Environmental Entomology最新文献

Interactions between parasitoids and herbivore hosts are complex as parasitism affects multiple components of host behavior and fitness through both consumptive and non-consumptive effects. Understanding how these multiple effects unfold is especially important in applied systems where parasitoids play a role in biological control. In lab-based experiments, we manipulated parasitism in striped cucumber beetles, Acalymma vittatum (Coleoptera: Chrysomelidae), a major pest of cucurbits in North America, using Celatoria setosa (Diptera: Tachinidae) to assess how parasitism affected multiple components of male and female fitness, including survival, herbivory, oviposition, and reproductive signaling through the emission of vittatalactone, a male-specific aggregation pheromone. In follow-up experiments, we investigated the potential non-consumptive effects of parasitoids on these metrics by exposing beetles to arenas with or without parasitoids. Parasitized female beetles experienced a 4-fold increase in mortality, consumed 49.6% less leaf tissue, and were less likely to oviposit eggs compared to non-parasitized control females. In addition, parasitized males in small groups emitted 52.5% less vittatalactone than non-parasitized control males. Lastly, we found some evidence of non-consumptive effects of parasitoids in which individual females and groups of males, exposure to parasitoids resulted in reduced foliar damage. Our findings highlight broad effects of tachinid parasitoids in a common pest and point to multiple mechanisms for reduced pest performance.

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.

Bark beetles are significant forest pests, with primary tree-killing species often relying on obligate mutualistic fungi carried in specialized mycangia. In contrast, secondary bark beetles, which do not typically attack healthy trees, often lack obligate fungal mutualists. However, all bark beetles vector fungi that may provide nutrition to them, improve substrate conditions, or act as antagonists, hindering their success. This study introduces a paired-tube choice test arena to assess bark beetle-fungal interactions using minimal phloem-media. We hypothesized that primary bark beetles with mycangial fungi (eg Dendroctonus frontalis Zimmermann and Dendroctonus barberi Hopkins) avoid phloem infested with nonmycangial fungi such as Ophiostoma minus (Hedgcock) Sydow & P. Sydow, while secondary beetles like Ips pini Say, which do not rely on mycangial fungi, show no preference for fungal-infested or fungus-free phloem. Our findings revealed that D. barberi preferred uninfested phloem, whereas I. pini preferred the O. minus-infested phloem. Interestingly, D. frontalis did not show a preference for either uninfested phloem or O. minus-infested phloem. These results underscore the importance of understanding the effects of fungal symbionts on tunneling behavior, with potential applications in pest management, such as deploying cues from antagonistic fungi as repellents.

Infestations of the small walnut aphid, Chromaphis juglandicola (Kalt.), seriously threatens the yield and quality of walnut in southern Xinjiang, China. Understanding the dominant natural enemies of pests in the crop is crucial for optimizing conservation strategies to enhance ecological services. Through field surveys, this study revealed that ladybugs and lacewings had the highest dominance and temporal niche breadth indices among predatory insects. The temporal niche overlap index between ladybugs (predominantly Hippodamia variegata (Goeze)), and C. juglandicola was the highest, with their population peaks strongly coinciding. In cage experiments with H. variegata under varying predator/aphid ratios (1 : 50, 1 : 100, 1 : 150, 1 : 200, 0), we found that a predator-to-prey ratio exceeding 1:100 effectively suppressed C. juglandicola population growth, achieving over 70% biocontrol efficacy within 1 wk. Furthermore, in the field, the growth rate of C. juglandicola was significantly and negatively correlated with the ratio of ladybugs to aphids. Path analysis indicated that for every unit increase in the predator-to-aphid ratio, biocontrol efficacy improved by 63.4% (the standardized effect coefficient in path analysis), and the aphid population growth rate decreased by 65.2%. This study confirmed that H. variegata is the dominant predator of C. juglandicola in walnut orchards of southern Xinjiang. A predator/aphid ratio exceeding 1:100 effectively suppressed aphid population growth, maintaining it at low levels. These findings provided critical theoretical support for developing biological control strategies using H. variegata to manage C. juglandicola in walnut orchards of southern Xinjiang.

A coherent understanding of adult western corn rootworm (Diabrotica virgifera virgifera) movement ecology has remained elusive because of conflicting evidence of short- and long-distance lifetime dispersal, a type of dilemma called Reid's Paradox. Attempts to resolve this paradox using population genetics strategies have been hindered by the lack of gene flow-genetic drift equilibrium in much of North America related to this species' recent range expansion out of the Great Plains across the Corn Belt. We addressed this challenge by studying a longer-established population in northeastern Colorado and western Kansas, where D. v. virgifera has been resident for >175 yr. We assessed population differentiation using 2,036 single-nucleotide polymorphism markers to obtain indirect estimates of dispersal distances. Significant isolation by distance and pairwise FST estimates across 14 locations suggest these populations are at or near gene flow-genetic drift equilibrium. Low FST values and shallow isolation-by-distance slopes suggest gene flow over longer distances (280 km) than supported by many direct measures of dispersal distance, another type of dilemma known as Slatkin's Paradox. Indeed, based on estimates of adult population density and Wright's neighborhood at each location, median estimated lifetime dispersal of ~87% of adults was only 174 m. Together, our genetic evidence and findings from earlier studies suggest that D. v. virgifera populations consist of 2 behavioral phenotypes, migrants that engage in long-distance dispersal and residents that disperse only locally by diffusion. The resulting bimodal dispersal distribution resolves both Reid's and Slatkin's paradoxes.

Understanding the combined contribution of insects and microbes to conditions in a grain mass is particularly relevant for pest management programs in bulk storage. There are important and strong interactions between Sitophilus oryzae (L.) and stored product fungi, especially Aspergillus flavus Link. The aims of this study were to determine how the introduction of S. oryzae, A. flavus, or both in a grain mass affected (i) the fitness of S. oryzae, and (ii) the abiotic conditions in a grain mass. Containers with 300 g of wheat were established with no insects or added microbes, 75 mixed-sex S. oryzae adults only, 11.6 g of A. flavus-inoculated grain only, or both, and dataloggers were placed in the masses to record temperature and relative humidity every 5 min. After 60 d, progeny were counted, and grain moisture was also measured. Although mean temperature was not consistently altered in the presence of A. flavus or S. oryzae, the combined inoculation of A. flavus and S. oryzae in a grain mass consistently elevated relative humidity by 7% to 8%. The presence of A. flavus or S. oryzae consistently elevated grain moisture from 10.8% prior to the experiment to about 13%. Importantly, there were 203-fold more F1 progeny produced by S. oryzae when A. flavus was present compared to when it was absent in a grain mass, possibly indicating a mutualistic relationship. Our work adds to the growing body of literature suggesting that insects and microbes should be managed in concert at food facilities.

The spotted lanternfly (Lycorma delicatula, Hemiptera: Fulgoridae) is a planthopper native to China and southeastern Asia invasive in North America. To inform the risk assessment of northward spread, we determined the cold tolerance strategy and lower lethal limits of overwintering eggs. We used field-collected egg masses from Pennsylvania, USA, and treated them with short (1 or 12 h) and long (10 or 15 d) low temperature exposures (0 °C to -25 °C). We determined that eggs were chill susceptible, and their supercooling points ranged from -17.4 °C to -27.7°C. We observed successful hatch after short- and long-term exposure to temperatures below -20 °C. Hatch rates were lower at or below -20 °C in the short exposures, or -15 °C in our long exposures experiments than hatch rate in egg masses not exposed to any treatment. Because L. delicatula eggs survived temperatures near their supercooling points, -27.7 °C could be used as an estimate of the lower lethal temperature. Our findings suggest that L. delicatula may be able to survive in colder climates than initially thought. Of the locations where L. delicatula has been intercepted in Canada-central and eastern provinces-Winnipeg is the only location where frequent or intense cold spells are likely to prevent hatch. Thus, low winter temperatures may not limit L. delicatula overwinter survival in many regions of Canada or other parts of the world that experience similar winter conditions.

The chestnut weevil, Curculio davidi Fairmaire (Coleoptera: Curculionidae) is a major pest of chestnuts. Damage caused by C. davidi has increased as beetle populations have expanded. To promote effective C. davidi management practices based on its host plant, we compared the susceptibility of local chestnut cultivar 'Qinli 2'(QL2) and introduced chestnut cultivar 'Hongli' (HL) in Qinling Mountains to this weevil. Number of eggs laid by C. davidi females in HL was significantly higher than that of QL2. Chestnut weevil females laid 6.25-fold and 3-fold more eggs in HL than QL2 in the choice tests and no-choice tests, respectively. From 2021 to 2023, C. davidi infestation rates of HL were significantly higher than that of QL2 in the field. HL was smaller, softer, and have lower cellulose content as compared with QL2. HL contained 4.61%, 13.76%, 10.09%, 26.53%, 9.24%, 18.4%, 6.28%, and 23.26% higher amounts of N, K, Ca, Mg, S, Na, Mn, and Cu respectively, than QL2. In contrast, QL2 contained 25.28%, 19.80%, and 16.83% higher amounts of Al, B, and Fe, than HL. Our results revealed that the introduced chestnut cultivar is more susceptible to C. davidi compared to the local chestnut cultivar in Qinling Mountain, which was associated with several physico-chemical changes in chestnuts. These findings may contribute to the future efforts for breeding of C. davidi-resistant chestnut cultivars.

Dung-associated beetles provide crucial ecosystem services including reducing pasture fouling and contributing to animal and pasture health. However, parasiticides used on cattle can negatively impact beetles. We assessed the exposure and impact of Clarifly (active ingredient [a.i.] diflubenzuron), LongRange (a.i. eprinomectin), and Safe-guard (a.i. fenbendazole) on beetles and flies. Using high-performance liquid chromatography, we quantified the residual concentrations of these chemicals in cattle feces for 150 d. We found fenbendazole excreted within the first 3 d after treatment, while diflubenzuron and eprinomectin persisted for 8 to 12 wk. To estimate the concentrations of these active ingredients that are toxic to beetles, we dosed cattle dung with diflubenzuron, eprinomectin, or fenbendazole, allowed insects to colonize in the field, and monitored the emergence of beetles. Dung beetle (Scarabaeidae) abundance was negatively impacted by diflubenzuron and eprinomectin while fenbendazole had no negative effects. Predatory beetles, families Carabidae, Histeridae, Hydrophilidae, and Staphylinidae, were unaffected by all chemicals. We found that dung from animals treated with LongRange was toxic to Scarabaeidae for 30 to 90 d after treatment. Similarly, diflubenzuron was toxic to Scarabaeidae when cattle consistently consumed it, although concentration of diflubenzuron in dung varied when cattle were fed using Clarifly. In contrast, the active ingredient in Safe-guard, fenbendazole, was not toxic at 10 mg/kg. Although, we found this product excreted at higher concentrations for 1 d after treatment, it likely poses little risk. Our results suggest that producers who value beneficial beetles as a management goal should avoid eprinomectin and diflubenzuron products that excrete for long periods.

Hierodula patellifera is the only widely distributed species in the genus Hierodula. The nominotypical subspecies ssp. patellifera is broadly distributed, while ssp. daitoana, an endemic subspecies, is found only on the Daito Islands, a group of oceanic islands 360 km from Okinawa, Japan. When H. patellifera males detect the sex pheromone released by females, they shake their bodies quickly (juddering movement). This behavior was observed in the males of both subspecies of H. patellifera. When the males of each subspecies were given volatiles from consubspecific or allosubspecific females that showed calling behavior, males of both subspecies showed the juddering movement only in response to volatiles from consubspecific females. This suggests that premating isolation mediated by sex pheromones has evolved between the two subspecies. However, as the two subspecies are allopatrically distributed, the differences in sex pheromone components do not appear to be the result of reproductive isolation driven by subspecies interaction.