Vairimorpha (Microsporidia: Nosematidae) is a microsporidian that infects honey bees especially in winter. Fumagillin can reduce infections, but whether overwintering survival is improved is unclear. The diet also may influence the severity of Nosema infections. We examined the relationship between Nosema and colony size and survival in hives overwintered in cold storage facilities. In year 1, no Fumagillin treatments were applied. Colony size and survival after cold storage and almond bloom were comparable between groups with high and low pre-cold storage infections. In year 2, size and survival were compared among colonies with and without Fumagillin treatment that were fed either pollen or protein supplement prior to overwintering. Colonies treated with Fumagillin had lower spore numbers than untreated, but colony sizes and survival were similar among the treatments. However, more colonies with zero spores per bee could be rented for almond pollination and were alive after bloom than those averaging >1 million spores per bee. Fat body metrics can affect overwintering success. In both years, fat body weights and protein concentrations increased, and lipid concentrations decreased while bees were in cold storage. Fat body metrics did not differ with Nosema infection levels. However, Fumagillin negatively affected pre-cold storage fat body protein concentrations and colony sizes after cold storage and almond bloom. Treating with Fumagillin before overwintering in cold storage might result in greater colony survival if spore numbers are high, but undetectable or even negative effects when spore numbers are low.

Bumblebees play a significant role as pollinators for many wild plants and cultivated crops, owing to their elongated proboscis, resilience to diverse weather conditions, robustly furred bodies, and their unique capacity for buzz-pollination. To better understand the effect of greenhouse microclimates on bumblebee foraging behavior and working modes, a long-term record of foraging activity for each Bombus terrestris L. (Hymenoptera: Apidae) forager was monitored by the Radio-frequency identification system. The pattern of task performance, including constant housing, foraging, and day-off rotation, was examined under the microclimate. In addition, the correlation between foraging activity of bumblebees and temperature, relative humidity, illumination in the greenhouse, and pollen viability of tomato plants was further analyzed. Our findings revealed that B. terrestris can respond to microclimatic factors and plant resources while also exhibiting a suitable working pattern within the colony. Day-off rotation was observed as a strategy employed by foragers to prolong their survival time. This division of labor and task rotation may serve as strategies for the survival and development of the colony. Our research may contribute to fully understanding how microclimate and plants influence pollinator behavior within greenhouses, thereby optimizing the pollination management of bumblebees on greenhouse crops.

Pollination by the European honey bee, Apis mellifera, is essential for the production of many crops, including highbush blueberries (Vaccinum corymbosum). To understand the impact of agrochemicals (specifically, neonicotinoids, a class of synthetic, neurotoxic insecticides) on these pollinators, we conducted a field study during the blueberry blooms of 2020 and 2021 in British Columbia (B.C.). Forty experimental honey bee colonies were placed in the Fraser Valley: half of the colonies were located within 1.5 km of highbush blueberry fields (“near” colonies) and half were located more than 1.5 km away (“far” colonies). We calculated risk quotients for these compounds using their chronic lethal dietary dose (LDD₅₀) and median lethal concentration (LC₅₀). Pesticide risk was similar between colonies located near and far from blueberry forage, suggesting that toxicity risks are regionally ubiquitous. Two systemic neonicotinoid insecticides, clothianidin and thiamethoxam, were found at quantities that exceeded chronic international levels of concern. We developed a profit model for a pollinating beekeeper in B.C. that was parameterized by: detected pesticide levels; lethal and sublethal bee health; and economic data. For colonies exposed to neonicotinoid pesticides in and out of the blueberry forage radii, there were economic consequences from colony mortality and sublethal effects such as a loss of honey production and compromised colony health. Further, replacing dead colonies with local bees was more profitable than replacing them with imported packages, illustrating that beekeeping management selection of local options can have a positive effect on overall profit.

White-spotted flower chafer adult (Protaetia brevitarsis, Coleoptera: Scarabaeidae), a serious omnivorous pest in regions with multiple fruits and crops, was studied to gain a deeper understanding of its damage patterns. DNA molecular tracking technology was used to identify host plant residues in adult P. brevitarsis midgut, and plant species with the most availability were determined during their growing season. Combining the 2019 and 2021 results, it was found that adults in the multi-cropped area fed on 32 plant species from 23 families, with grape (Vitis vinifera, 40%), peach (Prunus perisica, 23%) and mulberry (Morus alba, 14%) making up the majority of their diet. Some adults fed on multiple plant hosts, with four species detected in one adult and two to three species detected in one-third of adults. Adults shifted among host species during the season, moving from mulberry or grape to peach and then back to grape. These results provide a scientific basis for in-depth research to develop green integrated control technologies against P. brevitarsis adults.

The spread of toxigenic Aspergillus into maize by insects and the subsequent aflatoxin contamination poses a risk to humans and animals and has been investigated in North and South America.To evaluate this effect in an African context, Greenhouse studies were conducted in 2022 to determine the role of sap beetles, Carpophilus dimidiatus Fabricius, 1792 (Coleoptera: Nitidulidae) and maize weevils, Sitophilus zeamais Motschulsky, 1855 (Coleoptera: Curculionidae) on infection of maize kernels by Aspergillus flavus Link and the resultant aflatoxin accumulation. To test the beetles' efficacy, treatments were applied on partially opened primary ears at 3 different stages of kernel development (BBCH 75, 83, and 87). The treatments were: (i) distilled water, (ii) water with A. flavus spores, (iii) maize grits, (iv) maize grits with A. flavus spores, (v) C. dimidiatus, (vi) C. dimidiatus with A. flavus spores, (vii) S. zeamais, and (viii) S. zeamais with A. flavus spores. Data on kernel infection, maize rotting, yield, and aflatoxin content in kernels were collected. The highest kernel spoilage and yield loss were recorded for the co-inoculation of S. zeamais and A. flavus spores, followed by S. zeamais without A. flavus spores, and then C. dimidiatus with the fungal spores. Inoculation of maize at the BBCH 83 growth stage resulted in the highest kernel damage and aflatoxin contamination. S. zeamais and, to a lesser extent, C. dimidiatus effectively spread the A. flavus inoculum into non-wounded ears, resulting in fungal and aflatoxin contamination.The yield loss from S. zeamais-Aspergillus co-inoculation occurred due to the grain rotting and actual feeding of the maize weevils.Thus, insect management is important in reducing pre-harvest contamination of maize with mycotoxigenic fungi and their resultant toxins.

Graphical Abstract

The invasive fall armyworm (FAW), Spodoptera frugiperda, is a polyphagous pest that significantly threatens crops worldwide. FAW may undergo adaptation, enhancing its ability to infect specific plant hosts. However, there is limited knowledge on this topic. After 8 generations of constant rearing on peanut leaves, the performance and enzyme activities of FAW were investigated in this study. Compared to FAW fed on the peanut cultivars ‘Fuhua 8’ and ‘Quanhonghua 1’ for 2 generations, those grown on leaves for 5 to 8 generations had significantly shorter pre-adult development times and total preoviposition periods. Fecundity also increased significantly, resulting in an overall improvement in population fitness as measured by demographic parameters. However, the F2 generation of FAW fed on corn leaves outperformed the F8 generation of FAW fed on peanut leaves. In the F2 generation, the FAW peanut population exhibited 30–55% supernumerary larval molts, which decreased substantially in the F5 and F8 generations. Notably, supernumerary larval molts displayed pupation and emergence rates comparable to normal larvae, regardless of the peanut cultivar or rearing generation. The activities of lipase and acetylcholinesterase increased significantly from the F2 to F8 generations, showing substantial negative and positive correlations with larval development time and fecundity, respectively. In conclusion, FAW demonstrated inferior performance on peanut leaves compared to corn leaves, despite its performance was significantly improved after 5 to 8 generations of acclimation.These results suggest that corn will continue to be the primary target crop for FAW in China.

Graphical Abstract

Continuous rearing on peanut leaves significantly improved the performance of Spodoptera frugiperda, which showed a notable correlation with increased activities of lipase and acetylcholinesterase.

Farmers in Africa perceive the impact of fall armyworm (FAW) on maize to be significant, but field assessments have shown that yield losses are not significant enough to warrant pesticide interventions. This suggests that relationships between the crop stages, time, and duration of attack can affect the yield. Therefore, assessing the plant's recovery from damage using individual plants based on defoliation levels could guide whether and when pesticides should be applied. To study this, we selected 120 labeled maize plants corresponding to six levels of FAW defoliation, replicated 20 times, based on an initial damage rating. The rating scale ranged from 1 (no defoliation) to 5 (>75% defoliation) during four planting seasons. Plants with a rating scale of 1 were replicated and treated with a chemical insecticide to keep them undefoliated, and that served as a control. Damage severity was recorded weekly on all plants, starting from emergence until maturity, using the same damage rating scale. Results showed that damage severity varied significantly among different defoliation levels during all seasons. Higher levels of defoliation during dry seasons resulted in significant yield loss only for plants with damage levels 4 and 5, with damage severity ranging from 38.7% to 57.5%. These results indicate that FAW control is unnecessary in the rainy season. In contrast, pesticide interventions should be envisaged in seasons of erratic rainfall, with a significant defoliation threshold level of around 50%, occurring at 8 and 5 wk after planting weeks after planting, respectively for the early and late dry season.

The Nearctic leafhopper Scaphoideus titanus Ball (Hemiptera: Cicadellidae) is the main vector of the grapevine flavescence dorée (FD) phytoplasmas in Europe. To limit the impact of pest control activities on human health and the environment, EU legislation is withdrawing a growing number of active ingredients (a.i.), highlighting the need to evaluate alternative S. titanus management tools. In this context, we carried out a three-year (2021–2023) study in Italian vineyards characterized by high S. titanus populations. We compared the effectiveness of different insecticide-based strategies, i.e., targeting only nymphs (2021) or nymphs and adults (2022–2023), by spraying some of the currently allowed products (i.e., flupyradifurone, acetamiprid, sulfoxaflor, etofenprox, deltamethrin, and pyrethrins). The effectiveness of insecticide-based treatments was evaluated in terms of adult catches on yellow sticky traps. Furthermore, to achieve useful insights for optimizing current monitoring tools, we compared S. titanus catches on sticky traps of five different colors (i.e., yellow, green, blue, black, and white), as well as those achieved with two types of currently marketed yellow sticky traps. Results showed that etofenprox, deltamethrin, and sulfoxaflor were the most effective products for reducing S. titanus adult populations (33.64%, 30.30%, and 31.26%, respectively). Yellow and green sticky traps were more attractive to S. titanus adults than white, blue, and black ones. Moreover, a significant difference in capture efficiency was observed between two commercial yellow devices (i.e., tenfold higher catches using Glutor over Super color). Practical implications of our results are discussed in the context of current IPM against this key leafhopper vector of FD.

Graphical Abstract

In recent years, the use of artificial diet to rear silkworm Bombyx mori (L.) (Lepidoptera: Bombycidae) has advanced rapidly in China. However, significant differences are found in the production and performance of silk from silkworms reared on artificial diet and mulberry leaves, thereby affecting the development of artificial diet usage in sericulture. To understand the reasons for these differences, we tested the following 3 rearing methods: all-instar mulberry leaf rearing (Mul), all-instar artificial diet rearing (Diet), and instars 1–3 reared on artificial diet followed by instars 4–5 reared on mulberry leaf (Mix).The results showed that the silk production was significantly lower under Diet than Mix and Mul. Electron microscopy images revealed that the protein synthesis and energy supply were decreased under Dier and Mix compared with Mul. Subsequent strength analysis indicated that the relative strength of silk was highest under Mix, followed by Mul, and weakest under Diet. However, no significant differences in elongation were observed among treatments.The β-sheet content of silk was significantly higher under Mix than Diet and Mul, and a similar trend was observed for the crystallinity. Furthermore, the elevated expression of BmChiNAG and the reduced expression of BmTpn genes may be a significant factor for the notable disparities in cocoon silk fineness and strength among the threes.These findings provide deep insights into the differences in silk produced by silkworms reared on mulberry leaves and artificial diet, as well as providing a reference for improving artificial diet for rearing silkworms.

Bemisia tabaci (Gennadius), a major pest that can adversely affect economies and agriculture globally, is particularly sensitive to climate change-induced temperature fluctuations, which can intensify its outbreaks. Orius similis Zheng, a primary natural predator of B. tabaci, also experiences temperature-related effects that influence its biocontrol efficacy. Thus, understanding the response of O. similis to temperature changes is pivotal for optimizing its biocontrol potential. Herein, our investigations showed that the functional response of O. similis to both high- and low-instar nymphs of B. tabaci adheres to the type II model at temperatures of 19, 22, 25, 28, and 31 °C. At 28 °C, O. similis exhibits the highest instantaneous attack rate (high-instar: 1.1580, low-instar: 1.2112), and the shortest handling time per prey (high-instar: 0.0218, low-instar: 0.0191).The efficacy of O. similis in controlling B. tabaci nymphs follows the sequence: 28 °C > 25 °C > 31 °C > 22 °C > 19 °C. Additionally, search efficiency inversely correlates with prey density. Simulations using the Hessell–Varley interference model indicate that increased density of O. similis under any temperature condition leads to reduced predation rates. Moreover, O. similis shows a predation preference for low-instar nymphs of B. tabaci, with higher predation level observed at the same temperature. In conclusion, for effective control of B. tabaci in field releases, O. similis should be optimally released at temperatures between 25 and 28 °C to preferably target the egg or early nymph stages of B. tabaci and determining the appropriate number of O. similis is important to minimize interference among individuals and enhance biocontrol efficacy.

Graphical Abstract

The endoparasitoid Asecodes hispinarum (Bouček) (Hymenoptera: Eulophidae) serves as an effective biological control agent against Brontispa longissima (Gestro) (Coleoptera: Chrysomelidae), a notorious palm pest. Endosymbionts found in parasitoids and their hosts have attracted significant attention due to their substantial influence on biocontrol efficacy. In this study, we employed 16S rRNA sequencing, polymerase chain reaction, and fluorescence in situ hybridization to assess the symbiotic bacteria composition, diversity, phylogeny, and localization in A. hispinarum and its host B. longissima. Our findings showed significant differences in the richness, diversity, and composition of symbiotic bacteria among different life stages of B. longissima. Notably, the bacterial richness, diversity, and composition of A. hispinarum was similar to that of B. longissima. Firmicutes and Proteobacteria were the dominant phyla, while Wolbachia was the dominant genera across the parasitoid and host. It was discovered for the first time that Wolbachia was present in A. hispinarum with a high infection rate at ≥ 96.67%. Notably, the Wolbachia strain in A. hispinarum was placed in supergroup A, whereas it was categorized under supergroup B in B. longissima. Furthermore, Wolbachia is concentrated in the abdomen of A. hispinarum, with particularly high levels observed in the ovipositors of female adults. These findings highlight the composition and diversity of symbiotic bacteria in both A. hispinarum and its host B. longissima, providing a foundation for the development of population regulation strategies targeting B. longissima.

Graphical Abstract

Fertilizers generally influence the nutritional quality or defense ability of the plants, which can indirectly cause an increase in populations of herbivorous insect pests such as grape phylloxera, Daktulosphaira vitifoliae (Homoptera: Phylloxeridae, Fitch). The effects of nutrient solutions on grape–grape phylloxera interactions were analyzed using five concentrations (nitrogen content: 15, 30, 60, 120, and 180 mg/L) of Hoagland's nutrient solution to irrigateVitis vinifera L. ×Vitis labrusca L. (Kyoho). Life table variables and life history variables showed a hump-shaped or an inverted hump-shaped curve as nutrient input level increased. Sixty micro-gram per liter treatment resulted in the greatest longevity and egg incubation, shortened the nymph duration and significantly increased the adult lifespan. Overall, both excessive and insufficient nutrient inputs curbed growth and multiplication of D. vitifoliae.These results provide a theoretical basis for vineyards for amending fertilizer inputs to prioritize the prevention and control of this pest.

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Biological control is an effective and sustainable method of integrated pest management. Microplitis manilae (Hymenoptera: Braconidae) is a common internal parasitoid wasp of the order Lepidoptera. To determine a suitable host species for the reproduction of parasitoids, it is essential to assess host suitability and parasitic potential of the parasitized pests. Herein, we investigated host selection and exploitation of M. manilae. We evaluated the parasitic efficacy of M. manilae in 4 pest species in the Spodoptera and Mythimna genera of the Noctuidae family. The results indicated that the parasitism rate of M. manilae on 3 species in the Spodoptera genus is higher than on Mythimna separata in the Mythimna genus, with M. manilae exhibiting a higher parasitism rate and shorter development duration on Spodoptera litura compared to other species. The parasitism rate for 1st instars hosts was 86.67 ± 0.04%, while the development duration was 14.1 ± 0.03 days. However, when parasitizing the 3rd instar of Spodoptera frugiperda, parasitoids showed a higher sex ratio, of 0.71 ± 0.05. Additionally, M. manilae had parasitic effect on M. separata, providing a new choice for its parasitism. The results identify the optimal host, which could enhance and reproduction rate and survival rate of M. manilae, thus facilitating their large-scale propagation. Understanding the parasitic effects of M. manilae on pests can further its field application, also plays a major role in promoting the development of biological control technologies and sustainable agricultural production.

Wheat stem sawfly (WSS), Cephus cinctus Norton (Hymenoptera: Cephidae), is a major pest of cereal crops throughout the Northern Great Plains of North America. Native parasitoids, Bracon cephi (Gahan) and B. lissogaster Muesebeck (Hymenoptera: Braconidae), play a key role in suppressing WSS populations and limiting associated damage. Smooth brome grass (Bromus inermis Leyss.) serves as a potential trap reservoir for WSS when grown in areas surrounding wheat (Triticum aestivum L.) fields in Montana. Its unique biology allows it to support high WSS infestation while promoting significant larval mortality throughout the growing season. Late-season WSS survivors can then serve as hosts for WSS parasitoids. Our study investigated smooth brome as a host refuge for WSS parasitoids. We measured WSS larval infestation and survival rate inside smooth brome grown within WSS-inclusion cages, finding a maximum infestation of 66.5% and an end-of-year WSS survival of 5.7%. In addition, we collected stems from sites in central and north-central Montana to measure the WSS infestation and parasitoid prevalence in wheat and adjacent smooth brome. WSS infestation was high in both Big Sandy (64.5% smooth brome, 65.7% adjacent wheat) and Moccasin, MT (50.6%, 38.6%).Year-end WSS larval mortality was 43.6% greater in smooth brome compared to adjacent wheat at both field sites, but both hosted similar numbers of WSS parasitoids. This research underscores the importance of smooth brome in providing a sustainable host refuge for WSS parasitoids and highlights its significant role in supporting the economics of wheat cultivation.

Climate change can exacerbate pest population growth, posing significant threats to ecosystem functions and services, social development, and food security. Risk assessment is a valuable tool for effective pest management that identifies potential pest expansion and ecosystem dispersal patterns.We applied a habitat suitability model coupled with priority protection planning software to determine key monitoring areas (KMA) for tree insect pest risks under climate change and used forest ecoregions and nature reserves to assess the ecological risk of insect pest invasion. Finally, we collated the prevention and control measures for reducing future pest invasions.The KMA for tree insect pests in our current and future climate is mainly concentrated in eastern and southern China. However, with climate change, the KMA gradually expands from southeastern to northeastern China. In the current and future climate scenarios, ecoregions requiring high monitoring levels were restricted to the eastern and southern coastal areas of China, and nature reserves requiring the highest monitoring levels were mainly distributed in southeastern China.Tree insect pest invasion assessment using ecoregions and nature reserves identified that future climates increase the risk of pest invasions in forest ecoregions and nature reserves, especially in northeastern China.The increased risk and severity of tree insect pest invasions require implementing monitoring and preventative measures in these areas. We effectively assessed the pest invasion risks using forest ecoregions and nature reserves under climate change. Our assessments suggest that monitoring and early prevention should focus on southeastern and northeastern China.

The brown marmorated stinkbug, Halyomorpha halys Stål (Hemiptera: Pentatomidae), is a polyphagous invasive insect found in the eastern United States in 1998 but became a major agricultural pest in 2010. Environmental temperatures regulate the location of invasive species establishment in new locations. To determine those areas where an invasive species might establish it is essential to understand the metabolic response of all life stages to temperature. Differential scanning calorimetry is a useful tool to monitor living organisms' metabolism at different temperatures, providing vital information related to the ability of the species to survive in new environments. The information obtained from isothermal and scanning calorimetric experiments on all the life stages of H. halys indicates that the third instar is the most thermoresponsive stage and eggs and fifth instar are the least thermoresponsive, whereas the third instars exhibit a broad range of thermoresponsiveness as compared to all other developmental stages.The recorded values for lower, optimal, and upper developmental temperatures in this study were similar to those reported by other researchers using laboratory and field data to develop degree-day models.This method can help in the rapid development of degree day models to improve and synchronize control efforts for newly invasive species.

Knowledge of the ecology and behavior of biological control agents is essential for their effective use in biocontrol and Integrated Pest Management (IPM) programs. There is a lack of information regarding the courtship and mating traits that are crucial for successful mating in biocontrol population of coccinellids.To expand our current understanding in this area, 2 coccinellid species commonly used for the biocontrol of soft-bodied insects, Cryptolaemus montrouzieri (Mulsant) and Propylea quatuordecimpunctata (Linnaeus) (Coleoptera: Coccinellidae), were studied. A quantitative analysis was performed to compare their courtship and mating displays. Key behavioral traits of the precopulatory, copulatory, and postcopulatory phases were investigated. The courtship and mating sequences of C. montrouzieri and P. quatuordecimpunctata were similar to each other. During the mating phase, the key displays were the opening of the elytrae and wings followed by body shaking in C. montrouzieri and leg tapping followed by body shaking in P. quatuordecimpunctata. The mating success of both species was not correlated with any courtship display, such as antennal tapping. Only in C. montrouzieri mounting attempt showed a higher frequency from the backside without affecting male mating success. This research adds baseline knowledge about the courtship and mating behavior of the biocontrol population of coccinellids, contributing to the identification of potentially useful benchmarks (e.g., body shaking, leg tapping) for monitoring prolonged mass-rearing processes, thus reducing mating failures.

Graphical Abstract

The fall armyworm Spodoptera frugiperda (J.E. Smith; Lepidoptera: Noctuidae) is a notorious invasive insect pest. It is very important to understand the foraging behavior of this pest to develop more effective lures to monitor the immigration of this pest. In this study, the use of visual and olfactory cues in the foraging behavior of S. frugiperda was investigated through an attraction experiment in which color (produced from 8 different colored artificial flowers), odor (produced from honey water), and odorous color (produced from artificial flowers supplemented with honey water) were used. When we used 8 different colors to elicit adult responses, S. frugiperda showed a significant color preference despite limited activity (i.e., the total number of visits to the attractant), with black being the most preferred color, followed by orange preferred by both sexes and blue and green preferred only by females. When honey water was used as an attractant, S. frugiperda had relatively greater odor activity than color activity. When we sprayed the artificial flowers with honey, S. frugiperda showed even greater activity in terms of odor color than in terms of color or odor. Compared with male S. frugiperda, female adult S. frugiperda presented greater activity in response to all types of attractants. These findings suggest that S. frugiperda adults rely primarily on olfaction for foraging, with vision as a secondary sense, and that the combined use of olfactory and visual cues increases foraging efficiency. These results provide reference data for designing trapping strategies to monitor and control S. frugiperda.

In central Canada, surveys for the three invasive (Palearctic) Agriotes species—A. obscurus, A. lineatus, and A. sputator—commonly collect A. pubescens, a North American native (Nearctic) click beetle (Coleoptera: Elateridae) that generally co-occurs with Nearctic A. mancus. Despite the abundance of A. pubescens on farmland, its life history and potential economic impact remain largely unknown. Here, we report the identification and field testing of the A. pubescens sex pheromone. We collected headspace volatiles from a single female beetle on Porapak Q, then extracted the female's pheromone gland, and analyzed aliquots of both Porapak extract and pheromone gland extract by gas chromatographic–electroantennographic detection (GC–EAD) and by GC–mass spectrometry. In GC–EAD recordings of gland extract, two esters—geranyl butanoate and geranyl octanoate—elicited antennal responses from A. pubescens males. In a field experiment in Quebec, traps baited with a 1:1 blend of these esters captured approximately 100× more A. pubescens males than traps baited with a single ester.This is the same trap lure used for capturing A. lineatus. In this experiment, and in a similar one run in British Columbia, heterospecific pheromone components added to conspecific pheromone lures reduced captures of A. mancus, A. sputator, A. lineatus, and A. obscurus by 29%, 96%, 44%, and 71%, respectively. These data indicate that, in North America, lures containing pheromone components of multiple Agriotes congeners may not be optimally attractive to all target species.

Fruit volatiles play a crucial role in the host localization by the oriental fruit fly, Bactrocera dorsalis Hendel (Diptera:Tephritidae).This study focused on identifying the fruit volatiles from Sanyue plum and Sanhua plum (Prunus salicina Lindl.), which are 2 varieties of the same species, and examined their impact on the behavior of B. dorsalis by using aY-olfactometer. A total of 35 and 54 volatiles from Sanyue plum and Sanhua plum were identified, respectively. Among these, 23 volatiles elicited electroantennographic (EAG) responses by B. dorsalis adults, showing concentration-dependent effects in males and females. Ethyl butyrate, butyl acetate, butyl hexanoate, ethyl caproate, ethyl hexanoate, and hexyl acetate significantly attracted B. dorsalis compared to liquid paraffin, while nonaldehyde was avoided.There was no significant difference in the behavioral responses of both sexes to sorbitol esters, hexyl isobutyrate, and 1-tetradecene compared with the control liquid paraffin group. Interestingly, (3Z)-C-3-hexenyl acetate significantly attracted females, but not males.The above findings suggest that plum fruit volatiles are likely to facilitate the localization of host fruit by B. dorsalis adults and may even aid in mate-finding. This study opens up new avenues for exploring novel plant-based attractants that might be of value for the integrated management of B. dorsalis.

Anthocyanins are secondary metabolites which act as diverse functions during plant growth. Insects can discriminate host plants by their sensitive gustatory systems. It is hypothetical that chemosensory proteins (CSPs) play a crucial role in regulating this behavioral process. However, the underlying molecular mechanisms remain obscure. In the present study, we characterized a CSP SlitCSP8 from the Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae). Quantitative real-time-polymerase chain reaction analysis demonstrated that SlitCSP8 was mainly expressed in the head of the 7th S. litura larvae, especially labrum. Further, recombinant SlitCSP8 was obtained using bacterial expression system. Fluorescence competitive binding assays demonstrated that the purified SlitCSP8 exhibited a strong binding affinity to anthocyanins, a natural compound derived from the host plant. Silencing SlitCSP8 through RNAi significantly reduced the sensitivity of S. litura larvae to anthocyanins-treated leaf disks, the development from larva to pupae was not affected. These data provide insight into the molecular basis that CSP8 can detect anthocyanins in host plants by chemosensory system of insects. It can be further used in designing novel optimal food attractant targeting to the CSPs for pest control.

Graphical Abstract

Wing dimorphism is a distinguishing characteristic of brown planthopper Nilaparvata lugens (Stål) populations, wherein adults exhibit 2 distinct morphs: long-winged and short-winged. The presence of long-winged individuals often heralds the onset of migration, while short-winged morphs signify high reproduction and can be associated with population outbreaks. This phenomenon underscores the adaptability of these insects in response to environmental cues and their impact on agricultural ecosystems. Wing morphs of N. lugens are controlled by genetical and environmental factors. Mate choice between long and short-winged adults affects wing morphs of offspring. In this study, we found that the wild population had no persistent preference for choosing long-winged or short-winged adults to mate. But in 2 multigenerational selected lineages for long and short-winged morphs, the short-winged males preferred to short-winged females to mate and the long-winged males had no preference. In the nearly pure-bred lineages of long-winged and short-winged morphs, both wing morphs of females preferred for short-winged males. Purification of wing morph lineages enhanced mating preference for short-winged partners. When the wing developmental gene InR1 or InR2 was interfered by RNAi, the pure-bred lineage of long-winged morph mainly produced short-winged adults and the short-winged morphs produced long-winged adults, and these adults exhibited preference to mate with short-winged partners. The tendency to mate with short-winged morphs leads to more short-winged offspring which easily causes the rapid growth of populations.

Gynaephora alpherakii (Grum-Grschimailo) (Lepidoptera: Lymantriidae) is a major pest in alpine meadow areas in the Qinghai–Tibetan Plateau (QTP) and causes severe losses in the local livestock production industry. Assessing areas at high risk for G. alpherakii infestation is critical for the effective management of this pest. In this study, an ensemble distribution model was used to analyze areas suitable for G. alpherakii on the QTP. Risk zoning was performed based on the vegetation and environmental conditions in areas with high-occurrence points, and differences between high-occurrence points and other occurrence points were compared. The results revealed that the suitable areas for G. alpherakii on the QTP amounted to 28.27 × 10⁴ hm², accounting for 10.94% of the total area of the QTP; the area of high-risk was 19.07 × 10⁴ hm², and these areas were located mainly in the eastern part of the QTP. Qinghai Province had the highest risk, accounting for 77% of the total area identified as high-risk. In terms of habitat, G. alpherakii preferred alpine Kobresia meadows, which have abundant sunshine, loose soil, and scarce precipitation. This study supports efforts to manage G. alpherakii outbreaks and contributes to the ecological protection of the QTP.

Nitrogen has important effects on plant growth and defense. Although studies on the alternation in plant chemical defense by nitrogen fertilization have been extensively reported, how it affects physical defense is poorly understood. Two rice (Oryza sativa L.) (Poales: Poaceae) varieties (LDQ7 and YLY1) were applied with varying nitrogen regimes (0.90 and 180 kg ha^–1) to study their physical defense against the brown planthopper (BPH) Nilaparvata lugens (Hemiptera: Delphacidae) in this study. Results of the electrical penetration graph showed that BPH searching and penetrating duration time was shortened with increasing nitrogen application. Also, the tubercle papicle of rice leaves decreased with increasing nitrogen application, while rice leaves' surface structure and waxy composition changed with increasing nitrogen application. In field experiments, BPH populations increased with the application of nitrogen fertilizer.These findings suggest that nitrogen input can affect plant-insect interactions by reducing the physical defense of plants, which provides new ideas for the organic combinations of yield increase and pest control in rice fields.

Graphical Abstract

Nanoformulations of essential oils (EOs) improve stability of the active ingredient, and thereby its biological activity and persistence. Because compatibility of EOs with natural enemies is not explored sufficiently, we evaluated the impact of nanoformulations of EOs (aniseed, lemon) or pure products (farnesol) on different activities of the generalist predator Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae). In dual choice bioassay, chrysopid larvae were significantly attracted to aniseed-treated pepper disks and deterred by farnesol. Larval activities (resting, walking, and preying) on treated leaves infested with Myzus persicae (Sulzer) (Hemiptera: Aphididae) were compared.There were no differences among nanoemulsions, nor aphid consumption varied. We studied the toxicity of nanoformulations to larvae and evaluated their development after contact with treated leaf disks, ingestion of treated artificial diet, and both routes of exposure (application of biopesticides on aphid-infested plants).This is the first evidence of the compatibility of EO nanoformulations with C. carnea by single route of exposure. Whether any effect appeared, it was sublethal. Compounds significantly reduced aphid consumption after 6 h on double route exposure, but this negative short-term effect disappeared as time progressed. Our results showed the optimal biopesticide to apply depends on which biological feature of the natural enemy we targeted.The key element to introduce these nanoemulsions is to match their persistence period on the crop with the release of the appropriate biological stage of C. carnea. This reinforces the fact that the main activities of C. carnea can be substantially maintained in joint application with nanoemulsions of EOs.

Graphical Abstract

Florida is the second largest producer of strawberries in the United States. However, the production system faces numerous challenges, especially Scirtothrips dorsalis Hood (Thysanoptera: Thripidae) infestations. Management of this pest involves applying insecticides and use of predatory mites, particularly Amblyseius swirskii Athias-Henriot, Neoseiulus cucumeris Oudemans, and Neoseiulus californicus McGregor (Mesostigmata: Phytoseiidae). Strawberry growers in Florida are concerned about the compatibility of the commercial formulations of insecticides used in strawberry pest management with predatory mites.This study assessed the residual effect of commercial insecticides used in strawberry production on the survival, feeding, and oviposition of the 3 predators. Using Munger cells, predators were exposed to commercial formulations of spinetoram, cyantraniliprole, azadirachtin + pyrethrin, Beauveria bassiana, Cordyceps javanica, capsicum, garlic, and canola oil extracts, and water control.There was a gradual decline in the survival and feeding of predatory mites when exposed to all insecticides. Spinetoram had the highest impact on the survival and feeding of all predators compared to other insecticides, while C. javanica had the lowest impact. Cyantraniliprole and azadirachtin + pyrethrin significantly reduced predator survival after 72 h of exposure, whereas capsicum, garlic, and canola oil extracts caused a similar reduction after 96 h. All predators consumed low proportions of S. dorsalis across all treatments. Oviposition was low in all treatments, with no discernable variation among treatments. These results highlight the potential of using entomopathogenic fungi in conjunction with A. swirskii, N. cucumeris, and N. californicus for the management of S. dorsalis and T. urticae in strawberries.

Graphical Abstract

Macrosaccus morrisella (Fitch) (Lepidoptera: Gracillariidae) is a leaf-mining microlepidopteran native to North America recently reported feeding on soybean in the United States and Canada. Control methods for the management of this pest remain unknown. The insecticides Agri-Mek SC (abamectin) and Endigo ZXC (lambda-cyhalothrin + thiamethoxam) were evaluated for: (i) effects against immature stages of M. morrisella in potted soybean plants; (ii) effects against adults of M. morrisella through different routes of exposure; and (iii) efficacy of field applications against M. morrisella. In the experiment with immature stages, when either insecticide was applied to potted plants with M. morrisella in serpentine or blotch mines, significantly fewer adults emerged compared to the untreated plants. In contrast, adult emergence from potted plants treated with either insecticide when M. morrisella was in tentiform mines did not differ from untreated plants. In the experiment with adults, the survival of M. morrisella exposed to either insecticide through oral exposure or residual contact + oral exposure was significantly lower than that for residual contact exposure alone, which in turn was lower than the untreated control. Within each exposure route, the response to the 2 insecticides did not differ. In the field experiment, at 21 days after insecticide application, the mean percentage of leaf area mined was significantly lower in plots treated with Endigo ZCX compared to plots treated with Agri-Mek SC or those left untreated. These results suggest that Endigo ZXC and to a lesser extent Agri-Mek SC may have potential for management of M. morrisella.

The southern corn rootworm, Diabrotica undecimpunctata howardi Barber, is native to the US where it is a pest of peanut, Arachis hypogaea.The banded cucumber beetle, Diabrotica balteata LeConte, is native to the neotropics, but its range has expanded and currently includes most of the US peanut production area.The purpose of this study was to: (i) define seasonal variation in adult rootworm populations in peanut fields, and (ii) determine the effect(s) of proximity to a putative early season host (i.e., corn, Zea mays) and the presence of irrigation on rootworm infestation and pod injury in peanut. Seasonal abundance of adult rootworms in commercial peanut fields in Georgia was monitored in 2021 and 2022 using plant volatile lures attached to yellow sticky traps.Traps were located at 45, 90, and 180 m from the field edge in irrigated and nonirrigated peanut fields with and without a corn border.Two peaks in abundance were observed for both species in each year. Though peak abundance for the two species occurred nearly simultaneously, D. balteata was more abundant than D. u. howardi. Beetle abundance was highest in fields bordered by corn, but presence of irrigation was not as important for D. balteata as it was for D. u. howardi. Pod injury was greater in fields bordered by corn in both years, but there was no difference in pod injury between irrigated and nonirrigated fields.The number of beetles captured and incidence of pod injury within a field did not differ with distance from the field border.

A major limitation to producing high seed yields in berseem clover (Trifolium alexandrinum L.) is failure to set seed, predominantly due to lack of pollination. Despite the importance of berseem clover as a leading forage legume, the contribution of pollinators to seed set is scarce. In Pakistan, the honeybee population is declining mainly because of the extensive use of neonicotinoid pesticides and habitat fragmentation. This, combined with the region's harsh environment and the use of inferior, locally bred genotypes, has resulted in low seed yields. Insufficient seed availability leads to limited forage supply, resulting in poor livestock nutrition, which subsequently impacts livestock health and productivity, and reduces farmers' income.The present study estimated the seed production of 3 berseem clover genotypes resulting from honeybees [Apis mellifera L. (Hymenoptera: Apidae)] pollination in 2 growing seasons (2012–2014) in the central Punjab region of Pakistan. Experiments had 2 pollination treatments (open pollination and honeybee inclusion) and 3 seed genotypes, viz. farmer own-saved, market, and the improved variety cultivars. For both growing seasons, honeybee pollination resulted in significant increases in seed yields ranging from 35% to 67%, regardless of seed genotype. With the exception of the number of seed heads/m², all seed yield parameters also increased significantly in response to honeybee inclusion.The combination of improved variety and honeybee inclusion resulted in the production of a maximum number of seeds per head (45.3), 1,000-seed weight (3.7 g), and estimated seed yield (375.5 kg/ha). In addition, the increase in estimated net income of seed ranged from PKR 82,485 Rs/ha (US$844/ha) to PKR 168,975 Rs/ha (US$1728/ha) with the use of honeybees as an insect pollinator across all the seed genotypes. Honeybee pollination has broader implications for mixed farming systems by playing a key role in preserving biodiversity and promoting sustainable agriculture. It also enhances the quality and quantity of berseem crops by increasing the production of high-quality seeds and forage leading to improved livestock productivity and family food security which strengthens the economic resilience of rural communities.

Native to Asia, Euwallacea interjectus (Blandford) (Coleoptera: Curculionidae: Scolytinae) is a destructive and invasive pest of live trees, and now it has been found in the United States and Argentina. In recent years, this pest appeared in high densities in poplar monocultures from Eastern China (Jiangsu and Shanghai) and Argentina and caused significant poplar mortality. However, the origin of the pests related to tree damage and the Fusarium mutualists from some poplar zones in China remained unclear. Here, we provided a broader phylogeographic analysis of E. interjectus based on the mitochondrial gene (cytochrome c oxidase I) to determine the global genetic structure of this species. Five mitochondrial lineages were found in the native area. Populations introduced to the United States were originated from 4 localities. The Argentine population was derived from Japan. The species was observed with strikingly high level of cytochrome c oxidase I intraspecific divergence that exceeded interspecific divergence, but the high intraspecific variation was correlated with geographical locations among the native populations. Two nuclear genes (arginine kinase and carbamoyl-phosphate synthetase 2–aspartate transcarbamylase–dihydroorotase) were more conservative, and intraspecific differences were lower than interspecific differences. The mitochondrial genetic variation was probably caused by evolution of lineages among geographically isolated populations. But it is immature to infer the existence of cryptic species based on cytochrome c oxidase I differences. All samples collected from poplar populations were indigenous and formed close relationship with a specimen from eastern and southern China. Surprisingly, pests from poplar populations in Jiangsu and Shanghai showed different haplotypes and mutualists. This suggested that the control strategies should consider the genetic and mutualistic diversity of beetles at different poplar localities.

The laurel wilt disease complex is a destructive combination of a non-native beetle vector [redbay ambrosia beetle (RAB), Xyleborus glabratus Eichhoff (Coleoptera: Curculionidae: Scolytinae)] and a symbiotic fungus (Harringtonia lauricola (Ophiostomataceae) T.C. Harr., Fraedrich & Aghayeva), which serves as a pathogen in the host trees infested by RAB.The complex originated from Asia and was first discovered in the United States near Savannah, GA in 2002, and has rapidly made its way across the southeastern US, causing mortality for redbay and other important Lauraceae species, including sassafras, giving this disease complex the potential to have far-reaching ecological effects across North America. Our goal with this study was to examine the spatial distribution of RAB attacks in redbay and sassafras trees along the leading edge of disease progression. RAB attacks were clustered in both tree species, with attacks being most concentrated on the south side of the tree in sassafras, and with RAB clustering more with other RAB attacks on redbay. When comparing bolts that produced adult RABs, the average number of RABs emerged was higher in redbay compared to sassafras. Entrance hole density, RAB emergence, and moisture content were higher near the base of the stem compared to stems sections higher on the bole of both tree species. Our results suggest that physiological differences, such as size and structure of vessels, between these tree species may drive beetle attack patterns and, therefore, affect the progression and spread of disease throughout sassafras and other Lauraceae.

Climate change impacts the distribution of pests and its natural enemies, prompting this study to investigate the dynamics and shifts in distribution under current and future climate conditions.The spatial pattern of Psacothea hilaris (Pascoe) (Coleoptera: Cerambycidae) in China was analyzed, and the MaxEnt model was optimized to predict the potential geographic distribution of P. hilaris and its two natural enemies (Dastarcus helophoroides (Fairmaire) (Coleoptera: Bothrideridae) and Dendrocopos major (Linnaeus) (Piciformes: Picidae)) in China, to further analyze the key environmental factors affecting the survival of P. hilaris and its natural enemies, and to determine the potential of using D. helophoroides and D. major as natural enemies to control P. hilaris.The results showed that the suitable ranges of P. hilaris and natural enemies are expanding under the influence of climate change, and both have migrated to higher latitudes.The potential ranges of D. helophoroides, D. major, and P. hilaris are highly similar. It is noteworthy that the potential range of D. helophoroides completely covers the potential range of P. hilaris.This indicates that D. helophoroides and D. major can be employed as biological control agents to manage P. hilaris populations.This study provides a theoretical framework and empirical evidence for the development of early warning and green control strategies for P. hilaris.

Graphical Abstract

The spongy moth, Lymantria dispar L. (Lepidoptera: Eribidae), is a serious pest of deciduous forests and causes widespread defoliation. Despite this, few studies have evaluated the wide-ranging surveillance of adult male L. dispar using different types of pheromone-baited traps. We evaluated the effect of trap type on captures of adult male L. dispar at 18 sites in Europe; two in Slovenia, two in Spain, 12 in Greece, one in Hungary, and one in Croatia. Seven different trap types, G trap and eGymer 1–6, were evaluated June–September 2022 and 2023. Generally, captures of L. dispar started in late June and lasted until mid-August.Trap type affected captures.The G trap (consisting of a dark brown plastic rectangular parallel-piped body) caught significantly more L. dispar than other trap types in many instances, particularly when the peak of the flight period occurred. Captures of L. dispar in pairs of different trap types showed a significant correlation in trap catch in most investigations, suggesting that most detected comparable fluctuations in L. dispar abundance. We recommend that the G trap be used for wide-ranging surveillance of L. dispar in Europe.

The Asiatic garden beetle, Maladera formosae Brenske (AGB), has become a significant pest of commercial mint fields in northern Indiana. Larval feeding on mint roots can cause stunted growth and plant death when densities are high. Sampling approaches that provide reliable estimates of larval densities in mint have not been established, leaving farmers without the knowledge necessary to implement integrated pest management (IPM) strategies. To address this knowledge gap, we evaluated strategies for estimating AGB larval densities and plant performance in commercial mint systems. We used 2 sampling methods to collect larval density and plant performance data from 3 mint fields and conducted simulations to optimize sampling intensity (accuracy and precision) and sampling scheme (random vs. systematic) using these data. Additionally, we examined the sensitivity and efficiency of each sampling method. Compared to the cup-cutter method, the quadrat method provided the most accurate and precise estimates of larval density and plant performance, with ≤ 7 samples required per 0.2 ha. Quadrat excavation was also more sensitive, increasing the probability of detecting AGB larvae within a 32 m² plot by 76.7%, and requiring significantly less time to survey an equivalent volume of soil for AGB larvae. When the quadrat method was employed, random sampling schemes provided below-ground biomass estimates that were significantly closer to the true mean of the sampling area. The results of this research will facilitate the development of IPM decision-making tools for farmers and support future research for AGB and other soil insect pests affecting mint production.

Thaumatotibia leucotreta Meyrick (Lepidoptera: Tortricidae) is a major threat to the production and marketing of pepper (Capsicum spp.) in Ghana. To reduce the damage of the pest on pepper farming, it is important to find appropriate control methods, which may include the use of resistant host plants. This study investigated the relative susceptibility of 6 pepper varieties commonly cultivated in Ghana: Legon 18, Bird's eye, Scotch bonnet, Cayenne, KA2, and sweet pepper (Yolo wonder+ variety). Choice and no-choice ovipositional preference tests were conducted and the population growth rate of T. leucotreta was determined by establishing life table parameters including the net reproductive rates (R₀), the mean generation time (G), intrinsic rate of natural increase (r_m), the population doubling time (T), and the finite rate of increase (λ). In the no-choice test, females exhibited oviposition preference for sweet pepper (12.08 eggs/fruit), while Bird's eye was the least preferred (5.00 eggs/fruit). The same results were observed in the choice test. However, the population growth rate of T. leucotreta was highest on the Scotch bonnet and Cayenne, with r_m of 0.124 and 0.127, respectively, while the Bird's eye and sweet pepper recorded the least r_m of 0.116. Thus, the tested varieties had varying levels of susceptibility to T. leucotreta infestation. Bird's eye was the least susceptible variety, while Cayenne and Scotch bonnet were the most susceptible varieties. These findings could direct farmers on the choices of pepper varieties for cultivation and proffer potential opportunities to breed new varieties resistant to T. leucotreta infestation.

The revocation of chlorpyrifos tolerances in 2022 left sweetpotato growers without their most important tool to combat a complex of soil-borne root pests that includes wireworms (Coleoptera: Elateridae). Since then, growers have reported increased root damage despite a rapid pivot to pyrethroid-based management systems to replace mechanically incorporated preplant chlorpyrifos broadcast sprays. Our goal was to evaluate the efficacy of alternative insecticide chemistries and application methods to expand the portfolio of management options for wireworms, specifically Conoderus spp. and Melanotus communis (Gyllenhal). We tested (i) insecticidal transplant water drenches and (ii) a foliar spray program targeting adult elaterids. We found that incorporating insecticides into transplant water reduced wireworm damage when compared to untreated transplant water. Our treatments included a recently registered meta-diamide, broflanilide, which represents a promising path to diversify active ingredients and shift away from an overreliance on preplant and post-directed pyrethroid soil sprays. Foliar spray plots had less damage than plots that did not receive foliar sprays. One benefit of adult-focused management is the availability of effective monitoring tools such as sex pheromones and blacklight trapping. Developing a robust adult monitoring program would enable more precise applications of foliar insecticides versus season-long prophylactic soil sprays targeting larvae. Our results demonstrated a significant benefit to both alternative delivery methods.These management alternatives could expand treatment options beyond traditional preplant and post-directed pyrethroid sprays.

Previously developed behavioral approaches for controlling the apple maggot fly, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae), include attract-and-kill (AK) systems such as perimeter trapping using either, odor-baited red sticky spheres or odor-baited, sticky-free attracticidal spheres with contoured tops that ensure the sustained release of both insecticide and feeding stimulant. Here, over a 3-year span in 26 commercial apple orchards across Massachusetts, New Hampshire, and Maine, we evaluated the effectiveness of a novel AK strategy for R. pomonella management. Synthetic apple blend lures were deployed on perimeter-row trees to attract the pest, while perimeter-row insecticide sprays blended with 2% sugar, a known phagostimulant, served as the lethal component. Comparatively, grower standard (GS) blocks received full-block insecticide sprays devoid of sugar and lures. Monitoring revealed that red sticky spheres in AK blocks captured significantly more R. pomonella adults than unbaited monitoring spheres in GS blocks. Penetration of R. pomonella into block interiors remained consistently low and statistically similar for both AK and GS blocks. Whole-block infestation levels showed no significant difference between the 2 management approaches. Notably, insecticide application in AK blocks was reduced by 75%, 64.7%, and 64.2% in 2019, 2020, and 2021, respectively, compared with GS blocks. This grower-friendly AK approach could be integral to a reduced insecticide spray-based strategy for apple cultivation in the northeastern United States.

We used the Photonic Fence Monitoring Device (PFMD) to evaluate orientation by Musca domestica L. (Diptera: Muscidae), and Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae) to the Zevo Flying Insect Trap Model 3.The PFMD's dual cameras record infrared light (IR) reflected from a wavelength-specific fabric; insects do not reflect IR at the same wavelength and are tracked in 3 dimensions as moving objects. The plug-in trap emits ultraviolet and blue light from behind an opaque shield; attracted insects enter the space between the shield and the wall and are trapped on a sticky cartridge facing the wall. An experiment (N = 10) with replicates of approximately 40, 1- to 7-day-old mixed-sex flies of each species was conducted in a 6.1 m³ arena. Prior to turning the trap on, the fly movement was not directed toward the trap on the back wall of the arena, regardless of whether the overhead light was on or off. When the overhead light was off, the mean first catch of both species occurred within 5 min after the trap was turned on, and 33.1% and 41.8% of M. domestica and C. vicina, respectively, were caught. House flies flew toward the trap, many approaching from below, while C. vicina apparently walked or flew outside the field of view of the PFMD until they appeared on the vertical reflective surface, and then walked toward the trap from all directions. Our results show that the Zevo Trap attracts and catches flies, and that the PFMD can be used to track flying and walking flies.

The Eastern subterranean termite, Reticulitermes flavipes (Kollar) (Blattodea: Rhinotermitidae), is a significant pest, causing extensive damage to structures that amount to substantial economic losses. Boric acid is widely used for wood preservation due to its stability and broad-spectrum insecticidal properties, yet its impact on termite gut microbiomes and the implications of such effects remain understudied. Our study evaluates the dose-dependent mortality of R. flavipes upon being provided boric acid treated filter papers and investigates the resulting dysbiosis within the termite gut microbiome. Consistent with reports from other insects, mortality increased in a dose-dependent manner, with the highest boric acid concentration (203.7 µg/cm² of filter paper) significantly reducing termite survival. 16S rRNA gene sequencing of the gut bacterial microbiome revealed notable shifts in composition, indicating boric acid-induced dysbiosis. Aside from an overall decrease in bacterial diversity, the relative abundance of some symbionts essential for termite nutrition decreased in response to higher boric acid concentrations, while several opportunistic pathogens increased. Our findings extend the understanding of boric acid's mode of action in termites, emphasizing its ability to significantly modulate the bacterial symbiont community, which can have dire effects on termite biology. Considering its ability to protect wood from further termite consumption, our study supports the continued use of boric acid and related compounds for termite-resistant treatments for wood.

The diamondback moth, Plutella xylostella (Linnaeus), is one of the most important insect pests of Brassica crops worldwide. In October 2016, outbreaks of an invasive P. xylostella population and unexpected control failures occurred on broccoli and cauliflower crops throughout all vegetable-growing regions in Arizona. Nineteen populations of Plutella xylostella were collected from 2016 to 2021 from various commercial cauliflower fields in Yuma and Scottsdale, Arizona, and from experimental broccoli plots at the University of Arizona, Yuma Agricultural Center (UAYAC), Yuma, Arizona. Populations collected from the commercial cauliflower fields had been transplanted with seedlings produced in a local Yuma nursery in 2016 and Salinas, CA in 2017 to 2018, whereas experimental broccoli plots were direct seeded. These populations were evaluated for their susceptibility to chlorantraniliprole, spinetoram, emamectin benzoate, and cyantraniliprole. In this study, field rate laboratory bioassays, serial dilution laboratory bioassays, and field efficacy spray experiments were performed. The field rate laboratory bioassay results showed that spinetoram, emamectin benzoate, and cyantraniliprole remained effective at controlling P. xylostella, but chlorantraniliprole did not control P. xylostella at the field rate. Additionally, serial dilution bioassays confirmed significant levels of cyantraniliprole and chlorantraniliprole resistance in the P. xylostella populations collected from transplanted cauliflower fields. However, the results of the multiyear/growing-seasons study monitoring the susceptibility of P. xylostella populations collected from direct-seeded broccoli and field efficacy trials conducted at the UAYAC indicated that the resistance to diamide insecticides was neither uniform nor persistent following the 2016 outbreak. Nevertheless, the risk for P. xylostella resistance in Arizona vegetable-growing regions exists, particularly in Brassica transplants.Therefore, we recommend that Arizona Brassica growers remain vigilant and practice rigorous insecticide resistance management to offset the development of resistance.

Sogatella furcifera (Horváth) (Hemiptera: Delphacidae), a serious rice pest, has developed significant resistance to a wide range of pesticides. Neonicotinoid insecticides are currently the primary choice for controlling S. furcifera, yet their impact on the species remains poorly understood. In this study, we investigated the binding sites of a conventional insecticide (dinotefuran) and a novel insecticide (flupyrimin), and evaluated their sublethal effects on S. furcifera. Our results revealed that the LC₅₀ of dinotefuran and flupyrimin were 2.51 mg/L and 2.80 mg/L in third-instar S. furcifera, respectively. RNA interference (RNAi) knockdown of S. furcifera nicotinic acetylcholine receptor (nAChR) alpha2 subunit (Sfα2) and S. furcifera nAChR beta1 subunit (Sfβ1) significantly reduced the susceptibility to dinotefuran by 18.7% and 16.8%, respectively, but had no effect on flupyrimin. Reproduction of the F0 and F1 generations was significantly inhibited by the LC₂₅ of both dinotefuran and flupyrimin. In the dinotefuran treatment at LC₂₅, the intrinsic growth rate (r) and finite growth rate (λ) were reduced to 0.15 and 0.16 days, respectively; the mean generation time (T) increased to 27.77 days, and the relative fitness was only 0.76 compared to the control. Additionally, the relative fitness (R_f) of the flupyrimin-treated group was reduced to 0.93 and 0.86 times that of the control group. The population dynamics of S. furcifera are significantly affected by both dinotefuran and flupyrimin, making these insecticides valuable tools for integrated pest management and the rational use of insecticides.

Graphical Abstract

Maximum dose bioassays were conducted to assess the efficacy of multiple registered active ingredients for diamondback moth (DBM), Plutella xylostella (L.), control in Georgia and Florida from 2021 to 2023 as a follow-up to an earlier study. Low efficacy (<40% mortality) was recorded for the highest labeled rate of Bacillus thuringiensis var. kurstaki strain ATBS-351 in Georgia, as well as chlorantraniliprole, cyantraniliprole, and cyclaniliprole in Georgia and Florida.The active ingredients with the highest efficacy (>80% mortality) in both states were naled, emamectin benzoate, and spinetoram. Independent analysis of data by state indicated that the efficacy of bifenthrin, chlorantraniliprole, cyantraniliprole, tolfenpyrad, and methomyl was higher in Florida populations than in Georgia populations. In addition, a comparison of these data to a recent DBM maximum dose survey in the same region suggested that these DBM populations have rapidly developed high levels of resistance to cyantraniliprole and cyclaniliprole.This work provides growers in the region with a recent ranking of insecticide efficacy that documents the loss of control for certain active ingredients, which assists pest managers in the planning of ongoing insecticide rotations for DBM resistance management.

Grapholita molesta (Busck) (Lepidoptera: Tortricidae) is a globally significant fruit pest traditionally managed using chemical insecticides such as lambda-cyhalothrin. However, repeated applications have led to the development of resistance in field populations. The mechanisms and fitness costs associated with lambda-cyhalothrin resistance in G. molesta remain poorly understood. In this study, we established a lambda-cyhalothrin-resistant strain (RS) of G. molesta through continuous selection with lambda-cyhalothrin in the laboratory for 21 generations, resulting in a 249.6-fold increase in resistance. Bioassay data from the F₁ progeny (F₁RS and F₁SR) of reciprocal crosses between RS and susceptible strain (SS) showed similar degrees of dominance (0.40 for F₁RS and 0.32 for F₁SR). Significant differences between observed and expected mortalities of backcross individuals suggested that resistance to lambda-cyhalothrin is polygenic. Compared to the SS strain, the RS strain exhibited significantly prolonged periods of larval, prepupal, and pupal stages, as well as a significant decrease in larval weight. In addition, the RS strain showed significant reductions in fecundity, cumulative flight distance, maximum flight distance, cumulative flight time, maximum flight time, and average flight speed. These results suggest that resistance to lambda-cyhalothrin in G. molesta is autosomal, incompletely dominant, and polygenic. Life-history traits such as fecundity and flight capacity were significantly reduced in RS strains compared with the SS strain. These findings provide valuable insights for mitigating lambda-cyhalothrin resistance development and promoting sustainable control of G. molesta in the field.

Graphical Abstract

Western corn rootworm, Diabrotica virgifera virgifera (LeConte) (Coleoptera: Chrysomelidae), is a major pest of maize in the United States. Transgenic maize producing insecticidal toxins from the bacterium Bacillus thuringiensis (Bt) have been used to manage this pest since 2003. Refuges of non-Bt maize have been used to delay resistance to Bt maize by western corn rootworm, and are planted in conjunction with maize producing single or multiple (i.e., pyramids) Bt toxins.Two Bt toxins, Cry3Bb1 and Gpp34/Tpp35Ab1, were used individually before being combined as a pyramid, at which point resistance had already evolved to Cry3Bb1. Pyramids targeting western corn rootworm therefore contained at least one toxin to which resistance had evolved. Western corn rootworm has now evolved resistance to all four commercially available Bt toxins used for rootworm management. We used laboratory and field-generated data to parameterize a deterministic model to simulate the effectiveness of refuges and Bt pyramids to delay resistance to Bt maize in western corn rootworm. Resistance to the pyramid of Cry3Bb1 with Gpp34/Tpp35Ab1 evolved more rapidly when resistance to Cry3Bb1 was already present. This effect arose when model conditions affecting initial resistance allele frequency, inheritance of resistance, and fitness costs were varied. Generally, resistance evolved faster when initial resistance allele frequencies were higher, inheritance of resistance was nonrecessive, and fitness costs were absent, which is consistent with previous models that simulated resistance evolution. We conclude that new transgenic pyramids should pair novel, independently acting toxins with abundant refuges to minimize the risk of rapid resistance evolution.

Foxglove aphid, Aulacorthum solani Kaltenbach (Hemiptera: Aphididae), is a major pest worldwide. It can infest various crops, including soybean, and reduce yields. The use of insect-resistant cultivars can effectively manage pests. Dowling is a soybean cultivar that can control Aphis glycines through antibiosis and antixenosis. In this study, we investigated the feeding behavior of A. solani using electropenetrography (EPG), and its life-history traits using an age-stage, two-sex life table, and its settling preferences on Dowling (resistant) and Heinong 51 (HN51, susceptible) soybean cultivars.The Dowling cultivar showed strong antibiosis against A. solani. Aphids feeding on Dowling exhibited significantly reduced survival, fecundity, and longevity, and increased nymph duration. Moreover, Dowling had negative impacts on the demographic parameters of the aphids.The number of A. solani individuals was significantly less on Dowling than on HN51, indicating the antixenotic effects of Dowling. As shown using EPG, the mechanical blocking wave (F) of A. solani was significantly longer after feeding on Dowling than after feeding on HN51, indicating that Dowling has a higher mechanical resistance. In conclusion, Dowling exhibited strong resistance to A. solani.These results are beneficial for integrated pest management in soybean fields and breeding programs.

The olfactory responses of Araecerus fasciculatus Degeer to the volatiles of 5 traditional Chinese medicine plant products (CMPPs; i.e., Codonopsis pilosula Franch., Ophiopogon japonicus Linn. f., Astragalus membranaceus Fisch., Dendrobium nobile Lindl., and Angelica dahurica Fisch.) were studied using Y-tube, 4-arm, and 6-arm olfactometers.The volatile components of these CMPPs were analyzed using gas chromatography–mass spectrometry (GC–MS). A. fasciculatus significantly preferred the CMPPs volatiles in the order of O. japonicus > C. pilosula > A. membranaceus ≥ D. nobile = A. dahurica. In the volatile profiles of O. japonicus, C. pilosula, A. membranaceus, D. nobile, and A. dahurica, GC–MS identified 27, 61, 63, 52, and 71 components, respectively, and β-elemene (30.58%), hexanal (12.69%), selina-3,7(11)-diene (12.31%), d-limonene (18.59%), and α-curcumene (8.88%) were the most abundant volatile components. A. fasciculatus were attracted to β-elemene, α-selinene, and β-selinene (main components of the volatile profiles of the most preferred CMPPs of O. japonicus) at different concentrations, with 1, 50, and 25 µg/µl being the most attractive, respectively.The olfactory preferences of A. fasciculatus were β-elemene > α-selinene = β-selinene based on the 4-arm olfactometer bioassays for comparisons at their most attractive concentrations.Therefore, differences in the volatile profiles among CMPPs significantly influenced the olfactory responses of A. fasciculatus, offering insight into the mechanisms of host preferences in stored-product pests based on chemical ecology. β-elemene showed the greatest potential to be developed as an attractant for the monitoring and control of this pest.

Graphical Abstract

The Hessian fly, Mayetiola destructor (Say) belonging to the order Diptera (family: Cecidomyiidae), is a destructive pest of host wheat (Triticum aestivum L.) causing significant economic losses. Although planting resistant wheat cultivars harboring an effective Hessian fly resistance gene (H) is the most economical and environmentally friendly pest management strategy, it imposes selection pressure on the insect populations and can lead to the evolution of Hessian fly virulence. This results in the eventual failure of the deployed H gene. New sources and novel types of resistance are urgently needed to expand the repertoire of H genes and enable strategies that are more effective and durable over the long-term. New sources of Hessian fly resistance have been identified from tetraploid (T. turgidum L., AABB) and hexaploid (T. aestivum, AABBDD) wheat species, as well as from wheat's D-genome donor (Aegilops tauschii Coss., DD). In contrast, diploid einkorn wheat (T. monococcum L., AA) has not been extensively explored for Hessian fly resistance. In this study, we phenotyped 506 T. monococcum accessions belonging to 2 subspecies, T. monococcum L. subsp. monococcum (205 accessions) and T. monococcum subsp. aegilopoides (Link) Thell. (301 accessions), for resistance against 2 predominant Hessian fly biotypes, L and GP (Great Plains).Three and 6 accessions belonging to subsp. monococcum and aegilopoides, respectively, showed > 70% resistance. These accessions provide additional resources for improving wheat cultivars as mitigating strategies for Hessian fly management.