Journal of Applied Entomology最新文献

Myochrous armatus Baly, 1865 (Coleoptera: Chrysomelidae) has expanded its occurrence significantly into soybean-growing areas of Brazilian Cerrado and became an important early-season soil pest. Experiments were performed under field conditions from 2020 to 2023 to assess several aspects: (1) population behaviour over crop season and offseason; (2) day/night behaviour during the early stages of soybean plants and (3) injury to plants and potential damage to soybean yield to establish the Economic Injury Level (EIL). Adults of the M. armatus population presented a season-long abundance during the specific period from late October to January, with major captures in November and December (end of Spring), either inside or on the edge of soybean fields. Weeds and volunteer plants of corn and cotton hosts adults and eggs. These findings suggest an univoltine life cycle. Behavioural assessments revealed that M. armatus does not exhibit a specific day, night or crepuscular behaviour, performing deeds at any time. The majority of insects (40% to 70%) were found in the soil throughout the day and night. Adults feed on soybean plants by scraping or cutting the stem, cotyledon, petiole and apical sprouting. Their preference is initially for the stem and cotyledon (up to 14 days after emergence), and later for the petiole (after 21 days of emergence). After 7 days of coexistence at V1-V3 soybean stages, we observed a potential yield reduction of 35% for each insect per plant. Dynamic EIL estimations are between 0.4 and 1.9 adults per row metre, depending on the grower productivity expectation, control costs and soybean market value. Our results are fundamental for establishing Integrated Pest Management for M. armatus in soybean and other crop systems.

Bacillus thuringiensis subsp. tenebrionis (Btt) was discovered in 1982 and has been used as a biological control agent against the Colorado potato beetle (Leptinotarsa decemlineata) since the early 1990s. In this study, we sequenced, assembled and analysed the genome of strain DSM 2803, which is the patent deposit of the original Btt isolate BI 256-82. A high-quality reference genome is provided that allows investigating the genomic changes throughout the commercial history of Btt. Strain DSM 2803 (BI 256-82) is particularly interesting since the subspecies description of ‘tenebrionis’ is based on it and because it represents the genomic origin of the commercial Btt strain currently used in plant protection. Comparative genome analysis of six Btt strains derived from BI 256-82 revealed that the genomes were generally highly similar. However, some plasticity in the profile of extrachromosomal elements was detected, including recombination-dependent plasmid differences and the presence/absence of a circular plasmid-like prophage.

Body size is a characteristic of many animal species that is correlated with many fitness-related traits. Parasitoids are important biological control agents of pests; larger parasitoids often have greater fitness and enhanced performance. Host size is a major influence on parasitoid size, which has been explored in the important egg parasitoid Anastatus disparis (Hymenoptera: Eupelmidae), a potential biological control agent for several Lepidopteran pests. Here, we found that the body size of A. disparis females increased with increasing host egg size, while host egg size did not significantly affect male size. In addition, both female and male offspring sizes significantly increased with increasing maternal size, and female offspring produced by younger mothers were also larger. Furthermore, the body sizes of both females and males appeared to increase when the total development time from egg to adult eclosion decreased. Male offspring produced by larger females have shorter development times, while female offspring produced by older females have longer development times. Consequently, our results suggested that the effect of maternal status on offspring size may be mediated by influencing development time. In summary, our results indicated that the body size of A. disparis is determined by multiple factors with differing effects on females and males, and our results provide guidance for its effective mass rearing and its performance in the field.

In Brazil, the common earwig Doru luteipes (Scudder) (Dermaptera: Forficulidae) is considered an important biocontrol agent for the maize crop, consuming the fall armyworm Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) eggs and caterpillars from 1st to the 3rd instar. Despite this, several aspects of the interaction between these species have not yet been studied. We aim to evaluate the non-consumptive effects of earwigs on the oviposition of moths, the earwig's predatory preference between eggs and neonates and its functional response to S. frugiperda eggs. In no-choice tests between plants with or without the presence of the predator, S. frugiperda moths deposited a smaller number of eggs on plants with risk of predation. In choice-based tests, earwigs initially attacked newborn caterpillars, but preferred to feed on eggs. Males and females fed more on eggs with increasing supply density and consumption was adjusted to the type II functional response curve. D. luteipes males were more efficient predators than females when exposed to higher egg densities. These findings clarify aspects of the predatory role of D. luteipes on S. frugiperda that had not yet been addressed and suggest that the earwig has potential for impacting the colonization and population growth of S. frugiperda in maize crops, if conditions are favourable to its early arrival.

The contribution of insects to pollination constitutes a globally important ecosystem service. Due to the increasing demand for entomophilous crops, the nutritional and economic importance of insect-pollinated crops and the inability of managed pollinators (Apis mellifera L) to meet the high demand for their services indicate that agriculture heavily relies on wild pollinators. Almonds are an economically valuable crop in Morocco. Therefore, it is essential to understand the fundamental pollination requirements of major almond varieties to promote their production. The main objectives of this study were to assess the dependency of three almond cultivars (Espoir, Largueta and Planeta) on insect pollination, and then to evaluate the pollination deficit resulting from the lack of these pollinators. For this purpose, we used insect-proof net bags constructed around branches of almond trees to compare fruit set and yield with open and open + hand-pollinated flowers. The results of the fruit set experiment confirmed that all three varieties require insect pollination, as fruit set and yield were significantly higher in insect-pollinated than insect-isolated trees. All three almond varieties were categorized as obligatory dependent on biotic pollinators. In addition, two out of the three studied almond varieties showed high pollination deficit resulting from the lower abundance and/or diversity of pollinating insects. The results of the current study highlights the important role of insect pollinators for almond crops and the urgent need for the implementation of sustainable strategies to preserve pollinators within agricultural ecosystems.

Monochamus alternatus is one of the most important borers of conifers and the main vector of the pinewood nematode, Bursaphelenchus xylophilus, the causal agent of pine wilt disease. It causes massive death of pine trees and seriously affects the health of forest ecosystems. Traditionally, adults or larvae are identified by morphological or molecular methods. However, diagnosing M. alternatus larvae at different instars collected from forests is expensive and time-consuming. Non-destructive molecular diagnostic protocols are, therefore, being developed to detect biological traces (i.e. exuviae, excreta) and to determine the distribution and spread of this pest. In this study, based on the alignment of mitochondrial DNA cytochrome oxidase subunit I (COI) gene sequences of M. alternatus and other insect species, we designed the primer pair of Mal-SF/Mal-SR and probe of Mal-P for M. alternatus. TaqMan probe-based qPCR was developed to identify the occurrence of M. alternatus in forests by amplifying the DNA samples obtained from its adult, larva, frass, excreta and exuviae. The amplification results were very effective. The lowest amount of M. alternatus DNA that could be detected with a Cq of 31.93 in the mixed samples was 0.64 pg, showing very high sensitivity. This assay can easily identify M. alternatus from other non-target wood-borer species using its frass and exuviae, providing a new diagnostic protocol for monitoring the occurrence and distribution of M. alternatus in forests.

Insecticides have been instrumental in the prevention and management of key agricultural insect pests, thereby contributing to increased food production. However, the effectiveness of insecticides diminishes when targeted pests develop resistance, a phenomenon linked to species evolution and survival instincts. The Arthropod Pesticide Resistance Database, maintained by Michigan State University, has documented 18,934 cases of resistance to insecticidal active ingredients worldwide from 1914 to the present. This special collection comprises eight original research articles that delve into the monitoring, mechanism and management of insecticide resistance. Two papers present multi-year resistance monitoring results in Chilo suppressalis and Spodoptera litura. Two studies employ transcriptome data to examine the candidate genes implicated in solanine-induced response in Phthorimaea operculella and chlorantraniliprole-induced response in Galeruca daurica, respectively. Additionally, two papers describe the genetic and physiological impacts of insecticides, while others explore the potential mechanisms underlying chlorfenapyr resistance in Glyphodes pyloalis and pyrethroids resistance in Laodelphax striatellus. The new results, conclusions and suggestions presented in this collection are anticipated to contribute to the advancement of knowledge on insecticide resistance and facilitate the development of a sustainable approach to managing insect pests.

Three rice planthopper species, Nilaparvata lugens, Sogatella furcifera and Laodelphax striatellus, are destructive rice pests that cause serious economic losses in major rice-producing regions of China. Understanding their dispersal patterns and potential distribution areas is crucial for effective management and control. Based on historical climate data and simulated future climate data combined with species occurrence data, the dispersal patterns of three planthopper species were analysed and their potential distributions were predicted. The results showed that from 1993 to 2022, the suitable areas for the three rice planthoppers gradually expanded. By 2022, the total suitable area for S. furcifera reached 478.35 × 10⁴ km², followed by 376.02 × 10⁴ km² for L. striatellus and 264.97 × 10⁴ km² for N. lugens. The optimum area for S. furcifera exhibited the most significant increase, expanding by 136.07 × 10⁴ km². The species has extended its range from southern China to the northeastern and northwestern regions within the past three decades. The suitable areas for L. striatellus and N. lugens did not show a significant spread trend. In addition, compared to that in 2022, the total suitable area for the three rice planthopper species increased slightly from 2041 to 2060. The study revealed that the wettest monthly rainfall and the lowest temperature were the most influential factors affecting the distributions of these planthopper species. This study provides valuable insights into the dispersal patterns and potential distribution of rice planthoppers in China and provides a theoretical basis for effective prevention and control strategies for destructive rice pests.

Halyomorpha halys is an invasive stink bug, native to east Asia, responsible for extensive economic loss in numerous crops. Since several factors can influence the severity of the recorded injury level, we performed field and semi-field experiments in commercial apple orchards to monitor their interaction. To establish how position (both in the orchard and on the canopy), management and cultivar interact in determining pre-harvest injury levels, more than 100,000 apples, distributed over 106 orchard blocks, were examined in the field. Apples located higher in the canopy, on edge rows and in orchards with organic management had a higher number of external injuries and such factors were more relevant when occurring in combination, and on mid and late-season cultivars. Exclusion cages were used to assess if the injury severity changed with the apple growth stage and with the life stage of H. halys, exposing Red delicious apples to adults and nymphs for 48 hours, from May to July. Early-season injuries did not evolve in distinct depressions nor in wide areas with necrotic tissue. Later in season, the injury severity was higher and similar for adults and older nymphs (fourth and fifth instars), with the development of depressions externally and necrotic tissue internally. Thus, even a low number of individuals could cause severe damage, over a short exposure period, when it happened near full maturation. The combined results offer new insights to support the development of informed and sustainable control strategies.

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), is an invasive pest species that has incurred massive economic damages in areas cultivating economically important crops like corn, rice, cotton and many others. Known to be a native of the Western Hemisphere, FAW has since then established itself in many parts of Africa, Asia and Australia and Oceania. The Philippines had been among the Asian countries vulnerable to FAW invasion, which was validated in June 2019. This study aims to characterize the existing strains and haplotypes of FAW and describe the genetic structure and the signature of its recent demographic history nationwide. COI sequences reveal the predominance of rice-strain over the corn-strain FAW, while Tpi sequences are more accurate in defining the corn-strain found in corn and sugarcane. Discordant COI-Tpi configurations frequently occur the most in the entire FAW population at 65.29%. Nucleotide and haplotype diversity are low with an average of 0.005976 and 0.4019 respectively. In addition to non-significant values in neutrality tests suggesting neutral evolution, the low nucleotide and haplotype diversity indicate population contraction from founder effect. Variations are mostly found within regions, and genetic structure is moderate among regions (F_ST = 0.14375). These results can be attributed to low selective pressures accompanying its establishment, or more likely due to recent migration and/or human-assisted factors such as trade. Implications on pest management and prospective studies in the future are also discussed in this study.