Journal of Insect Science最新文献

Insect responses to warming temperatures are determined partly by their physiology, which is influenced by genetic factors and plasticity induced by past temperature exposure. The effect that prior high temperature exposure has on insect thermal tolerance is complex and depends on the degree of heat stress experienced; high heat exposure may allow for individuals to tolerate higher temperatures through hardening or may reduce an individual's capacity to withstand higher temperatures through accumulated heat stress. In this study, we assessed how short exposures to high temperatures and a laboratory colony's geographical origin affected the critical thermal maximum (CTmax) of western corn rootworm (Diabrotica virgifera virgifera LeConte), an economically important pest. Despite a wide latitudinal range of source populations, western corn rootworm colonies did not differ in their CTmax. Regardless of colony origin, we found that exposing western corn rootworm to higher temperatures resulted in lower CTmax, which suggests that heat stress accumulated. This study highlights how western corn rootworm experiences heat stress at temperatures near the temperatures they experience in the field, which may have important and currently unknown implications for its behavior.

An economically important global maize pest, fall armyworm (Spodoptera frugiperda (J.E. Smith)), feed on all above-ground portions of maize plants, primarily the whorl tissues. One of our research unit missions is to identify and develop maize germplasm with resistance to fall armyworm. One method to measure resistance in maize to fall armyworm is visual rating of leaf-feeding damage after infestation with neonates into the whorl. The objective of this study was to compare leaf-feeding damage ratings after infestation with different rates of fall armyworm neonates. The ultimate goal was to select the smallest infestation rate which could give the same damage effect on maize leaves as the larger infestation rates. Four susceptible and 7 resistant maize germplasm lines were planted in replicated experiments with a split plot arrangement in the field in the summer of 2023 and 2024. Plants were infested with fall armyworm at 10-, 20-, 30-, 40-, and 50-neonate infestation rates (treatment). Leaf-feeding damage was scored 14 d after infestation. In general, 10-neonates infestation rate exhibited less damage in comparison to the higher infestation rates indicating much less pressure from fall armyworm to exhibit resistance in maize regardless of the lines. Overall results showed that 20-, 30-, and 40-neonate infestation rates did not differ in the leaf-feeding damage scores among each other. These rates were able to clearly distinguish the damage between susceptible and resistant lines; hence, 20-neonate rate could be used as the standard infestation rate for future infestation in the maize resistance research program.

Hybridization between eastern and western lineages of the biological control agent, Leucotaraxis argenticollis (Zetterstedt) (Diptera: Chamaemyiidae), was demonstrated in the laboratory. The western lineage is abundant on hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae) in western North America while a genetically distinct eastern lineage feeds mostly on pine adelgids (Hemiptera: Adelgidae: Pineus spp.). Western flies have been released in eastern North America but establishment has not been observed. When reared on A. tsugae in the laboratory, many eastern L. argenticollis larvae did not survive, and of those that did reach pupariation, 21% survived to the adult stage. To assess hybridization, eastern females were placed with western males for no-choice mating. They produced hybrid offspring with 8% survival to the adult stage when reared on A. tsugae. Further investigation of hybrid fitness, assortative mating, and the prey-seeking strategies of Leucotaraxis would aid in predicting the outcome of potential hybridization in the field.

We developed a two-choice spatial olfactometer to evaluate the response of adult secondary screwworm (Cochliomyia macellaria), house fly (Musca domestica), and flesh fly (Sarcophaga bullata) to two commercially available fly-trap attractants, Captivator and FliesBeGone in three-dimensional space. Liquid fly baits were prepared according to the manufacturer's recommendations and aged to discern the relative attraction of fresh and older baits. Each 0.07 m3 (2.5 ft3) arena was fitted with two fresh air intake ports, collection chambers containing the attractant or a blank control, and air exhaust ports. We released adult flies into an arena with sufficient space to allow free flight and response to the test attractants. Each comparison was replicated eight times with fresh flies. Flies were more responsive to commercial bait than the water control. Air flowrates, as measured through the intake ports, was determined to be a limiting factor for C. macellaria and S. bullata with significant responses rates observed to flowrates ≤0.14 m3/min (5 ft3/min) and ≤0.25 m3/min (9 ft3/min), respectively. In contrast, M. domestica appeared to respond similarly to all flowrates tested (≤0.31 m3 (11 ft3/min). In direct comparisons with a water control, M. domestica was attracted to baits regardless of bait age. In similar experiments, C. macellaria was significantly responsive to FliesBeGone aged 2 and 3 d but not Captivator regardless of age. Lastly, S. bullata was most responsive to FliesBeGone aged 3 and 4 d, and Captivator aged 4 d. Female flies responded to fly baits more frequently than males.

Gynaephora menyuanensis Yan & Zhou is one of the most devastating pests that harm the ecosystem of alpine meadows and hinder the advancement of animal husbandry. However, the current knowledge of the morphology of the different developmental stages within G. menyuanensis reveals an information deficit that needs to be addressed. This study is the first to report the life history, sexual dimorphism, and morphology of eggs, mature larvae, pupae, and adult antennal sensilla types of G. menyuanensis. This study used a K-means clustering method, based on the head width, body length, body width, and the number of crochets of larvae at each instar, to differentiate instars of G. menyuanensis; the description of the morphology of larvae, pupae, and adult antennae employed light microscopy and scanning electron microscopy photographs. The results revealed that the instar grouping was reliable and verified by the Brooks-Dyar combined with Crosby rules, revealing that the larval stage of G. menyuanensis comprises 7 instars. This species produces one generation per year in the alpine meadow, with its life cycle lasting approximately 300 d in total. The pupae and adult antennae significantly differed between the sexes, indicating sexual dimorphism in the 2 genders. Nine types and 14 subtypes of antennal sensilla were observed in male antennae (bipectinate), while only 3 types and 3 subtypes were found in female adult antennae (club-like). Our findings have implications for better understanding the life history, adaptation strategies under extreme environmental conditions on the Qinghai-Tibet Plateau and developing scientific and effective pest control methods.

Böhm's bristles are mechanosensory structures located on the basal segments of antennae of most insects and provide sensory feedback for antennal positioning. The bristles are located near the head-scape and scape-pedicel joints, and evidence demonstrates that as the joints bend, the bristles are mechanically deflected by contact with the reconfiguring flexible cuticle of the joint, providing sensory information about joint angles. If the Böhm's bristles are only detecting joint position, and the full range of motion of that joint is detected by the array of Böhm's bristles, it follows that the extent of the array should correspond to the length of the segment covered by the flexible cuticle during bending. The spatial arrangement of the bristles should provide insight into the joint movement range, joint type, and the resolution of the joint angle available as sensory input. To evaluate this, we characterized the Böhm's bristles in Acheta domesticus (L.) (two hinge joints) using scanning electron microscopy (SEM). Our SEM analysis revealed one field of Böhm's bristles on the dorsal side and two on the ventral side of the scape, and two additional fields of Böhm's bristles on the lateral and medial sides of the pedicel. Bristles are positioned such that they are all deflected when the scape or pedicel is completely bent; thus, the arrangement of bristles matches the range of joint movement. In addition, we suggest that the number of bristles in the direction of joint movement may indicate the resolution of detection of the movement of the joint.

The wheat stem sawfly, Cephus cinctus Norton, is a major pest of cultivated wheat (Triticum aestivum L.) and other cereals in North America. The native congeneric parasitoids Bracon cephi (Gahan) and B. lissogaster Muesebeck are important biocontrol agents and play a crucial role in managing wheat stem sawfly outbreaks and damage. Smooth brome grass (Bromus inermis Leyss) has been found to be an effective wheat stem sawfly sink and parasitoid source when grown in areas neighboring wheat fields in Montana. To better understand the ecology of the system, we investigated both the wheat stem sawfly-induced volatile organic compounds produced by smooth brome and winter wheat, and the electrophysiological and behavioral response of B. cephi and B. lissogaster to the collected volatiles via coupled electroantennography and gas chromatography-flame ionization detection. Volatile concentration analysis indicated significantly increased production of (Z)-3-hexenyl acetate, 6-methyl-5-hepten-2-one, and (E)-2-hexenal in wheat stem sawfly-infested smooth brome, and elevated production of 6-methyl-5-hepten-2-one in infested smooth brome and winter wheat when compared to their uninfested counterparts. Both B. cephi and B. lissogaster exhibited significant electrophysiological and behavioral response to (Z)-3-hexenyl acetate, 6-methyl-5-hepten-2-one, and hexahydrofarnesyl acetone. Our results provide important evidence supporting habitat management recommendations that will enhance the effectiveness of biological control, contributing to more sustainable agricultural practices and the preservation of vital ecological functions.

Spotted wing drosophila, Drosophila suzukii (Matsumura), native to Asia, has become a significant threat to soft fruit crops globally. To develop a classical biological control program for this pest, the obligate parasitoid Ganaspis kimorum (Buffington) was approved in the United States for field release in 2021 as a biological control agent. However, challenges in mass production and maintenance of parasitoid colonies have been common. Here, we share improved methods and offer insights into mitigating issues that limit parasitoid production. Additionally, we present a modified rearing protocol using 2-l plastic containers to produce an average of 307 G. kimorum per container. This information is crucial for implementing successful classical biological control programs against spotted wing drosophila with this parasitoid.

This research evaluated the AedesTech Mosquito Home System (AMHS), an ovitrap employing autodissemination with pyriproxyfen, to monitor and manage mosquito populations. It involved 3 studies of the AMHS: a baseline study, an effectiveness study, and an autodissemination study on Aedes (Diptera: Culicidae) mosquitoes. Forty AHMS units filled with water were deployed for the baseline study. During the effectiveness study, 40 untreated AMHS units with water were placed alongside 40 AMHS units treated with Mosquito Home Aqua (MHAQ) solution, the retail solution used for AMHS. The autodissemination study featured 40 AMHS units treated with MHAQ alongside 40 control AMHS units without MHAQ, together with 25 Aedes aegypti (Linnaeus) larvae. Notably, treated traps in the effectiveness study exhibited a significant reduction in the Ovitrap Index (OI) compared to the baseline traps in the baseline study. The effectiveness study validated AMHS's efficacy, with treated traps displaying a significantly lower OI than untreated counterparts (P < 0.05). The study also showed a decrease in the percentage of egg hatching and percentage of adult emergence in treated traps compared to untreated traps. Autodissemination was evident, marked by a significant percentage of adult emergence decrease of Ae. aegypti larvae, without affecting sex ratios. It strongly suggests that AMHS can effectively reduce Aedes populations through direct contact and autodissemination without affecting sex ratios.