Environmental Entomology最新文献

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.

Tracking individual insects with harmonic radar (HR) allows observations of insect movement behavior under wild and semi-wild conditions. However, attaching tags to insects has the potential to alter natural behavior. Quantifying the negative effects of tag attachment may allow researchers to correct movement parameters to account for deviations from natural movements, thus producing more accurate estimates of insect behavior. Using two HR tag sizes, ~350 (small) and ~570 μg (large), the movements of Ceratitis capitata and Bactrocera dorsalis were investigated in flight tubes and an outdoor field cage. Bactrocera dorsalis with small tags attached did not perform differently than untagged flies in flight tubes, while flies with large tags took longer to exit the tubes. Time to exit did not vary with B. dorsalis body size, wing area, or wing length for any tagged status (untagged, small, or large). However, B. dorsalis exit times did vary with rearing and irradiation status but not with sex. For C. capitata, negative impacts were observed on both the time to exit and the failure to exit rate. Field cage experiments revealed differences in movement parameters among tested groups. For instance, female, colony-reared, non-irradiated, B. dorsalis showed the greatest bias in (pseudo) turning angles; male, wild, non-irradiated, B. dorsalis showed the weakest correlation between flight and wind direction (β); and colony-reared C. capitata showed random movement directions (other groups showed directional biases). This study shows the feasibility of tracking tephritids as small as C. capitata and demonstrates the advantages of using the smallest possible tags.

As an emerging forestry pest characterized by rapid spread, wide distribution, and significant damage, Euwallacea interjectus necessitates comprehensive and scientifically validated chemical control measures. Currently, there is a lack of large-scale and precise experimental data on the efficacy of insecticides and fungicides for chemical control. Even for closely related ambrosia beetles, existing chemical control methods have unresolved aspects. Given the high dependency of E. interjectus life cycle on its symbiotic fungi, this study employed fungicides as a pivotal control strategy. Additionally, to mitigate potential secondary environmental hazards associated with broad-spectrum insecticides, detailed toxicity tests were conducted in laboratory settings, followed by field spray experiments. An organosilicon compound was utilized to examine the synergistic effects of insecticides, and liquid chromatography was employed to quantify insecticide residues in the xylem of host trees. In the laboratory, beta-cyfluthrin exhibited the lowest LC50 value (8.989 mg/L), achieving an 80.6% reduction in beetle infestations after 30 d. The addition of adjuvants increased residue levels by 2.5%, thereby enhancing control efficacy. Among the tested fungicides, a 4:1 mixture of fludioxonil and prochloraz-manganese chloride complex demonstrated the highest efficacy, with an EC50 value of 2.669 mg/L. In field experiments, spraying at a concentration of 2000 mg/L resulted in a 58.7% reduction in beetle infestations after 60 d. The findings provide a scientific basis for the control of E. interjectus and the judicious application of chemical pesticides, offering technical support for the management of wood-boring pests in forestry production.

Cornegenapsylla sinica is a devastating pest of longan that vectors the longan pathogen witches' broom virus (LgWB), leading to significant agricultural losses. Efficient control strategies targeting this pest are imperative for sustainable longan production. However, the genetic research on C. sinica is relatively limited, which may hinder the discovery of effective control strategies. Accurate gene expression analysis under various conditions using RT-qPCR is essential for advancing our understanding of this pest and for identifying potential targets for management. In this study, a comprehensive array of specific algorithms, including geNorm, Normfinder, BestKeeper, and the ΔCt method, was applied to assess the stability of 8 candidate reference genes under 4 distinct experimental conditions: developmental stages, sex, tissue, and temperature. Through the application of RefFinder software, a ranking of expression stability among the candidate genes was established. The results indicated that RPL13 and RPL6 were the most stable reference genes under varying developmental stages and temperatures, ATPB and RPL13 were the top choices for different sexes, and RPL13 and EF1α were the most stable in different tissues. Additionally, heat shock protein 70 (Hsp70) served as a reporter gene to validate the selected reference genes. This study is the first to report detailed data on comprehensive reference genes suitable for RT-qPCR in C. sinica, laying the groundwork for biological control and functional target gene research in this species, which is crucial for preventing the spread of longan witches' broom virus in longan trees.

The Asian longhorned beetle (ALB), Anoplophora glabripennis (Motschulsky), is a polyphagous woodboring beetle that infests and damages hardwood host trees in Asia, Europe, and North America. Native to China and the Korean peninsula, ALB is invasive in both North America and Europe. Due to the large environmental and economic impacts associated with ALB, much effort has been placed on its management and eradication from invaded areas. Eradication programs consist of visual surveys, regulatory quarantines, host removal, public outreach and education, and in some cases, insecticides. Host removal is effective but is laborious and costly, and while insecticides have been useful as a component of some eradication programs, they can be expensive, ineffective, and environmentally detrimental. Thus, several arthropod biological control agents (BCAs) have been evaluated which could support a more environmentally friendly management strategy to supplement traditional ALB management tactics. Here, we review the biological control strategy for ALB, including the exploration within the native and invaded ranges of the pest, to find potential arthropod BCAs. We discuss the ecological premise behind the method as well as the potential for its success, and we identify knowledge gaps and future considerations for the enactment of this method. While biological control shows promise, care will be needed in utilizing this method, and further research must explore the success of BCAs in field settings.

Understanding the demography of Xyleborini ambrosia beetles and accurately estimating their optimal growth temperatures remains a challenge due to their cryptic behavior and complex reproductive habits. In this study, we reared the ambrosia beetle Xyleborus bispinatus at five distinct temperatures (17 °C, 20 °C, 26 °C, 29 °C, and 35 °C) over a 36-d period. Population dynamics, growth rates, and life cycle durations were assessed through destructive sampling every 4 d for each temperature treatment. To analyze temperature-dependent growth and development, a nonlinear model was fitted to the intrinsic growth rate values at each temperature, allowing us to determine the species' optimal temperature and corresponding maximum growth rate. In the laboratory, X. bispinatus exhibited optimal growth rates between 26 °C and 29 °C, with rates of 0.10 and 0.12, individuals/individuals/day, and life cycle durations of 20 and 16 d, respectively. However, based on the fitted growth curve, the thermal optimum was estimated at 26.2 °C, where the maximum intrinsic growth rate reached 0.13 individuals/individuals/day. Given its potential to transmit Harringtonia lauricola, these findings provide valuable insights into the thermal effects on X. bispinatus throughout its life cycle and offer a practical approach for estimating growth rates and thresholds in species with cryptic behavior or where cohort tracking is challenging for demographic assessments.