Gypsy Moth Research Articles

Geographic variation in larval cold tolerance and exposure across the invasion front of a widely established forest insect.

Under global climate change, high and low temperature extremes can drive shifts in species distributions. Across the range of a species, thermal tolerance is based on acclimatization, plasticity, and may undergo selection, shaping resilience to temperature stress. In this study, we measured variation in cold temperature tolerance of early instar larvae of an invasive forest insect, Lymantria dispar dispar L. (Lepidoptera: Erebidae), using populations sourced from a range of climates within the current introduced range in the Eastern United States. We tested for population differences in chill coma recovery (CCR) by measuring recovery time following a period of exposure to a nonlethal cold temperature in 2 cold exposure experiments. A 3rd experiment quantified growth responses after CCR to evaluate sublethal effects. Our results indicate that cold tolerance is linked to regional climate, with individuals from populations sourced from colder climates recovering faster from chill coma. While this geographic gradient is seen in many species, detecting this pattern is notable for an introduced species founded from a single point-source introduction. We demonstrate that the cold temperatures used in our experiments occur in nature during cold spells after spring egg hatch, but impacts to growth and survival appear low. We expect that population differences in cold temperature performance manifest more from differences in temperature-dependent growth than acute exposure. Evaluating intraspecific variation in cold tolerance increases our understanding of the role of climatic gradients on the physiology of an invasive species, and contributes to tools for predicting further expansion.

Neuromuscular Anatomy and Motor Patterns at the Base of Calling Behaviour in the Female Spongy Moth Lymantria dispar.

"Calling behaviour" is a stereotyped rhythmic motor pattern displayed by female moths, by which they emit the sex pheromone to attract of conspecific males. Calling occurs through a squeezing mechanism based on the turtleneck-like folding and unfolding of the ovipositor cuticle during its telescopic extensions and retractions. This mechanism is under the control of the terminal abdominal ganglion (TAG). By combining anatomical and electrophysiological approaches, here we studied the morpho-functional organisation of the abdominal muscles and the activity of motoneurons from TAG nerve N4-N6 as correlated to the ovipositor movements during calling in the female spongy moth Lymantria dispar. Our results show that the three abdominal segments S7, S8 and S9 (ovipositor) are highly specialized structures containing cuticular appendages, hinges, apodemes and several large muscles, innervated by N4 and especially by N5. N6 mainly innervates the oviductal tract. We also identified a number of motor units from N4 and N5, the spike activity of which is correlated with the ovipositor movements during calling. In conclusion, the release of sex pheromones in the female spongy moth is obtained by extensions and retractions of the ovipositor operated by a coordinated motor program, which is mainly sustained by the activity of a few motor units under the control of TAG nerves N4 and N5.

Draft Genome Sequencing of the Bacillus thuringiensis var. Thuringiensis Highly Insecticidal Strain 800/15

The Bacillus thuringiensis serovar thuringiensis strain 800/15 has been actively used as an agent in biopreparations with high insecticidal activity against the larvae of the Colorado potato beetle Leptinotarsa decemlineata and gypsy moth Lymantria dispar. In the current study, we present the first draft genome of the 800/15 strain coupled with a comparative genomic analysis of its closest reference strains. The raw sequence data were obtained by Illumina technology on the HiSeq X platform and de novo assembled with the SPAdes v3.15.4 software. The genome reached 6,524,663 bp. in size and carried 6771 coding sequences, 3 of which represented loci encoding insecticidal toxins, namely, Spp1Aa1, Cry1Ab9, and Cry1Ba8 active against the orders Lepidoptera, Blattodea, Hemiptera, Diptera, and Coleoptera. We also revealed the biosynthetic gene clusters responsible for the synthesis of secondary metabolites, including fengycin, bacillibactin, and petrobactin with predicted antibacterial, fungicidal, and growth-promoting properties. Further comparative genomics suggested the strain is not enriched with genes linked with biological activities implying that agriculturally important properties rely more on the composition of loci rather than their abundance. The obtained genomic sequence of the strain with the experimental metadata could facilitate the computational prediction of bacterial isolates’ potency from genomic data.

Feasting on the ordinary or starving for the exceptional in a warming climate: Phenological synchrony between spongy moth (Lymantria dispar) and budburst of six European tree species.

Global warming is affecting the phenological cycles of plants and animals, altering the complex synchronization that has co-evolved over thousands of years between interacting species and trophic levels. Here, we examined how warmer winter conditions affect the timing of budburst in six common European trees and the hatching of a generalist leaf-feeding insect, the spongy moth Lymantria dispar, whose fitness depends on the synchrony between egg hatch and leaf emergence of the host tree. We applied four different temperature treatments to L. dispar eggs and twig cuttings, that mimicked warmer winters and reduced chilling temperatures that are necessary for insect diapause and bud dormancy release, using heated open-top chambers (ambient or +3.5°C), and heated greenhouses (maintained at >6°C or >10°C). In addition, we conducted preference and performance tests to determine which tree species the larvae prefer and benefit from the most. Budburst success and twig survival were highest for all tree species at ambient temperature conditions, whereas it declined under elevated winter temperature for Tilia cordata and Acer pseudoplatanus, likely due to a lack of chilling. While L. dispar egg hatch coincided with budburst in most tree species within 10 days under ambient conditions, it coincided with budburst only in Quercus robur, Carpinus betulus, and, to a lesser extent, Ulmus glabra under warmer conditions. With further warming, we, therefore, expect an increasing mismatch in trees with high chilling requirements, such as Fagus sylvatica and A. pseudoplatanus, but still good synchronization with trees having low chilling requirements, such as Q. robur and C. betulus. Surprisingly, first instar larvae preferred and gained weight faster when fed with leaves of F. sylvatica, while Q. robur ranked second. Our results suggest that spongy moth outbreaks are likely to persist in oak and hornbeam forests in western and central Europe.

Host-specific growth responses of Larix kaempferi and Quercus acutissima to Asian gypsy moth defoliation in central Korea

As the risk of gypsy moth outbreaks that have detrimental effects on forest ecosystem in the Northern Hemisphere increase due to climate change, a quantitative evaluation of the impact of gypsy moth defoliation is needed to support the adaptive forest management. To evaluate the host-specific impact of gypsy moth defoliation, radial growth and annual carbon accumulation were compared for one severely defoliated (Larix kaempferi (Lamb.) Carrière) and one moderate defoliated (Quercus acutissima Carruth.) host, in defoliated and non-defoliated site using tree-ring analysis. Finally, the resilience indices of radial growth variables were calculated to assess the ability of sampled trees to withstand defoliation. Gypsy moth defoliation mainly decreased latewood width and caused reduction in annual carbon absorption more than 40% for both tree species. However, L. kaempferi, showed the reduced growth until the year following defoliation, while Q. acutissima, showed no lagged growth depression and rapid growth recover. The findings show how each species reacts differently to gypsy moth defoliation and highlight the need of managing forests in a way that takes resilient tree species into account.

CncC-Keap1-P450s pathway is involved in the detoxification of emamectin benzoate in the spongy moth Lymantria dispar

The detoxification of insecticides in insects is dependent on the expression and activity of multiple detoxification enzymes. As an important modulator of detoxification enzymes, the CncC-Keap1 pathway was involved in the detoxification of various pesticides. However, whether the CncC-Keap1 pathway is involved in the detoxification of emamectin benzoate (EMB) is unclear. In this study, we cloned the LdCncC and LdKeap1 from spongy moths (Lymantria dispar). Our results showed that EMB exposure induced oxidative stress, and activated the CncC-Keap1 pathway at mRNA and protein levels. Removing ROS by N-acetylcysteine remarkably decreased H2O2 levels and restored the expression of LdCncC and LdKeap1. The silencing LdCncC, not LdKeap1, by dsRNA significantly decreased the cytochrome P450 activities, and increased the sensitivity of larvae to EMB. Besides, the expression of CYP6B7v1, CYP321A7 and CYP4S4v1 were significantly decreased after silencing LdCncC. Notably, the knockdown of CYP6B7v1, CYP321A7 or CYP4S4v1 significantly increased the mortality induced by EMB exposure. Therefore, we proposed that activation of CncC-Keap1 pathway induced by ROS increased the detoxification of EMB in spongy moths by regulating the expression of CYP6B7v1, CYP321A7 and CYP4S4v1. Our study strengthened the understanding of the detoxification of EMB from the perspective of CncC-Keap1-P450s pathway.

Chromosome-level genome assembly of the Asian spongy moths Lymantria dispar asiatica

The Asian spongy moth, Lymantria dispar asiatica, is one of the most devastating forestry defoliators. The absence of a high-quality genome limited the understanding of its adaptive evolution. Here, we conducted the first chromosome-level genome assembly of L. dispar asiatica using PacBio HIFI long reads, Hi-C sequencing reads and transcriptomic data. The total assembly size is 997.59 Mb, containing 32 chromosomes with a GC content of 38.91% and a scaffold N50 length of 35.42 Mb. The BUSCO assessment indicated a completeness estimate of 99.4% for this assembly. A total of 19,532 protein-coding genes was predicted. Our study provides a valuable genomics resource for studying the mechanisms of adaptive evolution and facilitate an efficient control of L. dispar asiatica.

Lepidopteran Pests of Apple Trees on the Territory of the City of Vanadzor

Key Words: Lori region, pomaceae, egg, caterpillar, pupa, imago Lepidopteran pests of apple trees in the Lori region have been documented in specialised literature; however, research on these pests in Vanadzor has not been done, despite the fact that many dangerous insects, including lepidoptera, flooded into private gardens in the city of Vanadzor after extensive clearing of orchards nearby. In this area, private farms suffer substantial damage from caterpillars. Additionally, some pests' caterpillars can induce allergic reactions, some of which can be very dangerous, when they come into contact with people's skin, particularly that of youngsters. The investigation of this matter is the focus of this work. As a result of our research, we identified 14 species of leafrollers of apple trees, which belong to the orders Lepidoptera, Coleoptera, Hemiptera and Homoptera. The greatest damage is caused by Apple ermine (Hypomoneuta malinellus Z.), Gypsy (spongy) moth (Lymantria dispar L.), Lackey moth (Malacosoma neustria L.), Brown-tail moth (Euproctis chrysorrhoea L.), Apple blossom weevil (Anthonomus pomorum L.), Tortrix moths especially Rose tortrix moth (Archips rosana L.), and Large fruit-tree tortrix (Archips podana L.). Entomophages have also been obtained, which belong to the families of Braconidae and the Ichneumonidae.

Climate change and human footprint increase insect defoliation across central boreal forests of Canada

Anthropogenic climate change is contributing to increased insect infestation globally, leading to pest population growth, expansion of niche and geographic ranges as well as increased outbreak frequencies, resulting in economic losses and reduction in food security. In recent years, spongy moth (Lymantria dispar dispar), jack pine budworm (Choristoneura pinus pinus), large aspen tortrix (Choristoneura conflictana) and spruce budworm (Choristoneura fumiferana) caused widespread defoliation across one of Canada’s most forested provinces, Ontario. Observations of such outbreaks have been limited to field sightings around Ontario, with few studies focused on mapping of outbreak occurrence across the province or exploring potential anthropogenic and climatic drivers of infestation. Using random forest probability estimates and satellite data resampled to 1 km spatial resolution from the Moderate Resolution Imaging Spectroradiometer (MODIS), we reveal greater expansion of insect defoliation across Ontario between 2018 and 2020 than previously recorded. Much of the geographic expansion of outbreaks was driven by increasing temperature, and the proximity of roads. With ongoing global warming and growing economic development, infestations will not only continue to increase across Ontario but also expand northward due to their responses to accelerated warming at higher latitudes. This expansion presents an important and alarming new challenge for forest conservation and management in Ontario, in particular, and Canada in general.

Growth response of oaks to insect defoliation: Immediate and intermediate perspectives

In this study, we investigate the immediate and short-term consequences of defoliation by the spongy moth Lymantria dispar on secondary growth of oaks (Quercus robur L. and Quercus petraea (Matt.) Liebl.), including the interplay between defoliation and water availability during the defoliation period within a large-scale field experiment in south-eastern Germany. Furthermore, the impact of defoliation on oak secondary growth is explored retrospectively based on tree core measurements.Within the large-scale filed experiment, secondary growth of 880 oaks in 44 oak-dominated stands was monitored using permanent girth tapes over a three-year period following a spongy moth outbreak. Insecticide treatments were applied to half of the plots to obtain trees without defoliation, and canopy cover dynamics were subsequently monitored ground based and from satellites in all plots.We found that moth defoliation significantly reduced oak secondary growth by 10–60% during the outbreak year, with the impact on secondary growth being directly proportional to defoliation intensity. The negative impact of defoliation on secondary growth was aggravated by increased water availability during the outbreak year.In the post-outbreak year, secondary growth of oaks that had endured mild defoliation was no longer different from that of non-defoliated oaks. In contrast, oaks that had experienced substantial defoliation still exhibited a significant 10–30% reduction in secondary growth. Regardless of defoliation intensity, no further reduction in secondary growth was detected two years after the event compared to control trees. Our complementary retrospective analysis, utilizing core samples from oaks previously subjected to a defoliation event under distinct weather conditions, disclosed a strikingly analogous recovery of secondary growth from defoliation instigated by the spongy moth. Thus, validating that our experimental findings possess broad temporal transferability.

АЛГЕБРАИЧЕСКИЙ АЛГОРИТМ СТАТИСТИЧЕСКОЙ ОЦЕНКИ ПАРАМЕТРА БИНОМИАЛЬНОГО РАСПРЕДЕЛЕНИЯ И ПРИМЕР ЕГО ПРИМЕНЕНИЯ В ОДНОЙ ГЛОБАЛЬНОЙ ГЕОИНФОРМАЦИОННОЙ ЗАДАЧЕ ПРИКЛАДНОЙ КЛИМАТОЛОГИИ

The binomial distribution is often used in modeling, including in applied climatology, when assessing the likelihood of adverse or dangerous climate-related impacts. The article outlines an algebraic algorithm for obtaining such estimates based on climate monitoring data or modeling data. Using only algebraic operations in calculations minimizes calculation time, which is important when performing detailed global assessments. As an example of such a calculation, the result of an assessment of the global climatic range of a dangerous insect pest of forest and garden trees and shrubs, the gypsy moth, is given.

Возможное влияние летне-осенних сумм эффективных температур на динамику плотности популяции непарного шелкопряда Lymantria dispar (L.) в лесных насаждениях на северной границе ареала

Практически одновременно в 2016 г., вдоль северной границы ареала непарного шелкопряда Lymantria dispar (L.) на огромном пространстве более 1000 км в долготном направлении от Екатеринбурга (56,5° с.ш., 60,4° в.д.) до п. Кыштовка (Новосибирская область), 56,4°с.ш., 76,6°в.д. на сотнях тысяч гектар сформировались очаги непарного шелкопряда. Такая синхронность в возникновении очагов может указывать на воздействие единого модифицирующего фактора. Цель исследования - выявление общего модифицирующего фактора, который мог спровоцировать вспышку массового размножения непарного шелкопряда на основании анализа погодных условий в вегетационные сезоны, предшествующие формированию очагов и в период вспышки. На значительной территории, охватывающей зауральскую и западносибирскую популяции, в их северной части сценарии изменения погодных условий перед и в ходе реализации вспышки 2016-2018 гг. существенно различались по условиям влажности, но были схожи по теплообеспеченности. Два-три года теплообеспеченность была значительно ниже нормы, затем наступил сезон с теплообеспеченностью значительно выше нормы и резким возрастанием плотности популяции, приведшей к значительной дефолиации насаждений на следующий год при возвращении теплообеспеченности вегетационного сезона к норме. Это указывает на то, что на севере ареала вида модифицирующие факторы, провоцирующие вспышки массового размножения, отличаются от таковых в южных его частях. Возможно, вегетационные сезоны с низкой теплообеспеченностью приводят как к элиминации потомства особей популяции с большой длительностью развития до имагинальной стадии, так и к сокращению длительности развития личиночной стадии особей, получивших необходимую, но крайне небольшую сумму летне-осенних температур для завершения раннеэмбрионального развития и подготовки к зимовке. При наступлении вегетационного сезона с теплообеспеченностью значительно выше нормы снижается элиминация потомства особей с большей длительностью развития, что приводит к росту плотности популяции и значительной дефолиации на следующий год. Almost simultaneously in 2016, along the northern border of the range of spongy moth Lymantria dispar (L.) over a huge area of more than 1000 km in the longitude direction from Yekaterinburg (N 56.5 °, E 60.4°) to the village of Kyshtovka(Novosibirsk region), (N 56.4°, E 76.6°) the outbreaks of the spongy moth have formed on hundreds of thousands of hectares. Such synchronicity in the occurrence of outbreaks can indicate the impact of a single modifying factor. The purpose of the study is to identify a single modifying factor that could provoke an outbreak of the spongy moth, based on an analysis of weather conditions in the growing seasons preceding the formation of outbreaks and during their implementation. Over the large area covering the Trans-Ural and West Siberian populations, in their northern part, the scenarios of weather conditions changes before and during the implementation of the outbreak of 2016-2018 differed significantly in terms of humidity conditions but were similar in terms of heat availability. For two or three years, the heat availability was significantly lower than normal, then become the season with heat availability significantly higher than normal and a sharp increase in population density that provide the severe defoliation of stands for the next year when the heat availability of the growing season returns to normal. That indicates the differences in modifying factors provoking outbreaks at the north of the range of the spongy moth in comparison with southern parts of the range of this species. Possibly, growing seasons with low heat availability lead both to the elimination of the offspring of individuals in the population with a long duration of development till the imaginal stage, and to a reduction in the duration of development at the larval stage of individuals that have received the necessary, but an extremely small amount of summer-autumn temperatures to complete early embryonic development and preparation for wintering. With the onset of the growing season with a heat availability significantly higher than normal, the elimination of individuals with a longer duration of development decreases, which results in the population density increase and significant defoliation in the next year.

Unveiling invasive insect threats to plant biodiversity: Leveraging eDNA metabarcoding and saturated salt trap solutions for biosurveillance.

The negative global impacts of invasive alien species (IAS) on biodiversity are second only to habitat loss. eDNA metabarcoding allows for a faster and more comprehensive evaluation of community species composition, with a higher taxonomic resolution and less taxonomic expertise required than traditional morphological-based biosurveillance. These advantages have positioned eDNA metabarcoding as the standard method for molecular-based detection of invasive alien species, where fast and accurate detectability allows prompt responses to mitigate their adverse effects. Here, eDNA metabarcoding is used for biosurveillance of invasive alien species regulated by Canada in high-risk areas with four main objectives: i) validate the effectiveness of eDNA metabarcoding of salt trap solutions as a molecular technique for IAS detection, ii) compare detection from DNA extracts obtained from filter quarters versus whole filters, iii) benchmark two different bioinformatic pipelines (MetaWorks and mBRAVE), and iv) compare canopy and ground level trapping. eDNA from up to five IAS (Agrilus planipennis, Daktulosphaira vitifoliae, Lymantria dispar, Popillia japonica, and Trichoferus campestris) were successfully detected across years from 2017 to 2022 in southern Ontario, Canada, with successful morphological validation for all except Lymantria dispar and Trichoferus campestris. Analysis of filter quarters in contrast to whole filters was demonstrated to be insufficient for effective IAS detection in each sample. All IAS were detected in only one filter quarter, suggesting a patchy eDNA distribution on the filter. The MetaWorks and mBRAVE bioinformatics pipelines proved effective in identifying IAS, with MetaWorks yielding a higher success rate when comparing molecular and morphological identifications. Ground-level and canopy-level sampling showed differential IAS recovery rates based on the molecular detection, which also varied per collection year, with all found IAS detected at the canopy level in 2022 while only one (Lymantria dispar) in 2020. The present study ratifies the efficacy and importance of eDNA-based detection in a regulatory context and the utility of adding eDNA metabarcoding of saturated salt trap solutions, a critical tool for IAS detection.

Insecticidal activity of three 10–12 nucleotides long antisense sequences from 5.8S ribosomal RNA gene of gypsy moth Lymantria dispar L. against its larvae

Insecticidal activity of three 10–12 nucleotides long antisense sequences from 5.8S ribosomal RNA gene of gypsy moth Lymantria dispar L. against its larvae

Diplodia twig canker (Diplodia gallae) of northern red oak (Quercus rubra) in the northeastern United States

AbstractThe 2015–2018 outbreak of spongy moth (Lymantria dispar) in southern New England initiated a severe oak decline and mortality event. While defoliation was a primary driver, increased secondary pest and pathogen activity contributed to decline and death. Following this large defoliation event, Diplodia was frequently recovered from northern red oaks (Quercus rubra) with serious outbreaks of twig cankering. Given the many recent reports of Diplodia corticola on oak in eastern North America, it was presumed to be the causal agent. To confirm, a limited survey was conducted from five states in the region (Maine, Massachusetts, New Hampshire, New York, and Vermont). Based on ITS, tef1 and tub2 sequences generated from 28 isolates collected primarily from northern red oak, Diplodia gallae, two potentially novel Diplodia species and Diplodia sapinea were identified. Surprisingly, D. corticola was not found in this study. ITS sequences alone failed to discriminate among isolates of D. gallae and D. corticola, creating uncertainty over previous reports of D. corticola in eastern North America. Only a combined ITS + tef1 dataset successfully distinguished D. gallae and D. corticola along with two other closely related species that also occur on oak (Diplodia quercicola and Diplodia quercivora). Additional cankering and endophytic fungi (Coryneum, Dendrostoma, Gnomoniopsis, Pestalotiopsis and Tubakia) were also found on symptomatic oaks in the region. Identification of Diplodia isolates from non‐Quercus hosts also detected Diplodia neojuniperi on Juniperus chinensis and Microbiota decussata, which has not been reported previously in North America.

Epizootic in gypsy moth (Lymantria dispar) population in the field protective forest belts of State Hunting Enterprise Balchik in 2022

Biological control of gypsy moth (Lymantria dispar) was carried out in 2021 in the field protective forest belts at the territory of the State Hunting Enterprise Balchik by introducing the entomopathogenic fungus Entomophaga maimaiga (Entomophthorales: Entomophthoraceae). In the same year a mortality rate of 26.1% of the pest population was registered. In 2022 E. maimaiga and multiple nuclear polyhedrosis virus of L dispar (LdMNPV) caused a population collapse of the pest in the region. Azygospores of E. maimaiga were reported in the cadavers of about 5% of middle- and late-instar dead host larvae with LdMNPV polyhedra, which is an indirect indication of initial infection by the fungal pathogen. The epizootic of gypsy moth in the Balchik region is the first recorded case of coinfection by E. maimaiga and LdMNPV in Bulgaria. 

Pre-egg hatch efficacy of dormant applications against Lymantria dispar (Lepidoptera: Erebidae).

Lymantria dispar L. is an invasive, non-native defoliating Lepidopteran established in North America that feeds on forest and urban trees. While many products are available to manage L. dispar post-emergence, few exist to prevent egg hatch when applied to egg masses. Here, we present the results of 3 separate experiments aimed at determining the efficacy of pre-emergent insecticides against L. dispar egg hatch. We found that the labeled rate (1:1) of Golden Pest Spray Oil (GPSO; AI: 93% soybean oil) can prevent L. dispar larvae from emerging in both field and lab assays. In large public spaces, we found that this treatment was ineffective at preventing L. dispar emergence or defoliation. Acelepryn (AI: 18.4% chlorantraniliprole) resulted in some suppression of egg hatch at a very low rate (.06 ml/ 3.8 liter) in both lab and field settings and the efficacy of higher rates should be further investigated. We also tested GPSO against Lepitect (97.4% acephate) in a public area that also received a Foray 48B (12.65% Bacillus thuringiensis, subsp. kurstaki) aerial application. On large oak trees in public areas, GPSO and Lepitect were not effective at reducing defoliation. Dormant pesticide applications generally reduce the risk of affecting negatively predator and parasitoid communities and are therefore desirable. Lymantria dispar pre-egg hatch applications will not work in every situation but should be considered as part of an integrated pest management (IPM) strategy for individual homeowner trees where thorough coverage can be obtained.

Traits-mediated responses of caterpillar communities to spongy moth outbreaks and subsequent tebufenozide treatments.

Outbreaks of the spongy moth Lymantria dispar can have devastating impacts on forest resources and ecosystems. Lepidoptera-specific insecticides, such as Bacillus thuringiensis var. kurstaki (BTK) and tebufenozide, are often deployed to prevent heavy defoliation of the forest canopy. While it has been suggested that using BTK poses less risk to non-target Lepidoptera than leaving an outbreak untreated, in situ testing of this assumption has been impeded by methodological challenges. The trade-offs between insecticide use and outbreaks have yet to be addressed for tebufenozide, which is believed to have stronger side effects than BTK. We investigated the short-term trade-offs between tebufenozide treatments and no-action strategies for the non-target herbivore community in forest canopies. Over three years, Lepidoptera and Symphyta larvae were sampled by canopy fogging in 48 oak stands in southeast Germany during and after a spongy moth outbreak. Half of the sites were treated with tebufenozide and changes in canopy cover were monitored. We contrasted the impacts of tebufenozide and defoliator outbreaks on the abundance, diversity, and functional structure of chewing herbivore communities. Tebufenozide treatments strongly reduced Lepidoptera up to six weeks after spraying. Populations gradually converged back to control levels after two years. Shelter-building species dominated caterpillar assemblages in treated plots in the post-spray weeks while flight-dimorphic species were slow to recover and remained underrepresented in treated stands two years post-treatment. Spongy moth outbreaks had minor effects on leaf chewer communities. Summer Lepidoptera decreased only when severe defoliation occurred, whereas Symphyta declined one year after defoliation. Polyphagous species with only partial host plant overlap with the spongy moth were absent from heavily defoliated sites, suggesting greater sensitivity of generalists to defoliation-induced plant responses. These results demonstrate that both tebufenozide treatments and spongy moth outbreaks alter canopy herbivore communities. Tebufenozide had a stronger and longer lasting impact, but it was restricted to Lepidoptera, whereas the outbreak affected both Lepidoptera and Symphyta. These results are tied to the fact that only half of the outbreak sites experienced severe defoliation. This highlights the limited accuracy of current defoliation forecast methods, which are used as the basis for the decision to spray insecticides.

Применение Ooencyrtus kuvanae Howard против непарного шелкопряда

The gypsy moth, Lymanria dispar, is one of the most widespread pest-insects in the Russian Federation. Anastatus japonicus Ashmead and Ooencyrtus kuvanae Howard are parasites that live on the eggs of L. dispar. They can be found in the European part of Russia, where the insects were imported from North Korea in 1988. The usage of O. kuvanae to limit the gypsy moth populations requires recognition of the release rates and effectiveness in preventing mass pest outbreaks, as well as for the evaluation of the possibility of elimination. An experimental release of O. kuvanae (237 500 specimens) was conducted in 2019 during a gypsy moth outbreak in the Orenburg region, which covered the basin of the Ural River within the territory of three forestries. The average number of clutches of O. kuvanae varied from 1 to 20 clutches per tree. The control of efficiency was made 48–52 after the release, during the incubation period of the 3ed generation of O. kuvanae. The clutches were collected and experimentally analyzed. The release rate of L. dispar ranged 82.9–90.3 % at the locations with a density of 107–268 thousand eggs/ha and did not exceed 47.3 % at the locations with a density of 3800 thousand eggs/ha. A coefficient for estimation of the optimal number of O. kuvanae specimens per 1 ha was proposed based on the proportion of the released egg parasitoids per 1 ha and the absolute number of the destroyed eggs of L. dispar. The regulation of the gypsy moth’s population by O. kuvanae should be done at the biggening of the foci formation. The usage of the entomophage in the active reproductive foci of the gypsy moth, with an infestation rate higher than 1.5 clutches per tree, cannot reduce the phytophage numbers to a harmless level. The application of O. kuvanae can be a part of an integrated system of preventive measures: chemical or biological pesticide treatments to reduce gypsy moth populations, and after initiate the release of the entomophages. For citation: Sergeeva Yu.A., Dolmonego S.O. Application of Ooencyrtus kuvanae Howard Against Gypsy Moth. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 3, pp. 69–83. (In Russ.). https://doi.org/10.37482/0536-1036-2023-3-69-83

Symbiotic Bacteria Modulate Lymantria dispar Immunity by Altering Community Proportions after Infection with LdMNPV.

The symbiotic bacteria-insect interaction is considered to be associated with immunity and drug resistance. However, the wide variety of insect species and habitats is thought to have a significant impact on the symbiotic community, leading to disparate results. Here, we demonstrated that symbiotic bacteria regulated the immune response by changing the proportion of the Gram-positive and the Gram-negative bacterial community in Lymantria dispar (L. dispar) after infection with its viral pathogen, L. dispar Nucleopolyhedrovirus (LdMNPV). After oral infection, the immune deficiency pathway was activated immediately, and the expression of Relish was up-regulated to promote the secretion of antimicrobial peptides. Meanwhile, the abundance of the Gram-negative bacterial community increased at the same time. Moreover, the Toll pathway was not regulated in the same way as the Imd pathway was after infection. However, the change in the Toll pathway's expression remained positively correlated to the abundance of Gram-positive bacteria. This finding implied that the ratio of Gram-negative to Gram-positive bacteria in the LdMNPV infected larvae had an effect on the immune response. Our findings revealed that the immune regulation of L. dispar was regulated by the relative abundance of its symbiotic bacteria at different infection times with LdMNPV, which provides a new way to understand symbiotic bacteria-insect interactions.