Journal of Insect Science最新文献

Longitarsus candidulus (Foudras) is a thermophilic flea beetle species widely distributed in the Mediterranean Basin and associated with Daphne gnidium L. and Thymelaea hirsuta (L.). Longitarsus laureolae Biondi and Longitarsus leonardii Doguet, phylogenetically closely related to L. candidulus, show together a peculiar and rare disjunct distribution along the central-southern Apennines and the Cantabrian-Pyrenean mountain system, respectively. Both are associated with Daphne laureola L. in mesophilic habitats. We used "ecological niche modeling" to infer the Pleistocene dynamics in the distribution of the three flea beetle species and their host plants. We interpreted their current distributions, paying particular attention to the presumed time of species divergence as inferred from recent studies. The differentiation of L. laureolae and L. leonardii from L. candidulus likely represents a response to the marked climatic changes during the Late Pliocene. Such a split was likely associated with a trophic niche shift of the laureolae/leonardii ancestor towards the typically mesophilic host plant D. laureola. The subsequent split between L. laureolae and L. leonardii, possibly due at first to the niche competition, was then boosted by an allopatric divergence during the Middle Pleistocene, likely caused by a large area of low environmental suitability for both species, mainly located between the northern Apennines and the south-western Alps.

The ambrosia beetles Xylosandrus germanus (Blanford) and Xylosandrus crassiusculus (Motschulsky) are nonnative pests in orchards and nurseries in North America. They construct galleries in the sapwood of stressed woody hosts and culture a symbiotic fungus as food for their offspring. Preventing attacks is preferred but a better understanding of their biology may elucidate additional avenues for control. Recent phenological studies are lacking for X. germanus that is common in New York, and biological information on brood and gallery development is lacking for the less abundant X. crassiusculus. We conducted both outdoor rearing and laboratory studies to better understand the timing of key events in the maturation of their galleries, particularly associated with the symbiotic fungi. Two and a partial third summer generation were consistently observed over 2 yr for X. germanus; and thus, 3 flights of adult females (foundresses) occurred each summer from mid-April to late September. In both the field and laboratory, initial growth of the symbiotic fungus occurs within a few days of gallery initiation. The rapid development of the reproductive tract and oviposition by X. germanus appears to be stimulated by the presence of the fungus. Fungal, reproductive, and brood development are similar for the related X. crassiusculus in laboratory studies; the 2 species mainly appear to differ in size. The lag between beetle colonization and reproduction currently seems too brief to be exploited for management. Disruption of other stages in gallery development should also be explored to minimize the beetle damage if attacks cannot be prevented.

The American cockroach, Periplaneta americana (Blattodea: Blattidae), is a prevalent urban pest with significant public health implications. This study aimed to develop and validate novel microsatellite markers to understand the genetic diversity and population genetic structure of P. americana. In this study, a total of 397,898 microsatellite markers were developed based on 24.6 million genomic DNA sequences. Twenty microsatellite markers were selected and amplified with varying numbers of alleles ranging from 0 to 35. Seven out of 20 markers were characterized for their polymorphism and amplification efficiency. The polymorphic information content (PIC) values of these markers were high (0.669 to 0.950) implying their effectiveness. These markers also revealed 7 to 35 alleles per locus across tested samples, highlighting their utility in assessing the extensive genetic variation within Periplaneta americana populations. These results provide insightful information that may be applied to the genetic analysis of the American cockroach population using the developed species-specific microsatellite marker.

Heilipus lauri is a specialist avocado seed feeding weevil native to parts of México and is an invasive pest in Colombia. This weevil is considered an incursion risk because possible unintended introductions into areas outside of its native range can result in establishment, which threatens avocado production in invaded regions. Despite being a well-recognized pest of avocados, relatively little is known about oviposition biology, behavior, and cultivar preferences of this weevil. Field studies in commercial Hass avocado orchards in México and laboratory studies in a quarantine facility in California (USA) indicated that H. lauri prefers to oviposit into middle and bottom thirds of fruit. In the laboratory, an average of 1.7 eggs (range 1-6 eggs) are laid over a 24-h period in oviposition chambers by individual females. Conspecifics add eggs to these clutches, with up to 17 eggs being recorded in 1 oviposition chamber. This finding suggests that H. lauri does not use an oviposition deterring pheromone. Female weevils readily oviposit in artificial holes representing mechanical wounds on fruit. In comparison to the commercially dominant Hass variety, fruit from Lamb Hass and G22, a native Guatemalan variety, and to a lesser extent Gem, may be less preferred for oviposition when females have a choice of fruit in which to oviposit. Videography studies indicated that H. lauri exhibits predominantly diurnal activity with respect to oviposition behaviors, feeding, and walking.

This study aimed to investigate the effects of symbiosis on the life history of host insects and address their implications at the host population level. We evaluated the effects of symbiotic bacteria Caballeronia insecticola on its host Riptortus pedestris (Fabricus) (Hemiptera: Alydidae) from cohorts for nymphal development, adult survivorship, and female reproduction. Then, life table parameters were compared between symbiotic and apo-symbiotic groups, and the effects of symbiosis on the abundance of R. pedestris were simulated for varying proportions of symbiotic individuals in host populations. We found that symbiosis significantly accelerated the nymphal development and reproductive maturation of females. However, symbiosis incurred survival cost on adult females, reducing their longevity by 28.6%. Nonetheless, symbiotic females laid significantly greater numbers of eggs than the apo-symbiotic during early adult ages. This early reproductive investment negated the adverse effect of their reduced longevity, resulting in the mean lifetime fecundity to not significantly differ between the 2 groups. Indeed, total cohort fecundity of the symbiotic group was 1.3-fold greater than that of the apo-symbiotic group. Life table analysis demonstrated shorter generation time and greater population growth rate in the symbiotic population. Finally, the simulation model results indicate that an increase in the proportion of symbiotic R. pedestris favored the population growth, increasing the population size by 1.9 times for every 25% increase in the proportion of symbiotic individuals. Our study demonstrates that symbiont-mediated changes in the life history parameters of host individuals favor the host population growth, despite substantial reduction in the female longevity.

Dietary supplementation has been proposed as a sustainable way to improve the health and resilience of honey bees (Apis mellifera, L.), as the decline in their numbers in recent decades has raised scientific, environmental, and economic concerns. Spermidine, a natural polyamine, has been shown to be a promising substance for honey bee supplementation, as its health-promoting effects have been demonstrated in numerous studies and in different organisms. As already shown, supplementation with spermidine at a certain concentration prolonged lifespan, reduced oxidative stress, and increased antioxidative capacity in honey bees. The aim of the present study was to investigate whether spermidine supplementation affects gene expression and/or enzyme activity of antioxidative and detoxification enzymes and immune response markers in honey bee workers. The different gene expression and enzyme activity patterns observed in abdominal and head tissues in response to spermidine supplementation suggest tissue-specific and concentration-dependent effects. In addition, the immune response markers suggest that spermidine has the ability to boost honey bee immunity. The observed changes make a valuable contribution to understanding the molecular mechanisms by which spermidine may exert its beneficial effects on the bee's health and lifespan. These results support the idea of the use of spermidine supplementation to promote bee health and resilience to environmental stressors, emphasizing that the dose must be carefully chosen to achieve a balance between the pro- and antioxidant effects of spermidine.

Insulin receptor substrate (IRS) proteins are key mediators in insulin signaling pathway. In social insect lives, IRS proteins played important roles in caste differentiation and foraging, but there function in disease defenses such as active immunization has not been reported yet. To investigate the issue, we successfully suppressed the IRS gene 3 days after dsRNA injection. Suppressing IRS gene increased the contents of glucose, trehalose, glycogen, and triglyceride and decreased the content of pyruvate in termites, and led to the metabolic disorder of glucose and lipids. IRS suppressing significantly enhanced grooming behaviors of nestmates of fungus-contaminated termites and hence increased the conidial load in the guts of the nestmates. Additionally, IRS suppressing led to significant downregulation of the immune genes Gram-negative bacteria-binding protein2 (GNBP2) and termicin and upregulation of the apoptotic gene caspase8, and hence diminished antifungal activity of nestmates of fungus-contaminated termites. The above abnormal behavioral and physiological responses significantly decreased the survival rate of dsIRS-injected nestmates of the fungus-contaminated termites. These findings suggest that IRS is involved in regulation of active immunization in termites, providing a better understanding of the link between insulin signaling and the social immunity of termites.

This research focuses on the effect of environmental factors on the phenology and distribution of the Tentyria species (Coleoptera: Tenebrionidae) from Doñana National Park (SW Iberian Peninsula). Data are derived from the results of a project carried out 20 years ago, aimed at inventorying the coleopteran of the park. This information provides a framework for comparison with current or future states since the time elapsed is long enough to detect variations. As the classification of Tentyria species is complex and controversial, the first aspect to be addressed was the taxonomical verification of the species. Indeed, they were T. platyceps Steven., T. subcostata Solier., T. bifida Bujalance, Cárdenas, Ferrer and Gallardo, and T. donanensis Bujalance, Cárdenas, Ferrer and Gallardo. Sampling consisted of 2 years of monthly pitfall trapping, encompassing the surface of the park and adjacent areas. Data on adult seasonal activity and spatial distribution of the species were obtained from the specific abundance in each sampling plot. Phenologically, the 4 species were mainly summer species, with unimodal or bimodal curves depending on the species. The distribution of the species was quite uneven: while T. donanensis was ubiquitous, T. subcostata was restricted to the southern coastal area of the park, and T. platyceps and T. bifida were recorded in the northern half, in marshes or inland forests, respectively. Our results also suggest that extreme temperatures may impose major constraints on the spatial distribution of Tentyria species, which could affect Doñana's biodiversity in the future scenery of thermal rise linked to climate change.

Poplar is a valuable tree species that is distributed all over the world. However, many insect pests infest poplar trees and have caused significant damage. To control poplar pests, we transformed a poplar species, Populus davidiana × P. bolleana Loucne, with the dsRNA of the chitinase gene of a poplar defoliator, Clostera anastomosis (Linnaeus) (Lepidoptera: Notodontidae), employing an Agrobaterium-mediated approach. The transgenic plant has been identified by cloning the T-DNA flanking sequences using TAIL-PCR and quantifying the expression of the dsRNA using qPCR. The toxicity assay of the transgenic poplar lines was carried out by feeding the target insect species (C. anastomosis). The results showed that, in C. anastomosis, the activity of chitinase was significantly decreased, consistent with the expression on mRNA levels, and the larval mortality was significantly increased. These results suggested that the transgenic poplar of dsRNA could be used for pest control.

World food supplies rely on pollination, making this plant-animal relationship a highly valued ecosystem service. Bees pollinate flowering plants in rangelands that constitute up to half of global terrestrial vegetation. Livestock grazing is the most widespread rangeland use and can affect insect pollinators through herbivory. We examined management effects on bee abundance and other insect pollinators on grazed and idle sagebrush rangelands in central Montana, USA. From 2016 to 2018, we sampled pollinators on lands enrolled in rest-rotation grazing, unenrolled grazing lands, and geographically separate idle lands without grazing for over a decade. Bare ground covered twice as much area (15% vs. 7) with half the litter (12% vs. 24) on grazed than idle regardless of enrollment. Bee pollinators were 2-3 times more prevalent in grazed than idle in 2016-2017. In 2018, bees were similar among grazed and idled during an unseasonably wet and cool summer that depressed pollinator catches; captures of secondary pollinators was similar among treatments 2 of 3 study years. Ground-nesting bees (94.6% of total bee abundance) were driven by periodic grazing that maintained bare ground and kept litter accumulations in check. In contrast, idle provided fewer nesting opportunities for bees that were mostly solitary, ground-nesting genera requiring unvegetated spaces for reproduction. Managed lands supported higher bee abundance that evolved with bison grazing on the eastern edge of the sagebrush ecosystem. Our findings suggest that periodic disturbance may enhance pollinator habitat, and that rangelands may benefit from periodic grazing by livestock.