Glavendekić & Mihajlović: Exposure of noctuid and geometrid development stages in oak forests
EXPOSURE OF NOCTUID AND GEOMETRID DEVELOPMENT STAGES IN OAK FORESTS
Milka M. Glavendekić, Ljubodrag S. Mihajlović
Faculty of Forestry University of Belgrade, Kneza Višeslava 1, 11030 Belgrade, Serbia (e-mail: [email protected])
Abstract The research was carried out in the period 1985-2005 in oak forests in Serbia. During the research of winter moths in oak forests of Serbia we recorded 9 outbreaking winter moth species: Colotois pennaria L., Agriopis aurantiaria Hbn., Erannis defoliaria Cl., Alsophila aescularia D.& Sch., A. aceraria D.& Sch., Operophtera brumata L., Apocheima pilosaria D.& Sch., Agriopis leucophaearia D.& Sch., A. marginaria F. The most significant noctuids are Orthosia spp. There are 38 parasitoids of the winter moths recorded and they fall into the families Braconidae, Ichneumonidae, Eulophidae, Torymidae, Trichogrammatidae, Scelionidae and Tachinidae. Egg parasitoids were recorded at 3 localities: Brankovac, Mala Moštanica and wide area of National Park Djerdap. Hyperparasitoids of winter moths in Serbia have also been studied. We recorded altogether 12 species of winter moth hyperparasitoids. The method of exposure was applied in egg and larva stages. While total parasitism in the natural population varies between 12.50-28.57 %, in the exposed conditions there were between 27.31-43.75 % parasitized caterpillars were recorded. The method of host exposure could be suitable for the local increase of abundance of parasitoids of winter moth eggs, larvae and pupae.
Keywords: Defoliators, oak, Geometridae, Noctuidae
1. Introduction
In Serbia forests cover about 2,313,000 ha, or 26.2 % of the whole territory. They are managed by the State Enterprises for Forest Management, PE “Srbijašume” and PE “Vojvodinašume”. The average standing volume is 101.6 m3/ha. The average annual increment is 2.70 3 /ha and total annual increment 6.18 million m3.
Forests are mainly state and socially owned. The state owns 1.38 million ha (56.2 %) of forest area. Under private ownership is 1.17 million ha (43.8 %) of Serbian forests. The average size of private forest holdings is about 0.5 ha (Glavonjic et al., 2005). As for the stand composition, according to the Ministry of Agriculture, Forestry and Water Management, pure deciduous stands are dominant (60%). Mixed deciduous stands occupy 30%, pure coniferous stands 5%, mixed deciduous-coniferous stands 3% and mixed coniferous stands 2%. There are the following forest complexes in Serbia: alluvial hygrophilous forests (0.11%), xerothermophilous Hungarian oak-Turkey oak forests (15.41%), xeromesophilous sessile oak- Turkey oak-hornbeam forests (12.49%), mesophilous beech forests and beech coniferous forests (52.58%) and thermophilous pine forests (12.92%). Beech is the main broadleaf species (47%) followed by oak (25%), poplar (1%), other broadleaves (16%), spruces (5%), pines (2%), fir (3%) and other conifers (1%).
Damage in forests can be caused by fire. It varies from year to year. In 1990 almost 60% of damages were caused by fire. In 2000, 300 fires occurred and damaged 4,000 ha of forest. In
IUFRO Working Party 7.03.10 Proceedings of the Workshop 2006, Gmunden/Austria 126 Glavendekić & Mihajlović: Exposure of noctuid and geometrid development stages in oak forests
1997 up to 40 % of damage in forests was caused by insects and diseases. The most severe dieback was recorded in oak forests 1983-1994. They were caused due to cumulative defoliations caused by insects and synchronous attack of pathogens and vascular fungi.
More than 121 species of insects were identified as trophically related to oak (Quercus petraea (Matt.) Lieblein, Q. cerris L. and Q. frainetto Tenore) forests in the region of NP Đerdap. They belong to the orders Homoptera, Coleoptera, Diptera, Lepidoptera and Hymenoptera. The insects feed on or spend a part of their lives on the foliage, branches, in the stem, buds or proliferations of plant tissues that they cause themselves. The consequences of the damage are mostly insignificant for forest ecosystems and without an economic significance (53.33%). Somewhat more than 1/3 of insects are occasionally harmful (36.67%) and outbreaking, economically significant and dangerous insect pests in oak forests account for 10% of the identified species of phytophagous insects.
The most important insect pests in oak stands are defoliators: Lymantria dispar L. (Lepidoptera: Lymantriidae), Tortrix viridana L., Aleimma loeflingiana L. (Lepidoptera: Tortricidae), Orthosia spp. (Lepidoptera: Noctuidae), Colotois pennaria L., Agriopis spp.., Erannis defoliaria Cl. Alsophila spp., Operophtera brumata L. and Apocheima spp. (Lepidoptera: Geometridae) (Glavendekić, 2002). The research on oak defoliators was carried out in the period 1987-2006 in oak forests in Serbia (Mihajlović & Glavendekić, 2006). The task of the research was to investigate qualitative composition of the winter moths: Colotois pennaria, Alsophila aceraria, A. aescularia, Agriopis aurantiaria, A. leucophaearia, A. marginaria, Operophtera brumata, Apocheima pilosaria, Erannis defoliaria (Lepidoptera: Geometridae) and noctuids: Orthosia cruda, O. incerta, O. munda, O. s tabilis, O. miniosa (Lepidoptera, Noctuidae). Their biology, population dynamics and natural enemies - especially parasitoids were studied.
2. Material and methods
Investigations were done at the following sample plots at the localities: Brankovac (National Park Fruška Gora), Košutnjak, Mala Moštanica (Forest Estate Belgrade) and National Park Djerdap from 1985-2005. In addition to permanent sample plots, the study region was extended to several localities with different oak stands and ecological conditions, in order to obtain the most complete data on the winter moth population dynamics and on the complex of their parasitoids in Serbia. The method of exposure in nature was applied to eggs and larvae either by exposing the masses of eggs reared in the laboratory or by using sticky bands at the time of female activity. Females laid egg masses in bark crevices below sticky bands. The parts of the bark with eggs were cut and the samples were taken to the laboratory for rearing and processing. Sticky bands were also used for larval exposure in April and May. Sticky bands were placed at breast height, width 80-100 mm. During their return to the crown, the larvae aggregated on the stem and thus the exposure effect was achieved. The caterpillars at different stages were collected, packed in plastic bags or boxes with ventilation net and brought to the laboratory for individual rearing.
IUFRO Working Party 7.03.10 Proceedings of the Workshop 2006, Gmunden/Austria 127 Glavendekić & Mihajlović: Exposure of noctuid and geometrid development stages in oak forests
3. Results
3.1 Parasitoids of the winter moths and noctuids
There are 42 parasitoids recorded (Braconidae, Ichneumonidae, Eulophidae, Torymidae, Trichogrammatidae, Scelionidae and Tachinidae). The following egg, larval and pupal parasitoids were recorded in Serbia: Aleiodes gastritor (Thunb. 1822), Acampsis alternipes Brulle, 1846, Apanteles enephes Nixon, 1965, Protapanteles immunis Hal.,1834, Protapanteles sp., Cotesia hyphantriae Riley, 1886, Cotesia limbata Marshall, 1885, Cotesia jucunda Marshall, 1885, Cotesia spuria Wesmael, 1837, Cotesia congestus (Nees, 1834), Apanteles sp. (sensu lato) (Hymenoptera: Braconidae). Itoplectis alternans Grav., 1829, Netelia (B.) latungula Thom.1888, Aptesis jejunator Grav., 1807, Casinaria ischnogaster Thom. 1887, Casinaria moesta Grav., 1829, Phobocampe crassiuscula Grav.,1829, Phobocampe pulchella Thom., 1887, Phobocampe sp. 1, Phobocampe sp.2, Phobocampe sp.3, Ophion minutus Kriechb., 1879, Ophion ventricosus Grav., 1829, Agrypon flaveolatum Grav., 1807 (Hymenoptera, Ichneumonidae); Torymus sp., (Hymenoptera: Torymidae), Euplectrus bicolor (Swe., 1795), Eulophus larvarum (L., 1758) (Hymenoptera: Eulophidae), Trichogramma sp. (Hymenoptera: Trichogrammatidae), Telenomus minutus Ratz., Telenomus ? dalmanni Ratz., 1844 (Hymenoptera: Scelionidae), Phorocera obscura Fallén, 1810, Blondelia nigripes Fall., 1810, Compsilura conncinnata Meig., 1824, Phryxe magnicornis Zett., 1838, Phryxe nemea Meig., 1824, Phryxe vulgaris Fall., 1810, Peribaea apicalis R. – D., 1863, Peribaea fissicornis Str. 1909 (Diptera: Trichogrammatidae). Parasitoids of Noctuidae in Serbia are: Macrocentrus abdominalis F., Cotesia spuria Wesmael, Meteorus versicolor, M. scutellator Nees (Hymneoptera, Ichneumonidae), Phobocampe pulchella Thoms. (Hymenoptera, Ichneumonidae), Perilampus ruficornis (Hymenoptera, Perilampidae); Compsilura concinnata Mg., Blondelia nigripes Fall. (Diptera: Tachinidae).
3.2 Hyperparasitoids of the winter moths and noctuids
The following hyperparasitoids of the winter moths are recorded in Serbia: Acrolyta rufocincta Gravenhorst, 1829, Gelis areator Panzer, 1804, Gelis sp, Bathythrix lamina Thomson, 1884, Astiphromma sp., Mesochorus sp., Brachymeria secundaria Ruschka,1922, Perilampus ruficornis (Fabricius, 1793), Habrocytus chrysos Walker, 1836, Tetrastichus sp., Pediobius foliorum Geoffroy in Fourcroy, 1785 and Pediobius sp. Fore some hyperparasitoids, winter moths have not been previously recorded as hosts: Acrolyta rufocincta Grav., Brachymeria secundaria Ruschka, Habrocytus chrysos Walk., Tetrastichus sp. Populations of parasitoids and hyperparasitoids were monitored in the culmination and in the post culmination phases in managed forests. The larva of hyperparasitoid hatches in the host but its development depends on a larva of the primary parasitoid. If host larva or pupa is not parasitized by primary parasitoids, hyperparasitoid cannot survive; it remains at the level of the first instar larva. Hyperparasitoids fly before primary parasitoids. The efficacy of hyperparasitoids (coincidence with primary parasitoid larva) was low compared to their frequency. In the phases of retrogradation and latency, the coincidence was even lower.
3. 3. Larval parasitism of the winter moths in natural population
It was found that parasitism in natural population varied from 12.50 - 28.57 %. It depends on the local circumstances and the phase of outbreak. Hyperparasitism in natural populations
IUFRO Working Party 7.03.10 Proceedings of the Workshop 2006, Gmunden/Austria 128 Glavendekić & Mihajlović: Exposure of noctuid and geometrid development stages in oak forests also varied from 10.34 - 68.75% It was estimated that the coincidence of parasitoids and hyperparasitoids was relatively low 8.70 - 14.28 %. The highest level of parasitism and coincidence of parasitoids and hyperparasitoids was at the end of the second decade of April. The highest level of hyperparasitism was recorded at the end of the third decade of April. It could be suggested that control measures timing should be so estimated as to avoid the period when parasitoids are at the highest activity.
3. 4. Larval parasitism of the winter moths on exposed populations
Larval parasitism in exposed population varied from 27.31 - 43.75 %. At the same plots, hyperparasitism varied very strongly (38.46 - 93.75 %). Although population of hyperparasitoids reached a very high level, their coincidence with parasitoids remained relatively low (9.09 - 31.25). The highest level of parasitism, hyperparasitism and their coincidence was at the end of the third decade of April. Results of t-test (LSD), for the differences in the time of sampling, T-test proves that there is no statistically significant difference in the percentage of parasitism between the samples collected on 5th May and 29th April (risk 0.05). There is a statistically significant difference between the parasitism recorded in the sample collected on 15th May and the preceding two sampling times. This is due to the composition of parasitoids. On 15th May, the mature winter moths’ larvae were parasited by tachinides. As it was the culmination phase of gradation, their population was very high. Absolute parasitism of exposed caterpillars and pupae was recorded at Brankovac (NP Fruska Gora), in the first postculmination year, 64.51% were parasitized. At this locality the investigation was done in the postculmination phase. The hyperparasitoid larvae were present in 12.90 % of dissected hosts. The coincidence of parasitoids and hyperparasitoids occurred only in 9.68 %. In the field conditions (no control measures, locality Kožica, NP Djerdap) relationship parasitoid-hyperparasitoid was investigated in the post-culmination phase. There were 68.97% of mature larvae parasitised (primary parasitoid). The presence of hyperparasitoids in larval population was only 6.9%. The coincidence of parasitoids and hyperparasitoids was 3.45%. In the following year, relative abundance of the host decreased by half, but the percentage of parasitism remained high – 37.5%. Hyperparasitoids were recorded in 15.63% of larvae and all of them coincided with primary parasitoids.
3.5. Egg parasitism
By renewing the sticky belts in the autumn and in spring, the females were prevented from going to the crown, so they laid their eggs below the belt. Egg parasitoid T. minutus was identified at the locality Miroč, (East Serbia). Total parasitism of the winter moth eggs was 43.51%. There were eggs of O. brumata under highest parasitism (30.00 %). Only 8.11% of E. defoliaria were parasitized. The lowest egg parasitism was recorded on A. aurantiaria (5.4%). Parasitised eggs should be distinguished by brown coloration when they are parasitized by T. minutus. Absolute egg parasitism in the exposed conditions was 90% (NP Djerdap). In the N P Djerdap, the wasps Trichogramma sp. (Hymenoptera: Trichogrammatidae) were reared from the winter moth eggs. Parasitised eggs are distinguished by their dark brown colour. The winter moth egg parasitism varied from 16.33% at Boljetinska Reka, compartment 44, to 33.95% at Zlatica, compartment 96. Absolute egg parasitism in the natural conditions was 44%. At Zlatica, compartment 59, the total mortality of eggs was 58.49%; in compartment 96 altogether 44.65%.
In the investigated area, there was achieved latency of geometrid and noctuid defoliators for more than 15 years. During the last two years, it was found that oak defoliator etiology was
IUFRO Working Party 7.03.10 Proceedings of the Workshop 2006, Gmunden/Austria 129 Glavendekić & Mihajlović: Exposure of noctuid and geometrid development stages in oak forests changing (Glavendekic, 2005). Fifteen years ago, there were pure outbreaks of gypsy moth, whereas spring defoliators (Tortricidae, Geometridae and Noctuidae) used to outbreak together, but separately from gypsy moth. In spring 2006, in the same forests (east Serbia), spring defoliators caused defoliation in April-May and gypsy moth also over populated. The forest ecosystem was threatened from two severe defoliations.
4. Discussion and conclusion
Insect defoliators are of the highest economic importance in oak forests in Serbia. Nine species of the winter moths and 5 noctuids are among the most significant oak defoliators. The method of exposure was applied in the stages of egg and larva with satisfactory results. It is useful for monitoring of parasitoids, especially the winter moths egg parasitoids. While the total parasitism in the natural population rarely exceeded 20%, in the exposed population the percentage of parasitised caterpillars was more than 60%. The method of host exposure is suitable for the local upswing of larval and pupal parasitoid abundance. The method of statistical analysis of natural populations of winter moths and the populations of exposed winter moths shows that there is no correlation between the increase of parasitoid abundance in the exposed population and hyperparasitoids. Recently recorded changes in the qualitative composition of oak defoliators could increase the hazard for oak ecosystems.
5. Acknowledgements
Recent investigations were done with the support from the Ministry of Agriculture, Forestry and Water Management of Serbia.
6. References
GLAVONJIĆ B, & JOVIĆ B. & VASILJEVIĆ A. & KANKARAS R. 2005: Forest and Forest Products Country Profile: Serbia and Montenegro. Geneva Rimber and Forest Discussion Papers 40. United Nations, Geneva, 90 pp (in English) GLAVENDEKIĆ M. 2002: The Winter Moths (Lepidoptera: Geometridae) in Oak Forests in Serbia. Andrejević Endowment, pp.130, Belgrad GLAVENDEKIĆ M., 2005: The role of Defoliators and soil born Pathogen Phytophthora quercina H.S. Jung in oak Dieback. Šumarstvo, 3: 97-106 (in Serbian, summary in English) MIHAJLOVIĆ L. & GLAVENDEKIĆ M. 2006: The most important entomological problems in suburban oak forests in Serbia. Šumarstvo, 3: 77-97 (in Serbian, summary in English).
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