Environmental Entomology最新文献

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.

Anoplophora glabripennis (Motschulsky), the Asian longhorned beetle, is a serious wood-boring pest of hardwood trees. There have been records that suggest Elaeagnus angustifolia L. (Elaeagnaceae) might be an "attract and kill" tree species for A. glabripennis, i.e., a tree that is attractive to A. glabripennis adults but kills their oviposited eggs. To evaluate the possibility of E. angustifolia as a control measure for A. glabripennis, we carried out a series of behavioral experiments in the laboratory and in the field. Results showed that: (i) A. glabripennis females preferred E. angustifolia branches and leaves over poplar tree species evaluated; the weight of feces from both female and male A. glabripennis feeding on E. angustifolia was significantly higher than from those feeding on Populus deltoides 'Shalinyang' or Populus alba. L. var. pyramidalis; (ii) the average lifespan of females and males feeding on E. angustifolia was significantly longer than those feeding on other host trees evaluated; (iii) in the laboratory oviposition choice experiment, there were significantly fewer egg notch grooves on E. angustifolia than on P. deltoides 'Shalinyang', and those made in E. angustifolia were without eggs; (iv) in the field, the number of egg notch grooves on E. angustifolia was 43.6 ± 18.1 per stem, but the number of eggs laid was only 14.4 ± 6.4 per stem; and (v) Field surveys of existing mixed forests showed that when E. angustifolia was planted with P. alba. var. pyramidalis or Populus simonii × (Populus pyramidalis + Salix matsudana) 'Poparis' in the mixed forest, both poplar varieties suffered greater infestation than E. angustifolia. Therefore, E. angustifolia is not a suitable attract and kill tree to be extensively planted in mixed forests for control of A. glabripennis.

The rice water weevil, Lissorhoptrus oryzophilus (Kuschel), is the most widely distributed and destructive early-season pest of rice in the United States. Injury caused by feeding of weevil larvae on rice roots results in significant yield losses. In Louisiana, a complex of stem-boring lepidopteran pests also attacks rice. Of this complex, the Mexican rice borer, Eoreuma loftini (Dyar), has recently invaded Louisiana and now poses a consistent threat to rice production. To study the effects of planting date on rice water weevil density and stem borer damage (whiteheads), field experiments were conducted in Louisiana from 2018 to 2020. Six rice cultivars (CL152, Cheniere, Cocodrie, Jazzman-2, Jupiter, and PVL01) were drill-planted in small plots across 6 planting date ranges per year. Weevil densities on rice roots were evaluated 3 and 4 weeks after permanent flood establishment, and stem borer infestations were assessed by recording the total number of whiteheads in each plot at 100% heading. At grain maturity, entire plots were harvested. Weevil infestation levels remained high throughout all planting dates; however, densities were slightly lower in the later planting dates. The rice cultivar 'Jupiter' supported higher weevil densities compared to 'Cheniere'. Whitehead densities increased with later planting. The rice cultivar 'PVL01' consistently had the highest number of whiteheads. In addition, yields were lower at late planting dates. Results from this study suggest that rice water weevil poses a consistent threat throughout the range of typical planting dates, whereas the stem borer incidence tends to become more problematic in later-planted rice.

Nepytia janetae is a previously innocuous non-eruptive species that has recently incurred multiple devastating outbreaks in the American Southwest. We report information on the life cycle, biology, and impact of this species learned during the first 3 known outbreaks in spruce-fir and mixed-conifer forests of the Pinaleño Mountains and White Mountains of Arizona and the Sacramento Mountains of New Mexico. N. janetae is a univoltine, autumn- and winter-feeding wasteful defoliator with 3-yr eruptive outbreaks. Outbreaks terminate with parasitism, viral infection, starvation, and in one outbreak with heavy rainfall during egg deposition. Conifer mortality varied between outbreaks but approached 100% in some stands in all three study areas. Only severely defoliated trees died. Mortality was associated with defoliation severity, moisture availability in the last growing season of the outbreak and/or in the first post-outbreak growing season, and bark beetle activity. Other site and stand variables associated with defoliation and mortality varied between outbreaks, highlighting the need to evaluate multiple outbreaks before identifying factors related to susceptibility and vulnerability to a new pest species. The emergence of this insect as a serious pest is probably related to warming climate but the mechanisms are unclear; the only consistent pattern is an association with low or early loss of snowpack in either the year immediately preceding or the first year of the outbreaks. Differences in host specificity and larval coloration between the distant mountain ranges indicate that N. janetae may be a complex of multiple species or subspecies.

Pesticide drift into sensitive habitats is an increasing concern in agricultural landscapes due to negative impacts on non-target animals including wild bees and other beneficial insects. Creating buffer zones between the crop and sensitive habitats has been commonly proposed as a mitigation measure for reducing off-target pesticide deposition. Given prior evidence of significant pesticide deposition in wildflower plantings adjacent to highbush blueberry farms in Michigan, the aim of this study was to determine the buffer zone needed to significantly reduce pesticide deposition in these plantings. We used silicone bands as passive pesticide samplers placed at varying distances between 0 and 32 m from the crop at conventionally managed blueberry farms during the fruit ripening period when insecticide applications are common. We found there was no significant reduction in number of active ingredients detected in samples at any measured distance from the crop. There was also no significant reduction in pesticide concentration (summed mass of all active ingredients) until 24 m from the field border, and this change was driven by reductions in concentrations of fungicides as there was no significant reduction in total insecticide or herbicide deposition at any of the tested distances. Drift reduction measures, such as installation of windbreaks and use of precision application methods are recommended to reduce off-target pesticide movement.

Cold winter temperatures affect the distribution and abundance of the mountain pine beetle, Dendroctonus ponderosae Hopkins, an eruptive tree-killing bark beetle native to pine forests of western North America. The cold-tolerant larval stage often overwinters but adults also enter winter in some regions or years yet little is known about their ability to survive winter. Here we report on experiments to assess the cold tolerance of mature, brood adults. Adult mountain pine beetles exhibited a strong cold-hardening response over a period of weeks to months that intensified at colder temperatures; however, adult beetles from Cranbrook, which experiences cold winters, were more cold hardy than adults from Victoria, which has mild winters. These results are consistent with a seasonal cold-hardening response that is affected by both environmental factors and local adaptation to climate. The lowest mean and minimum lethal temperatures recorded for preconditioned adults during the study were ‒26.8 and ‒32.2 °C, respectively. Preconditioned adults from Cranbrook and Victoria challenged with prolonged exposure to a cold temperature (‒18 °C) suffered negligible mortality after 8 d; almost half of the Victoria adults and three-quarters of the Cranbrook population were still alive after 28 d. Adults had a limited ability to rapidly cold harden but possessed substantial basal cold tolerance. Our results on the cold tolerance of the adult stage of the mountain pine beetle are expected to contribute to models of forest disturbances that incorporate the population dynamics and climatic suitability of forests for tree-killing bark beetles.