Journal of Pest Science最新文献

Due to their potential role in pathogen transmission, invasive mosquitoes pose considerable threats to human and animal health. Several studies have identified the most important ecological drivers mediating the establishment and spread of key mosquito species (e.g., Aedes aegypti, and Ae. albopictus), and made predictions for future distribution. We evaluated the effect of an exhaustive list of environmental predictors on the distribution of three invasive species in Hungary (Ae. albopictus, Ae. japonicus, and Ae. koreicus) by using the same standards for data collection based on citizen science observations. Current distribution maps of these species were generated from a 5-year survey, then were compared with various predictor maps reflecting climate, habitat type, food supply, traffic, and interspecific competition by using a boosted regression trees approach that resulted in a subset of variables with the strongest impact. The best predictor sets were used to predict the probability of occurrence of the focal species for the whole country, and these predictions based on citizen science were evaluated against the results of an independent recent field surveillance. We uncovered species-specific patterns and found that different predictor sets were selected for the three different species, and only predictions for Ae. albopictus could be validated with direct trapping data. Therefore, citizen science informed distribution maps can be used to identify ecological predictors that determine the spread of invasive mosquitoes, and to estimate risk based on the predicted distribution in the case of Ae. albopictus.

The Fall Armyworm, Spodoptera frugiperda, invaded China late in 2018 and was responsible for substantial crop losses, especially to maize. This work focuses on the suitability of climate across China for Fall Armyworm survival and spread. It uses climate metrics derived with guidance from experts to enable assessment of the risks posed by Fall Armyworm on maize production in different regions of China. The locations and time of year when temperature conditions are within a viable range for Fall Armyworm survival (minimum temperature higher than 9.7(^circ)C and maximum temperature lower than 39.2(^circ)C) are used to estimate the spatial distribution of winter breeding and overwintering zones, which helps understand the regions and timing of Fall Armyworm migration risk into northern maize production regions. In addition, meridional wind conditions across the Yangtze River basin area are assessed, and a metric of migration potential from the winter breeding and overwintering regions in the south towards northern regions with maize production is established. Results show that temperature during the winter months currently limits Fall Armyworm winter breeding populations to the very southern regions of China (and bordering countries to the south). However, due to the consistent timing and direction of the East Asian Summer Monsoon winds, the Fall Armyworm could easily be directed northwards to the Yangtze River basin during summer months with a peak in July. For this reason, pest management actions against the Fall Armyworm on summer maize should be taken.

Phosphoinositide-dependent kinase PDK, a key component of the insulin signaling pathway, plays an important role in the regulation of insect growth and development. However, the functional significance of the PDK gene in Tuta absoluta, a destructive invasive tomato leaf miner, remains unknown. In this study, we identified and characterized a PDK gene (designated TaPDK) and analyzed its physiological roles in molting and reproduction of T. absoluta. Our results showed that the TaPDK expression levels were elevated in the 5- and 6-day-old pupae before ecdysis and declined immediately after eclosion. TaPDK was predominantly expressed in the head, midgut and abdomen. When the TaPDK was knockdown, the larval-pupal molting and female reproduction were severely affected. Injecting dsRNA of TaPDK into 2-day-old female pupae resulted in severe phenotypic changes (cuticular shrinkage) in 31.29% of pupae, ultimately leading to death. Knockdown of TaPDK significantly reduced the 20E titer and chitin content and downregulated the expression levels of genes involved in the 20E pathway and chitin metabolism. Further investigation revealed that the suppression of TaPDK impaired ovarian development, resulting in significantly reduced fecundity and hatchability. In addition, the JH titer and vitellogenin content of TaPDK-deficient females were reduced, and the expression of Vg, VgR, and JH signaling pathway genes were significantly decreased. Collectively, our study provides a deep insight into the PDK-mediated regulation of pupal ecdysis and female reproduction in T. absoluta.

The egg parasitoids, Trichogramma evanescens Westwood and T. pinto Voegelé (Hymenoptera: Trichogrammatidae), play central roles in the management of lepidopteran crop pests. However, their effectiveness highly depends on the employment of compatible pesticides, with a particular focus on novel insecticides that are promising in pest control. This study investigated the lethal, sublethal and transgenerational effects of two novel insecticides, afidopyropen and broflanilide, on T. evanescens and T. pintoi in terms of biological and behavioral traits. The eggs of the factitious host, Ephestia kuehniella Zeller (Lepidoptera: Pyralidae), with parasitoids at the preimaginal developmental stages (egg-larval, prepupal and pupal) were immersed in insecticide solutions. The emergence rates of both parasitoids were negatively affected by preimaginal treatments with different concentrations of afidopyropen and broflanilide. In transgenerational experiments, broflanilide treatments significantly reduced the parasitism performance of the treated generation (F0), emergence rate of F1 and F2, sex ratio of F1 T. evanescens and the emergence rate and sex ratio of F1 T. pintoi. Afidopyropen treatments reduced the emergence rate of F3 T. evanescens adults. The longevity of the F0 females and males of both parasitoids and that of the F1 females of T. evanescens were significantly reduced by broflanilide treatments. Broflanilide also decreased the walking speed of both species while afidopyropen enhanced the resting frequency of T. evanescens. This comprehensive study provides insights into the toxicological assessment of afidopyropen and broflanilide on Trichogramma species, employing parameters corresponding to their population and behavioral dynamics. Finally, this study concludes that the integration of afidopyropen and broflanilide into integrated pest management (IPM) strategies necessitates careful consideration, particularly regarding potential non-target effects on Trichogramma species.

The papaya mealybug, Paracoccus marginatus, is an invasive pest that causes significant damage to various tropical fruits and ornamentals worldwide. Lambda-cyhalothrin, an effective insecticide in integrated pest management (IPM) strategies, can control P. marginatus. This study evaluated the sublethal effect of lambda-cyhalothrin on the life table parameters and the detoxification enzymes activities of P. marginatus. Furthermore, transcriptome sequencing analysis revealed the potential mechanisms of the detoxification-related genes associated with enzymes activities. The study reported that lambda-cyhalothrin showed high activity against P. marginatus, with LC₃₀ values of 8.98 mg/L. Two-sex life table results showed that the development duration of the second instar nymphs, preadults, and adult female longevity was significantly prolonged, and the fecundity was stimulated in the F₁-CY of P. marginatus when the parental generation was exposed to LC₃₀ lambda-cyhalothrin. Moreover, lambda-cyhalothrin treatment significantly increased the activities of Cytochrome P450 monooxygenases (P450) and glutathione-S-transferase (GST) enzymes. Additionally, significant expression levels of P450, GST, carboxylesterase, and esterase genes were observed in P. marginatus subjected to the sublethal lambda-cyhalothrin exposure. Our findings demonstrate that sublethal concentrations of lambda-cyhalothrin influenced the development and fecundity of P. marginatus, and changes in enzymes activities and differential expression of detoxifying genes might be involved in the response and detoxification metabolism of lambda-cyhalothrin in P. marginatus. These results could contribute to a comprehensive risk assessment and provide guidance for the scientific use of lambda-cyhalothrin in IPM strategies.

Spodoptera frugiperda is a major pest in corn crops, causing significant productivity losses and exhibiting high resistance to synthetic insecticides. Essential oils (EOs) are natural substances known for their insecticidal activity against various agricultural pests. This study describes the chemical composition and bioactivity of Drimys brasiliensis EO against S. frugiperda larvae. The EO was extracted using the steam distillation method in a vat, and its chemical composition was determined using gas chromatography coupled with mass spectrometry (GC–MS). The insecticidal activity of this EO was assessed by the contact method to estimate the lethal concentration (LC₅₀ and LC₉₀) and to evaluate the effects on biochemical markers, including glutathione S-transferase (GST), esterase-α (EST-α), esterase-β (EST-β), superoxide dismutase (SOD), acetylcholinesterase (AChE) and lipid peroxidation (LPO), in 3rd instar larvae of S. frugiperda. Twenty-nine compounds were identified by GC–MS, accounting for 81.32% of the total chemical composition D. brasiliensis EO resulted in 100% mortality of S. frugiperda larvae at a concentration of 2.5%, with LC₅₀ and LC₉₀ values of 0.90 and 1.40%, respectively. Both lethal concentrations increased AChE and LPO activity, while only LC₉₀ affected the EST-α and EST-β enzymes. Drimys brasiliensis EO exhibits insecticidal activity against S. frugiperda with neurotoxic effects, as well as cellular damage, demonstrating its potential as a control method in managing this pest in conventional and organic production methods.

Cold treatment with rigorous regulatory oversight is often mandated to manage horticultural trade-related biosecurity threats, such as invasive, cold-sensitive fruit flies (Diptera: Tephritidae). Cold treatment schedules, developed through rigorous laboratory experiments, require a set temperature and duration to ensure at least a probit 8.7 (99.99%) mortality rate, regardless of infestation likelihood. This threshold is costly to demonstrate for each pest and commodity combination and the resultant treatment may be harmful to fruit quality. Moreover, these stringent schedules do not account for cold-induced mortality already occurring in commercial supply chains. We developed a predictive temperature-dependent mortality function using 28 published cold treatment studies of pest fly species to support more flexible and proportionate use of cold treatment. The daily mortality rate was unaffected by the duration of cold exposure (0–20 days). The mortality rate varied primarily by pest species (10 species) and developmental stage (eggs and larval stages), and to a lesser extent by temperature (0–7 °C) and host (13 fruit types). Our model mostly predicted fewer days to meet probit 9.0 mortality compared to empirical results from large-scale studies, suggesting these studies can be overly conservative. By leveraging previous empirical studies, our model enables estimation of temperature-dependent daily mortality for unstudied pest developmental stage host–temperature combinations, which can then be empirically validated through targeted studies. It is hoped these results will shift cold treatment usage from highly regulated, fixed temperature treatments with a target mortality rate requirement to a more flexible approach that accounts for existing commercial supply chain practices and infestation likelihood in produce.

Single-cell RNA sequencing (scRNA-seq) has emerged as a powerful tool for studying complex cellular composition and gene expression dynamics of biological systems. In this study, we analyzed the midgut of the fall armyworm (FAW), Spodoptera frugiperda, utilizing scRNA-seq technology. scRNA-seq analysis yielded high-quality sequencing data from two replicates, showcasing robust sequencing integrity, mapping efficiency, and reproducibility. We identified twelve clusters of midgut cells, including enterocytes, enteroblasts, enteroendocrine cells, goblet cells, and stem cells, each with unique marker gene expression indicative of their specialized functions. Further analysis revealed intricate gene expression profiles and enriched biological pathways associated with each cell type, shedding light on the molecular mechanisms underlying midgut function. Additionally, lineage trajectory analysis identified the differentiation pathways of midgut cell populations, confirming canonical relationships among stem cells, enteroblasts, enterocytes, and goblet cells. Furthermore, we also studied the expression of genes coding for insecticide target sites and metabolizing enzymes in different midgut cell types. Overall, our studies provide a comprehensive understanding of midgut cellular diversity and gene expression dynamics in the FAW, offering valuable information that could be used to develop methods for managing this and other pests.

Plant secondary metabolites are crucial in affecting the interactions between insect herbivores and entomoviruses. However, there is limited knowledge regarding the impact of such metabolites on the susceptibility of insect herbivores to entomoviruses. In this study, we adopted the allicin, caterpillars (Spodoptera exigua) and nucleopolyhedrovirus (SeMNPV) as a system, and found that allicin significantly increased the mortality of S. exigua larvae infected with SeMNPV by 36.03–59.45% when infected with the virus at a concentration of 2.12 × 10³ OB·mL⁻¹. Furthermore, NPV-infected larvae together treated with allicin inhibited the growth and development of larvae, comparing to individual NPV-infected larvae. Notably, we observed a significant enrichment of differentially expressed genes involved in the cytochrome P450-mediated metabolism pathway between the NPV-infected and allicin combined with NPV-treated groups. The silencing of CYP340AA1 through RNA interference significantly increased the mortality of larvae infected with SeMNPV. This investigation indicates that allicin might be a potential candidate for improving the performance of the NPV against insect herbivores and identifies that CYP340AA1 gene is important in this process.

Diaphorina citri is the vector of “Candidatus Liberibacter asiaticus” (CLas), a bacterium associated with the citrus disease known as Huanglongbing (HLB). Previous mitochondrial genome (i.e. mitogenome) population analyses revealed the prevalence of two major mitochondrial groups (MGs) of D. citri in China, separated by elevation gradients. We assessed the population diversity of D. citri from 54 major citrus-producing areas within 11 provinces/regions of China. Additionally, endosymbiont genomes were assembled for “Ca. Carsonella ruddii” (CaCr) and “Ca. Profftella armatura” (CaPa) from next-generation sequencing of 31 new Chinese samples. Most of the D. citri diversity came from single nucleotide polymorphisms (SNPs) within five mitochondrial genes: nad3, cox2, rrnL, cob, and atp6. Nine SNPs clustered the analyzed D. citri mitogenomes into three major MGs comprising seven subgroups. Independent phylogenetic trees were generated for the endosymbionts CaCr and CaPa, and a CaPa plasmid, supporting the patterns obtained for D. citri mitogenomes while adding complexity layers. Genomic data from CaCr, CaPa, along with the plasmids from CaPa contribute to the genetic diversity—consisting of 68 SNPs and two genomic gaps—reproducing phylogenetic structures outlined by previous mitochondrial genomic studies. Additionally, both the mitogenomes and the endosymbiont genomes revealed subgroups within the original MG clusters, based on further 154 SNPs and 17 gaps. Thus, the combined genomic approach reveals further aspects about population diversity and natural history of this invasive species. Further understanding of D. citri and its endosymbionts can, therefore, aid D. citri HLB management protocols and help forecast territorial expansion events.