studies enabled to produce the phenological table of the spruce bud scale (Physokermes piceae) suitable to Lithuanian climatic conditions (Table 3). In the future, the results of this study will enable a timely and appropriate reaction to arising outbreaks of spruce bud scale in Lithuanian Norway spruce stands. As well as the timely control measures that will allow to obtain the desired effect in the combat against these insects.

Table 3. Phenology table of spruce bud scale (Physokermes piceae).

Months IV V VI VII VIII IX X XI-III Decades 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3

Life

stag

es Adult females ~ ~ ~ ~ ~

Eggs ~ ~ ~ ~ ~

1st instar nymphs ~ ~ ~ ~ ~

2nd instar nymphs ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~

2.3. Complex of natural enemies of the spruce bud scale During the records carried out in 2013 and assessment of the insects parasitizing the

spruce bud scale in Dubrava EEFE, out of 148 checked scale females there were only three larvae of A. nebulosus, also 10 oviposition of the scale was destroyed by these pests, and in general this accounted only 8% of all ovipositions checked (Table 4). In 2014, 124 females of the spruce bud scale were checked and in 18 there were larvae of this beetle, and another 12 oviposition of the scale was completely destroyed by these entomophages, which accounted 24% of the oviposition. This suggest that after outbreaks of the spruce bud scale has ceased in 2011, the abundance of Anthribus nebulosus has also decreased, but the population of scale insects slightly increased, and these predatory insects also began reproduce rapidly.

Table 4. Number of females of the spruce bud scale, damaged by predator A. nebulosus and

parasite A. physokermis in Dubrava EEFE.

Number of females

Damaged by Anthribus

nebulosus, %

Damaged by Aphycoides

physokermis, %

Destroyed by Anthribus

nebulosus, %

Destroyed by Aphycoides

physokermis, % 2013 m. 148 2 1.6 6.8 2 2014 m. 124 14.5 5 9.6 11.3

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While assessing pests of the spruce bud scale in 2012, in the oviposition of the scale females, larvae of parasitic hymenopterous (Encyrtidae) were detected feeding on eggs of scale insects. In 2013, observation of insects parasitizing the spruce bud scale in Dubrava EEFE showed that out of 148 ovipositions of the scale insects only 3% of these were damaged by hymenoptera. In 2014, the abundance of these entomophages, as well as Anthribus nebulosus, increased and they damaged 16% of oviposition of the scale insects. The damage causing agent was Aphycoides physokermis Gir. (Тряпицын, 1989).

The latter two species of entomophages of the spruce bud scale, made a significant impact on population abundance of the spruce bud scale in Norway spruce stands. In 2013, both entomophages damaged or completely destroyed 11% of the scale insects, while in 2014 the abundance of parasitic insects increased and they damaged and/or destroyed 40 % of all spruce bud scale ovipositions (Table 4).

3.4. Occurrence of the spruce bud scale in Norway spruce stands in Lithuania and conditions determining decline of spruce

Analysis of the collected data revealed that the age of Norway spruce stands was the major factor affecting spread and outbreak of the spread of spruce bud scale. Based on age, damaged Norway spruce stands were distributed as follows: 31% were young spruce stands (of age 1-40), 29% were maturing spruce stands (age of 51-70), 27% were mature (age of 71-110) stands and 10% were middle-aged (age of 41-50) stands. Over mature stands (age of >111) accounted for only 3% of the damaged stands. Intensity of damage also differed in Norway spruce stands of different age. The least damaged were Norway spruce stands of young age, and these accounted 20 % of all stands damaged in 2010. Strongly and moderately damaged were most premature and mature Norway spruce stands, which comprised 10% of all damaged stands or 175.5-241.5 hectares (Table 5).

Table 5. Damaged forest stands (ha), according to the maturity groups.

Intensity of damage Maturity group Weakly, ha Moderately, ha Strongly, ha Total, ha

Young stands 1-40 m. 572.3 189.5 48.4 810.2 Middle age stands 41-50 m. 137.4 78.6 49.1 265.1 Maturing stands 51-70 m. 310 232.9 203.8 746.7 Mature stands 71-110 m. 278.7 241.5 175.5 695.7

Over mature stands 111 m.and> 32.2 37 2.8 72 Analysis of tree species composition in damaged stands showed that most

damaged were pure spruce stands (pure stand is a stand in which the volume of the main tree species growing in the first storey is at least 76 % of all stand volume), and such stands accounted for 43 % of all analyzed stands.

Damages by the spruce bud scale were not only in stands of different ages and of different species composition, but also in spruce stands growing in different forest types. The

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analysis of the stands growing in different soil types and damaged by the scale insects revealed that the most damaged stands were in characteristic forest types of Norway spruce. In myrtille-oxalidosum there were 1,132 hectares (46.27% of all spruce stands selected for the study), in myrtillosa - 491 hectares (20.08%), in oxalidosum - 208 hectares (8.51%) (Fig. 3). Although the analyzed stands were of 2589 hectares and represented only 0.6 % of Lithuanian Norway spruce stands, among these filipendulosa sicata forest type represented 10.7% of the spruce stands growing in Lithuanian territory (1,260 hectares in total in Lithuania). Also, a significant part of damaged stands were on myrtillosa forest type, and assessed territory included 3.1 % of this forest type (15,698 hectares in total in Lithuania) (Figure 3).

Figure 3. Distribution of spruce stands damaged by scale insects in 2010, according to forest

types, in different regions of Lithuania.

Another, important stand characteristic evaluated was forest habitat. The analysis of damaged forest stands showed that 69.8% of spruce stands grew in L hydrotop habitats, characterised by temporarily excessive moisture in the soil. 15.9% of the damaged spruce stands grew in N hydrotop habitats (soils of normal aeration), 11.8% were in P hydrotop habitats (drained and undrained marshy forest soils), and only 2.5% of all stands damaged by the scale insects grew in U hydrotop habitats (water logged soils, with permanently excessive moisture content in the soil).

3.5. Composition of fungal community colonizing needles and shoots of

Norway spruce and its impact on stand health damaged by the spruce bud scale After sequencing of the 500 P. abies lateral shoot samples (needles and shoots),

collected in Lithuanian Norway spruce stands (seed orchards) damaged at different intensity

by Physokermes piceae, 149,426 high-quality sequences (325 bp on average) was generated.

16

Clustering of sequences at 98.5% similarity level resulted in 1193 non-singleton contigs,

majority of which – 1,039 (87.1%) were representing fungi taxa, 145 (12.1%) - plant taxa, 7

(0.6%) - protozoa taxa and only 2 (0.2%) - were representing animal taxa. In this study, the

detected fungi were 74.7% Ascomycota, 24.7% Basidiomycota, 0.3% Chytridiomycota and

0.3% Glomeromycota. The absolute richness of fungal taxa was higher in damaged shoots

(893 taxa out of 78,832 sequences) than in undamaged shoots (608 out of 31,541).

Information on the 30 most common fungal taxa representing 70.3% of all fungal sequences

is shown in Table 6. Among these, however, 13 taxa representing 34.0% of fungal

sequences could not be identified to taxon or genus level and remained unidentified. Table 6. Occurrence and relative abundance of the 30 most common fungal taxa (shown as a

proportion of all fungal sequences) in damaged and undamaged needles/shoots of Picea abies. Taxon Phylum NCBI

reference sequence

Sequence similarity (%)a

Damaged shoots Undamaged shoots All

D1 D2 D3 D4 D5 All D H1 H2 H3 H4 H5 All H Unidentified sp.2168_2 Ascomycota FJ820734 316/320 (99) 4.1 3.6 4.1 5.2 40.6 11.6 1.0 0.7 0.1 0.8 0.7 0.6 8.4 Phialophora sessilis Ascomycota EU514700 339/344(99) 17.8 11.0 1.9 2.0 10.3 7.6 2.3 3.4 0.4 2.6 1.8 1.9 6.0 Unidentified sp.2168_4 Ascomycota JX243908 311/334 (93) 4.3 8.5 2.2 2.1 0.8 3.6 7.5 13.5 4.8 7.8 11.3 8.6 5.0 Setomelanomma sp. 2168_7 Ascomycota AF525674 287/302 (95) 0.3 0.6 0.4 0.0 0.2 0.3 6.8 13.6 0.0 24.2 25.7 14.2 4.3 Unidentified sp.2168_5 Ascomycota AB476541 324/328 (99) 0.8 0.1 11.9 11.5 0.4 5.5 2.7 0.6 0.3 0.5 2.5 1.1 4.2 Cladosporium cladosporioides Ascomycota KJ589639 303/308 (98) 6.1 11.8 1.0 1.1 1.9 4.3 2.1 3.2 2.6 1.5 1.3 2.1 3.7 Rhizosphaera kalkhoffii Ascomycota HQ115656 318/322 (99) 3.2 10.6 1.5 1.1 2.7 3.9 1.9 2.5 0.5 4.9 3.1 2.5 3.5 Unidentified sp.2168_9 Ascomycota GU566235 291/315 (92) 1.1 6.4 0.2 0.1 0.0 1.7 3.2 8.6 0.4 12.1 9.9 6.8 3.1 Ceramothyrium sp. 2168_10 Ascomycota KC978733 307/316 (97) 0.7 0.1 7.3 7.4 1.1 3.7 5.1 1.2 0.1 0.2 1.8 1.1 2.9 Unidentified sp.2168_13 Ascomycota HQ433032 301/321 (94) 0.0 - 4.6 2.9 0.6 1.8 0.3 1.0 14.3 2.5 0.0 5.1 2.7 Unidentified sp.2168_11 Ascomycota KF617768 280/306 (92) 0.0 - 0.7 0.3 0.0 0.2 10.9 13.4 10.1 3.2 7.0 8.4 2.6 Fellomyces sp.2168_14 Basidiomycota AJ608659 311/328 (95) 2.0 5.7 0.3 0.6 8.1 3.3 0.2 0.2 - 0.0 0.0 0.1 2.4 Unidentified sp.2168_17 Ascomycota JX136410 294/313 (94) 4.6 2.1 1.4 2.4 1.4 2.2 0.7 2.1 1.0 2.1 3.9 2.1 2.1 Sydowia polyspora Ascomycota KJ589593 315/318(99) 1.7 0.9 5.9 1.7 0.2 2.1 1.5 4.0 0.1 2.2 2.4 1.9 2.0 Trichomerium sp.2168_15 Ascomycota KP004468 319/332 (96) 0.2 1.0 5.5 4.3 0.8 2.6 1.3 0.4 0.3 0.6 0.6 0.5 2.0 Unidentified sp.2168_18 Ascomycota KC966333 300/322 (93) - - 1.1 9.9 - 2.6 - - - 0.0 - 0.0 1.8 Scleroconidioma sp. 2168_22 Ascomycota FR837912 304/321 (95) 15.6 0.0 1.4 0.0 - 2.2 0.1 0.1 - - 0.2 0.1 1.6 Epicoccum nigrum Ascomycota JN835210 308/311(99) 0.2 3.7 1.3 0.8 0.3 1.4 1.7 1.7 2.8 1.1 0.9 1.7 1.5 Aureobasidium pullulans Ascomycota KM877470 310/314 (99) 3.9 3.1 1.1 1.2 0.1 1.7 0.7 0.6 0.9 0.6 1.1 0.8 1.4 Unidentified sp.2168_23 Ascomycota KC965703 268/317 (85) - - 5.1 2.2 - 1.6 3.4 - 0.2 - - 0.3 1.2 Exobasidium bisporum Basidiomycota AB180368 327/333 (98) 1.3 1.1 1.3 1.7 1.5 1.4 0.5 0.9 0.0 0.3 0.3 0.3 1.1 Setomelanomma holmii Ascomycota AF525675 297/301 (99) - 0.5 0.2 0.0 0.4 0.2 1.2 0.1 9.4 0.0 0.1 2.9 1.0 Phaeosphaeria sp. 2168_26 Ascomycota KF251182 288/306 (94) 0.1 0.1 0.0 0.0 - 0.0 0.9 1.8 8.7 0.1 0.1 3.0 0.9 Unidentified sp.2168_29 Ascomycota JF449549 291/312 (93) 0.2 0.2 2.6 2.4 0.1 1.2 0.0 - - - 0.0 0.0 0.9 Cryptococcus sp.2168_30 Basidiomycota KM246292 290/300 (97) 3.2 2.4 0.0 0.0 0.1 1.0 - - - 0.1 0.0 0.0 0.7 Neosetophoma samarorum Ascomycota KF251162 306/310 (99) - - - - - - - 0.2 7.6 - - 2.3 0.7 Unidentified sp.2168_34 Ascomycota HQ873380 285/299 (95) 1.0 0.0 0.7 0.4 0.6 0.5 0.3 1.2 0.2 0.9 2.2 1.0 0.6 Unidentified sp.2168_31 Ascomycota KM494456 280/281 (99) 0.1 0.0 1.2 2.3 0.1 0.8 - - 0.0 0.0 - 0.0 0.6 Neosetophoma sp. 2168_40 Ascomycota KJ173536 305/315 (97) 0.0 0.1 0.0 0.0 0.0 0.0 - 0.0 6.1 0.8 - 2.0 0.6 Unidentified sp.2168_42 Ascomycota FR773250 275/296 (93) 0.1 0.1 0.0 0.4 - 0.1 - 0.4 - 1.5 5.9 1.8 0.6 Total of 30 taxa: 72.8 73.7 64.8 64.0 72.3 69.1 56.4 75.3 71.0 70.6 82.7 73.2 70.3

a Sequence similarity column shows base pairs compared between the query sequence and the reference sequence at NCBI (www.ncbi.nlm.nih.gov) databases, and the percentage of sequence similarity is shown in the parentheses.

17

The most common taxa were unidentified sp. 2168_2 (8.4%), Phialophora sessilis

(6.0%), unidentified sp. 2168_4 (5.0%), Setomelanomma sp. 2168_7 (4.3%) and

unidentified sp. 2168_5 (4.2%) (Table 6). The fungal pathogen R. kalkhoffii (3.5%) was the

seventh most common fungus which, at variable abundances, was detected in all study sites

representing both damaged and undamaged shoot samples. ANOVA analysis showed that

among the 30 most common taxa, the abundance of P. sessilis, unidentified sp. 2168_17,

Aureobasidium pullulans and Exobasidium bisporum was significantly higher in damaged

shoots than in undamaged shoots (P < 0.05), while in unidentified sp. 2168_11, it was

significantly higher in undamaged shoots than in damaged shoots (P < 0.05). The abundance

of the remaining 25 most common fungal taxa did not differ significantly between damaged

vs. undamaged shoots (P < 0.05).

The correspondence analysis (CA) showed that study sites representing damaged

(D1–D5) and undamaged (H1–H5) shoot samples were separated from each other on axis 1,

indicating that in these fungal communities, these were largely different. Among all the taxa,

431 (41.5%) were exclusively found in damaged shoots, 146 (14.0%) were exclusively found

in undamaged shoots, and 462 (44.5%) were common to both types of samples (Fig. 4).

Figure 4. Distribution of different fungal taxa: squares indicate taxa exclusively detected in P. abies shoots damaged by P. piceae, circles indicate taxa exclusively detected in undamaged shoots, and crosses indicate taxa detected in both types of samples.

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3.6. Assessment of damage caused by the spruce bud scale and sooty mold fungi to Norway spruce

3.6.1. Sanitary condition of Norway spruce stands damaged by the spruce bud scale

In all studied young Norway spruce stands (age class II-IV) in 2013, the crown defoliation was higher in spring (before the trees vegetation season) than in autumn. In spring, the crown defoliation in the studied stands ranged between 20% in Northern Lithuania and 32% in Western Lithuania region. Statistically significant difference (t = -3.45; P ≤ 0.01) in average crown defoliation was determined between the damaged and control stands in Central Lithuania. In damaged stands, it was higher (10%) than in control stands.

In the autumn, difference in defoliation of Norway spruce between damaged and a control stand in Western Lithuania has further decreased and no statistically significant differences were found. By contrast, in Northern and Central Lithuania the crown defoliation was significantly higher in damaged stands than in control stands (respectively t = 3.30 ir -3.82; P ≤ 0.01).

After assessment of tree defoliation, the higher defoliation was in mature stands (age class V-VII) than in young spruce stands. The average crown defoliation in the spring and in the autumn, in control and damaged stands in the West Lithuania, ranged between 35 and 40% (differences not significant). In Northern Lithuania, the crown defoliation of control stands was significantly (t = 4,63; P ≤ 0.001) higher (over 10%) than in the damaged stands, and after autumn assessments of defoliation this difference became statistically insignificant. Greater defoliation in the damaged stands were (comparing the regions) in the Central part of Lithuania in the spring and reached almost 43%, but in the autumn defoliation of the same spruce stands was only about 32%, the difference was statistically significant. In regions of the Western and Central part of Lithuania, in spring, the crown defoliation of damaged spruce stands was similar and was 41 and 43%, respectively. In Northern Lithuania, however, the crown defoliation of damaged spruce stands was significantly lower and was 32%; the difference between the regions was statistically significant (P ≤ 0.05).

Assessment of defoliation showed, that in spring, young spruce stands (age class II-IV), were weakened in all studied regions, because the majority (60-70 %) of the studied spruces was in the II category of damage, and this was both in controls and in damaged stands. While 20-40% of relatively healthy trees were found.

In maturing stands of spruce, other consistent patterns were determined than in young stands. In maturing stands damaged by different intensity, both before vegetation and after that, the majority of the spruces, in all Lithuanian regions, were in the II category of damage. It is noted, that in all stands the number of relatively healthy (I category of damage)

19

trees was lower than of declining trees (III category of damage). Comparing the spring and autumn, in all stands, the decrease of tree quantity was observed in the III category of damage.

3.6.2. Effect of Physokermes piceae and fungi causing sooty mold on growth of shoots and needles of Norway spruce

Results showed that before invasion of the Norway spruce bud scale and of associated fungi causing sooty mold, an average weight of dried spruce needles (N = 100) was 0.405 ± 0.030 g, when samples were from young spruces. However, such measurement done in 2010, i.e. at the time of the spruce bud scale outbreak, showed that weight of needles decreased 1.3 times as compared to values before the insect‘s invasion. Evaluation of stands damaged at different intensity showed that in 2010 an average weight of needles (N = 100) in moderatelly damaged stands was 1.3 times lower than in the undamaged (relatively healthy) stands, when both damaged and undamaged stands were growing in the same forest type conditions. Even higher weight loss of the needles was observed in strongly damaged stands, there the weight was up to 2 times lower in comparison to control stands. The difference was statistically significant (P < 0.05). Meanwhile, there was no difference in weight of needles between weakly damaged and control stands, although a slight decrease in weight of needles in these stands have also been determined (Figure 5).

Figure 5. Average weight of needles in young Norway spruce stands with different levels of

damage caused by the spruce bud scale during 2009-2013 in all research plots.

Comparing all damaged stands with control (relatively healthy) stands, already in 2009 the weight loss of needles was visible in stands of Western and Central Lithuania, i.e. in the areas where the first symptoms of damage by the spruce bud scale to spruce stands were observed. In these regions, already in 2009, the needles of damage stands lost about 16% of their needle weight. In stands of Central and Northern Lithuania, during the period

20

of mass damage by the spruce bud scale, the loss of the needle weight was lower than in Western Lithuania. In these two regions, weight of damaged needles of was about 20% lower than in controls. Next year, in the damaged plots in Western and Northern Lithuania, the weight of needles was similar to controls, however still remained lower and differed between 13% and 17% (Fig 6).

Figure 6. Needle weight in young Norway spruce stands growing in different regions of Lithuania.

Interaction between the spruce bud scale and sooty mold fungi negatively affected not only the weight of needles, but also the length of terminal shoots. The main negative reductions was registered during the mass attack of the pest in 2010. Measurements of the main lateral shoots of spruce branches showed that the average length of shoots in the strongly and moderately damaged spruce stands in 2009 (before the damage) was 14.11 ± 0.76 cm and 13.20 ± 0.48 cm, respectively. In the stands damaged at this intensity, the shoots length decreased by almost 1.5 times, during the period of mass damage (2010), and the differences was found to be statistically significant (t = 3.59 ir 3.49, P ≤ 0.001).

The average of shoot length in control sites was (12.45 ± 0.48 cm) 1.2 times longer than in strongly (10.44 ± 0.68 cm) and moderately (10.78 ± 0.50 cm) damaged plots in 2010, the differences statistically significant (t = 2.41 and 2.29, P ≤ 0.02 and 0.05, respectively) (Fig.7).

The results obtained from the various forest enterprises have shown that changes in growth of shoots and needles was the most notice able in the stands strongly damaged by the spruce bud scale. It should be noted that more sensitive to damage by the spruce bud scale were needles than shoots. In moderately or even weakly damaged stands, weight of the needles was lower during the mass damages, both comparing the controls, as well as period prior the damage.

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Figure 7. Dynamic of Norway spruce shoots length damaged at different intensity by the spruce bud scale, in all research plots in 2009-2013.

Meanwhile changes in growth of shoots remained constant in weakly or moderately

damaged Norway spruce stand. It was determined, that in comparison with control, damages by the spruce bud scale and associated sooty mold fungi to growth of shoots and needles were in most cases statistically significant (P < 0.05) in forest enterprises of Northern and Central Lithuania.

3.6.3. Correlation analysis of needle mass and annual shoot length Results revealed a direct correlation of needle mass and shoots length, showing

that during the increase of the shoots length, the mass of the needles also increased, and this was both in stands damaged by the spruce bud scale and in relatively healthy (control) spruce stands. Moderate correlation (r = 0.64 and r = 0.54, P ≤ 0.05) was revealed between the needle weight and shoot length in strongly and moderately damaged stands, respectively. In control stands, the correlation between these two parameters was r = 0.68, P ≤ 0.05. A weak correlation (r = 0.46, P ≤ 0.05) was in mildly damaged stands (Fig. 8).

22

Scatterplot (Spreadsheet1 2v *120c)

shoot length, cm = 3,0067+26,6263*x; 0,95 Conf .Int.

0,1 0,2 0,3 0,4 0,5 0,6 0,7

needle mass, g

4

6

8

10

12

14

16

18

20

22

24

26

28

shoo

t len

gth,

cm

needle mass, g:shoot length, cm: r = 0,6781; p = 0,0000

Scatterplot (Spreadsheet2 2v *165c)

shoot length, cm = 5,9959+15,9653*x; 0,95 Conf .Int.

0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9

needle mass, g

2

4

6

8

10

12

14

16

18

20

22

24

26

28

shoo

t len

gth,

cm

needle mass, g:shoot length, cm: r = 0,4565; p = 0,0000

Scatterplot (Spreadsheet3 2v*150c)

shoot length, cm = 5,8941+16,5036*x; 0,95 Conf.Int.

0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8needle mass, g

4

6

8

10

12

14

16

18

20

22

24

shoo

t len

gth,

cm

needle mass, g:shoot length, cm: r = 0,5351; p = 0,0000

Scatterplot (Spreadsheet4 2v *45c)

shoot length, cm = 2,7849+30,7329*x; 0,95 Conf .Int.

0,10 0,15 0,20 0,25 0,30 0,35 0,40 0,45 0,50 0,55 0,60 0,65

needle mass, g

6

8

10

12

14

16

18

20

22

24

26

shoo

t len

gth,

cm

needle mass, g:shoot length, cm: r = 0,6421; p = 0,000002

A B

C D

Figure 8. Relationship between needle weight (g) and shoot length (cm) in Norway spruce

stands of various intensity of damage by the spruce bud scale: A - control, B - weakly damaged, C - moderately damaged, D - strongly damaged.

3.6.4. Effect of the spruce bud scale and fungi causing sooty mold on radial growth of Norway spruce

During the studies, the effect of damage caused by the spruce bud scale and sooty mold fungi were determined for the radial growth of spruce. Larger differences were in maturing stands, when comparing between controls and different intensity of damaged trees. Comparing the spruce radial growth, before the damage (2009) of the bud scale, and the radial growth during the damage period (2010), it was found that the radial growth in weakly damaged spruce stands decreased on average by 1.3 times, in moderately damaged stands by 1.5 times, and in strongly damaged stands – 1.6 times, in all cases the differences were statistically significant (P < 0.001). Comparing the radial growth in stands damaged at different intensity and relatively healthy (control) spruce stands, showed that there were significant difference between control stands and moderately damaged spruce stands (t = 2.59, P < 0.05). Even higher significant differences in radial growth were between control stands and strongly damaged spruce stands (t = 3.07, P < 0.01). Statistically significant difference in radial growth of strongly damaged and control spruce was also in 2011 (t = 2.26, P < 0.05) (Fig. 9).

23

Figure 9. Changes in Norway spruce radial growth during 2006-2013, in maturing stands

damaged at different intensity. During the analysis of the radial growth in young spruce stands, it was observed

the same consistent pattern as in middle-age stands, i.e. a great losses of radial growth was seen during the period of damage as compared to the period before the damage. In all stands damaged at different intensity, the radial growth has decreased by 30-35%, and the difference was significant at P < 0.001. Comparing damaged stands with the controls, in the damage period, detected differences in radial growth of spruce were not high and did not differ significantly (Fig. 10).

Figure 10. Changes in spruce radial growth during 2006-2013, in young spruce stands

damaged at different intensity.

In young spruce stands as well as in maturing stands, recovery of tree radial growth was observed in next year after damage. In these stands, the radial growth of weakly damage trees, recovered already next year to pre-damage level and remained higher than in control stands, the differences significant (P < 0.05).

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Variation component analysis was performed, where all data of the stands (young and maturing stands) were analyzed together and included the period of damage and the period after the spruce bud scale damage (2009-2013). This analysis revealed that damages of scale insects and related fungi had a greater impact on formation of overall annual ring or it parts, than individual year indicators of the stand. It was also found that interaction between year and damage was insignificant, indicating that in individual years, the reaction to the bud scale damage, of all stands selected for the study, was the same or at least similar. The obtained results showed that age of stands was of key importance to damage intensity of the spruce bud scale, while the area (FE) had no significant impact on damages caused by the scale insects. Furthermore, stand age played an important role in the formation of annual ring, especially for the spruce growing in different hydrotop habitats. In the selected stands, the stocking level together with damages of different intensity had high impact only on late wood formation, which cannot be said about the development of the whole ring (Table 7).

Table 7. Components of variation (%), the accuracy (%) and reliability (as well as fixed

effects reliability) by analyzing the 2009-2013 period.

Attribute Random effects (component of variation (%), accuracy (%), level of significance)

Fixed effect (F criterion, reliability)

Year Damage year x damage interaction

Forest Enterprise

Habitat hydrotop

Stocking level

Age

Ring of wood 6.81 1.91 *** 18.79 6.65 *** 1.13 0.71 . . 0.92 . 67.29 *** 2.18 . 2084.86 ***

Ring of early wood 6.9 1.88 *** 9.38 3.18 *** 0.35 0.68 . . 1.08 . 22.19 *** 3.34 . 961.36 ***

Ring of late wood 2.43 0.89 ** 13.82 4.71 *** 0.23 0.68 . . 1.12 . 42.31 *** 11.94 *** 1112.39 ***

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CONCLUSIONS 1. The phenology of spruce bud scale (Physokermes piceae) determined in this study for the first time in Lithuanian climatic conditions revealed that that development period of the spruce bud scale females coincides with the beginning of Norway spruce bud burst, and the maximum of female body parameters reaches in the middle of June. The life cycle and morphology of the spruce bud scale females and larvae in Lithuania was not significantly different from ones in other countries where this insect is present. 2. It was identified two species of entomophages: parasitic Aphycoides physokermis Gir. (Hymenoptera: Encyrtidae) and predatory Anthribus nebulosus F. (Coleoptera: Anthribidae), which are significant for controlling abundance of the spruce bud scale. These entomophages destroyed between 11% and 40% of the spruce bud scale ovipositions in the spruce stands, indicating that sufficient abundance of these entomophages can effectively regulate population of the pest. 3. For the development of the spruce bud scale, the best were pure young (up to 40 years) and maturing (51-70 years) stands of Norway spruce growing in spruce-characteristic forest types: myrtillosa and mirtilio-oxalidosum. 4. The absolute richness of fungal taxa was higher in damaged shoots and needles than in undamaged shoots and needles. The fungal pathogen R. kalkhoffii was detected in all study sites, and the abundance of Phialophora sessilis, Aureobasidium pullulans and Exobasidium bisporum was significantly higher in damaged stands than in control spruce stands. 5. Results demonstrated that in maturing and young-age spruce stands damaged by the spruce bud scale, the biggest part of spruce were weakened and belonged to the II category of damage. The sanitary condition in studied young spruce stands was better than in the maturing stands, in which the crown defoliation was about 1.5 times higher. 6. Changes in growth of spruce annual shoots were most noticeable on trees moderately and strongly damaged by the spruce bud scale and fungi causing sooty mold, where the growth of shoots decreased by 1.5 times. Also a clear changes in needle weight was observed in strongly damaged stands, in which needle biomass was 1.7 to 4.5 times lower than in the period before the damage. As a result, direct interdependence was determined between weight of needles and length of shoots, which showed, that increased length of shoots resulted in increased weight of needles. In this respect, moderate and strong correlations were observed in stands strongly damaged by the spruce bud scale and in relatively healthy spruce stands. 7. The spruce bud scale and fungi causing sooty mold had negative effect on tree radial growth. It was found that radial growth decreased by 56% in selected young Norway spruce stands damaged by the spruce bud scale and this was significantly lower than in control stands (P < 0.05). Damages developed mainly in Central and Western regions of Lithuania, where the young spruce stands have lost up to 40% of increment in stem diameter. However, effect of the spruce bud scale and fungi causing sooty mold on radial growth was not long-lasting, and trees recovered over the next two years after the damages.

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15. Schwenke, W. 1972. Die Forstschädlinge Europas. Band 1. Parey Hamburg und Berlin, 413-417. 16. Smirnov, N. 1948. Table for estimating the goodness of fit of empirical distributions. Annals of Mathematical

Statistics, 19: 279–281. 17. State Forest Service, 2014: Lithuanian statistical yearbook of forestry. Ministry of Environment.

Kaunas Lututė, 184 pp. 18. State Forest Service, 2012: Lithuanian statistical yearbook of forestry. Ministry of Environment.

Kaunas Lututė, 184 pp.

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19. Stravinskienė, V. 1994. Medžių gręžinių paėmimas ir radialinio prieaugio matavimas, atliekant dendrochronologinius ir dendroindikacinius tyrimus (metodinės rekomendacijos). Kaunas: Girionys. 23.

20. Turguter, S., Ulgenturk, S. 2006. Biological aspects of Physokermes piceae (Schrank) (Spruce Bud Scale) (Hemiptera: Coccidae). J. Agric. Sci., 12 (1): 44-50. (in Turkish).

21. Vasseur, R., Schwester, D. 1957. Biologie et ecologie du Pou de San Jose (Quadraspidiotus perniciosus Comst.) in France. Ann. I.N.R.A., (Sec. C) epiph. 38: 5-66.

22. White, T. J., Bruns, T., Lee, S., Taylor, J. 1990. Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics. In: Innis MA, Gelfand DH, Sninsky JJ, White TJ (eds) PCR protocols: a guide to methods and applications. Academic, San Diego, 315–322.

23. Žiogas, A. 1997. Miško entomologija [Forest Entomology]. Kaunas, LŽŪU Leidybinis centras, 272 pp. (in Lithuanian).

24. Žiogas, A. 2006. Miško patologijos tyrimo metodika. Vilnius, 26. (in Lithuanian) 25. Воронцов, В. Н., Мозолевская Э. Г., Соколова Э. С. 1991. Технология защиты леса. М.,

Экология, 304. 26. Тряпицын В. А. 1989. Наездники-энциртиды (Hymenoptera, Encyrtidae) Палеарктики. Л.:

Наука, 488.

LIST OF AUTHOR’S PUBLICATIONS

Scientific papers published in impact-factor journals referred in the Thomson

Reuters Web of Science (WoS) database and included into Thomson Reuters Journal

Citation Reports (JCR):

• Gedminas, A., Lynikienė, J., Marčiulynas, A. and Povilaitienė, A. 2015. Effect of

Physokermes piceae Schrank. on Shoot and Needle Growth in Norway Spruce stands in

Lithuania. Baltic Forestry 21:162-169.

• Menkis, A., Marčiulynas, A., Gedminas, A., Lynikienė, J., Povilaitienė, A. 2015.

High-Throughput Sequencing Reveals Drastic Changes in Fungal Communities in the

Phyllosphere of Norway Spruce (Picea abies) Following Invasion of the Spruce Bud Scale

(Physokermes piceae).Microbial Ecology 70(4): 904-911.

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CURRICULUM VITAE ADAS MARČIULYNAS

Doctoral Student Institute of Forestry, Lithuanian Research Centre for Agriculture and Forestry

Tel.: +370 600 88998; E-mail: adasmarciulynas@gmail.com Date of Birth: 28th of October, 1986.

EDUCATION PhD student 2011–present MCs in Forest ecology And environmental research 2009–2011 BSc in Forestry 2005–2009 PROFESSIONAL EXPERIENCE 2015–present INTERNSHIPS

PARTICIPATION IN RESEARCH PROJECTS

Institute of Forestry of Lithuanian Research Centre for Agriculture and Forestry: a third-year doctoral student in Forestry (specialization: forest entomology). Thesis Title: “Biology and significance of the spruce bud scale (Physokermes piceae Shrank.) to sanitary conditions of Norway spruce (Picea abies (L.) H. Karst.) in Lithuania”. Supervisor: prof. hab. dr. Rimantas Rakauskas Lithuanian University of Agriculture, Kaunas, Lithuania. Master thesis: “Research of sprout protection with insecticides against weevils of Hylobius tribe in Jurbarkas and Druskininkai forests”. Lithuanian University of Agriculture, Kaunas, Lithuania. Junior Researcher at the Department of Forest Protection and Game Management, Institute of Forestry of Lithuanian Research Centre for Agriculture and Forestry, Kaunas, Lithuania. 1) Short Term Scientific Mission at the Department of Forest Mycology and Plant Pathology. Uppsala BioCenter at the Swedish University of Agricultural Sciences (SLU) from 10.28 to 12.15, 2013. Uppsala. Sweden. COST Action No. FP1103. Fraxinus dieback in Europe: elaborating guidelines and strategies for sustainable management (FRAXBACK). 2) Short Term Scientific Mission at the Department of Forest Mycology and Plant Pathology. Uppsala BioCenter at the Swedish University of Agricultural Sciences (SLU) from 02.10 to 03.15, 2014. Uppsala, Sweden. COST Action No. FP1002. Pathway Evaluation and pest Risk Management In Transport (PERMIT). 1) Title: „Ecological interactions between massively tree-devastating insects and associated microorganisms in the context of climate change”. The project is financially supported by the European Regional Development Fund according to Commission Regulation (EC) No. 1828/2006 article 8 part 4. Project No. VP1-3.1-ŠMM-07-K-02-001. Duration: 2012–2015. 2) Title: “Impact of Spruce bud scale (Physokermes piceae Schrank.) on spruce dieback in Lithuania“. Foundation: Research Council of Lithuania. Project No. Nr. MIP-035/2012; Duration: 2012–2014.

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ĮVADAS Paprastoji eglė (Picea abies (L.) Karst.) – viena iš pagrindinių spygliuočių medžių

rūšių Lietuvos miškuose (Navasaitis ir kt., 2003). Miškų ūkio statistikos duomenimis, Lietuvoje eglynai užima 0,43 mln. ha (tai yra 20,8 % viso šalies miškų ploto). Tai sudaro 82 mln. m3 medienos (Lietuvos miškų ūkio statistika, 2014). Eglės medynai labiausiai išplitę Vakarinėje, Šiaurinėje ir Vidurio Lietuvos dalyse.

Paprastoji eglė jautri vėjo pažeidimams. Spygliai ir jauni ūgliai kenčia nuo vėlyvų pavasario šalnų. Užsitęsę sausringi vasaros laikotarpiai eglės medynuose dažnai lemia kenkėjų ir ligų išplitimus. Dažniausiai Lietuvoje sutinkamas ir didžiausią žalą paprastosios eglės medžiams darantis kenkėjas yra žievėgraužis tipografas (Ips typographus L.). Didesni ar mažesni šio kenkėjo pažeidimai mūsų šalyje fiksuojami kiekvienais metais.

Pastaraisiais metais žymių nuostolių eglynams pridarė anksčiau Lietuvoje gana retu laikytas netikrasis eglinis skydamaris (Physokermes piceae Schrank.). 2010 metais šis kenkėjas įvairiu intensyvumu pažeidė 7700 ha eglynų, iš kurių nemaža dalis buvo iškirsta vykdant sanitariniuis kirtimus (State Forest Service, 2012).

Netikrasis eglinis skydamaris didžiojoje jo paplitimo arealo dalyje buvo aptinkamas ant eglių, augančių parkuose ar kitose dekoratyviosiose miestų zonose. Jose medžiai labiau kenčia nuo taršos ar mechaninių pažeidimų, vyrauja aukštesnė aplinkos temperatūra, mažesnis oro santykinis drėgnumas, didesnis saulės apšviestumas (Žiogas, 1997; Belova ir kt., 2000; Turguter ir Ulgenturk, 2006).

Kadangi netikrasis eglinis skydamaris piečiau Lietuvos esančiose šalyse buvo dažnai pastebimas medžių kenkėjas, todėl jose yra plačiai nagrinėta kenkėjo biologija, fenologija ir natūralūs priešai, sudarytos šio kenkėjo fenologinės lentelės (Schmutterer, 1956; Novak, 1974; Turguter ir Ulgenturk, 2006; Graora ir kt., 2012). Visgi Turkijos, Vokietijos ar Serbijos klimatas nuo Lietuvos gana stipriai skiriasi, todėl mūsų šalyje šios fenologinės lentelės netenka prasmės. Natūralių priešų kompleksas dėl skirtingų gyvenimo sąlygų taip pat neatitinka Viduržemio jūros regiono šalių vabzdžių įvairovės.

Masiniai netikrojo eglinio skydamario pažeidimai kelia didelį pavojų eglių sveikatingumui. Dėl kenkėjo, kuris aptinkamas net ant pirmamečių eglės kultūrų, daromos žalos, žūsta įvairaus amžiaus medžiai (State Forest Service, 2012). Šis kenkėjas čiulpdamas jaunų ūglių ir spyglių sultis ne tik silpnina medžius, taip sukeldamas priešlaikinį spyglių geltimą ar lajų nykimą, bet kartu sudaro sąlygas parazitinių grybų, tokių kaip Rhizosphaera kalkhoffii infekcijoms, kurios per žaizdas užkrečia spyglius, pumpurus ir šakeles, atsiradimui (Ben-Dov ir Hodgson, 1997; Menkis ir kt., 2015). Be to, skydamarių maitinimosi vietose spygliai ir šakos padengiamos lipčiumi, ant kurio auga suodligę sukeliantys grybai. Šie grybai stabdo medžių fotosintezės ir kvėpavimo procesus, taip dar labiau silpnindami medžius.

Nors aiškiai matoma netikrojo eglinio skydamario ir kelių grybų rūšių tarpusavio sąsaja, tačiau kenkėjo poveikis grybų įvairovės sudėčiai yra neaiškus. Kadangi tokie grybų bendruomenių tyrimai netikrojo eglinio skydamario židiniuose nebuvo atlikti ne tik Lietuvoje, bet ir visoje Europoje, todėl svarbu išsiaiškinti, kokią įtaką šis kenkėjas daro ant eglių spyglių ir ūglių sutinkamų grybų rūšių gausai ir įvairovei.

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Užsienio šalių mokslininkai teigia, kad netikrojo eglinio skydamario invazijos atskirose Europos šalyse kilo dėl klimatinių veiksnių. Eglinių skydamarių išplitimo pagrindine priežastimi Vokietijos mokslininkai laikė 2002 ir 2003 m. buvusius neįprastai sausus ir šiltus orus pavasarį ir vasaros pradžioje, kurie lėmė, jog 2004 metais kenkėjai išplito eglynuose (Forster ir Meier, 2005). Švedijoje atliktais tyrimais nustatyta, kad šioje šalyje kenkėjų paplitimui turėjo įtakos medžių nusilpimas, atsiradęs dėl 2006 ir 2008-2009 ir 2010 m. birželio mėnesiais vyravusių sausrų (Mc Carthy ir Skovsgaard 2011). Tačiau nei vienoje iš šių šalių nebuvo nagrinėjama kenkėjų pažeistų eglynų rūšinė sudėtis, medynų skalsumas, augavietės tipas, pažeistų medynų miško tipas.

Nors netikrojo eglinio skydamario ir su jais susijusių grybų daroma žala medžiams aiškiai matoma, tačiau nėra žinoma, kiek skirtingo intensyvumo skydamarių pažeidimai lemia tai, jog prarandamas medžių asimiliacinis aparatas, spygliai ir ūgliai sutrumpėja.

Dėl netikrojo eglinio skydamario veiklos medžiai netenka ir dalies savo prieaugio į skersmenį. Nors Švedijos miškininkai ir pateikė įrodymus, kad stiprūs šio kenkėjo pažeidimai, gerokai lemia medžių radialųjį prieaugį einamaisiais metais, tačiau nėra pateiktų duomenų apie radialiojo prieaugio sumažėjimą skirtingo pažeidimo intensyvumo medynuose ir radialiojo prieaugio atsistatymo procesus po skydamarių kenkimo (Mc Carthy and Skovsgaard, 2011).

Disertacinio darbo tikslas Ištirti netikrojo eglinio skydamario (Physokermes piceae Schrank.) biologiją ir

poveikį Lietuvoje augančių paprastosios eglės medžių būklei.

Mokslinių tyrimų uždaviniai 1. Ištirti netikrojo eglinio skydamario biologijos ir fenologijos ypatumus Lietuvos klimato

sąlygomis. 2. Ištirti netikrojo eglinio skydamario natūralių priešų kompleksą ir įvertinti jų gausą

skydamarių pažeistuose eglynuose. 3. Nustatyti netikrojo eglinio skydamario paplitimą 2010 metais pažeistuose Lietuvos

paprastosios eglės medynuose. 4. Nustatyti eglės spyglius kolonizuojančių grybų įvairovę netikrojo eglinio

skydamario pažeistuose medynuose. 5. Įvertinti netikrojo eglinio skydamario daromą žalą paprastajai eglei.

Darbo aktualumas Pastaraisiais metais miškininkams didelį rūpestį kelia ankščiau retai pastebėtas ir

Lietuvoje didelės žalos nedaręs kenkėjas – netikrasis eglinis skydamaris (Physokermes piceae). Jis iki šiol gausiau išplisdavo tik ant eglių, augančių parkuose ar kitose dekoratyviosiose miestų zonose. Paprastosios eglės medynus pažeisdavo retai, todėl ūkinės žalos šalies miškams jie nedarė iki 2009 metų. 2008 metais susiklosčius palankioms gamtinėms sąlygoms gausėti šiam eglių kenkėjui, 2009 metais netikrojo eglinio skydamario masinio išplitimo židiniai susiformavo 174 ha plote.

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2010 metais eglynuose skydamario pažeidimai dar labiau išplito. Naujai apniktų eglynų atsirado 7652 ha plote 39 miškų urėdijose. Įvairių rūšių sanitariniais kirtimais likviduota 997 ha skydamario židinių. 258 ha iš jų iškirsta plynais sanitariniais kirtimais. Dauguma iš šių medynų nebuvo pasiekę kirtimo amžiaus. Dėl netikrojo eglinio skydamario pažeidimų buvo stabdomas eglynų įveisimas buvusiuose skydamario židiniuose, čia sodinami lapuočiai arba spygliuočiai su lapuočių medžių rūšių priemaiša. Dažnai kirtavietės buvo paliekamos natūraliai atsikurti.

Po 2010 metų šaltos žiemos labai išryškėjo minėto kenkėjo daroma žala, nes skydamario maitinimosi vietose spygliai padengiami lipčiumi, ant kurio vėliau išplinta suodligę sukeliantys grybai, stabdantys medžio fotosintezės ir kvėpavimo procesus. Todėl eglės nepasiruošia žiemai ir kenčia nuo taip vadinamos žiemos sausros, kai medžiui pritrūksta drėgmės garinti. Taip pat sumažėja medžių ūglių prieaugis ir sutrumpėja kitų metų spygliai, medžiai netenka dalies prieaugio į skersmenį.

Skydamarių pažeisti bręstantys ir vyresni eglynai įgauna tamsesnę spalvą (dėl suodligę sukeliančių grybų veiklos): pirma laiko krenta spygliai, retėja lajos, medžiai skursta, pasižymi mažu prieaugiu, džiūsta viršūnės. Nusilpusius medžius užpuola pavojingi spygliuočių medžių liemenų kenkėjai. Netikrasis eglinis skydamaris pavojingas dar ir tuo, kad pagal amžių eglaičių nesirenka, gali kenkti tiek jaunuolynams, tiek ir brandiems medynams. Tačiau niekur neminimi duomenys apie kenkėjų pažeistų eglynų rūšinę sudėtį, pažeistų medynų skalsumą, augavietės tipą. Skydamarių pažeistų medynų dirvožemio savybės plačiau nagrinėtos tik Latvijos mokslininkų, o kitose šalyse į tai atsižvelgta nebuvo.

Iki šiol informacija apie netikrojo eglinio skydamario paplitimą ir pažeidimus Baltijos šalyse yra labai ribota. Yra tik keletas mokslinių publikacijų, kuriose aptariama šio kenkėjo daroma žala eglynams. Kadangi ir Lietuvoje netikrasis eglinis skydamaris pradėjo plisti tik pastaraisiais metais, todėl mūsų šalyje nėra tyrinėta šio kenkėjo žala paprastosios eglės spyglių bei ūglių augimui ir radialiojo prieaugio sumažėjimui. Taip pat iki šiol nėra atliktų darbų, apimančių netikrojo eglinio skydamario ir jo santykių su grybais nustatymą. Tyrimas aktualūs ypač šiuo laikotarpiu, kai dėl klimato kaitos galima tikėtis dažnesnių ir stipresnių naujų medžių kenkėjų invazijų.

Darbo mokslinis naujumas Vieni pirmųjų netikrojo eglinio skydamario (Physokermes piceae Schrank.) biologijos,

fenologijos ir šio kenkėjo entomofagų tyrimai atlikti Vokietijoje dar 1956 metais (Schmutterer et al., 1956). Kenkėjams pradėjus daryti didesnę žalą medynams, tyrimai atlikti ir kitose Europos šalyse. Lietuvoje šie tyrimai yra nauji: pirmą kartą sudaryta Lietuvos klimato sąlygoms tinkanti netikrojo eglinio skydamario fenologinė lentelė ir nustatyta dalis skydamarius parazituojančių vabzdžių.

Nors daugelyje Europos šalių kenkėjo padaryta žala eglynams didelė (šie buvo iškirsti sanitariniais kirtimais), tačiau nėra daug duomenų apie likusiems gyvybingiems medžiams padarytą žalą. Dėl kenkėjų daromos žalos vizualiai matomi eglių spyglių ir ūglių pakitimai einamaisiais metais, tačiau iki šiol tyrimai yra atlikti tik Švedijos mokslininkų, analizuojant medžių radialiojo prieaugio sumažėjimą vengrinio skydamario (Physokermes inopinatus) pažeistiems medžiams. Šio

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darbo metu atlikti išsamūs paprastosios eglės asimiliacinio aparato masės praradimo tyrimai yra nauji ne tik Lietuvoje, bet ir visoje Europoje.

Netikrasis eglinis skydamaris įvairiais savo gyvenimo tarpsniais maitinasi skirtingose paprastosios eglės lajos dalyse. Skydamario lervos visu vasaros laikotarpiu minta prikibusios prie eglių spyglių, taip atverdamas žaizdas, per kurias į augalą gali patekti ligų sukėlėjai. Skydamario patelės intensyviausiu medžių augimo periodu – pavasarį, maitinasi siurbdamos iš augalo maisto medžiagas ir išskirdamos saldžias į medų panašias išskyras – lipčių. Esant dideliems išskiriamo lipčiaus kiekiams, ant jo pradeda augti suodligę sukeliančios grybų rūšys, dažnai vadinamos bendru terminu – suodligė (ang. Sooty mould). Išsamesni grybų įvairovės, sutinkamos netikrojo eglinio skydamario židiniuose, tyrimai iki šiol nebuvo atlikti. Šio tyrimo metu gauti rezultatai leido įvertinti grybų rūšių įvairovę, pastebimą ant skydamarių pažeistų medžių spyglių ir ūglių.

Nors yra žinoma, kad netikrasis eglinis skydamaris dažniausiai pasirenka įvairaus amžiaus pelkiniuose nusausintuose miško dirvožemiuose augančius eglynus, tačiau nenagrinėti skydamario apniktų eglynų rūšinės sudėties, skalsumo, augavietės derlingumo rodikliai. Nustatyti skirtinguose miško augaviečių tipuose pažeistų eglynų taksaciniai rodikliai. Šio tyrimo metu tirta dalis 2010 m. Lietuvoje skydamarių pažeistų medynų leido tiksliai nustatyti, kurie medynai, susiklosčius sąlygoms, gali būti pažeisti šių kenkėjų.

Ginamieji teiginiai 1. Netikrasis eglinis skydamaris Lietuvoje turi natūralių priešų, kurių pakankamas

gausumas efektyviai reguliuoja netikrojo eglinio skydamario populiaciją. 2. Netikrasis eglinis skydamaris (Physokermes piceae) dažniausiai pažeidžia grynus

eglės medynus, augančius sausose ir mažo derlingumo augavietėse. 3. Netikrojo eglinio skydamario (Physokermes piceae) veikla ir jo išskiriamas lipčius,

sudaro palankias sąlygas plisti patogeniniams grybams paprastosios eglės (Picea abies) spygliuose ir ūgliuose.

4. Kompleksinė netikrojo eglinio skydamario ir suodligę sukeliančių grybų veikla daro neigiamą įtaką paprastosios eglės medžių sanitarinei būklei ir radialiajam prieaugiui, sukelia asimiliacinio aparato praradimą.

Disertacinio darbo aprobavimas Disertacijos tema parengti 2 moksliniai straipsniai. Šios mokslinės publikacijos

paskelbtos žurnaluose su citavimo indeksu (Impact Factor, Thomson Reuters Web of Knowledge). Darbas pristatytas 2-ose tarptautinėse konferencijose.

Disertacijos apimtis ir struktūra Disertaciją sudaro įvadas, literatūros analizė, darbo metodika, tyrimų rezultatų ir

jų aptarimo skyriai, išvados, literatūros sąrašas ir disertacijos tema paskelbtų mokslinių publikacijų sąrašas. Darbo rezultatai išdėstyti 6 skyriuose. Literatūros sąraše 184 šaltiniai. Disertacijos apimtis 88 puslapiai, tekstą iliustruoja 14 lentelių ir 37 paveikslai. Disertacijos pabaigoje pateikiami 2 priedai.

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IŠVADOS

1. Pirmą kartą Lietuvos klimato sąlygomis buvo nustatyta netikrojo eglinio skydamario

(Physokermes piceae) fenologija, patikslinta kenkėjo rūšis, morfologija ir biologija.

Nustatyta, kad netikrojo eglinio skydamario patelių vystymosi periodas sutampa su

paprastosios eglės pumpurų sprogimo pradžia, o patelės savo maksimalius kūno

parametrus pasiekia birželio mėn. viduryje. Skydamario patelių ir lervų vystymosi

ciklas ir jų morfologija Lietuvoje reikšmingai nesiskiria nuo kitose šalyse aptinkamų

šios rūšies skydamarių.

2. Tyrimo metu nustatytos dvi netikrojo eglinio skydamario populiacijos gausumui

reikšmingos entomofagų rūšys: parazitinis plėviasparnis Aphycoides physokermis Gir.

(Hymenoptera: Encyrtidae) ir grobuoniškas entomofagas Anthribus nebulosus F.

(Coleoptera: Anthribidae). Šių entomofagų sunaikintų netikrojo eglinio skydamario

dėčių kiekis medyne svyravo nuo 11 % iki 40 %, todėl esant pakankamai entomofagų

gausai, jie gali efektyviai reguliuoti kenkėjų populiaciją.

3. Netikrojo eglinio skydamario vystymuisi tinkamiausi gryni eglių jaunuolynai (iki 40 m.)

ir bręstantys (51-70) eglės medynai, augantys būdingiausiuose jiems miško tipuose:

mėlyniniame (myrtillosa) ir mėlyniniame kiškiakopūstiniame (mirtilio-oxalidosum).

4. Tyrimo metu nustatyta, kad grybų rūšių įvairovė ant netikrojo eglinio skydamario

židiniuose augančių eglių spyglių ir ūglių buvo didesnė, nei nepažeistuose

(kontroliniuose) medynuose. Patogeninis grybas R. Kalkhoffii buvo nustatytas visose

tyrimo teritorijose, o grybų Phialophora sessilis, Aureobasidium pullulans, Exobasidium

bisporum buvo gausiau skydamarių pažeistuose, nei kontroliniuose eglės medynuose.

5. Nustatyta, kad skydamarių pažeistuose bręstančiuose ir jaunuolynų amžiaus eglynuose

didžiausia dalis eglių buvo apsilpusios ir priklausė II pažeidimo kategorijai. Tirtų

eglės jaunuolynų būklė buvo geresnė, nei bręstančių medynų, kuriuose lajų defoliacija

buvo apie 1,5 karto didesnė.

6. Eglių metinių ūglių pakitimai labiausiai buvo pastebimi vidutiniškai ir stipriai

netikrojo eglinio skydamario ir suodligę sukeliančių grybų pažeistiems medžiams. Jų

ūgliai sutrumpėjo iki 1,5 karto. Stipriai pažeistuose medynuose pastebėtas ir ryškus

eglės spyglių svorio pakitimas. Lyginant su prieš kenkimą buvusių metų spygliais, jis

buvo 1,7-4,5 karto mažesnis. Nustatyta tiesioginė spyglių masės ir ūglių ilgio

tarpusavio priklausomybė, kuri parodė, kad didėjant ūglių ilgiui, didėja ir spyglių

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masė. Vidutinis ir stiprus koreliacinis ryšys užfiksuotas stipriai skydamario

pažeistuose ir sąlyginai sveikuose eglynuose.

7. Dėl netikrojo eglinio skydamario ir suodligę sukeliančių grybų veiklos, nustatytas

medžių radialiojo prieaugio sumažėjimas. Nustatyta, kad 56 % tyrimams parinktų

pažeistų eglės jaunuolynų radialusis prieaugis buvo statistiškai patikimai (P < 0,05)

mažesnis nei kontrolinių medynų. Labiausiai pažeidimai išryškėjo Vidurio ir Vakarų

Lietuvos regionuose. Eglių jaunuolynai neteko iki 40 % prieaugio į skersmenį. Tačiau

netikrojo eglinio skydamario ir suodligę sukeliančių grybų poveikis radialiajam

prieaugiui nebuvo ilgalaikis ir medžiai atsistatė per dvejus metus po kenkimo.

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ACKNOWLEDGEMENT I am sincerely thankful to my scientific supervisor Prof. Dr. Habil. Rimantas

Rakauskas for the leadership in scientific work, valuable ideas and advices in planning and conducting the research. In addition, I would like to thank to Dr. Artūras Gedminas and Dr. Audrius Menkis for their assistance in experimental studies, advices, gained knowledge and experience.

I am sincerely thankful to Dr. Jekaterina Havelka for the assistance in molecular studies and in received data analysis. I am also grateful to the colleagues at the Department of Forest Protection and Game Management of the LRCAF Forest Research Institute for all the assistance and good working environment.

I am sincerely thankful to my family, my wife and son, and parents for your support and patience.

In addition, the research was financially supported by the Global Ggrant (Grant

Agreement No. VP1-3.1-ŠMM-07-K) and by the Research Council of Lithuania (Grant Agreement No. MIP-035/2012).

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Netikrojo eglinio skydamario (Physokermes piceae Schrank.) biologija ir reikšmė paprastosios eglės (Picea abies (L.) H. Karst.) būklei Lietuvoje

Adas Marčiulynas

Daktaro disertacijos santrauka

SL 399. 2016 01 28. Sp. l. 2,25. Tiražas 50. Užsakymo Nr. 2. Leido ir spausdino ASU Leidybos centras – 2016. Studentų g. 11, 53361 Akademija, Kauno r.