Search Results (10)

The fall webworm, Hyphantria cunea (Drury) (Lepidoptera: Erebidae: Arctiidae), is a highly dangerous global invasive pest. It exhibits two races: the “red-headed” and “black-headed,” each with distinct ecological traits. However, much remains unknown regarding the climatic niche and potential global distribution suitability of these two races. This study utilized the COUE framework, and Maxent models to investigate the climatic niche differences between these two races and predict their respective potential suitable distributions globally. Our findings indicate substantial differences in the climatic niches between the two races of H. cunea, with the red-headed race demonstrating greater invasive potential compared to the black-headed race. Both races pose significantly larger potential threats globally than currently recognized. They are capable of survival in North America, South America, Europe, Asia, Africa, and Australia. Specifically, Asia and Europe exhibit potentially greater threats from the black-headed race, while other regions show greater potential harm from the red-headed race. This study highlights significant differences in the climatic niches between the two races of H. cunea, as well as the substantial presence of uninvaded suitable habitats globally for both races. Therefore, future efforts to prevent H. cunea invasions should prioritize control strategies tailored to each race and especially emphasize potential regions that have their respective suitable habitats that have not yet been invaded. Full article

Insects often encounter starvation stress, especially during invasion spread or population outbreaks. The fall webworm, Hyphantria cunea (Drury) (Lepidoptera: Arctiidae), is an important invasive pest in China, and the starvation resistance of its larvae determines population spread and resulting outbreak threat. In this study, we investigated the starvation resistance of H. cunea larvae and the effects of starvation stress on their life history and adult fitness. Larval starvation resistance increased along with the instar stage, and the second-day sixth instar molt was critical for starvation resistance. The response to starvation stress was reflected in multiple biological indicators observed in H. cunea. Complete food deprivation reduced the pupation survival rate of sixth instar larvae, prolonged their developmental duration, reduced pupal and adult body mass, shortened adult forewing length and lifespan, and reduced female egg production. The sixth instar larvae showed a certain ability to recover after refeeding. However, negative impacts of the starvation period on larval life history traits, such as pupation survival rate, pupal and adult body mass, adult longevity, and fecundity, were still observed even after refeeding, and the effects of refeeding were affected by larval starvation duration and refeeding mode. These results suggested that H. cunea larvae were highly resistant to starvation, that starvation stress negatively affected their larval life history and adult fitness, and that the pattern of the effects of post-starvation refeeding on larval and adult fitness was related to the duration of starvation and the refeeding mode. The results of this study offer important insights into understanding the physiological response mechanisms of invasive insects under starvation stress. Full article

Transgenic poplars have been used to control quarantine pests worldwide, such as the fall webworm (Hyphantria cunea, FW). However, the studies on the resistance mechanism of FW to Cry toxins are limited. This study obtained an FW strain with 45-fold resistance to Cry1Ab toxin by continuous screening in the laboratory. The resistance to Cry1Ab was autosomally completely recessive, and it had approximately 40-fold cross-resistance to Cry1Ac but no cross-resistance to Cry2Ab toxin. Analysis of indoor population life tables for the resistant and susceptible strains found no significant difference in the net reproduction rate (R₀) between the two strains. The resistant strain had an insignificantly longer larval development duration and a comparable pupation rate, pupal weight, emergence rate, eggs laidper female, and egg hatching rate compared to the susceptible strain. This indicated that there was no fitness cost for Cry1Ab resistance. Our study helps in evaluating the risk of resistance to Cry1Ab toxin and the mechanisms of resistance to Cry1Ab toxin in FW. Full article

The Lichen moth, Lyclene dharma dharma (Arctiidae, Lithosiinae), plays a significant role in forest ecosystem dynamics. A concise and novel method to synthesize the active sex pheromone components, (S)-14-methyloctadecan-2-one ((S)-1), (S)-6-methyloctadecan-2-one ((S)-2), and their enantiomers has been developed. Key steps in the synthesis include the use of Evans’ chiral auxiliaries, Grignard cross-coupling reactions, hydroboration–oxidation, and Wacker oxidation. The synthesized sex pheromone components hold potential value for studies on communication mechanisms, species identification, and ecological management. Full article

The fall webworm (FWW), H. cunea (Drury) (Lepidoptera: Erebidae: Arctiidae), is an extremely high-risk globally invasive pest. Understanding the invasion dynamics of invasive pests and identifying the critical factors that promote their spread is essential for devising practical and efficient strategies for their control and management. The invasion dynamics of the FWW and its influencing factors were analyzed using standard deviation ellipse and spatial autocorrelation methods. The analysis was based on statistical data on the occurrence of the FWW in China. The dissemination pattern of the FWW between 1979 and 2022 followed a sequence of “invasion-occurrence-transmission-outbreak”, spreading progressively from coastal to inland regions. Furthermore, areas with high nighttime light values, abundant ports, and non-forested areas with low vegetation cover at altitudes below 500 m were more likely to be inhabited by the black-headed FWW. The dynamic invasion pattern and the driving factors associated with the fall webworm (FWW) provide critical insights for future FWW management strategies. These strategies serve not only to regulate the dissemination of insects and diminish migratory tendencies but also to guarantee the implementation of efficient early detection systems and prompt response measures. Full article

The fall webworm Hyphantria cunea (Drury) is native to North America and Mexico and has currently expanded its distribution to the temperate areas of the Northern Hemisphere including Japan. According to the data on seasonal fluctuations of this moth for 18 years collected in western-central Japan, the abundance of adults of the overwintered generation showed a negative correlation with winter temperature. We investigated survival, weight loss, and fungal infection of diapausing pupae at 3.0 (an approximate temperature of cold winter) and 7.4 °C (a temperature of mild winter). In the results, mortality was higher and weight loss was larger in pupae exposed to 7.4 °C than in those exposed to 3.0 °C. In addition, pupae that were heavier at the start of cold exposure survived longer than lighter ones. Furthermore, almost all pupae that died at 7.4 °C were infected by fungi. It has been reported that the distribution range of this moth shifts to higher latitudes. According to the experiments conducted, it has been observed that warm winters can lead to a decrease in pupae weight and an increase in fungal deaths; however, the impact of warm winters on populations in the field can be more complicated and multifaceted. Full article

The pollination and the breeding system of Epidendrum densiflorum (Orchidaceae: Laeliinae) were studied through fieldwork and controlled pollinations in cultivated plants. Pollination is exclusively promoted by males of diurnal Lepidoptera: five species of Arctiinae and four of Ithomiinae were recorded as pollinators. These male insects are known to obtain alkaloids (through the nectar) in flowers of Asteraceae and Boraginaceae. However, the flowers of E. densiflorum are nectarless, despite presenting a cuniculus (a likely nectariferous cavity). Pollinators insert their proboscides into the flowers and remove or deposit the pollinaria while searching for nectar. The floral tube is very narrow, and insects struggle for up to 75 min to get rid of the flowers. Plants are pollinator-dependent and nearly fully self-incompatible. Pollinarium removal, pollination, and fruiting success (2.85%) were very low; facts that are consistent with the patterns globally observed in deceptive (rewardless) orchids. Nilsson’s male efficiency factor (0.245) was also low, indicating pollen loss in the system. Based on our field observations, we suggest that the fragrance of E. densiflorum likely mimics these plants that are normally used as a source of alkaloids by male Lepidoptera, a hypothesis that we intend to test in the future. Full article

Hyphantria cunea Drury (Lepidoptera: Arctiidae) is a worldwide quarantine pest that has a wide range of host plants. Quercetin is a secondary metabolite involved in chemical defense processes in plants. To understand how H. cunea adapt to quercetin in its host plants, we determined the effects of quercetin on larval mortality, growth, nutritional indices, and the activity or content of detoxification enzymes in H. cunea larvae by feeding them an artificial diet containing different concentrations of quercetin. Our results showed that 0.50% quercetin treatment significantly prolonged the development duration of H. cunea larvae and inhibited growth of H. cunea. Nutritional indices analysis indicated that quercetin significantly affected nutrient use, including effects on the approximate digestibility, consumption index, relative growth rate, and efficiency of conversion of ingested food to body substance. Furthermore, our results revealed that quercetin reduced the content of carboxylesterases, and increased the activity or content of glutathione S-transferases, UDP-glucuronosyltransferases, and ATP-binding cassette transporters in H. cunea larvae. These results provide a foundation for revealing the adaptation that H. cunea use to adapt to quercetin in host plants. Full article

RNA interference (RNAi) technology is a promising approach used in pest control. The efficiency of RNAi varies considerably among different insect species, and growing evidence suggests that degradation of double-stranded RNA (dsRNA) prior to uptake is an important factor that limits RNAi efficiency in insects. Our recent work on fall webworm (Hyphantria cunea), an important invasive pest in China, showed a relatively low silencing efficiency of RNAi through dsRNA injection, which is considered the most feasible dsRNA delivery method for inducing RNAi, and the factors involved in the mechanism remain unknown. Herein, we first detected the dsRNA-degrading activity in the hemolymph and gut content of H. cunea in ex vivo assays and observed rapid degradation of dsRNA, especially in the hemolymph, which was complete within only 10 min. To determine whether dsRNA degradation could contribute to the low effectiveness of RNAi in H. cunea, four dsRNA nuclease (dsRNase) genes, HcdsRNase1, HcdsRNase2, HcdsRNase3, and HcdsRNase4, were identified by homology searching against the H. cunea transcriptome database, and their transcript levels were subsequently investigated in different tissues, developmental stages, and after dsRNA injection. Our results show that HcdsRNases are highly expressed mainly in gut tissues and hemolymph, and the expression of HcdsRNase3 and HcdsRNase4 were significantly upregulated by dsGFP induction. RNAi-of-RNAi studies, using HcCht5 as a reporter gene, demonstrated that silencing HcdsRNase3 and HcdsRNase4 significantly increases RNAi efficacy via dsHcCht5 injection, and co-silencing these two HcdsRNase genes results in a more significant improvement in efficacy. These results confirm that the RNAi efficacy in H. cunea through dsRNA injection is certainly impaired by dsRNase activity, and that blocking HcdsRNases could potentially improve RNAi, providing a reference for related studies on insects where RNAi has low efficiency. Full article

Increasing areas of artificial afforestation and poplar monoculture in China have led to serious problems with insect pests. The development of genetic engineering technology, such as transgenic modification with Bacillus thuringiensis (Bt) genes, provides novel solutions to the pest problem. We generated a Bt-Cry1Ah1 gene incorporating codon optimization and transferred it into Populus deltoides × P. euramericana cv “Nanlin895” using an Agrobacterium-mediated method. The resulting Bt-Cry1Ah1 transgenic poplars were planted in the field with permission from the State Forestry Administration in 2017. Field and laboratory studies were conducted in Jiangsu, China, to investigate the effects of these transgenic poplars expressing the Cry1Ah1 protein on target and non-target pests and their parasitic natural enemy. Target pests included Hyphantria cunea (Lepidoptera, Arctiidae), Micromelalopha troglodyta (Lepidoptera, Notodontidae), and Clostera anachoreta (Lepidoptera, Notodontidae). Plagiodera versicolora (Coleoptera, Chrysomelidae) served as the non-target pest. Laboratory trials showed that the six transgenic poplar lines exhibited resistance against the target insects. The corrected mortality rates of the target pest larvae fed leaves from the six lines were as high as 87.0%, significantly higher than that of the control. However, the corrected mortality rate of the non-target pest larvae was markedly lower and did not differ significantly from that of the control. Field experiments showed that transgenic poplar exhibited resistance against H. cunea and M. troglodyta. Field mortality rates were slightly higher than laboratory mortality rates. In addition, we investigated Chouioia cunea (Hymenoptera, Eulophidae) as a parasitoid of H. cunea pupae that had been fed transgenic poplar leaves. The emergence time, parasitism rate, and abundance of C. cunea did not differ significantly from those of the control. Therefore, Bt-Cry1Ah1 transgenic poplar can be used to effectively control damage by target insect pests without negatively affecting non-target insects and parasitoids. Full article