Journal of Pest Science最新文献

Frankliniella occidentalis is a serious pest of various plant species and has different olfactory preferences for different host plants. Here, the olfactory responses of female F. occidentalis to the volatiles from different plants (Rosa chinensis, cucumber, and tomato) were tested using electroantennography (EAG) and behavioral bioassays in different types of olfactometers. Y-tube olfactometer bioassays indicated that R. chinensis was the preferred host for F. occidentalis. Fifty-five compounds were identified as components of the volatiles of R. chinensis by gas chromatography–mass spectrometry analysis, of which citronellol (11.62%), 1-hexanol (11.28%), and 3,5-dimethoxytoluene (11.45%) showed the highest relative abundance. EAG recordings showed that antennae of F. occidentalis were able to perceive these three compounds at a wide range of concentrations. In six-arm olfactometer bioassays, F. occidentalis showed significant positive responses to citronellol and 1-hexanol at various concentrations, with the most attractive ones being 10 μg/μL for citronellol and 1 μg/μL for 1-hexanol. When these two compounds at their optimal concentrations were placed in a four-arm olfactometer, significantly more F. occidentalis individuals were attracted to citronellol. F. occidentalis populations were significantly increased under the stimulation of citronellol at 10 μg/μL. Our results show that plant semiochemical volatiles play an important role in the host plant detection and selection of F. occidentalis, and they help guide it to preferred host plants that are suitable for its reproduction. Citronellol showed the greatest potential for development as a novel monitoring and control tool against this thrips species.

While climate change and pesticide use expose insect pests to multiple stressors, their combined effects remain poorly studied. Rising temperatures can accelerate insect life cycles and alter reproductive behaviours, while pesticides can impair physiological functions, reproduction, and survival. Understanding how global warming and pesticide exposure interact is crucial for predicting pest population dynamics and their impact on agroecosystems. As mating behaviour, including mate choice, plays a fundamental role in population growth, studying how these combined environmental stressors influence reproduction is critical. This study investigated how Bordeaux mixture fungicide affects the development, mating behaviour of Lobesia botrana under current (2002–2021) and projected (2081–2100) climatic scenarios. Larvae were reared with two fungicide concentrations and under two climatic conditions. Larval mortality, development time, and adult longevity were monitored. Mating behaviour was assessed using no-choice and choice experiments, measuring pre-mating latency, mating success and duration, fecundity and fertility. Key life parameters (R₀, T, Dₜ, rₘ, and λ) were estimated to investigate population dynamics. Results show that fungicide exposure negatively affected the development and survival of larvae until emergence, but these effects were modulated by climatic conditions. While Bordeaux mixture exposure prolonged development time, future climatic conditions shortened development time compared to current conditions. Choice experiments revealed that under future conditions, moths preferred unexposed partners, whereas no preference was observed under current conditions. These findings emphasize the importance of integrating climate change effects into pesticide risk assessments, as their interactions may have unexpected consequences for pest populations and sustainable management strategies in agroecosystems.

(E)-ß-farnesene (EBF) acts as an alarm pheromone of many aphid species and is also used as an aphid repellent by plants. Upon perception of EBF, aphids exhibit avoidance behavior. They walk away, stop feeding or drop from leaves. Moreover, EBF is an attractant for natural enemies of aphids. However, EBF is not used in pest management because it is expensive in its pure form. Therefore, we assessed the effect of a less expensive farnesene isomer mixture (FIM) on Myzus persicae (Sternorrhyncha: Aphidiae) on lettuce (Lactuca sativa var. Ulmo) in the laboratory and under field conditions. First, we tested under laboratory conditions if FIM has the same effect on M. persicae as it is described for pure EBF. The aphids were influenced by EBF. They stopped feeding, withdrew their stylets, went away from the danger zone, or developed and reproduced more slowly. Therefore, we studied the behavioral response of the aphids after FIM application and aphid reproduction under permanent exposure of FIM. Second, we tested in the field the reaction to FIM either directly applied to lettuce or released by dispensers. In the lab experiments, we found that M. persicae reacts to FIM by walking away and that reproduction tends to be reduced in the presence of FIM. In the field, we found lower numbers of aphids in the treatments with FIM. In particular, dispenser application caused higher aphid reduction compared to spray application on lettuce. In addition, more natural enemies of aphids could be found in dispenser-treated plots. Taken together, these results indicate that the use of FIM could contribute to insecticide-free aphid control in lettuce, but possibly also in other crops.

Huanglongbing, a devastating citrus disease, is associated with ‘Candidatus Liberibacter asiaticus’, ‘Ca. L. africanus’ or ‘Ca L. americanus’, bacteria transmitted by the psylloids Diaphorina citri and Trioza erytreae. Using a DNA-Seq and metabarcode sequencing integrated approach, the first catalogue of endosymbionts associated with T. erytreae from the Iberian Peninsula, South Africa and African Islands, was generated. The almost complete genome of two new bacteria, one facultative and one obligate, tentatively named Asaia-like endosymbiont of T. erytreae and Sodalis-like endosymbiont of T. erytreae, respectively, was assembled and annotated. The complete mitochondrial genomes of T. erytreae from the geographical areas studied were also assembled and phylogenetic analyses were performed, suggesting that T. erytreae populations currently present in the Iberian Peninsula and specimens analyzed from South Africa may have originated from a common ancestor. Similar results were obtained when the genetic distances between Sodalis-like endosymbiont of T. erytreae were taken into consideration, thus supporting the symbiont–host codivergence which suggests that this bacterium is approaching to an obligate status. Finally, a new genetic marker of T. erytreae, an insertion in the mitochondrial tRNA-Ser gene, was identified only in some European samples, showing for the first time the existence of two mixed subpopulations of T. erytreae. The integrated DNA-Seq and metabarcode sequencing approach used in this study, besides generating a catalogue of T. erytreae endosymbionts, provided novel data on the sequence variability of bacterial and insect mitochondrial genomes from different geographic areas, highlighting the possible original sources of currently spreading T. erytreae populations may be more complex than previously reported.

Protaetia brevitarsis (Lewis, 1879) is a serious agricultural and forestry pest. Since first report in Xinjiang (XJ), China in 2001, it has rapidly spread. This study explored the phylogeographic structure of Chinese P. brevitarsis as well as the origin and dispersal route of the XJ population using COI and EF-1α gene-based analysis, geometric morphometrics, and the optimized maximum entropy (MaxEnt) model. The results indicated Chinese populations exhibit high genetic diversity. Spatiotemporal reconstruction of the geographic dispersal indicated P. brevitarsis initially moved from its origin in the Huang-Huai region (HH) to XJ through the Hexi Corridor during the late Pleistocene, approximately 0.135 million years ago (Ma). Before 0.02 Ma, reciprocal active dispersal events occurred between XJ population and others, leading to the formation of the current phylogeographic pattern. This aligns with the demographic history, P. brevitarsis experienced continuous and rapid population expansion from 0.075 to 0.006 Ma. Based on the Procrustes distance cluster analysis of shape variation of the white spots on the elytra, the populations of HH, XJ, North China, and SGN (including Shaanxi, Gansu, and Ningxia regions) exhibit high morphological similarity, supporting the molecular research that these geographic populations are closely related. MaxEnt indicated suitable habitats in western Inner Mongolia during the Last Interglacial and the Hexi Corridor during the Last Glacial Maximum, facilitating dispersal from eastern China to XJ. During the Mid-Holocene and the current period, the corridor for active dispersion cut off. Gene flow between XJ population and eastern populations may be attributed to passive dispersion resulting from agricultural trade. These results alter previous understanding of the origin and evolutionary history in XJ, and provide scientific evidence for differentiated control measures for different geographic populations of P. brevitarsis.

RNAi for insect control is a promising alternative to synthetic insecticides. Intense research efforts over the years have allowed researchers to develop effective control strategies and, recently, the registration of a new product for the US market. To date, however, the insect stages targeted by RNAi are both juveniles and adults, while the egg stage has been largely ignored, although an early suppression of the pest would more efficiently limit its damage. Here we try to fill this gap by focusing on the silencing of Sl102, a gene that encodes precursors of functional amyloid fibrils involved in the immune response and that, based on literature reports, could have an important role in the modulation of the embryonic development of lepidoptera. We showed that Sl102 is expressed throughout the embryogenesis of Spodoptera littoralis, showing a peak 32 h after oviposition. The transcription level of this gene is strongly reduced by RNAi induced by soaking the eggs in a dsRNA solution. Interestingly, gene silencing is associated with a drastic reduction in egg hatching rate, which is complemented by a very high mortality of the few hatched larvae. Structural and ultrastructural analyses showed a significant delay in the development of silenced embryos, which also exhibited morphological alterations. Our results expand the understanding of the Sl102 gene function, indicating an important role in embryonic development that remains to be studied from a functional point of view. This paves the way toward the future development of effective control strategies for S. littoralis, based on the suppression of embryonic development through RNAi technology.

The utilization of pest behavior modulators in conjunction with conventional synthetic insecticides has emerged as a novel approach to enhance the efficacy of these applications. This integration involves the promotion of insect movement or the attraction of insects to treated areas, thereby optimizing the performance of the entire mixture. The present study aims to assess the effect of nine pest behavior modulators on the walking behavior of Euschistus heros (3rd instar nymphs and adults) using the automated computational tracking system (Ethovision^®). The findings revealed that Quimifol S450^® increased the total distance covered and sodium chloride (kitchen salt) reduced the walking speed of E. heros adults. Furthermore, physicochemical compatibility assessments employing the dynamic technique (with agitation) indicated that binary mixtures of all insecticides tested with Quimifol S450^® considerably increased the pH of the spray solution. Conversely, binary mixtures of insecticides with Atraksii^® exhibited a substantial increase in electrical conductivity. Moreover, laboratory tests (tarsal contact) and field trials (for two consecutive crop seasons), employing two conventional synthetic insecticides and four pre-selected pest behavior modulators, as well as their respective binary mixtures, demonstrated that the performance of stink bug control was diminished when sulfur-based dislodger Quimifol S450^® was mixed with acephate. Furthermore, the pest behavior modulators exhibited low activity after 15 min of insect exposure to treated surfaces. Our findings imply that the integration of homemade and commercial pest behavior modulators and conventional synthetic insecticides should be approached with caution, as potential antagonistic effects may be observed.

By attracting and stimulating feeding on spray droplets, phagostimulant baits provide an opportunity to increase the efficacy of crop protection products against the spotted wing drosophila (Drosophila suzukii). Here, we examined the use of a high-sugar, plant-derived bait (ProBandz^®, PB) in combination with low dose insecticides and an entomopathogenic fungus Metarhizium anisopliae strain 35.79 for control of D. suzukii. We compared the efficacy of treatments in laboratory jar bioassays and in semi-field strawberry experiments using laboratory D. suzukii cultures, and in field strawberry and raspberry experiments on natural D. suzukii infestations. M. anisopliae 35.79 increased D. suzukii mortality in jar bioassays but did not affect oviposition. There was no evidence that combining M. anisopliae 35.79 with PB led to increased efficacy, and in a semi-field experiment this combination led to an increase in D. suzukii larvae in fruit. Deltamethrin in PB droplets was effective in increasing mortality and reducing oviposition in jar bioassays but deltamethrin + PB bait sprays were ineffective in a field raspberry experiment. PB increased the D. suzukii control efficacy of lambda-cyhalothrin in jar bioassays. Low volume bait sprays with 8% of the full field rate of lambda-cyhalothrin in semi-field and field strawberry experiments were as effective in controlling D. suzukii as full rate, high volume insecticide sprays but without causing pesticides residues in the fruit. This work will provide evidence supporting the reduction of dependence and risk of resistance to the two main insecticides used for D. suzukii control: spinosad and cyantraniliprole.