Entomological Research最新文献

Thrips are serious crop pests with a worldwide distribution. The first step in the design of control methods is accurate species identification. However, the morphological identification of thrips can be complex, especially as there is morphological variation amongst individuals of the same species. Analyzing a fragment of cytochrome c oxidase subunit I (COI) has been used successfully in the identification of insects and other arthropods. Citrus is among the most important crops in the world, and Mexico is one of the largest producers. Despite this, formal reports on the species diversity of thrips found in Mexican citrus orchards are scarce. We explored the species diversity of thrips in selected citrus orchards (of Mexican orange, Key lime and Persian lime), based on morphological taxonomy and on partial sequences of COI. We analyzed 111 thrips specimens, distributed in two genera: Frankliniella, including Frankliniella insularis, Frankliniella invasor and Frankliniella occidentalis; and Scirtothrips, including Scirtothrips citri and Scirtothrips dorsalis. Frankliniella insularis and F. invasor were the most abundant species in Mexican orange (Citrus × sinensis) and Persian lime (Citrus × latofolia) orchards. Scirtothrips dorsalis was the most abundant species in Key lime orchards (Citrus × aurantiifolia). Analysis of molecular variance (AMOVA) and haplotype analyses performed on F. insularis sequences (the most abundant species) showed no significant effect of geographical origin or plant host on its genetic population structure. DNA barcoding is a valuable method to complement the morphological identification of thrips in citrus orchards, allowing more accurate identification to species level.

Body decomposition is influenced by various factors, including temperature, rainfall, body mass, and the activities of insects and carnivores in areas where carcasses are abandoned. However, the specific impact of carcass mass on the decomposition rate remains unclear. Therefore, this study aimed to compare the effects of carcass mass on decomposition rate with controlled domestic environmental conditions. Carcasses were categorized as small and large. Decomposition patterns were evaluated using a visual scatterplot to illustrate the relationship between total body scores and log accumulated degree days (ADD). To quantitatively compare decomposition rates, a linear regression model was employed to analyze differences between the two carcass groups. Regardless of carcass mass, a similar oviposition period for flies (Diptera) was observed, and the external appearance of the carcass remained relatively stable until 1.8 logADD, marking the emergence of maggots. However, decomposition dramatically accelerated after reaching 1.8 logADD, coinciding with maggots hatching from eggs and their commencement of scavenging. In contrast to larger ones, the hastened decomposition of small carcasses can be attributed to the relatively substantial volume of Diptera larvae within the small carcasses, expediting colonization and utilization. Therefore, carcass mass should factor into postmortem interval estimation based on the degree of body decomposition.

In order to clarify the prediction accuracy of eight models for predicting the peak occurrence of the first generation larvae of Dendrolimus punctatus and provide basis for the pest control, a catastrophe prediction model was established based on the peak occurrence of the first generation larvae of Dendrolimus punctatus in Qianshan City, Anhui Province from 1983 to 2016, and compared with other seven prediction models. Comparing the forecasting results in 2015 and 2016 with actual value and taking 1 head/plant as the error standard, the errors of multiple regression models with six factors as independent variables, namely, peak occurrence of pupae in overwintering generation, peak occurrence of eggs in the first generation, cumulative population in overwintering generation, peak occurrence of adults in overwintering generation, rainfall in early April and parasitic rate of Trichogrammatid in the first generation eggs of Dendrolimus punctatus, were 0.21 heads/plant and 0.23 heads/plant with accuracy rate of 100%. The errors of stepwise regression model with the same six factors were 0.23 head/plant and 0.29 head/plant. The prediction accuracy of artificial BP neural network model, Markov chain model, contingency table model, stationary time series model, and fuzzy comprehensive evaluation model was 100%, but variance period extrapolation model had an accuracy rate of 88%. The accuracy of catastrophe prediction model was related to the selection of catastrophe threshold. Comprehensive comparison of the above eight models, multiple regression, stepwise regression, artificial BP neural network, Markov chain model, stationary time series model, and catastrophe prediction model were more accurate.

This study was carried out to assess the nutritional composition of Protaetia brevitarsis larvae (Pbl) reared on different feed materials. Four different types of feed materials were used to rear Pbl prior to nutritional analysis. The results show that the new formulation of feed material enhanced the crude fat content of Pbl by 75%, compared with the control. A marked increase in unsaturated fatty acids such as linoleic acid and oleic acid, by 100% compared with the control, in Pbl reared on the new formulation of feed material was also observed.

Storage grain infestation is a critical problem, with insect pests and rodents causing economic losses and reductions in the quality of food grains and food products. It has been assessed as affecting 9% of goods in developed countries and more than 20% of goods in developing countries. The chemical insecticides used for storing products protect against insect pests, but introduce hazards associated with handling insecticides and the residues on food, which threaten nontarget organisms, and so represent a serious problem to the environment. Biorational methods are low risk, are obtained from animals, plants, bacteria and some minerals, and are segregated into microbial, plant-associated protectant and biochemical substances. This method encompasses temperature management, modified atmospheric storage, ionizing irradiation, the mixing of inert materials, pheromone traps, botanicals, insect growth regulators, entomopathogens and host plant resistance. Biorational methods have emerged as alternative or supplemental pest control methods. Biopesticides would help in preventing the use of large quantities of pesticides across the globe, thus providing residue-free food and a safe environment for living. Further investigation is needed to integrate these elements to enhance the efficacy, minimize the losses and diminish the reliance on pesticides for the preservation of stored commodities.

Grylloprimevala jilina Zhou & Ren is the third extant species of Grylloblattodea to be found in China. To understand the various physiological functions of the sensilla on the main sensory organs of G. jilina during its vital activities, this study used scanning electron microscopy to examine the sensilla morphology on its appendages and analyze their abundance and distribution on the antennae. The filiform antennae comprise scape, pedicel and flagellum. The maxillary palps comprise three segments, and the cerci contain four appendages in total. Altogether, 11 morphologically distinct sensilla types were identified on three organs: apertures; Böhm bristles (BB); sensilla auricillica (SA), sensilla basiconica (SB), sensilla campaniformia (SCa), sensilla capitulum (SCap), sensilla chaetica (SCh), sensilla coeloconica (SCo), sensilla filiform (SF) and sensilla trichodea (ST); and spines. Studies of the antennae of G. jilina have revealed that, except in some cases, the types and abundances of the sensilla gradually show a trend of diversification and enrichment as the antennae segments are extended forward. Functional predictions for the 11 morphologically distinct sensilla suggest that they include chemoreceptors, mechanoreceptors and temperature or humidity receptors. As wall-pore sensilla, SA, SB, SCo and ST could be involved in the perception of chemical signals emitted from their living environment. In addition, as mechanical receptors, BB, SCa, SCh and SF may be involved in the perception and feedback of mechanical stimuli. Our findings provide an essential insight into this rare and national first-class protected insect, and provide a necessary theoretical basis for studying the phylogeny of Grylloblattodea.

Frankliniella intonsa Trybom is a common flower-inhabiting thrips species and an economically important pest of numerous horticultural and agricultural crops. Olfactory cues are important for thrips to find host plants. In this study, the olfactory behavioral responses of F. intonsa to volatiles from five Rosa chinensis cultivars (Samantha, Zeprti, Queen Elizabeth, Golden Scepter, and Witte Koster) were tested in Y-tube and six-arm olfactometer experiments. Then the volatile components of the R. chinensis flowers were analyzed by SPME coupled with gas chromatography–mass spectrometry (GC–MS). Both female and male thrips showed significant preferences for volatiles from the five R. chinensis cultivars compared with clean air (CA). However, according to the six-arm olfactometer bioassays, female F. intonsa adults were better than male thrips at recognizing the odor stimulation and showed the strongest olfactory preference for Samantha, followed by Zeprti, Queen Elizabeth, Golden Scepter, and then Witte Koster. SPME-GC–MS analysis identified 56, 53, 53, 57, and 60 components in the volatile profiles of Samantha, Zeprti, Queen Elizabeth, Golden Scepter, and Witte Koster, respectively. Eugenol (12.53%) was the most abundant volatile compound in cultivar Witte Koster, ɑ-pinene was the most abundant compound in Samantha (18.26%) and Zeprti (23.73%), and phenylethyl alcohol was the most abundant in Queen Elizabeth (30.10%) and Golden Scepter (31.33%). Therefore, the olfactory responses of F. intonsa to different R. chinensis cultivars demonstrated that host-related volatiles play an important role in thrip host-searching. Future mitigation approaches, for example, attractant traps, could still be used for key monitoring and control of this pest.

The evolution of pest resistance to insecticidal proteins from Bacillus thuringiensis (Bt) restricts the sustainable application of transgenic Bt crops, and exploring other ecofriendly insecticides to efficiently suppress Bt-resistant populations is thus urgently needed. The plant secondary metabolite rutin possesses pest resistance effects and plays an important role in plant resistance to pests, but the effect of rutin on pink bollworms is unclear. We investigated the effects of rutin on two types (Bt-susceptible and Bt-resistant) of pink bollworms (Pectinophora gossypiella). Rutin had significant inhibitory effects on the growth, development, and oviposition of both Bt-susceptible and Bt-resistant strains. For both strains, rutin ingestion by larvae did not significantly affect larval survival at 7 days after treatment or egg hatching rate but significantly decreased pupation rate, eclosion rate, neonate-to-adult survival, pupal weight and eggs per female and significantly prolonged larval developmental periods, and the effect increased with increasing rutin content. The response to rutin ingestion was basically consistent between Bt-resistant and Bt-susceptible strains, indicating that the Bt-resistant strain did not exhibit cross-resistance to rutin. These results provide a reference basis for green control and resistance management of pink bollworms and may be used as a component of comprehensive management for this pest.

Wolbachia, an endosymbiotic bacterium, has a significant impact on the reproductive biology and pathogen transmission capabilities of various arthropods, including mosquitoes. This study aimed to assess the prevalence of Wolbachia in Culex molestus, a vector mosquito species, in South Korea. Mosquito samples were collected from different locations and taxonomically identified. Individual mosquito DNA was extracted, and polymerase chain reaction (PCR) was conducted targeting the Wolbachia surface protein gene (wsp) and three multi-locus sequence typing (MLST) (gatB, hcpA, and ftsZ) genes. Gel electrophoresis was performed to determine the prevalence of Wolbachia by analyzing PCR products. Our findings revealed that Wolbachia was present in 100% of the tested Culex mosquitoes from South Korea, with one major Wolbachia strain (supergroup B) detected using the wsp gene and subgrouping determined with the gatB as well as hcpA, and ftsZ. These results underscore the widespread occurrence of Wolbachia in Cx. molestus mosquito within the studied region, thus suggesting the potential for leveraging this endosymbiont to devise novel strategies for mosquito-borne disease control. Future research should investigate the influence of Wolbachia on mosquito biology and vector competence in South Korea.

Frankliniella occidentalis is an important pest globally and causing serious damage to vegetables and flowers. Exogenous phytohormones can induce host plant resistance and reduce loss caused by pests. This study investigated the effects of detoxification enzyme activity and related gene expression in F. occidentalis after feeding on jasmonic acid (JA)- and ethylene (ET)-cotreated faba bean plants. Change in MFO activity was nonsignificant at 6 and 48 h after F. occidentalis fed on the cotreated faba bean plants; but significantly decreased at 24 h compared with control group. The peak activities of carboxylesterase (CarE) and glutathione S-transferase (GSTs) at 48 h showed a significant increase of 2.31-fold and 1.15-fold, respectively. Additionally, CarE and GSTs activities remained consistent and significantly higher than those of the control group at the remaining timepoints. The expression levels of the P450 genes CYP4-3, CYP6-2, and CYP6-3 in F. occidentalis were significantly upregulated at 6 h and those of CYP6-2 and CYP4-5 were significantly upregulated at 24 h. The expression of the CarE gene CL4503.Conting2 was significantly upregulated at 6 and 48 h that of the GSTs gene FoGSTd1 was significantly upregulated at 24 and 48 h, that of FoGSTs1 was significantly upregulated at all three timepoints, and that of GSTs1 was only significantly upregulated at 6 h and significantly downregulated at 24 and 48 h. These results indicate that F. occidentalis can adjust the activity and gene expression of detoxification enzymes to adapt to the defense response of faba bean induced by JA and ET.