Journal of Pest Science最新文献

Floral resources such as nectar are essential for increasing survival and population growth of synovigenic parasitic wasps in agroecosystems. Although the bottom-up effect of cadmium (Cd) has been identified as a major ecological force influencing multitrophic interactions of synovigenic parasitoids, information on the direct effects of Cd-contaminated floral resources on the fitness of natural enemies which might impact their fitness and effectiveness are still lacking. In this study, we assessed the performance of three commonly used Trichogramma species exposed to Cd-contaminated sucrose solutions. Female survival, longevity, the female/male adult proportion, and F₁ emergence rate of T. japonicum were not affected by Cd concentrations. However, a decline in the survival rate of females, their longevity, and female/male adult proportion were observed for T. dendrolimi at high Cd concentration. No significant differences in female/male adult proporation and longevity of T. ostriniae were found at wide Cd concentration ranges. Our results suggest that Cd-contaminated nectar resources can negatively affect performance of some Trichogramma spp., indicating Cd contamination in nectar would directly reduce the potential value of these species in IPM programs. These results not only increase our understanding of interspecific variations in synovigeny of Trichogramma, but also suggest that releases of T. japonicum and T. ostriniae rather than T. dendrolimi should be considered at Cd-contaminated sites.

The pivotal role of gut microbiota in maintaining the insect host’s well-being has been extensive researched. Here, our research objective was to determine the microbes in the gut of larvae of the potato tuberworm (Phthorimaea operculella) and to investigate the role they play in the host development, metabolism, gut structure integrity and immune deficiency (Imd). Shotgun metagenomics sequencing from specimens collected in major potato-producing regions in China, and principal coordinate analysis revealed that the geographic location explained much of the variance in bacterial composition, but Enterococcus mundtii was dominant in all samples. KEGG analysis demonstrated that carbohydrate metabolism was the major function of the P. operculella’s gut microbiome. Subsequently, with the use of artificial diet supplemented with antibiotics, the gut microbes were removed, especially the bacteria of the Enterococcus genus were significantly decreased. Typically, insects fed with antibiotics showed a lower carbohydrate metabolism, survival rate, longer developmental period and poorer fecundity. Metabolomics analysis also confirmed that the antibiotics treatment had a striking impact on the metabolic profile in the gut, especially for starch degradation. In addition, the gut homeostasis with its microbiota composition, metabolism and gut structure was damaged in the antibiotics-treated insects. In summary, our data provide evidence that a complex interaction exists between the microbiome of the gut and the metabolism and structure integrity of the host insect, which is essential for its growth and development. These findings enhance our comprehension of the microbiota's function in insects and facilitate the advancement of environmentally friendly management strategies for this pest.

The Melaleuca genus has insecticidal activity against agricultural pests. In particular, Melaleuca rhaphiophylla essential oil (MREO) showed high toxicity against some stored product weevils in a short period. Therefore, the present study aimed to evaluate the sublethal dose and the effect on biochemical markers of MREO and its emulsion (MREM) against Sitophilus zeamais and Sitophilus oryzae. The emulsion was prepared by combining hydroxypropyl methylcellulose (HPMC) (2 wt%) with MREO to concentrations of 39.18 and 25.61 μL of substance L⁻¹ of air for S. zeamais and S. oryzae, respectively. The insecticidal activity of both MREO and MREM was evaluated by the fumigation method, followed by the determination of Glutathione S-Transferase (GST), esterase-α, esterase-β, superoxide dismutase (SOD), acetylcholinesterase (AChE) activities, and lipid peroxidation (LPO). The MREO caused a mortality rate above 25%, with an increase of AChE and LPO for both species, there was altered esterase-α for S. zeamais and inhibition of GST, esterase-α, esterase-β and SOD activity for S. oryzae. Meanwhile, the MREM caused a mortality rate of less than 1.5%, with an increase in GST, SOD, and LPO enzymes for both species, and an increase in the enzymatic activity of esterase-α for S. oryzae. Therefore, we concluded that MREO demonstrated higher insecticidal activity, while MREM caused continuous toxicity at fragmented doses caused by emulsion exposure, stimulating detoxification and resistance mechanisms.

The increasing spread and destructiveness of the honeydew moth, Cryptoblabes gnidiella (Lepidoptera: Pyralidae: Phycitinae), requires an effective pest management approach, in which the application of insecticides is based on the presence and abundance of the insect in the vineyard. Pest monitoring, however, is challenging because of the difficulties in identifying eggs and larvae. Forecasting models, particularly physiologically based demographic models (PBDMs), are helpful tools in the management of several agricultural insect pests. No PBDMs of note are available for C. gnidiella to date. Herein, we adapted a PBDM for Lobesia botrana to C. gnidiella by using literature data on insect developmental rates to fit temperature-dependent equations, and we validated the model by using independent data consisting of weekly male catches in pheromone traps placed in 16 wine-growing areas of Central and Southern Italy, between 2014 and 2022. Comparison of model predictions versus trap data of adults provided R² = 0.922, CRM (coefficient of residual mass, a measure of the model tendency to overestimate or underestimate the observed values) = 0.223, and CCC (the concordance correlation coefficient) = 0.924. Goodness-of-fit results showed that the model was capable of correctly predicting C. gnidiella flights, with a little tendency to underestimate real observations. Overall, our results make the model quite realistic and potentially useful to support insect monitoring activities and decision-making in crop protection, at least in the contexts in which the model was validated. Further validations should be carried out to test the model ability to also predict the presence of C. gnidiella juvenile stages.

Plants employ different defensive strategies to limit or avoid nematode attacks, including the recruitment of beneficial microorganisms that can support plants by enhancing their defence mechanisms. We investigated the effect of the two nematode egg parasitising fungi, Niesslia gamsii and Polydomus karssenii, on nematode suppression on tomato using greenhouse experiments. Their potential against Meloidogyne hapla was evaluated by analysing direct parasitism and the expression of plant defence-related genes, through quantitative reverse transcriptase PCR. Niesslia gamsii and P. karssenii were originally isolated from naturally infested eggs of the cereal cyst nematode Heterodera filipjevi, and their nematode pathogenicity was proven through Koch’s postulates. Fungal treatments with N. gamsii and P. karssenii reduced by 32–31% M. hapla egg numbers per root system, respectively. Both treatments also significantly lowered the nematode reproduction rate (Rf value) when compared to the control. Both fungi affected the nematode root invasion by limiting penetration of M. hapla second-stage juveniles (J2) into tomato roots, 3 and 7 days after inoculation. The results showed a substantial effect of both fungi on inducing defence responses in tomato plants towards M. hapla. Pre-treatment with N. gamsii and P. karssenii led to the expression of different marker genes associated with pathogen response pathways, including salicylic and jasmonic acid/ethylene-regulated defensive. These findings suggest that N. gamsii and P. karssenii could prime the plant host for enhanced defence upon nematode attack.

Promoting pest control provided by soil arthropod communities can enhance sustainable agricultural production. Despite years of research aimed at predicting the pest control potential of these communities, few studies have described natural enemy communities composed of multiple taxonomic orders through a functional lens and identified traits involved in predator–prey interactions. Arthropod predator communities consist of individuals from several taxonomic orders exhibiting significant physical and behavioral differences that likely contribute differently to pest control. These inter-order differences justify the adoption of a functional approach, rather than a taxonomic one, to describe predator communities. However, there is no generalized functional trait identified to describe arthropod predator communities and predict the pest control potential by these communities. To address this knowledge gap, we reviewed 194 relationships from the literature, examining various traits and feeding characteristics for different groups of ground-dwelling arthropod predators (spiders, Coleoptera, and Chilopoda). We tried to determine whether a functional trait can be identified to explain the pest control potential across a multi-taxonomic assemblage. Each relationship was described in terms of the trait, the feeding characteristic, and the direction of the relationship in quantitative studies. Across all taxonomic groups, we consistently observed a positive relationship between predator body size and prey body size. This relationship was the most tested and the most shared among orders. Consequently, this study provides a proxy trait (body size) that can be used to predict a potential of predation and therefore inform on the pest control provided by multi-taxonomic assemblages of predators.

Parasitoids are important biological control agents, which play an active role in controlling agricultural and forestry pests. The diapause of parasitoids is crucial for controlling pest populations and preserving the ecological equilibrium in natural environments. Diapause has been studied for over 80 years. To date, diapause has been studied in approximately 178 species of parasitoids, including major families such as Braconidae, Trichogrammatidae, Ichneumonidae, and Encyrtidae. Among them, at least five species including Trichogramma dendrolimi, T. cacoeciae, T. japonicum, T. brassicae, and Aphidius gifuensis, have been utilized for production and application using diapause manipulation in parasitoid rearing. The development of omics technologies has accelerated the study of the underlying mechanism, but there remains a lack of in-depth investigation. This article reviews the research progress of diapause in parasitoids, encompassing environmental and biological factors inducing diapause, biological, and physiological response after diapause, and the mechanisms involved in diapause. Additionally, the potential applications of diapause parasitoids are explored. A deeper understanding of the diapause phenomenon in parasitoids and its molecular mechanisms is sought, with the goal of offering more effective strategies for ecosystem management and agricultural production.

Genetic resistance, particularly through transgenic Bt maize, has demonstrated high efficacy in pest control under field conditions. However, in storage conditions, maize is susceptible to different pest species, which compromises its quality. It is unknown how effectively the Bt maize functions in storage environments or if resistance is being inherited in later generations. This study investigates two commercial maize genotypes: a transgenic genotype expressing the Cry1Ab protein and its near-isoline counterpart. It utilizes commercial seeds of both genotypes (F1), along with seeds obtained from field-grown transgenic and near-isoline plants (F2), which represent the seeds stored by farmers and the agricultural industry. The aim is to assess their vulnerability to common insect pests that affect stored products. By assessing grain damage and insect population dynamics, we identify differences in resistance among these different maize genotypes and generations. Our findings show that transgenic maize exhibits strong resistance against Sitotroga cerealella but lower resistance against Sitophilus zeamais. The impact of Oryzaephilus surinamensis on both genotypes was negligible. Additionally, the resistance diminishes in the F2 generation. With S. cerealella the F2 transgenic experienced 55% more damage compared to the F1. Similarly, in the case of S. zeamais, the F2 maize produced five times more frass than the F1, highlighting a significant reduction in resistance. This research identifies the resistance characteristics of maize, highlighting the most suitable traits for assessing pest resistance in stored maize. It emphasizes the need for sustainable pest control with genetic resistance, ensuring long-term protection of stored grains, and minimizing post-harvest losses.

Artificial selection for stress resistance in natural enemies is a promising approach to enhance their effectiveness in biological control. However, documented cases regarding artificial selection for starvation resistance in natural enemy insects are lacking. This study addresses this gap by selecting starvation-resistant lines of the parasitoid wasp Pachycrepoideus vindemmiae, including food deprivation resistance lines and food and water deprivation resistance lines. Our results demonstrate that all selected lines exhibited significantly improved survival abilities compared to non-selected lines. Moreover, resistance to starvation persisted across generations without artificial selection under starvation conditions, indicating stable inheritance of this trait. We also observed extended lifespan in female adults and enhanced resistance to desiccation and low temperature in both males and females from the resistance lines. Additionally, we conducted preliminary exploration of the mechanisms underlying starvation resistance in these resistant lines through transcriptome sequencing for the first time. The analysis revealed that, under starvation stress, pathways such as amino acid metabolism and nucleotide metabolism exhibited consistent expression patterns in both resistant and non-resistant lines. However, specific pathways including arachidonic acid metabolism in lipid metabolism, and glyoxylate and dicarboxylate metabolism as well as glycolysis/gluconeogenesis in carbohydrate metabolism, were upregulated only in the resistant lines. These findings suggest that starvation resistance in the resistance lines involves multiple molecular pathways. This study represents the first successful artificial selection for starvation-resistant natural enemy lines, offering valuable insights for utilizing natural enemies effectively and understanding stress resistance mechanisms for potential genetic modification of beneficial traits.

Botanical larvicides, such as essential oils (EO) from the Piper species, offer eco-friendly mosquito control by targeting Culicidae larvae while exhibiting low toxicity to non-target aquatic animals. This study investigated the larvicidal activity and mechanism of action of the essential oil (EO) from Piper brachypetiolatum and its main compound, (E)-nerolidol, against Aedes aegypti, as well as the effects on non-target aquatic organisms Toxorhynchites haemorrhoidalis, Anisops bouvieri, and Diplonychus indicus. The EO was extracted from the leaves of P. brachypetiolatum using hydrodistillation, yielding 1.5 ± 0.7%. Gas chromatography revealed the presence of sesquiterpenes (64.70%), oxygenated sesquiterpenes (17.64%), monoterpenes (11.76%), and oxygenated monoterpenes (5.88%), with (E)-nerolidol as the major compound (64.32%). The EO and (E)-nerolidol exhibited significant larvicidal activity against A. aegypti, with LC₅₀ values of 15.51 and 9.50 mg/L, respectively. They also inhibited AChE activity (IC₅₀ values of 44.97 and 11.07 mg/L, respectively) and induced RONS overproduction (p < 0.05) compared to the positive control, α-cypermethrin. Additionally, the EO and (E)-nerolidol showed no lethal effects on T. haemorrhoidalis, A. bouvieri, and D. indicus, with these species exhibiting 100% survival after exposure. In contrast, α-cypermethrin caused 100% mortality in these species. These findings highlight the potential of the EO from P. brachypetiolatum and (E)-nerolidol as effective and environmentally friendly alternatives for controlling A. aegypti larvae.