Insects最新文献

Estimating the minimum post-mortem interval (PMI-min) is crucial in criminal investigations for identifying victims and the circumstances surrounding their death. Traditional post-mortem indicators are reliable only within the first 48-72 h post-mortem. This study explored forensic entomology as an alternative method for PMI estimation, focusing on three cases in Busan, South Korea. Forensic cases involving insect specimens collected from bodies found in Busan from 2022 were examined. Personal and photographic data were documented, and insect specimens were collected, preserved, and identified based on both their morphological characteristics and DNA sequences. To enhance the estimation accuracy, corrected death scene temperatures were calculated using an electronic thermo-hygrometer and meteorological data, applying both quadratic regression and the Support Vector Machine (SVM) model. The PMI-min was estimated using growth models and developmental data from established studies. Lucilia sericata (Meigen) at different life-cycle stages were discovered in all of the cases, whereas Chrysomya megacephala (Fabricius) was found in only two out of the three cases. In each case, the estimated time of death based on the necrophagous flies differed from the deceased's last known activity by approximately one-two days. These discrepancies may arise from the pre-colonization interval (PCI), a critical but often overlooked factor for accurate PMI-min estimation. Additional factors, including weather conditions, oviposition timing, mixed fly populations, and maggot-generated heat, further contribute to the uncertainty of PMI-min estimates. Future research should integrate these variables and employ advanced technologies such as machine learning to improve the accuracy of these estimates.

The pepper weevil, Anthonomus eugenii Cano, 1894 (Coleoptera: Curculionidae), poses a significant threat to pepper cultivation, causing extensive crop damage and economic losses. While numerous studies have addressed its occurrence, biology, and control methods, less attention has been given to how climate change might alter its distribution. This research utilized the optimized MaxEnt model to project the current and future habitat suitability of the pepper weevil under four distinct climate scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5) for the periods spanning the 2030s to 2090s. Optimal model performance was achieved with a regularization multiplier of two and a feature combination of QHP, yielding high predictive accuracy with mean testing AUC values of 0.921. The analysis identified annual mean temperature (Bio1) and precipitation of the coldest quarter (Bio19) as the primary environmental factors influencing the pest's distribution. Currently, in China, suitable habitats for A. eugenii encompass an area of 273.74 × 10⁴ km² or 28.47% of the nation's territory, predominantly located in central, eastern, southern, and southwestern regions. Future projections suggest that suitable areas are expected to shrink across various scenarios, barring increases in specific instances like SSP126-2050s, SSP245-2070s, and SSP370-2050s, with shifts towards southwestern regions. This investigation deepens our comprehension of agricultural pest dynamics under climate change and supports the formulation of preemptive management strategies to safeguard agricultural productivity.

The brown planthopper (Nilaparvata lugens) is an insect pest of rice, which mainly feeds on the phloem sap of the leaf sheath. RNA interference (RNAi) has application prospects in pest control, but it is necessary to select target genes and design suitable dsRNA fragments for RNAi so that it can achieve effective pest control and avoid risks to non-target organisms. NlAtg3 is a key protein in the autophagy pathway of N. lugens. Three kinds of dsRNA fragments of the NlAtg3 gene (dsNlAtg3-474×1, dsNlAtg3-138×3 and dsNlAtg3-47×10) were designed to compare the RNAi efficiency and specificity against the target insect N. lugens and non-target organisms through microinjection. The results showed that the fragment dsNlAtg3-474×1 showed strong inhibitory effects on the survival of N. lugens, which resulted in the survival rate decreasing to zero on the fifth day, while the survival rate of a closely related species, Sogatella furcifera, dropped to 2.22%. In contrast, dsNlAtg3-47×10 specifically designed against N. lugens only showed slight or no inhibitory effects on S. furcifera and other non-target organisms such as Drosophila melanogaster, but still showed good lethal effects against N. lugens, with the survival rate dropping to 18.89% on the ninth day. In addition, after being fed N. lugens injected with dsNlAtg3-47×10 fragments, the survival rate of the natural enemies Dolomedes sulfureus and Tytthus chinensis did not show significant change, compared with those treated with the dsGFP control. Our results suggest that the NlAtg3 gene can serve as a potential target for controlling N. lugens. Moreover, by designing suitable RNAi fragments, it is possible to avoid harm to non-target organisms while effectively inhibiting the target insect N. lugens.

Uneven heating is the biggest obstacle to the application of radio frequency (RF) technology in insecticidal applications. Since many existing studies have focused on the RF heating uniformity of granular materials, few RF treatment solutions have been reported for leaf materials. To improve the RF heating uniformity of tobacco leaves, a combined RF-hot air treatment method was developed for disinfestation in this study. The experiments were conducted to determine the effects of three process parameters (electrode gap, sample thickness, and hot air temperature) on the RF heating rate and uniformity of tobacco leaves. The results showed that the heating rate of RF-hot air combined treatment increased with decreasing electrode gap but increased with increasing sample thickness and hot air temperature. The RF heating uniformity in tobacco leaves decreased with increasing heating rate but could be significantly improved with the conveyor movement. Considering the heating uniformity and heating rate, the material thickness of 60 mm and electrode gap of 110 mm were selected as optimal process parameters. The results of the study may provide a feasible method to improve the RF heating uniformity in tobacco leaves and potential applications for effective disinfestations.

The Belostomatidae is a family of aquatic Heteropteran insects that normally inhabit swamps of tropical, subtropical and temperate regions where they naturally feed on a large range of prey, mainly fish, amphibians and reptiles. However, these arthropods can occasionally bite humans when provoked, causing pain. The only species of giant water bug known to be found in Europe is Lethocerus (L.) patruelis. We reported the finding of a specimen of female L. patruelis in Southern Italy. The arthropod was collected by a tourist on his body while he lying down on a beach close to a nature reserve. To finalize the giant water bug identification, both morphological and molecular tools were used for the first time in our country. Herein, information on cases of patients bitten by giant water bugs belonging to the Belostomatidae family are reported, and circumstances involving their contact with humans are also discussed.

Conservation biological control (CBC) is the application of agricultural practices that utilize insectary plants to conserve and enhance natural enemies, thereby increasing their efficiency to suppress pests. Most of the insectary plants used in CBC are non-native invasive insectary plants, which are costly and pose threats to the local ecosystems and biodiversity. Alternative to non-native insectary plants, the use of native plants is proposed. Hence, the aim of this study is to identify native plant species that can be used as alternatives to non-native insectary plants to conserve and promote indigenous natural enemies (INEs) for sustainable pest management. To achieve this, first, we bio-prospected the surrounding habitats of organic fields in the western region of Japan (i.e., Hiroshima Prefecture) to identify native plant species as prospective native insectary plants. As a result, among various Japanese native plants surveyed, Polygonaceae plant species seem to host a variety of INEs, showing potential as a native insectary plant. We then conducted open field experiments to test the role of Polygonaceae plants in promoting INEs, thereby indirectly suppressing pest densities on vegetable crops such as eggplants. Results show that significantly high densities of INEs (green lacewing, p = 0.024; Orius spp., p = 0.001: GLM) were observed on eggplants with Polygonaceae plants compared to eggplants without Polygonaceae plants, leading to a significant reduction in pest densities (thrips, p = 0.000; whiteflies, p = 0.002: GLM) on the eggplants with Polygonaceae plants. Furthermore, molecular analysis revealed that Orius spp., as a representative INE in this study, migrated from Polygonaceae plants to eggplants, suggesting that Polygonaceae plants may conserve and promote INEs to vegetable crops, resulting in pest suppression. Here, we discuss the roles of Polygonaceae plants (and other native plants) in regulating pest densities on crops.

The insect order Lepidoptera contains many species that are considered to be agricultural pests. Specific double-stranded RNA-degrading enzymes in some moth species decrease the efficiency of RNA interference (RNAi). RNAi refers to the efficient and specific degradation of homologous mRNA induced by highly conserved, double-stranded RNA during evolution. The dsRNase enzymes can specifically recognize exogenous dsRNA, and bind to and degrade dsRNA, resulting in the inability of dsRNA to play its role. Although dsRNases play an important role in dsRNA degradation, there has been limited research on these enzymes. In this study, we successfully identified four genes related to dsRNases (named SeRNase1, SeRNase2, SeRNase3 and SeRNase4) from the genome of Spodoptera exigua. To overcome the rapid degradation of dsRNA in the midgut of S. exigua, we combined nanotechnology with biology and developed a new strategy to administer RNAi to insect pests. This binding block directed contact between the dsRNA and SeRNases to improve the efficiency of RNAi in suppressing gene expression. We demonstrate the potential of using nanotechnology to provide a novel RNAi delivery method for pest control.

Grape phylloxera, Daktulosphaira vitifoliae (Fitch), is an economically significant pest of grapevines. Identification of phylloxera genotypes is an important aspect of management as genotypes differ in virulence and susceptibility to control using resistant rootstocks. Microsatellite markers developed on polyacrylamide gel systems have been the most widely used molecular method for phylloxera genotype identification, but this approach has been superseded by fluorescent capillary-based genotyping. The current study presents new laboratory methods for amplifying a standard set of eight phylloxera microsatellite markers using PCR-incorporated fluorescently labelled primers, genotyped on an ABI capillary platform. Comparison of allele size data scored on (i) polyacrylamide, (ii) capillary, and (iii) high-throughput sequencing (HTS) platforms revealed that the capillary genotyping most closely matched the HTS allele sizes, while alleles of loci originally scored on a polyacrylamide platform differ in size by up to three base pairs, mostly due to the presence of previously uncharacterised DNA sequence indels. Seven common clonal lineages of phylloxera known from Australia are proposed as reference samples for use in calibrating genotyping systems between platforms and laboratories to ensure universal scoring of allele sizes, providing a critical link for accurately matching previous phylloxera genotype studies with current research.

Background: Amylase activity is a critical biomarker for assessing the freshness of honey. Historically, bees have been considered the sole source of honey amylase. However, recent studies suggest that Bacillus subtilis may also contribute to amylase production in the honey sac of Apis mellifera.

Methods: In this study, amylase levels were measured in samples of nectar, honey sac fluid, and honey. The identification of B. subtilis in nectar, honey sac, and honey was evaluated. An in vitro bacterial culture system and a feeding experiment were developed to simulate honey sac conditions.

Results: Our results showed that B. subtilis was detected in all sample groups, with the highest concentration in honey sac samples. Amylase levels in honey sac and honey samples were significantly higher than those in nectar. In the simulation experiment, amylase activity was only observed in cultures containing both B. subtilis and sucrose/nectar; no activity was detected in cultures containing only H₂O or no B. subtilis. In the feeding experiment, bees fed sucrose or nectar showed higher amylase activity in their honey sacs than those fed water.

Conclusions: Our data show that B. subtilis can produce amylase and offer potential for more standardized quality assessment of honey.

The taxonomy of genus Ambulyx Westwood, 1847 from China is reviewed based on analysis of wing morphology, male and female genitalia and phylogenetic relationships derived from DNA barcodes. A new species, Ambulyx wukong sp. nov. is described from NW Yunnan, China. A male of the rare species, A. zhejiangensis from Yintiaoling Nature Reserve, Chongqing, China is examined and its male genitalia illustrated for the first time. Two taxa are newly recorded from China, A. tattina tattina from Xishuangbanna, Yunnan, and A. semiplacida montana from Pingbian, Yunnan. Distribution maps, biological notes, and ecological records are also given.