Environmental Entomology最新文献

Mating disruption is achieved by releasing synthetic pheromones into crop systems to disrupt natural mating behavior of targeted pests. Dispensers of synthetic pheromones are deployed in various crops with the intent of limiting males from finding females thereby reducing or delaying mating to lower pest populations over time. Codling moth (CM) (Cydia pomonella L.) and oriental fruit moth (OFM) (Grapholita molesta) (Busck) are worldwide pests of pome and stone fruits. We investigated the hypothesis that pupal exposure to species-specific sex pheromones affects subsequent mate-finding ability, mating behavior, and reproductive output of adult CM and OFM. Laboratory experiments revealed that pheromone exposure during the pupal stage significantly impacts CM reproductive output and mate-finding, whereas these effects were not observed with OFM. Our findings suggest that targeted deployment of pheromones to cause pupal exposure may enhance control of certain species such as CM.

The stimulatory and protective response known as hormesis elicits an often over compensatory response resulting in life-history trait improvements. There are an array of abiotic and biotic agents that have been shown to trigger hormesis; most commonly studied are chemicals, temperature, and low oxygen. Investigations into low-oxygen exposures that activate the hormetic response reveal that insect performance can be dramatically improved by single short low-oxygen events, but the focus of this work has been primarily on short-term, transitory protection afforded by hormesis. Few reports examine whether the effect is longer lasting or lifelong. We previously reported that one hour of anoxia was enough to induce a hormetic response in the alfalfa leafcutting bee, Megachile rotundata (Hymenoptera: Megachilidae). Here, we investigated the long-term effects of this response by looking at starvation resistance, flight, and locomotory activity throughout the life of the adult bees. In addition, we studied the effects of anoxia hormesis on multiple reproductive metrics. Anoxia hormesis had lifelong positive effects for flight in both sexes. We also recorded higher starvation survival in bees that experienced hormesis. This improvement in performance came at a steep reproductive cost (ie reduction in fecundity). However, no costs or benefits were passed to the next generation. We hypothesize that using anoxia hormesis in the context of pollination services by this species should result in bees that are more active in the field, thereby increasing the numbers of visits to flowers throughout their entire life.

Exotic granulate ambrosia beetle, Xylosandrus crassiusculus (Motschulsky), black stem borer, Xylosandrus germanus (Blandford), and black twig borer, Xylosandrus compactus (Eichhoff) are serious pests of woody ornamental trees in nurseries. Woodlots often surround ornamental nurseries, where the ambrosia beetles fly into nurseries and attack young trees. The woodlots are either dominated by hardwood trees, such as Oaks (Oak spp.), maples (Acer spp.), or pine trees, mainly loblolly pine (Pinus taeda L.). It is unclear if the woodlot type would influence the abundance of ambrosia beetle pests flying outside the woodlot. Thus, this study aimed to determine whether the hardwood or pine-dominated stand affects the relative abundance of ambrosia beetle pests outside the woodlot. In 2023 and 2024, experiments were conducted by deploying 3 ethanol-lured plastic bottle traps in 4 hardwood and 4 pine-dominated woodlots in mid-Georgia (USA). The overall captures of X. crassiusculus and X. germanus were significantly greater in the hardwood than in the pine-dominated woodlots in both years. The numbers of X. crassiusculus and X. germanus collected in traps were not consistently significantly different between the hardwood and pine-dominated woodlots for most sampling dates. The captures of X. compactus were not influenced by woodlot type. This suggests that although ambrosia beetle pests were collected from both hardwood and pine-dominated woodlots in both years, the risk of infestation in nurseries is greater from the adjacent hardwood than pine-dominated woodlots.

Aggregation-sex pheromones, that attract both sexes, are produced by male cerambycid beetles (Coleoptera: Cerambycidae) of the subfamilies Cerambycinae, Lamiinae, and Spondylidinae. Here, we present the results of a field experiment conducted at multiple sites in southern Texas, primarily near the border with the state of Tamaulipas, Mexico. At each site, we deployed traps baited with a 6-component blend of known pheromones of cerambycine and lamiine species + an ethanol lure, a 5-component blend of lamiine pheromones + an ethanol lure, an ethanol lure alone, and a solvent control. Over a ~3-wk period, 846 beetles of 51 species were trapped, representing 36 cerambycine, 14 lamiine, and one prionine species, and one species in the closely related family Disteniidae. For species collected from at least 5 study sites, nonparametric tests of treatment effects revealed that the generic 6-component blend + ethanol attracted significant numbers of one cerambycine species, while the lamiine blend + ethanol attracted one cerambycine species and 2 lamiine species. The ethanol lure attracted 2 additional cerambycine species in significant numbers. For species that were captured at fewer sites, chi-square goodness-of-fit tests showed that the 2 pheromone blends + ethanol attracted significant numbers of another 6 species of cerambycines and 4 species of lamiines. Captures noteworthy from the standpoint of collection records include the rare species Leptostylopsis lutea Dillon, and Lochmaeocles cornuticeps cornuticeps (Schaeffer) and Thryallis undatus (Chevrolet), 2 species which have rarely been reported outside Sabal Palm Sanctuary in Cameron County, Texas.

Disturbance plays a critical role in the ecology of forests including influencing the abundance and diversity of fauna. Although numerous studies have focused on forest responses to various disturbance events, less attention has been given to arthropod community responses. California experienced an extreme, multi-year drought from 2012 to 2015 which severely stressed trees and incited epidemics of several bark beetle species (Coleoptera: Curculionidae: Scolytinae). Water stress and bark beetles contributed to a significant mortality event of hundreds of millions of trees in the central and southern Sierra Nevada, causing significant structural and compositional changes in forests. Our study sought to characterize woodborer and wood-decay-related beetle responses to various levels of tree mortality and snag (dead standing tree) retention resulting from this tree mortality event. Of particular interest were responses to differences in the orientation of dead wood, standing snags versus fallen snags. Ethanol-baited panel flight intercept traps were deployed for multiple weeks in 2022 and 2023 on plots representative of 3 disturbance classes: (i) low tree mortality (<30%), (ii) high tree mortality (>50%) with low snag fall (≤50%), and (iii) high tree mortality (>50%) with high snag fall (>60%). Woodborers and wood-decay-related beetle assemblages were compared at the family and species level. Our analyses revealed several significant differences in community assemblages among disturbance classes. Despite these differences, our results failed to reveal clear, qualitatively distinctive assemblages among disturbance classes. Rather, we could only conclude general patterns from the observed dissimilarities in richness and abundance. In general, we observed a greater diversity of woodborers on high-mortality plots than on low-mortality plots. Similarly, the diversity of wood-decay-related beetles generally increased with greater amounts (basal area) of snag fall. The amount of tree mortality and snag fall were positively related to several woodborer and wood-decay-related beetles. Observed beetle assemblages, their corresponding life histories, and the influences of altered habitat availability are discussed.

The mechanisms used to facilitate mate location among insects-such as pheromones-can inhibit interspecific attraction and confer reproductive isolation. However, pheromone components seem conserved within the genus Monochamus (Coleoptera: Cerambycidae) with the compound 2-(undecyloxy)ethanol (referred to as monochamol) being identified as the sex-aggregation pheromone or putative pheromone attractant for at least 15 species in this genus. This pheromone parsimony suggests the existence of additional isolating mechanisms. Here we describe the results of laboratory and field assays of additional mechanisms, including laboratory volatile collections and field trapping experiments that assessed the potential presence of additional pheromone components, diel rhythms of pheromone production, and phenological/diel flight activity in the reproductive isolation of sympatric populations of three species of Monochamus in the Great Lakes Forest Region of Ontario, Canada. Chemical analyses of volatile extractions indicate that monochamol is produced by male Monochamus maculosus and Monochamus scutellatus, but no qualitative differences were observed in male extracts of these two species suggesting that there are no additional pheromone components that confer specificity. No quantitative differences were found in the production of monochamol by male M. scutellatus during the photophase and scotophase suggesting there is no diel rhythm in pheromone production. Our results indicate that M. scutellatus flies earlier in the season and day than M. maculosus and Monochamus notatus, which could partially contribute to their reproductive isolation. Overall, no obvious differences in pheromone composition were observed but minor differences in flight times were observed, suggesting other isolating mechanisms may exist.

The larval stage of the army cutworm, Euxoa auxiliaris (Grote), is an agricultural pest in the Great Plains region of North America. Adult migration to alpine aggregation sites to escape extreme summer temperatures and depleted food resources provides a critical food resource for the grizzly bear, Ursus arctos horribilis (Linnaeus, Carnivora: Ursidae), in the Rocky Mountains. However, little is understood about the ecological consequences of the thermal tolerance of adult E. auxiliaris. Therefore, we investigated thermal tolerance of lab-reared and wild-caught individuals by assessing their critical thermal limits (CTLmax and CTLmin). Using a ramping tolerance assay, we began at 25 °C and adjusted the temperature at a rate of 0.3 °C/min until individuals lost control of their righting response. Adult moths had a CTLmax (lab-reared: 44.13 °C, wild-caught moths: 43.28 °C) typical for a temperate lepidopteran species. However, their CTLmin (lab-reared: -2.24 °C, wild-caught: -1.9 °C) reflects an extraordinary ability to remain active and feed when ambient temperatures are low. These findings provide insights into the thermal ecology of E. auxiliaris which are essential for predicting the range distribution of the species, and, consequently, the continued availability of this key food source for Rocky Mountain grizzly bears. As climate change continues to affect ambient temperatures, these results underscore the importance of studying thermal tolerance to anticipate ecological shifts and ensure the conservation of both E. auxiliaris and the grizzly bears that depend on them.

Stored-product insects may pose food safety concerns due to their capacity to vector harmful microbes. As climate change progresses, the propensity for vectoring may be affected by temperature. Vectoring capacity may also fluctuate over the season. Thus, we evaluated (i) how the area of microbial growth and morphospecies richness vary over the season from field-collected Sitophilus oryzae that were allowed to disperse onto a novel food patch habitat comprised of agar and (ii) whether temperature in the week preceding collection of S. oryzae affected growth and richness. On a weekly basis during 2022 and 2023, we introduced S. oryzae onto agar, and photographed patches at 3 and 5 d, characterizing growth with ImageJ and visually scoring richness. There was 1.4- to 1.6-fold more microbial growth in patches at 5 d compared to 3 d in both years. The greatest microbial growth consistently occurred from S. oryzae collected during the wheat and maize harvest in grain bins, while morphospecies richness increased progressively over time. We observed an 11-fold and 3-fold increase in the number of morphospecies at the end of the season compared to the beginning in 2022 and 2023. There was 2.1- to 316-fold more microbial growth during the wheat (Jun to Jul) and maize harvest (Sep to Oct) compared to early May. We found a positive exponential relationship between temperature in the field and microbial growth in both years. This study expands our understanding of insect-microbe interactions after harvest and highlights variable periods of risk by food facilities over the season.

The Asian longhorned beetle, Anoplophora glabripennis (ALB, Coleoptera: Cerambycidae), is a federally regulated invasive species capable of infesting several different genera of hardwood trees. Accurate knowledge of ALB's phenology is critical for the effective implementation of management and eradication plans. We updated the ALBLT prediction model and used empirical data collected in South Carolina, USA to validate ALBLT v. 2.0. The new model largely agreed with ALB life stages found in field collections, except for late instars and pupae. We also ran the model at 8 other potentially high-risk cities in the contiguous United States with latitudes ranging from 28°N (Tampa, FL) to 41°N (Chicago, IL) to predict how long a single ALB generation might take to develop in these environments. Model predictions ranged from a 2-3-yr lifecycle in Chicago to a potential life cycle of < 1 yr in Tampa. These predictions can help inform managers and invasive species specialists should ALB be found in new environments, and these data can aid in developing an adequate management and eradication plan.

Wind affects the movement of most volant insects. While the effects of wind on dispersal are relatively well understood at the population level, how wind influences the movement parameters of individual insects in the wild is less clear. Tephritid fruit flies, such as Bactrocera jarvisi, are major horticultural pests worldwide and while most tephritids are nondispersive when host plants are plentiful, records exist for potentially wind-assisted movements up to 200 km. In this study, harmonic radar (HR) was used to track the movements of both male and female lab-reared B. jarvisi in a papaya field. Overall flight directions were found to be correlated with wind direction, as were the subset of between-tree movements, while within-tree movements were not. Furthermore, the effect of wind direction on fly trajectories varied by step-distance but not strongly with wind speed. Mean path distance, step distance, flight direction, turning angle, and flight propensity did not vary by sex. Both male and female movements are well fit by 2-state hidden Markov models further supporting the observation that B. jarvisi move differently within (short steps with random direction) and between (longer more directional steps) trees. Data on flight directionality and step-distances determined in this study provide parameters for models that may help enhance current surveillance, control, and eradication methods, such as optimizing trap placements and pesticide applications, determining release sites for parasitoids, and setting quarantine boundaries after incursions.