Environmental Entomology最新文献

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.

Symbiotic nitrogen-fixing plants such as Russian olive can significantly impact soil chemistry and invertebrate biodiversity in riparian ecosystems. Here, the effects of Russian olive on soil chemical properties and invertebrate communities in riparian zones of the southwestern United States were investigated. Russian olive stands were compared to native cottonwood stands and restoration sites by analyzing soil nitrogen (N), phosphorus (P), and moisture levels, and arthropod diversity and abundance. Sites where Russian olive is present led to a net increase in soil nitrogen, a decrease in soil phosphorus, and greater soil moisture compared to both native cottonwood stands and restoration sites. Native cottonwood stands showed lower soil N and higher P levels, as well as higher arthropod diversity. This increased diversity could be linked to the soil's nutrient stoichiometry, as there is a negative correlation between taxonomic diversity and the soil N:P ratio. Moreover, there was a greater abundance of detritivorous arthropods in Russian olive stands compared to native vegetation. Soil nitrate (NO3-) levels showed a strong positive correlation with detritivorous arthropod abundance (r2 = 0.98), but only a moderate correlation with herbivores (r2 = 0.38), and NO3- was unrelated to predator abundance (r2 = 0.01). These results suggest that Russian olive stands can alter soil chemistry in ways that disproportionately benefit detritivores, potentially disrupting the balance of arthropod communities and reducing overall biodiversity in riparian ecosystems. The study underscores the need for careful management of invasive, symbiotic N2-fixing plant species to preserve the ecological integrity of riparian habitats.

During the eradication program undertaken against Anoplophora glabripennis (Motschulsky) in the Greater Toronto Area, information was collected on the numerous signs of injury found on wounded trees. Herein, we used a portion of this information to assess the characteristics of logs with signs of oviposition (i.e., pits). Specifically, we related the basal diameter, type (log bole vs. log branch), height above ground, and branch hierarchy level of logs with pits to tree size (i.e., height and diameter at breast height) and level of infestation intensity. In general, pits were concentrated on logs from the bole and branches that were 8-14 cm in diameter in the lower 8 m of the bole and in the first 2 levels of the branching hierarchy. Oviposition pit location was strongly influenced by tree size-both height and diameter at breast height, with more pits on the lower bole in small trees and then higher on the bole and into the branches as tree size increased. As tree-level infestation intensity increased, pits were found on both larger and smaller diameter portions of the trees, presumably as preferred oviposition sites became saturated. These findings can improve the efficacy of surveillance activities for A. glabripennis.

This study addresses how gut symbiont, Caballeronia insecticola, could change reproductive capacity, mating behaviors, and copulation success of host insect, Riptortus pedestris (Fabricius) (Hemiptera: Alydidae). First, we evaluated symbiotic effects on the female reproductive capacity with varying numbers of males available to a female. Overall, symbiotic females displayed on average a 1.8-fold increase in egg production compared to aposymbiotic individuals. However, eggs from symbiotic females were on average 42% less viable, compared to those from the aposymbiotic, when paired with single male. The decrease in the hatchability was alleviated to 12% when paired with 3 males. Consequently, this yielded significant increase in the number of viable offspring by symbiotic females when multiple males were available. Second, we evaluated symbiotic effects on male morphometric characteristics including hind legs used as weapon, and found significant increases in hind leg sizes associated with symbiosis. Finally, we investigated mating behaviors between a female and 2 males of different symbiotic status. Symbiotic females displayed on average a 1.4-fold increase in the number of copulations compared to the aposymbiotic. From both female types, however, no significant difference was observed in their mate choice and copulation success rate between aposymbiotic and symbiotic males. However, symbiotic females exhibited on average 17% reduction in copulation duration compared to the aposymbiotic. Copulation failure was caused more frequently by female's rejection than by intruder male's disruption for both female types. Our study demonstrates that symbiotic females benefit from the symbiosis increasing their reproductive capacity and copulation frequency.

Harvester ants play a crucial role as ecosystem engineers, particularly in nest-building activities that involve clearing nest-disks of vegetation. These clearings can be large and influence plant communities affecting rangeland management. In some cases, colony density may be increased by grazing but studies are sparse with conflicting results. We examined the effects of grazing on 2 harvester ant species (Pogonomyrmex occidentalis and Pogonomyrmex rugosus) at 5 sites in northern Arizona. We used preestablished grazing-exclusion treatments to compare colony density and spacing adjacent to and within grazed areas. At all sites, colony density was marginally higher in excluded treatments. Only P. occidentalis showed significant spatial patterns in response to grazing, where nests were evenly spaced on small distances (>5 m) in the grazing-excluded treatment. We observed large differences in nest size and density between ant species. Pogonomyrmex occidentalis made larger nests and cleared more land area than P. rugosus. Pogonomyrmex occidentalis peaked in density at 37 nests/ha occupying 1.87% of land area with smaller nearest neighbor distances (10.6 to 13.6 m), while P. rugosus peaked at 16 nests/ha occupying 0.20% of land area with larger nearest neighbor distances (17.9 to 24.3 m). Together our results provide limited but interesting evidence of negative effects of grazing on harvester ant nests. We discuss our findings in the context of other studies measuring colony densities in rangelands and conclude that grazing effects on nest spatial arrangements are inconsistent and differ among locations, highlighting the need for future studies.

Whether host plant fruiting phenology variation affects eclosion times and generates allochronic isolation across trophic levels for Rhagoletis flies (Diptera: Tephritidae) and their braconid parasitoids is largely unknown, except in the Rhagoletis pomonella (Walsh) hawthorn-apple system. Here, we investigated how fly and wasp eclosion times in 4 systems-Oregon grape, Rhagoletis berberis Curran; red osier dogwood, Rhagoletis tabellaria (Fitch); bitter cherry, Rhagoletis indifferens Curran; and snowberry, Rhagoletis zephyria Snow-in Washington state, USA correspond to host phenology. Fruiting patterns differed among plants. Oregon grape and bitter cherry fruited once in relatively narrow temporal windows, while red osier dogwood and snowberry fruited multiple times or more widely through the season. Fruiting times differed for plants from earlier to later: based on fruit set, Oregon grape < red osier dogwood = bitter cherry < snowberry; first ripening fruit, Oregon grape < bitter cherry = snowberry; percent mature fruit in early August, Oregon grape = red osier dogwood < bitter cherry < snowberry. Mean fly eclosion times generally matched host fruiting times: red osier dogwood fly < Oregon grape fly = bitter cherry fly < snowberry fly. Parasitoid and fly eclosion matched except snowberry fly wasps eclosed before bitter cherry fly wasps. Differences in eclosion times between flies or wasps resulted in allochronic isolation from 1% to 96%. Nonconcordance between timing of fruit maturity and fly/wasp eclosion may be related to differences in precise host fruit or fly stages attacked by different species. Fruiting phenology may select for variable fly eclosion times, leading to a range of allochronic isolation between different Rhagoletis species and their associated guilds of parasitoid wasps.

Females of most species of click beetles (Coleoptera: Elateridae) emit sex pheromones that attract males, and these chemicals can be utilized in monitoring and managing pest species. Here, we conducted dose-response trials with sex attractants of 5 elaterid species native to Illinois. Synthesized attractants were dispensed from polyethylene sachets, with doses of 0 (solvent control), 1, 3.3, and 10 mg. For 2 Gambrinus species, only traps baited with 10 mg doses of limoniic acid captured significantly more beetles than did control traps. However, for another 3 elaterid species, traps baited with 3.3 and 10 mg of attractants captured more beetles than did control traps, including Elater abruptus Say (attractant 5-methylhexyl [Z]-4-decenoate), Melanotus ignobilis Melsheimer (11-dodecenyl butyrate), and Parallelostethus attenuatus (Say) (1,8-octanediol dihexanoate). A separate field experiment, that tested 2 types of dispensers loaded with attractants, showed that traps baited with polyethylene sachet dispensers captured significantly more males of E. abruptus and P. attenuatus than did traps baited with rubber septa. We also assessed seasonal and daily activity periods of E. abruptus, M. ignobilis, and P. attenuatus, using attractant-baited panel traps. Flight periods of all 3 species were generally unimodal and confined to the summer months. Diel activity periods, assessed with attractant-baited panel traps fitted with collection jars that rotated at intervals of 1 to 2 h, showed that males of E. abruptus and P. attenuatus were primarily diurnal, flying from early morning through the evening, whereas males of M. ignobilis were nocturnal.