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Orgyia trigotephras (Boisduval) is a polyphagous moth which is bivoltine in Tunisia, with two generations (spring and autumnal). This work, carried out in northeastern and northwestern Tunisia, aimed at studying pupal mortality of this pest on two host species, Quercus coccifera L. and Pistacia lentiscus L. Two types of antagonist factors were assessed: natural mortality (dried pupae) and mortality caused by parasitoids. Three pupal parasitoids species belonging to Hymenoptera order were identified: Brachymeria tibialis (Walker), Pimpla rufipes (Miller) and Monodontomerus minor (Ratzeburg). [ABSTRACT FROM AUTHOR]

Key message: During outbreak, a discrepancy between larval performance and the main host used for egg laying was found in Orgyia trigotephras. It results mostly from intraspecific competition, but reduced egg mortality on the less suitable host plant may play a secondary role. Context: Host range of polyphagous herbivores often comprises plants of low nutritional quality, which may however provide other benefits to the animal. Understanding the effect of host plants use on insect fitness and its population dynamics are central questions in insect-plant ecology . O. trigotephras Boisduval is a polyphagous Mediterranean defoliator. During outbreaks, larvae are frequently found on two unrelated host species, Pistacia lentiscus L. and Quercus coccifera L. Aim: The aim of this study was to clarify the effect of population density on host use and the effects of host tree on insect performance. Methods: The realized fecundity and egg mortality were measured during 3 years showing different population levels of the defoliator. Larval performance on the two host species was analyzed. Results: Larvae fed on Q. coccifera had faster development, lower mortality, higher female/male ratio, and higher fecundity than larvae fed on P. lentiscus. Yet, at high population densities, under high intraspecific competition, P. lentiscus was the most used for egg laying. During outbreak, higher levels of parasitism by Aprostocetus sp. and predation by Coccidiphila rungsella Nel and Brusseaux were found on eggs laid on Q. coccifera compared to those laid on P. lentiscus. Conclusions: The results indicate a discrepancy between host use and larvae performance, possibly ruled by resources exploitation and intraspecific competition. The reduced egg predation on P. lentiscus during outbreaks might also provide an indirect benefit to the insect. [ABSTRACT FROM AUTHOR]

The article presents a study on morphology and antipredator behavior in larval Orgyia Leucostigma of the order Lepidoptera. Topics include antipredator defense mechanisms in terrestrial insects like hairs, spines, and thick sclerotized cuticles; changes in caterpillar antipredator behaviors depending on vulnerability; and effect of hair clipping or clipping control on the behavioral defenses of the animal.

trans-11,12-Epoxy-(6 Z,9 Z)-6,9-henicosadiene (posticlure) has been identified from a pheromone gland of the lymantriid species, Orgyia postica. Since the diversity of Lepidoptera suggests that some species utilize the structure-related epoxy compound as a sex pheromone component, epoxydienes and epoxytrienes derived from (6 Z,9 Z,11 E)-6,9,11-trienes and (3 Z,6 Z,9 Z,11 E)-3,6,9,11-tetraenes with a C-C chain were systematically synthesized and the chemical data were accumulated in order to contribute to a new pheromone research. Peracid oxidation of each triene and each tetraene produced, respectively, a mixture of three epoxydienes ( cis-6,7-epoxy-9,11-diene; cis-9,10-epoxy-6,11-diene; and trans-11,12-epoxy-6,9-diene) and four epoxytrienes ( cis-3,4-epoxy-6,9,11-triene; cis-6,7-epoxy-3,9,11-triene; cis-9,10-epoxy-3,6,11-triene; and trans-11,12-epoxy-3,6,9-triene). While the 9,10-epoxy compounds were unstable and, interestingly, converted into 9-ketone derivatives after chromatography over SiO, each positional isomer was isolated by HPLC equipped with an ODS column, and the chemical structure was determined by NMR analysis. On the GC-MS analysis with a DB-23 column, the positional isomers were also eluted separately and characteristic mass spectra were proposed. By comparing the spectral data of the epoxy compounds with a different carbon chain, diagnostic fragment ions reflecting the chemical structure were determined as follows: m/z 79, 109, 113, and M-114 for the 6,7-epoxydienes; m/z 69, 97, 111, 139, and M-111 for the 9,10-epoxydienes; m/z 57, 79, 109, 136, M-151, and M-111 for the 11,12-epoxydienes; m/z 79, 91, 105, and 119 for the 3,4-epoxytrienes; m/z 79, 124, M-124, M-96, and M-69 for the 6,7-epoxytrienes; m/z 79, 95, 109, 137, and M-108 for the 9,10-epoxytrienes; and m/z 79, 134, M-149, M-109, and M-95 for the 11,12-epoxytrienes. [ABSTRACT FROM AUTHOR]

Abstract: In plants attacked by insects, metabolic changes can reflect the direct and indirect ability of those plants to resist infestation. However, the metabolic pathways involved in this process remain unclear, especially for plants which belong to ancient Tertiary relict taxon. To analyze the changes in metabolites and identify specific metabolic patterns induced by herbivorous and continuous mechanical wounding, the metabolism of Ammopiptanthus mongolicus seedlings damaged by Orgyia ericae Germar or continuous mechanical wounding were analyzed using nuclear magnetic resonance (NMR) combined with multivariate data analysis (MVDA). Principal component analysis (PCA) and orthogonal signal correction projections to latent structure discriminate analysis (OPLS-DA) showed that O. ericae feeding and mechanical wounding induced different changes in the metabolic profile of A. mongolicus both in local and systemic leaves. O. ericae feeding was associated with higher concentrations of many primary and secondary metabolites in local and systemic leaves than continuous mechanical wounding. In this way, the response of A. mongolicus to wounding was shown to be both specific to the metabolism, systemic, and to involve both primary and secondary metabolic pathways. [Copyright &y& Elsevier]

The complete genome of the Orgyia leucostigma nucleopolyhedrovirus (OrleNPV) isolated from the whitemarked tussock moth (Orgyia leucostigma, Lymantridae: Lepidoptera) was sequenced, analyzed, and compared to other baculovirus genomes. The size of the OrleNPV genome was 156,179 base pairs (bp) and had a G+C content of 39%. The genome encoded 135 putative open reading frames (ORFs), which occupied 79% of the entire genome sequence. Three inhibitor of apoptosis (ORFs 16, 43 and 63), and five baculovirus repeated ORFs (bro-a through bro-e) were interspersed in the OrleNPV genome. In addition to six direct repeat (drs), a common feature shared among most baculoviruses, OrleNPV genome contained three homologous regions (hrs) that are located in the latter half of the genome. The presence of an F-protein homologue and the results from phylogenetic analyses placed OrleNPV in the genus Alphabaculovirus, group II. Overall, OrleNPV appears to be most closely related to group II alphabaculoviruses Ectropis obliqua (EcobNPV), Apocheima cinerarium (ApciNPV), Euproctis pseudoconspersa (EupsNPV), and Clanis bilineata (ClbiNPV). [ABSTRACT FROM AUTHOR]

1. Leaves possess traits that mediate the preference and performance of herbivores. Most evidence for the importance of leaf traits as defences against herbivory comes from studies of few model plant species. 2. In a phylogenetically explicit comparison, I explain the differences in preference and performance of tussock moth ( Orgyia vetusta Boisduval) larvae on leaves of 27 oak ( Quercus) species using nine putative leaf defences. 3. The preference for an oak species correlated positively with the survival of caterpillars. The correlation between preference and performance did not differ between oak species native to the range of tussock moth versus those from outside the herbivore's range. 4. The first principal component of leaf traits predicted survival of caterpillars on oak leaves but only marginally predicted their preference between oak species. A multiple regression model showed that evergreenness, toughness, and condensed tannin content were the best predictors of caterpillar survival, and leaf toughness was the best predictor of host preference. 5. Generalist caterpillars may accurately assess the value of novel food sources. Moreover, many leaf traits that have been found to affect herbivory within a plant species can also be used to predict the fitness of a generalist herbivore between species. [ABSTRACT FROM AUTHOR]

Organisms have evolved morphological and behavioral traits that reduce their susceptibility to predation. However, few studies have considered how morphological structures work to provide informational inputs necessary for effective behavioral responses to predation risk. In this study, we demonstrate that the hairs of Orgyia leucostigma (Lymantriidae) caterpillars not only function as physical barriers that deter predators but also act to provide sensory inputs triggering behavior that reduces predation risk. In particular, the way in which caterpillars respond when their hairs are touched is predator specific. Mechanical parameters of the interaction determining the response were identified correlatively and confirmed manipulatively. Caterpillars predominantly dropped in response to high hair bending velocities and predominantly walked away in response to low hair bending velocities. These stimulus-specific responses appear to be adaptive as they led to increased survival. Our results demonstrate a functional link between morphology and behavior. The ability to respond effectively only after the initiation of a predator attack should reduce the costs associated with antipredator behaviors. [ABSTRACT FROM PUBLISHER]

The white spotted tussock moth, Orgyia thyellina, is a typical insect that exhibits seasonal polyphenisms in morphological, physiological, and behavioral traits, including a life-history tradeoff known as oogenesis-flight syndrome. However, the developmental processes and molecular mechanisms that mediate developmental plasticity, including life-history tradeoff, remain largely unknown. To analyze the molecular mechanisms involved in reproductive polyphenism, including the diapause induction, we first cloned and characterized the diapause hormone-pheromone biosynthesis activating neuropeptide (DH-PBAN) cDNA encoding the five Phe-X-Pro-Arg-Leu-NH2 (FXPRLa) neuropeptides: DH, PBAN, and a-, b-, and c-SGNPs (subesophageal ganglion neuropeptides). This gene is expressed in neurosecretory cells within the subesophageal ganglion whose axonal projections reach the neurohemal organ, the corpus cardiacum, suggesting that the DH neuroendocrine system is conserved in Lepidoptera. By injection of chemically synthetic DH and anti-FXPRLa antibody into female pupae, we revealed that not only does the Orgyia DH induce embryonic diapause, but also that this neuropeptide induces seasonal polyphenism, participating in the hypertrophy of follicles and ovaries. In addition, the other four FXPRLa also induced embryonic diapause in O. thyellina, but not in Bombyx mori. This is the first study showing that a neuropeptide has a pleiotropic effect in seasonal reproductive polyphenism to accomplish seasonal adaptation. We also show that a novel factor (i.e., the DH neuropeptide) acts as an important inducer of seasonal polyphenism underlying a lifehistory tradeoff. Furthermore, we speculate that there must be evolutionary conservation and diversification in the neuroendocrine systems of two lepidopteran genera, Orgyia and Bombyx, in order to facilitate the evolution of coregulated life-history traits and tradeoffs. [ABSTRACT FROM AUTHOR]

Environmental perturbations such as starvation and poor diet often prevent animals from attaining their optimal sizes. When the perturbation has a transient character, compensatory responses are expected in terms of faster growth or a prolonged developmental period. In the case of insect larvae, details of such responses are insufficiently known at the proximate level. Attention to responses at the level of particular larval instars should promote an understanding of insect developmental plasticity also in a more general context. To provide an instar-specific analysis of compensatory growth, larvae of the moth Orgyia antiqua (L.) are reared on inferior diet during one larval instar. Responses in growth parameters are recorded in the course of the manipulated instars, as well as at the level of the entire larval period. The negative relationship between development time and size in response to the inferior food quality, typical of the entire larval periods, is also observed within the manipulated instars taken separately. The manipulated larvae remain smaller than the larvae of the control group (significant in males only), even by the end of the subsequent instar during which all individuals are provided with superior host. In males, close to full size compensation by the time of pupation is achieved only by means of adding an extra larval instar. The inability of larvae to fully compensate during one and even two instars is considered as an indication of the presence of constraints on the within-instar growth pattern. An alternative, adaptational explanation for the incomplete compensation could be based on the cost of prolonged development period. Given the ecological context of the species' life history, such an explanation appears less likely. [ABSTRACT FROM AUTHOR]

Larvae of the whitemarked tussock moth, Orgyia leucostigma (J.E. Smith) (Lepidoptera: Lymantriidae), defoliate and contaminate blueberries, Vaccinium corymbostun L., in eastern North America, but infestations are often not detected until economic damage has been caused. To improve monitoring techniques and understand the phenology of the whitemarked tussock moth in blueberry, we compared four trap types and determined temperature-based phenology of this pest over two growing seasons. Large delta traps captured the greatest number of male moths, and similar moth captures were found with or without monthly lure changing. Traps placed at field perimeters adjacent to woods trapped significantly more moths than those inside fields, whereas position in the canopy (high versus low) did not affect captures. Under laboratory conditions, the lower develop- mental threshold for larvae was 12.3°C, in close agreement with field studies indicating a 12.8°C threshold. Using the 12.8°C threshold, monitoring of O. leucostigma cohorts on caged blueberry plants revealed a spring generation with egg hatch starting at 206 ± 3 growing degree-days (GDD) and a late-summer generation with egg hatch starting at 1,157 ± 52 CDD. Combined use of optimized monitoring methods and the phenology model for 0. leucostigma is expected to improve integrated management of this pest in blueberry. [ABSTRACT FROM AUTHOR]

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Polyphenol oxidase (PPO) is commonly believed to function as an effective antiherbivore defense in plants. PPO is induced in plants following herbivory, and insect performance is often negatively correlated with PPO levels. However, induced defenses create numerous changes in plants, and very little work has been done to test the direct effects of PPO on insect herbivores separately from other changes. This study examined the impacts of high levels of PPO on the performance of two species of tree-feeding caterpillars ( Lymantria dispar and Orgyia leucostigma) on poplar. Transgenic PPO-overexpressing poplar ( Populus tremula × Populus alba) was used as a source of elevated-PPO leaves, thereby controlling for the multiple effects of induction. In addition, the impacts of treating poplar foliage with high levels of purified mushroom PPO were examined on the two caterpillar species. Contrary to expectation, in several cases increased PPO levels had no significant effect on insect consumption or growth rates. Although one of the mechanisms by which PPO is believed to impact herbivores is via increased oxidative stress, the ingestion of large amounts of PPO had little or no effect on semiquinone radical and oxidized protein levels in the gut contents of lymantriid caterpillars. PPO activity in caterpillars is likely limited by the low oxygen and high ascorbate levels commonly found in their gut contents. This study questions whether induced PPO functions as an effective post-ingestive defense against tree-feeding caterpillars, and indicates that controlled, mechanistic studies are needed in other plant–herbivore systems to test for a direct effect of PPO on insect performance. [ABSTRACT FROM AUTHOR]

The article presents the results of bioassaying 39 samples of TM Biocontrol-1, a viral insecticide, from 10 different lots and various sizes of vacuum-sealed packages that were stored at -10°C for 5-15 yr. This is the first study to present potency data for a registered virus product stored for this length of time. Laboratory bioassays in insects from the same colony from which the TM Biocontrol-1 was produced showed that the stored viral insecticide is still effective, although it lost ≈30% of its effectiveness during storage. A direct correlation of this loss with the length of time in storage is not apparent. Bioassays also showed that there are significant differences in the susceptibility of Douglas-fir tussock moth, Orgyia pseudotsugata (McDunnough), larvae from different geographic regions to OpMNPV (family Baculoviridae, genus Nucleopolyhedrovirus) infection, Package size did not affect the potency of stored TM Biocontrol-1. There were no clear, significant differences in the effectiveness among lots of TM Biocontrol-1 processed by different organizations. [ABSTRACT FROM AUTHOR]

The slow-growth-high-mortality hypothesis proposes that increased development time in arthropods feeding on suboptimal food may result in an increased vulnerability to natural enemies. We measured the development time of the forest caterpillarOrgyia leucostigmaJ.E. Smith (Lepidoptera: Lymantriidae: Orgyiini) on two of its host plants and used a 7-year database on parasitism of this species to test the slow-growth-high-mortality hypothesis. We found that femaleO. leucostigmadeveloped faster when fed on willow (Salix nigraMarsh) than when fed on box elder (Acer negundoL.). However, only one of the parasitoids of the parasitoid community that attack these larvae followed the prediction of the slow-growth-high-mortality hypothesis. Overall parasitism ofO. leucostigmaon willow was greater than in box elder, contradicting the slow-growth-high-mortality hypothesis prediction. This is the first test of the hypothesis to consider parasitism by several species in the parasitoid community attacking a free-feeding herbivore on two distantly related plant species. [ABSTRACT FROM AUTHOR]

Abstract: The satin moth Leucoma salicis L. (Lepidoptera, Lymantriidae) is a frequent defoliator of poplar trees (Populus spp.) in Europe and Asia (China, Japan). Around 1920 the insect was introduced into the USA and Canada. In this paper, a multicapsid nucleopolyhedrovirus isolated from L. salicis larvae in Poland (LesaNPV) was characterized and appeared to be a variant of Orgyia pseudotsugata (Op) MNPV. O. pseudotsugata, the Douglas fir tussock moth (Lepidoptera, Lymantriidae), occurs exclusively in North America. Sequences of three conserved baculovirus genes, polyhedrin, lef-8, and pif-2, were amplified in polymerase chain reactions using degenerate primer sets, and revealed a high degree of homology to OpMNPV. Restriction enzyme analysis confirmed the close relationship between LesaNPV and OpMNPV, although a number of restriction fragment length polymorphisms were observed. The lef-7 gene, encoding late expression factor 7, and the ctl-2 gene, encoding a conotoxin-like protein, were chosen as putative molecular determinants of the respective viruses. The ctl-2 region appeared suitable for unequivocal identification of either virus as LesaNPV lacked a dUTPase gene in this region. Our observations may suggest that LesaNPV, along with L. salicis, was introduced into O. pseudotsugata after introduction of the former insect into North America in the 1920s. [Copyright &y& Elsevier]

Temporal and spatial variability in herbivory can be influenced by plant genotype, environmental conditions and their interactions. However, few studies correctly control for the relative influence of these factors. Here, I report results from a reciprocal common garden experiment designed to lease apart the effect of local environmental variation and plant genotype on the abundance of four insect species: Dasineura lupini (Felt), D. lupinorum (Gagne), Epinotia infuscana (Walsingham) and Orgyia vestusta (Boisduval). Full-sib/half-sib families of Lupinus arboreus. Sims were made within three different natal populations; replicates from each lupine family then were transplanted back into common gardens located in each of the three parental populations. In two separate years I measured how insect density varied between local environments, within a population of related lupine and among the three populations of lupine. For each insect species, local environment influenced density substantially and microsite variation within environments explained a significant amount of variation. Two insect species (E. infuscana and O. vetusta) congregated on plants originating from the same parental population more than lupine from other populations, while the other two insect species showed this pattern only in specific environments. Even though these insects were differentially abundant on lupine from the three natal populations, they rarely discriminated among individual genotypes within a population. Thus, insect density was affected by environmental factors unique to each site and partly by genotypes originating from the same natal origin, but rarely by fine-scale differences among genotypes from within one parental population. [ABSTRACT FROM AUTHOR]

(6Z,9Z, 11 S)-6,9-Heneicosadien- 11-ol (Z6Z9-1 1 S-ol-C21) and (6Z,9Z, L1R)-6,9-heneicosadien-11-ol (Z6Z9-1 LR-ol-C21) were identified as major sex pheromone components of female tussock moths, Orgyia detrita Guérin-Méneville (Lepidoptera: Lymantriidae), on the basis of (1) analyses of pheromone gland extracts of female O. detrita by coupled gas chromatographic- electro antenno graphic detection (GC-EAD) and CC mass spec tro metry, and (2) field trapping experiments with synthetic standards. Z6Z9-l 1S-ol-C21 and Z6Z9- 11 R-ol-C2 1 in combination, but not singly, attracted significant numbers of male moths. Racemic Z6Z9-11-ol-C21 was more attractive than the 1:3.5 (R:S) blend ratio found in pheromone gland extracts from female moths. Lower and higher homologues of Z6Z9-1 l-ol-C21 were also detected in GC-EAD recordings of pheromone extracts, and the racemic compounds enhanced attractiveness of Z6Z9-11-ol-C21 in field experiments, Because of trace amounts of these homologues in extracts, their enantiomeric composition could not be deter- mined. This is the first report of secondary alcohols as pheromone components in the ditrysian (advanced) Lepidoptera. [ABSTRACT FROM AUTHOR]

Empirical studies of spatial heterogeneity in parasitism by insect parasitoids have focused largely on patterns, while the many possible underlying mechanisms have been little studied in the field. We conducted experimental and observational studies on Tachinomyia similis (Diptera: Tachinidae) attacking western tussock moths (Orgyia vetusta; Lepidoptera: Lymantriidae) on lupine bushes at Bodega Bay, Calif., USA. We examined several foraging behaviors that have been hypothesized to create density-dependent variation in parasitism rates, including spatial aggregation of parasitoids to high host density, mutual interference among searching parasitoids and decelerating functional responses of the parasitoid. At the spatial scale of individual bushes, we detected both aggregation to a high density and a decelerating functional response. The resulting spatial pattern of parasitism was best fit by two models; one included an effect of parasitoid aggregation and the other included an effect of aggregation and a decelerating functional response. Most of the variation in parasitism was not correlated with density of O. vetusta. [ABSTRACT FROM AUTHOR]

The Op-iap3 gene from the baculovirus Orgyia pseudotsugata M nucleopolyhedrovirus (OpMNPV) inhibits apoptosis induced by a mutant of Autographa californica MNPV (AcMNPV) that lacks the antiapoptotic gene p35, as well as apoptosis induced by a wide range of other stimuli in both mammalian and insect cells. However, the role of Op-iap3 during OpMNPV infection has not been previously examined. To determine the function of the Op-IAP3 protein during OpMNPV infection, we used RNA interference (RNAi) to silence Op-iap3 expression during OpMNPV infection of Ld652Y cells. Infected cells treated with Op-iap3 double-stranded RNA (dsRNA) did not accumulate detectable Op-iap3 mRNA, confirming that the Op-iap3 gene was effectively silenced. Op-IAP3 protein was found to be a component of the budded virion; however, in OpMNPV-infected cells treated with Op-iap3 dsRNA, the Op-IAP3 protein that was introduced by the inoculum virus decreased to almost undetectable levels by 12 h after dsRNA addition. Apoptosis was observed in infected cells treated with Op-iap3 dsRNA beginning at 12 h, and by 48 h, almost all of the cells had undergone apoptosis. These results show for the first time that Op-IAP3 is necessary to prevent apoptosis during OpMNPV infection. In addition, our results demonstrate that the RNAi technique can be an effective tool for studying baculovirus gene function. [ABSTRACT FROM AUTHOR]

The whitemarked tussock moth (WMTM), Orgyia leucostigma (J. E. Smith), is a major pest of coniferous and deciduous trees in eastern Canada. Chemical identification of its sex pheromone depended primarily on GC-EAD and HPLC analysis, with confirmation of behavioral activity by wind tunnel and field tests. We identified (Z,Z)-6,9-heneicosadien-11-one (Z,Z-6,9-ket) at 4-5 ng/female as the only essential sex pheromone component. Also detected in female extracts were (Z)-6-heneicosen-11-one (Z6-ket) at 2.5 ng/female, (Z,E)-6,8-heneicosadien-11-one (Z,E-6,8-ket) at about 0.5 ng/female, and a trace amount of (Z,E)-6,9-heneicosadien-11-one. Traps containing as little as 1 µg of Z,Z-6,9-ket attracted males at low population levels, indicating it is a potent sex attractant. Traps baited with Z6-ket attracted few males, and in windtunnel bioassays it was at least 100-fold less attractive to males than Z,Z-6,9-ket. No improvement in trap catch occurred with the addition of Z6-ket in various binary mixtures with Z,Z-6,9-ket, including the female ratio, and a ternary mixture of Z,Z-6,9-ket, Z6-ket, and Z,E-6,8-ket in the 9:5:1 ratio detected in females was no better than Z,Z-6,9-ket alone. We attribute the presence of Z,E-6,8-ket and Z,E-6,9-ket in female extracts to the spontaneous and rapid stereospecific isomerization of Z,Z-6,9-ket at room temperature. Male flight began at sunset but peaked during the second half of the night. [ABSTRACT FROM AUTHOR]

Between 1996 and 1998 an eradication programme was undertaken in Auckland's eastern suburbs against the newly established lymantriid moth, Orgyia thyellina. The operation involved the aerial application of Btk over 4000 hectares of suburban Auckland and ground spraying of all known infested sites. Key components of the programme were: accurate definition of the infested area, quarantine action to prevent further spread, aerial and ground application of Btk, intensive monitoring using live female moths and a synthetic pheromone, strong science input to every facet of the programme, and a major communications initiative. Orgyia thyellina was declared eradicated in June 1998 and has not reappeared since then. Operation Ever Green, as the programme was named, was the first ever successful eradication of a forest pest established in an urban area, worldwide. [ABSTRACT FROM AUTHOR]

Initiation of insect outbreaks is poorly understood, and may involve sporadic events that temporarily release insect populations from predation or parasitism. While studying a declining outbreak of the western tussock moth (Orgyia vetusta) on bush lupine (Lupinus arboreus), we witnessed the onset of a new tussock moth outbreak, separated by 1,000 m in space and 2 months in phenological timing from the original population. This new population underwent explosive growth for 2 years and then collapsed because of a massive die-off of lupines. We tested whether during its growth phase, this new outbreak benefited by escaping in either space or time from the natural enemies attacking the original population. In experimental populations on single bushes, we compared predation and parasitism at the sites of the new and the old outbreak. At the site of the old outbreak, we compared predation and parasitism early and late in the season. Parasitism was significantly lower and population growth significantly higher at the new outbreak site than the old one. Neither seasonal timing, predator exclusion, nor their interaction significantly affected survival at either site. Thus the new outbreak appeared to escape in space from parasitism. These results corroborate our previous experimental findings, which suggest that as predicted by theory, the interaction between the tussock moth and its parasitoids can produce large-scale spatial patterning in population densities. [ABSTRACT FROM AUTHOR]

The white-spotted tussock moth, Orgyia thyellina, was found in Auckland, New Zealand, in 1995. An eradication campaign against this potential pest is currently underway, but in the event that it is unsuccessful, agents for population suppression will be required. As no pathogens were available from O. thyellina, two nucleopolyhedroviruses (NPVs) from Orgyia pseudotsugara (OpMNPV ‘Virtuss[sup TM]’) and Orgyia leucostigma (OrleSNPV) were imported from Canada and tested for virulence against O. thyellina. At 10[sup 5] polyhedral inclusion bodies per cm[sup 2] and above, 100% mortality was achieved with first to second instar larvae by 15 days. Molecular comparison of sequences from the pol gene region of each virus demonstrated that they were from different genotypic groups of NPVs. [ABSTRACT FROM AUTHOR]

Presents research which supported spatial models in ecology predicting that populations may form patchy distributions within continuous habitats through strong predator-prey or host-parasitoid interactions combined with limited dispersal. Study of tussock moths, Orgyia vetusta; Implications of research.