Journal of Insect Science最新文献

Insecticide resistance is a major public health concern. Biopesticides, derived from naturally occurring substances such as plant extracts and fungal metabolites, are utilized as natural control agents against mosquito vectors. This study focuses on biopesticides to reduce chemical insecticide use in Penang Island, Malaysia. Ipomoea cairica Linnaeus Sweet (Solanales: Convolvulaceae) leaf extracts, Metarhizium anisopliae s.l. (Metsch) Sorok (Ascomycota: Clavicipitaceae) strain Meta-G4, and synergistic effects of both agents were demonstrated against Aedes albopictus Skuse (Diptera: Culicidae) and Aedes aegypti Linnaeus (Diptera: Culicidae) using larvicidal bioassays. Before assessing synergism, the compatibility of both agents was performed to minimize inhibition of mycelial growth on potato dextrose agar. The results showed that Ae. aegypti field strains (urban and suburban) are significantly more susceptible to I. cairica leaf extracts compared to Ae. albopictus field strains (urban and suburban) due to the lower lethal concentrations (LC50 and LC95). Aedes albopictus suburban field strain is significantly more susceptible than other strains when tested with M. anisopliae due to the lower LC50. The combination of M. anisopliae (1 × 106 conidia/ml) with I. cairica leaf extracts (350 ppm) achieved the lowest LT50 and LT95 against Ae. aegypti urban field strain. This study indicates that the synergistic combination of both agents exhibits significant larvicidal efficacy and holds promise for future biological control strategies targeting Aedes populations.

Nezara viridula (L.) and Halyomorpha halys (Stål) are stink bug pests that damage fruit in a variety of crops throughout the southeastern United States. Trichopoda pennipes (F.) parasitizes N. viridula late instars and adults, however, little is known regarding parasitism of H. halys by this tachinid in systems where both stink bug species coexist. Thus, our main objective was to analyze patterns of T. pennipes parasitism for adult N. viridula and H. halys in corn, cotton, and soybean. We also assessed location of T. pennipes eggs on stink bug bodies as well as successful emergence from parasitized adults (ie at least 1 parasitoid egg per host body). Overall, the proportion of parasitized adults was higher for N. viridula compared to H. halys and higher in corn and cotton compared to soybean. Males were parasitized more often than females for both species. For N. viridula, T. pennipes developed to adults more often when eggs were laid on the ventral thorax. Supernumerary oviposition by T. pennipes was evident for both species. Even though T. pennipes readily oviposited on H. halys, new adults did not emerge from parasitized adults. For N. viridula, mortality of first instar T. pennipes was high due to their difficulty in entering the body; consequently, larval competition within the body was minimal. Adult T. pennipes emerged more often when two to four eggs were deposited on an adult stink bug. We conclude that T. pennipes prefers N. viridula as a host. Therefore, conservation biocontrol is an important management strategy for this pest.

Juvenile hormone (JH) has been revealed to be a critical factor in regulating photoperiod reproductive diapause in various insect species, however, little information is known about the detailed mechanisms. In this study, we investigated the roles of JH signaling in photoperiod reproductive diapause in a green lacewing, Chrysoperla nipponensis (Okamoto), which is a potentially important biological control predator. Our results showed that the short-day condition induces a diapause state including JH synthesis suppression, ovarian development arrest, and triglyceride accumulation. The interference of JH response genes, Krüppel homolog 1 (Kr-h1), in reproductive females exhibited a diapause-related phenotype such as ovarian development arrest and larger triglyceride storage. Exogenous JH III suppresses diapause to promote ovarian development and inhibit triglyceride synthesis. However, exogenous JH III fails to rescue the Kr-h1-silenced phenotype. Accordingly, our results demonstrate the critical role of Kr-h1 in regulating JH signaling to promote reproduction.

Surveillance is integral for the targeted and effective function of integrated vector management. However, the scale of surveillance efforts can be prohibitive on manpower, given the large number of traps set, collected, processed, and enumerated. For many public health agencies, the sheer effort of weekly trapping, combined with the processing of numerous traps, is a major capacity challenge. To reduce employee fatigue and increase throughput, estimation methods are used in a diagnostic capacity to determine threshold numbers of mosquitoes (Diptera: Culicidae) for operational decision-making. Historically, volume and mass measures correlated to a known number of mosquitoes are the oldest and most widely used within mosquito control programs. Image processing methods using digital counting software, such as ImageJ, have not been tested rigorously in the context of high throughput usage experienced in mosquito operations. We stress-tested volume, mass, and image processing methods using sample calibrations from early in the year and applied them throughout a mosquito active season. We additionally tested resilience with samples that had been frozen, desiccated, old, or from an excessively large trap collection. Furthermore, we compared magnitudes of error after intentionally deviating from best practices. In all cases, mass and volume encountered significant errors. In contrast, the digitized-optical counting method was resilient to going long periods of use without recalibrating, handling different species compositions, and processing aged or damaged samples. If a program has limited logistical power, the aforementioned image-processing method confers the best balance of accuracy and expediency for time-sensitive workloads and efficient operational decision making.

Tracking tagged individuals is an emerging tool to locate invasive wasp nesting sites. Both tag size and transmitter/transceiver cost can limit the applicability of these technologies for eradication measures. This pilot study used a combination of lightweight, inexpensive harmonic radar tags fabricated with superelastic nitinol wire, and off-the-shelf transceivers designed for backcountry rescue. Larger tags weighing ~10 mg (~14 mg with adhesive) were used to track three vespid wasps, Delta esuriens (F.), Polistes aurifer Saussure, and Vespula pensylvanica (Saussure), while smaller tags ~5 mg (~8 mg with adhesive) were used only with V. pensylvanica. Wasps were successfully tagged in both laboratory and field settings. Tagged P. aurifer were shown to be flight capable in a large outdoor field cage. Subsequently, wasps were tracked in a macadamia nut field (D. esuriens and P. aurifer), a coastal habitat (D. esuriens), and in Hawai'i Volcanoes National Park (V. pensylvanica). Flight paths up to 6 steps (maximum 126.7 m) were recorded for D. esuriens (maximum single flight 76.6 m). Vespula pensylvanica were tracked to one nest; several other attempts failed to identify a nest location but did demonstrate the practicality and limitations of following wasps through dense vegetation. Additionally, we demonstrated that V. pensylvanica would carry off tags embedded in small pieces of meat although this technique did not lead to the discovery of any nests. This study demonstrates the feasibility of using an inexpensive method to track wasps, potentially allowing for a rapid and simplified method of locating invasive wasp nests.

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.