Gypsy Moth Research Articles

Desperate times call for desperate measures: Short-term use of the common ash tree by gypsy moth larvae (Lepidoptera: Erebidae) under density and starvation stress

Gypsy moth, Lymantria dispar L. (Lepidoptera: Erebidae) feeds on a large number of tree species, while ash, Fraxinus spp. (Lamiales: Oleaceae) species are considered resistant and are only sporadically eaten. To assess the conditions under which late instar gypsy moth larvae (GML) can temporarily use non-host common ash (CA) (F. excelsior L.), and to evaluate their ability to recover from ingestion of this toxic food, we determined the relative growth rate, the relative consumption rate and the amount of produced feces in different laboratory feeding trials. Our report is the first to show that under specific circumstances, the resources acquired after short-term consumption of CA leaves can be utilized for larval growth. We varied the intensity of density and starvation stress prior to feeding on CA leaves. We observed that after moderate stress a group of GML was temporarily capable of coping with CA leaves. Although observed growth and consumption were much lower on CA than on the optimal host oak, Quercus cerris L. (Fagales: Fagaceae), CA-oak-switched larvae showed the ability to recover from short-term use of a toxic non-host foliage. This suggests that feeding on CA might enable GML to survive under conditions of food shortage.

Monitoring vitalnosti šumskih ekosistema (ICP šume, Nivo I) sa posebnim osvrtom na oštećeni deo stabla u Republici Srbiji

Trees condition on the sample plots of the ICP forests, Level I, is especially considered and monitored by the typically damaged and affected part of the tree on which it occurs. Due to the need to enter unique data for the measured parameters (visible damages), their codes are assigned for each damage. These are the results from Sample plots, Level I, based on the ICP methodology. The results are entered into a single database for all participating countries. Infested assimilation organs - leaves or needles are direct indicators of the condition of the trees. The most common damage to leaves is caused by miners, gnats, beetles, and insects that totally bite the leaves so parts of the leaves are completely missing (Lymantria dispar L.). The leaves are mined by Stigmellidae, Gracillariidae, Cynipidae forming galls; there are also damages from the early oak defoliators Geometridae and Tortricidae. Apart from defoliators, the most common are xylophagous insects (for example, bark beetles) as well as root pests. The fungi that most commonly occur on the leaves are oak powdery mildew (Erysiphe alphitoides) and Rhytisma acerinum (which attacks species of the genus Acer). Other damages that occur are verticillium wilt (diseases of the conducting vessels), beech bark disease, then rot of the appendix, trunk, and branches. The paper presents the observed damage and diseases on the experimental plots of the ICP forests, Level I, in Serbia, according to the parts of the tree where they were discovered.

Biological features of individual phases of the development of unpaired silkworms in Uzbekistan of the walnut fruit zone of the bassen river chirchik (Lymantria Dispar L)

Truss traps based on disparlur allow you to accurately set the start dates for males, to track the entire period of their flight and end. The use of truss traps is necessary for monitoring the appearance of outbreaks of mass reproduction of unpaired silkworms in walnut stands. In the conditions of the Tashkent region, the Chirchik river bassin in walnut-fruit stands, the development of caterpillars from the moment of their birth to pupation took 55–61 days. A biometric analysis of pupae of males and females revealed that the weight categories can fluctuate significantly and an increase in the proportion of pupae with the smallest weight, both in females and males, shows that the studied population of unpaired silkworm has entered the attenuation phase. The timing of the development of the caterpillars depends on the species of fodder trees.

Characterization of gypsy moth Lymantria dispar (Linnaeus, 1758) (Lepidoptera Lymantriidae) eggs in Cork oak forests of the Kabylie region (Jijel-Algeria)

Characterization of gypsy moth Lymantria dispar (Linnaeus, 1758) (Lepidoptera Lymantriidae) eggs in Cork oak forests of the Kabylie region (Jijel-Algeria)

Reassessment of the status of Lymantria albescens and Lymantria postalba (Lepidoptera: Erebidae: Lymantriinae) as distinct ‘Asian gypsy moth’ species, using both mitochondrial and nuclear sequence data

AbstractFor regulatory purposes, the name ‘Asian gypsy moth’ refers to a group of closely related Asian Lymantria species and subspecies whose female moths display flight capability, a trait believed to confer enhanced invasiveness relative to the European gypsy moth, Lymantria dispar dispar, whose females are flightless. Lymantria albescens and Lymantria postalba are Asian gypsy moths occurring in the southern Ryukyu Islands and in the northern Ryukyu and adjacent Kyushu and Shikoku Islands of Japan, respectively. Although once considered subspecies of L. dispar, their status as distinct species, relative to the latter, is now well established. While postalba was subsequently considered a subspecies of L. albescens, largely on the basis of differences in forewing ground colour in males, both taxa were later given distinct species status by Pogue & Schaefer (2007) following their revision of the genus Lymantria. Here, we re‐examined the validity of this revised status through the sequencing of a large portion of the mitochondrial genome (c. 60%) and multiple nuclear marker genes [elongation factor 1‐alpha (Ef‐1α), wingless (Wgl), internal transcribed spacer 2 (ITS‐2), ribosomal protein S5 (RpS5)] in representative specimens of both taxa and other Lymantria species, including L. monacha, L. xylina, L. mathura and members of the L. dispar + L. umbrosa clade. A comparison of the number of substitutions in these genomic regions among the taxa we considered showed lower or equivalent variation between L. albescens and L. postalba compared with subspecies of L. dispar, for mitochondrial and nuclear sequences, respectively. This finding was reflected in the maximum likelihood trees generated independently for mitochondrial and nuclear data, where L. albescens and L. postalba formed, in both analyses, a short‐branch sister clade basal to the L. dispar + L. umbrosa clade. We further sequenced three markers [cytochrome c oxydase 1 (COI), EF‐1α, Wgl] in multiple L. albescens–L. postalba specimens collected along a south‐to‐north transect across the Ryukyu Arc and observed no clear distinction among the sampled specimens as a function of taxonomic designation. We conclude that L. albescens and L. postalba form a single species, with postalba representing a darker‐winged morph along an apparent south‐to‐north wing colour cline. Accordingly, L. postalba is relegated to synonymy under L. albescens (syn.n.).

The improved resistance against gypsy moth in Larix olgensis seedlings exposed to Cd stress association with elemental and chemical defenses.

Cadmium (Cd), as an environmental pollutant, can endanger various biological and chemical characteristics of plants in multiple aspects. In this study, the effects of Cd contamination or exposure for 30 and 60 days at 1, 2, 4 mg kg-1 concentrations on the resistance of Larix olgensis seedlings to the gypsy moth (Lymantria dispar) larvae were investigated. Our results showed that Cd stress did not significantly affect the growth and biomass parameters of the larch seedlings, which might be attributed to the scavenging mechanism of reactive oxygen species (e.g. superoxide dismutase and peroxidase). Regarding the phytochemical defense, we found that Cd stress significantly changed the contents or activities of protease inhibitors (such as trypsin and chymotrypsin inhibitors) and secondary metabolites (tannins and phenolic acids) in L. olgensis seedling needles; however, their response trends varied with Cd exposure concentrations with a significant increase at low concentrations and a significant decrease at high concentrations. Moreover, both chemical and elemental defenses contributed to the resistance of L. olgensis seedlings to the gypsy moth larvae, and their synergistic effects (between toxic elements and organic metabolites) could provide an overall improved defense of L. olgensis seedlings even at low concentrations of single components, resulting in a detrimental effect on the growth of gypsy moth larvae. These findings call for an urgent need to adjust and optimize pest control strategies in heavy metal polluted areas based on the effects of heavy metal stress on woody plant resistance to pest insects. © 2019 Society of Chemical Industry.

Facilitation between invasive herbivores: hemlock woolly adelgid increases gypsy moth preference for and performance on eastern hemlock

1. Interactions between invertebrate herbivores with different feeding modes are common on long‐lived woody plants. In cases where one herbivore facilitates the success of another, the consequences for their shared host plant may be severe. Eastern hemlock (Tsuga canadensis), a canopy‐dominant conifer native to the eastern U.S., is currently threatened with extirpation by the invasive stylet‐feeding hemlock woolly adelgid (Adelges tsugae). The effect of adelgid on invasive hemlock‐feeding folivores remains unknown.2. This study evaluated the impact of feeding by hemlock woolly adelgid on gypsy moth (Lymantria dispar) larval preference for, and performance on, eastern hemlock. To assess preference, 245 field‐grown hemlocks were surveyed for gypsy moth herbivory damage and laboratory paired‐choice bioassays were conducted. To assess performance, gypsy moth larvae were reared to pupation on adelgid‐infested or uninfested hemlock foliage, and pupal weight, proportional weight gain, and larval period were analysed.3. Adelgid‐infested hemlocks experienced more gypsy moth herbivory than did uninfested control trees, and laboratory tests confirmed that gypsy moth larvae preferentially feed on adelgid‐infested hemlock foliage. Gypsy moth larvae reared to pupation on adelgid‐infested foliage gained more weight than larvae reared on uninfested control foliage.4. These results suggest that the synergistic effect of adelgid and gypsy moth poses an additional threat to eastern hemlock that may increase extirpation risk and ecological impact throughout most of its range.

Effect of dispenser type, trap design and placement on catches of pine-tree lappet moth, Dendrolimus pini

Dendrolimus pini is one of the most harmful defoliators of Scots pine in Poland and other countries in Europe and Central Asia. The monitoring of this insect needs to be improved and to include the use of pheromone traps. Laboratory studies were conducted to compare changes in the residual amounts of (Z,E)-5,7-dodecadienal and (Z,E)-5,7-dodecadien-1-ol, the major components of the D. pini pheromone, in four types of dispensers. The two most promising dispensers, red rubber cylindrical dispensers (rubber cylinders) and polyethylene vials, were tested in the field for their ability to attract D. pini males. In addition, the effects of trap type (sticky wing, non-sticky cross-vane, bucket, funnel and modified gypsy moth milk carton) and height of trap placement (1.5 m, 5–6 m and tree crown) on trap catches were tested in the field. The vials provided the longest half-lives for both the aldehyde and alcohol under laboratory conditions. These dispensers were also significantly more effective in attracting D. pini males to the traps than the rubber cylinders in the field experiment. The cross-vane and bucket traps were the most effective among the tested traps. The height of trap placement had a significant effect on catches, with more males caught in traps that were hung at 5–6 m above the ground than those hung in the tree crowns. Our results may be useful for developing a monitoring system for D. pini in Europe and other regions where it occurs.

Microsatellite and Morphological Analyses Reveal Unexpected Diversity in Lymantria dispar in China

The gyspy moth Lymantria dispar Linnaeus, a widely distributed leaf-eating pest, is considered geographically isolated in the world, with two Asian gypsy moth subspecies, Lymantria dispar asiatica and Lymantria dispar japonica. In China, only one subspecies, L. d. asiatica, has been observed. In this study, we characterized gypsy moth diversity and divergence using 427 samples covering a wide range of the species distribution, with a focus on sampling along a latitudinal gradient in China. We combine the quantitative analysis of male genitalia and the genetic diversity analysis of nine microsatellite loci of nuclear genes nuclear genes to study the structure of gypsy moth individuals in 23 locations in the world and the male genitalia of gypsy moths in some areas. In mixed ancestry model-based clustering analyses based on nuclear simple sequence repeats, gypsy moths were divided into three well-known subspecies, a unique North American cluster, and a southern Chinese cluster with differentiation between the Asian gypsy moth and European gypsy moth. We also found individuals identified as European gypsy moths in two distant regions in China. The results of a quantitative analysis of male genitalia characteristics were consistent with an analysis of genetic structure and revealed the differentiation of gypsy moths in southern China and of hybrids suspected to be associated with L. d. japonica in the Russian Far East. Admixture in gypsy moths can be explained by many factors such as human transport. In China, we detected European gypsy moths, and found unexpectedly high genetic diversity within populations across a wide range of latitudes.

Comparing generalized and customized spread models for nonnative forest pests.

While generality is often desirable in ecology, customized models for individual species are thought to be more predictive by accounting for context specificity. However, fully customized models require more information for focal species. We focus on pest spread and ask: How much does predictive power differ between generalized and customized models? Further, we examine whether an intermediate "semi-generalized" model, combining elements of a general model with species-specific modifications, could yield predictive advantages. We compared predictive power of a generalized model applied to all forest pest species (the generalized dispersal kernel or GDK) to customized spread models for three invasive forest pests (beech bark disease [Cryptococcus fagisuga], gypsy moth [Lymantria dispar],and hemlock woolly adelgid [Adelges tsugae]), for which time-series data exist. We generated semi-generalized dispersal kernel models (SDK) through GDK correction factors based on additional species-specific information. We found that customized models were more predictive than the GDK by an average of 17% for the three species examined, although the GDK still had strong predictive ability (57% spatial variation explained). However, by combining the GDK with simple corrections into the SDK model, we attained a mean of 91% of the spatial variation explained, compared to 74% for the customized models. This is, to our knowledge, the first comparison of general and species-specific ecological spread models' predictive abilities. Our strong predictive results suggest that general models can be effectively synthesized with context-specific information for single species to respond quickly to invasions. We provided SDK forecasts to 2030 for all 63 United States pests in our data set.

Expansion of LINEs and species-specific DNA repeats drives genome expansion in Asian Gypsy Moths

Two subspecies of Asian gypsy moth (AGM), Lymantria dispar asiatica and L. dispar japonica, pose a serious alien invasive threat to North American forests. Despite decades of research on the ecology and biology of this pest, limited AGM-specific genomic resources are currently available. Here, we report on the genome sequences and functional content of these AGM subspecies. The genomes of L.d. asiatica and L.d. japonica are the largest lepidopteran genomes sequenced to date, totaling 921 and 999 megabases, respectively. Large genome size in these subspecies is driven by the accumulation of specific classes of repeats. Genome-wide metabolic pathway reconstructions suggest strong genomic signatures of energy-related pathways in both subspecies, dominated by metabolic functions related to thermogenesis. The genome sequences reported here will provide tools for probing the molecular mechanisms underlying phenotypic traits that are thought to enhance AGM invasiveness.

Influence of Bacillus thuringiensis application timing on population dynamics of gypsy moth in Mediterranean cork oak forests.

The gypsy moth, Lymantria dispar, is one of the main pests of oak forests worldwide and causes extensive defoliation during its periodic outbreaks. In the Mediterranean region, control of gypsy moth populations in cork oak forests is based on application of Bacillus thuringiensis serovar kurstaki (Btk) formulations. This research investigated the effects of Btk applications carried out in two different population development phases on gypsy moth population dynamics. With this aim, temporal and spatial fluctuation patterns of L. dispar egg density were monitored in cork oak forests treated with Btk applications from 2004 to 2009 in Sardinia (Italy). Applications undertaken during the progradation and culmination phases protected the oak canopies equally in the year of application, leading to a similar decrease in pest population density in the following year. However, the medium-term effectiveness of Btk differed between the two application timings, because only applications in the culmination phase caused a gradual decrease in L. dispar infestations throughout subsequent years. By contrast, when the application was undertaken during the progradation phase, population density increased again after 2-3 years. Moreover, Btk applications in the culmination phase reduced significantly the number of years in which gypsy moth density was damaging compared with those done in progradation. Our results indicate that Btk applications during the culmination phase were more effective than those in the progradation period, because application in the latter case did not suppress the population, but only postponed the outbreak peak by 2-3 years. © 2019 Society of Chemical Industry.

Synthesis of Isotopically Labelled Disparlure Enantiomers and Application to the Study of Enantiomer Discrimination in Gypsy Moth Pheromone‐Binding Proteins

To study the binding mechanism of disparlure (7,8)‐epoxy‐2‐methyloctadecane enantiomers with pheromone‐binding proteins (PBPs) of the gypsy moth, oxygen‐17 or 18 and 5,5,6,6‐deuterium labelled disparlure enantiomers were prepared in an efficient, enantioselective route. Key steps involve the asymmetric α‐chlorination of dodecanal by SOMO catalysis and Mitsunobu inversion of a 1,2‐chlorohydrin. The pheromone, (+)‐disparlure (7R, 8S), was tested in two infested zones, demonstrating that it is very attractive towards male gypsy moths. Studies of the binding of (+)‐disparlure and its antipode to gypsy moth PBPs by 2H &17O NMR at 600 MHz are reported. Chemical shifts, spin‐lattice relaxation decay times (T1) and transverse relaxation decay times (T2) of deuterium atoms of disparlure enantiomers in 2H NMR show that the binding of disparlure enantiomers to PBP1 differs from binding to PBP2, as expected from their opposite binding preferences (PBP1 binds (–)‐disparlure, and PBP2 binds (+)‐disparlure more strongly). Models of the disparlure enantiomers bound to one internal binding site and two external binding sites of both PBPs were constructed. The observed chemical shift changes of deuterated ligand signals, from non‐bound to bound, T1 and T2 values are correlated with results from the simulations. Together these results suggest that the disparlure enantiomers adopt distinct conformations within the binding sites of the two PBPs and interact with residues that line the sites.

Characterization of a novel baculovirus isolate from Malacosoma neustria (Linnaeus, 1758) (Lepidoptera: Lasiocampidae) in Samsun and its pathogenicity in different hosts

Malacosoma neustria (Linnaeus, 1758) (Lepidoptera: Lasiocampidae) causes economic losses in apple, pear, plum, willow, oak and other economically important trees. In this study, an alphabaculovirus was isolated from the larval population of M. neustria from Samsun in the central Black Sea Region of Turkey between 2015 and 2016. Electron microscope analysis of occlusion bodies (OBs) obtained from dead larvae showed that the nucleocapsids of a new isolate (ManeNPV-T4) are multiply enveloped. The Kimura two-parameter analysis and the phylogenetic tree were performed based on concatenated nucleotide and amino acid sequences of the partial lef-8, lef-9 and polh genes from ManeNPV-T4 isolate compared to those of other 51 baculoviruses. Insecticidal activity tests against third instar M. neustria larvae produced 48 to 100% mortalities. The LC 50 of ManeNPV-T4 was 0.78 x 10 3 OBs/ml in M. neustria . Additionally, the isolate caused mortalities lower than 50% in Spodoptera exigua (Hübner, 1808) (Lepidoptera: Noctuidae) , Lymantria dispar (Linnaeus, 1758) (Lepidoptera: Erebidae) , Hyphantria cunea (Drury, 1773) (Lepidoptera: Arctiidae) and Helicoverpa armigera (Hübner, 1805) (Lepidoptera: Noctuidae) larvae. Consequently, the new nucleopolyhedrovirus is infectious on M. neustria larvae and other lepidopterans.

Functional form and interactions of the drivers of understory non‐native plant invasions in northern US forests

Abstract The number and rate of non‐native plant invasions in forests have been steadily increasing over the last century with profound consequences for the composition, structure and functioning of these ecosystems. While multiple regional, landscape and local environmental factors are known to drive the spread of non‐native invasive plant species (NNIPS) into forests, such factors have rarely been analysed within a unified analytical framework allowing for the assessment of their relative importance, possible non‐linear behaviour and interactions. Obtaining such knowledge would improve the understanding and allow prediction of forest plant invasions and help prioritize actions for effective NNIPS control and mitigation. We used boosted regression trees and Bayesian non‐linear regression to analyse forest inventory data spanning 14 northern US states in combination with data on climate, land use and disturbance. Within each framework, we assessed the magnitude, direction and functional form of the effects of 18 regional to local environmental factors and their interactions on the probability of presence and richness of NNIPS in the forest understory, while controlling for sampling intensity, data collection time and spatial autocorrelation. The studied drivers together captured nearly 50% of the variation in NNIPS occurrence and richness and were sufficient to obtain sensible predictions. Most drivers exhibited monotonic non‐linear individual effects and several drivers showed non‐additive combined effects. Temperature and landscape openness were the two major determinants of NNIPS presence and richness, but their effects were to a different degree moderated by elevation, climatic and topographic wetness, and stand age. Stand age was a more important predictor of NNIPS invasion than stand productivity. Deer density tended to be positively associated with NNIPS, whereas gypsy moth outbreaks possibly have increased resistance to plant invasions. Synthesis and applications. To optimize non‐native invasive plant species (NNIPS) control efforts in forests, it is important to explicitly account for the functional form and interactions among the factors operating across spatial and temporal scales. Increasing the average stand age at the landscape and regional levels is essential for buffering against further invasions. Recurrent canopy disturbance likely slowed down NNIPS invasion previously, yet whether this holds under higher propagule pressure remains unknown.

Spatiotemporal variability in Allee effects of invading gypsy moth populations

The Allee threshold, the critical population density separating growth from decline in populations experiencing strong Allee effects, can vary over space and time but few empirical studies have examined this variation. A lack of geographically extensive, long-term studies on low density population dynamics makes studying variability in Allee effects difficult. We used North American gypsy moth population data from 1996 to 2016 to quantify Allee thresholds in 11 regions of the invasion front. Allee thresholds spanned a continuum from being undetectable due to strong population growth at all densities, to being unmeasurable because populations declined across all densities. The lag-1 temporal autocorrelation in Allee thresholds tended to be negative and spatial synchrony in Allee thresholds extended no further than adjacent regions. This work furthers understanding of spatiotemporal variation in Allee effects using extensive empirical data at the range edge of an invasive insect.

Relating Aerial Deposition of Entomophaga maimaiga Conidia (Zoopagomycota: Entomophthorales) to Mortality of Gypsy Moth (Lepidoptera: Erebidae) Larvae and Nearby Defoliation.

We collected data on mortality of late-instar gypsy moth, Lymantria dispar (L.), from outbreak populations over 4 wk in June 2017 at 10 sites in the New England region of the United States, along with estimated rainfall at these sites. Deposition of airborne conidia of the fungal pathogen, Entomophaga maimaiga Humber, Shimazu & R.S. Soper, was measured at these same sites as well as at seven other locations in New England. We also quantified the geographical distribution of gypsy moth-caused defoliation in New England in 2017 and 2018 from Landsat imagery. Weekly mortality of gypsy moth larvae caused by E. maimaiga correlated with local deposition of conidia from the previous week, but not with rainfall. Mortality from this pathogen reached a peak during the last 2 wk of gypsy moth larval development and always exceeded that caused by LdNPV, the viral pathogen of gypsy moth that has long been associated with gypsy moth outbreaks, especially prior to 1989. Cotesia melanoscela (Ratzeburg) was by far the most abundant parasitoid recovered and caused an average of 12.6% cumulative parasitism, but varied widely among sites. Deposition of E. maimaiga conidia was highly correlated with percent land area defoliated by gypsy moths within distances of 1 and 2 km but was not significantly correlated with defoliation at distances greater than 2 km. This is the first study to relate deposition of airborne conidia of E. maimaiga to mortality of gypsy moths from that agent.

Insect Defoliators in Recovering Industrial Landscapes: Effects of Landscape Degradation and Remediation Near an Abandoned Metal Smelter on Gypsy Moth (Lepidoptera: Lymantriidae) Feeding, Frass Production, and Frass Properties.

Although insect defoliators are recognized as major agents of ecological change in North American forests, their ecology in industrially degraded landscapes with poor-quality soils, metal contamination, and marginal vegetation growth is largely unknown. We fed gypsy moth larvae (Lymantria dispar L.) paper birch leaves (Betula papyrifera Marsh) (Fagales: Betulaceae) collected from four forested catchment areas near an abandoned Cu/Ni smelter in Sudbury (Ontario, Canada) with different histories of industrial degradation and remediation (reference, remediated, natural recovery, and degraded). We measured caterpillar feeding, frass properties and decomposability, and the effects of frass on the growth of ticklegrass (Agrostis scabra Willd.) (Poales: Poaceae). Caterpillars generally ate more (+25-50%) and produced more frass (+30-40 %) on a diet of leaves from the more industrially degraded sites. Frass had an overall positive effect on plant survivorship (+4.1-10.8 effect size) and growth (+0.1-0.5 effect size), although the smallest benefits came from frass derived from vegetation from the more heavily degraded sites. Our results suggest that defoliating insects respond to differences in environmental degradation and remediation and that industrial landscapes may be particularly susceptible to more extensive defoliation and increased conversion of foliar biomass into frass, which could alter plant growth and survivorship, soil development, and nutrient and metal cycling. Some of these effects may pose additional challenges to landscape recovery (e.g., increased defoliation) while others may be beneficial (e.g., enhanced plant growth and soil development).

Ground application of mating disruption against the gypsy moth (Lepidoptera: Erebidae)

AbstractThe gypsy moth, Lymantria dispar (L.) (Lepidoptera: Erebidae), is a non‐native defoliating insect that continues to expand its range in North America and undergo periodic outbreaks. In management efforts to suppress outbreaks, slow its spread and eradicate populations that arrive outside of the invaded range, aerial deployments of mating disruption tactics and pesticides are generally used. However, in some cases, such as in heavily urbanized areas or other landscapes where aerial deployments are not feasible or permitted, ground applications are required. Ground applications tend to be labour‐intensive to ensure adequate coverage. To better inform optimal deployment of ground applications of mating disruption, we measured the effectiveness of a pheromone formulation designed for ground application, SPLAT® GM, in forested areas of Virginia from 2011 to 2014 using different dosages and number of point applications. We observed that SPLAT® GM applied to the tree trunks at the dosages of 49.4 and 123.6 g AI/ha in 11 × 11 systematic grids (i.e., every 11 m) reduced male trap catch by >90% relative to untreated control plots, which based on previous studies corresponds to >95% reduction in gypsy moth mating success. Our observations suggest that ground applications of gypsy moth mating disruption can be a successful management tool when circumstances require it.

Spore viability of microsporidian species isolated from gipsy moth larvae (Lymantria dispar) after long-term storage in liquid nitrogen

U radu se prikazuju rezultati preživljenja mikrosporidija izoliranih iz gubara (Lymantria dispar) nakon dugotrajne pohrane u tekućem dušiku. Infektivnost osam mikrosporidijskih L. dispar izolata testirano je na ličinkama gubara: Vairimorpha disparis, Nosema lymantriae, Nosema portugal, Nosema sp. (Poljska), Nosema sp. (Ebergassing), Nosema sp. (Njemačka), Nosema sp. (Schweinfurt) and Nosema sp. (Veslec). Preživljenje spora u tekućem dušiku detaljno je praćeno kod N. portugal i Nosema sp. (Ebergassing) koje su tako čuvane skoro 19 godina i aplicirane oralnom infekcijom i ponaosob na svaku pojedinu ličinku gubara. Ostalih 6 izolata aplicirano je površinskom kontaminacijom hranjivog supstrata, također oralnim infekcijskim putem. Od 8 mikrosporidijskih izolata apliciranih površinskom kontaminacijom samo kod 4 izolata, Vairimorpha disparis, Nosema lymantriae, Nosema sp. (Ebergassing) i Nosema sp. (Poljska), došlo je do uspješne infekcije ličinki gubara. Dok je kod svih testiranih ličinki (100%) uspješno realizirana infekcija sporama prve tri mikrosporidije, tek 21,1% tretiranih ličinki uspješno je inficirano sporama Nosema sp. (Poljska). Na kraju inkubacijskog razdoblja, kod svih ličinki inficiranih sa sva 4 izolata disekcijom je utvrđen visok stupanj zaraze; tkiva su bila ispunjena sporama. Mikroskopska pretraga ličinki L. dispar individualno tretiranih sporama Nosema portugal uz tri različite doze (100, 1000 i 10000 spora) pokazala je da su spore N. portugal izgubile infektivnost nakon 19 godina pohrane u tekućem dušiku; niti jedna od testiranih ličinka nije bila zaražena. Naprotiv, spore Nosema sp. (Ebergassing) zadržale su infektivnost nakon istog razdoblja pohrane u tekućem dušiku od 18,75 godina. Niti jedna od testiranih ličinki nije zaražena nakon oralnog unosa od 100 spora. Oralna aplikacija od 1000 spora po ličniki rezultirala je ukupnom uspješnom infekcijom 4,1% ličinki, a aplikacija od 10000 spora s 68,8% inficiranih ličinki. U svim uspješnim slučajevima uspješno zaraženih ličinki, na kraju inkubacijskog razdoblja infekcija je bila dobro razvijena, a masno tijelo prepuno spora. Istraživanje je potvrdilo da je pohrana mikrosporidija Nosema i Vairimorpha vrsta i domaćina iz reda leptira prikladna opcija za dugotrajno čuvanje izolata. Spore su preživjele i do 18 i pola godina, iako je tijekom eksperimenta zamijećen i značajan pad njihove infektivnosti. U pojedinim slučajevima spore su odumrle već nakon 7 godina pohrane u tekućem dušiku. Preporuka je da prilikom skladištenja i pohrane mikrosporidijskih izolata u tekućem dušiku svakih 5 godina repozitorij obnavlja svježim izolatima. Materijal koji se dulje vrijeme skladišti u tekućem dušiku nije prikladan i ne bi se smio koristiti u infektološkim testovima.