Journal of Asia-pacific Entomology最新文献

Sogatella furcifera is a typical r-strategist insect with strong adaptability and one of the major pests in rice cultivation. Small heat shock proteins (sHsp) play a vital role in insects responding to external abiotic stress. However, little is known about the role of sHsp in the defense against abiotic stress in S. furcifera. In this study, four sHsp genes (SofHsp20.7, SofHsp21.6, SofHsp21.7, and SofHsp21.8) were identified from S. furcifera, and their gene expression patterns were analyzed at different developmental stages, temperature stress, insecticide exposure, and UV-A irradiation. The results indicated that four sHsp were expressed at various developmental stages of the S. furcifera, with the highest transcription levels in the first-instar nymphs, fourth day fifth instar nymphs, third-day adult females, and eggs, respectively. High-temperature stress (30 °C and 40 °C) significantly induced the expression of all four sHsp genes, while low-temperature stress (10 °C) reduced their expression. Sublethal concentrations (LC₁₀ and LC₂₅) of buprofezin increased the expression levels of SofHsp20.7 and SofHsp21.8. Under UV-A irradiation, the S. furcifera also significantly induced the expression of all four sHsp genes, with the highest expression observed at 90 min after exposure to the stress. These results suggest that sHsp genes are essential for the resistance or tolerance of S. furcifera to high temperature, buprofezin, and UV-A irradiation. This research provides a foundation for understanding the molecular mechanisms underlying the S. furcifera adaptation to abiotic stress.

The red-necked longhorn beetle Aromia bungii (Coleoptera: Chrysomeloidea: Cerambycidae) is a wood-boring pest of Prunus spp. We analyzed two complete mitochondrial genomes of A. bungii collected in South Korea. The complete mitochondrial genomes were 15,759 bp and 15,760 bp long, including a typical set of genes (13 protein-coding, 22 transfer RNA, and two ribosomal RNA genes) and one non-coding region. Phylogenetic analysis revealed that the two mitochondrial genomes of A. bungie clustered with previously reported three mitochondrial genomes from China in one clade and was a sister group to Closteromerus belonging to the tribe Callichromatini.

Myocyte enhancer factor-2 (MEF2) plays essential roles in a variety of developmental processes. Prominent amongst multiple MEF2 functions is the regulation of muscle differentiation in Drosophila melanogaster. Nevertheless, the physiological importance of MEF2 has not been explored in non-Drosophilid insect species. Here we found HvMef2 was highly expressed at the first-instar larvae, 0-day-old second- and fourth-instar larvae, pupae and adults, especially in adult muscle in a Coleopteran potato defoliator Henosepilachna vigintioctopunctata. Injection of 200, 500 or 1000 ng of dsMef2 into the third instar larvae significantly reduced the expression of HvMef2 and impaired larval-pupal-adult transition, in a dose-dependent manner. About 68 %, 77 % and 87 % of the resulting larvae arrested as stunted prepupae, which were gradually blackened and eventually died. Around 32 %, 23 % and 13 % of the HvMef2 depleted beetles formed pupae. Among these HvMef2 depleted pupae, 22 %, 16 % and 7 % became shriveled pupae until death; roughly 10 %, 7 % and 6 % emerged as malformed adults. The growth of the adult thorax muscles was repressed. The length and width of dorsal–ventral muscles were significantly reduced. Knockdown of HvMef2 at the fourth larval instar stage caused similar defects. Likewise, introduction of dsMef2 at a dose of 200, 500 or 1000 ng into pupae led to 27 %, 20 % and 11 % emergence percentages respectively, with deformed elytra and hindwings. Therefore, MEF2 plays vital roles during metamorphosis, especially in myogenic regulation network in H. vigintioctopunctata.

In recent years, the microbial degradation of cellulose has emerged in addressing environmental pollution and acting as a substitute for scarce animal feeds. This study conducted a whole-genome sequencing analysis of a cellulose-degrading bacterium known as Bacillus subtilis DC11, previously isolated from the silkworm excrement. A critical cellulase gene was identified, namely ytoP. The ytoP gene was successfully cloned and expressed in E.coli using genetic engineering. ytoP is a segment of the endoglucanase gene in Bacillus subtilis DC11 and was found to be 1074 bp in size and encoded 357 amino acids. This study effectively constructed the cellulase expression vector and achieved successful expression of the ytoP gene from strain DC11 in E. coli BL21 (DE3). SDS-PAGE electrophoresis revealed that the protein had an approximate size range of 40–50 KDa and a concentration of around 3.675 mg/mL. An assay of enzyme activity demonstrated that the purified protein, with a concentration of approximately 100 μg/mL, exhibited a maximum activity of 12.980 U/mL. Through the integration of whole-genome sequencing and genetic engineering techniques, the critical cellulase gene ytoP from Bacillus subtilis DC11 has been successfully cloned and expressed, achieving highly efficient cellulase production. This study lays the foundation for large-scale applications of microbial cellulose degradation in the future.

Chelonus munakatae Matsumura (Hymenoptera: Braconidae) is an important parasitoid of several lepidopteran species. The mitochondrial genome of this species is a crucial source for molecular identification and genetic studies. Here, we used next-generation sequencing to obtain the C. munakatae mitochondrial genome, which was found to be 14,868 bp in length and contained 13 protein-coding genes, 22 tRNAs and two rRNAs. The nucleotide composition exhibits a significant bias towards A + T content, with a value of 86.8 %. A large number of PCG and tRNA gene rearrangement events were detected (I-V-M-C-W-Q and A-N-S1-E-R-F), which represent a novel rearrangement type in Hymenoptera. Furthermore, synteny analysis based on the whole mitochondrial genomes showed that a significant rearrangement of homologous blocks had occurred within this Braconidae species. This study not only delineates the mitochondrial characteristics of C. munakatae but also significantly contributes to the repository of mitochondrial genetic information for the Braconidae family. Moreover, it highlights the occurrence of gene rearrangement within Hymenoptera species, offering valuable insights into the evolutionary dynamics and genomic variability of these insects.

Tetramoera schistaceana Snellen is an important stem borer of sugarcane, which causes severe damage to sugarcane in China. Temperature is a key factor affecting its development and reproduction. Development duration, reproduction and survival rate of T. schistaceana were determined at five different temperatures (20, 23, 26, 29 and 32 °C) in this study. Results showed that temperature had significant effects on the development duration, survival rate and reproduction of T. schistaceana. The development rate of T. schistaceana for each stage increased linearly with increasing temperatures between 20 and 32 °C. Egg hatching rate, larval pupation rate and pupal eclosion rate were the highest between 23 and 26 °C. The lower thermal threshold (T₀) for egg, larva, pupa, pre-adult and whole generation were 9.98, 9.80, 9.47, 9.50 and 8.87 °C, respectively and the thermal constant (K) for the development of the respective life cycle stages of were 89.29 for eggs, 400.00 for larvae, 151.52 for pupae, 625.00 for pre-adult and 666.67DD for whole generation, respectively. The average fecundity per female was also the highest between 23 and 26 °C. Therefore the optimum temperature range for the development and reproduction of T. schistaceana was between 23 and 26 °C.

Accurate larval identification is a prerequisite for integrated pest management, but remains a long-term difficulty in insect taxonomy. Previous descriptions are mainly focused on the most disruptive final instar larvae. However, earlier instars especially cross-instar larval morphological comparisons were rarely delivered hitherto. Polyphylla laticollis and Maladera orientalis are pests that damage peanut crops at various developmental stages. The first instar larvae of P. laticollis and the mature larvae of M. orientalis attack peanuts simultaneously and cause different types of damage. In this study, we compared the life histories and larval morphologies through field investigations and scanning electron microscopy (SEM) observations. These cross-instar white grubs are similar in sizes, but exhibit morphological differences on their mouthparts, thoracic legs, anal slits, and rasters. This study presents a novel approach to larval identification, with a goal of generating new insights into integrated pest control practices on white grubs.

Actinomycetes represent sources of potential alternatives to chemicals as biological pest control agents, and several actinomycetes are known to produce metabolites with insecticidal activities against insect pests. Although these metabolites are eco-friendly and effective, it is necessary to identify a novel insect-specific insecticidal agents that can minimize the occurrence of resistance. Thus, in this study, we screened the juvenile hormone disruptor (JHD) and insecticidal activities of crude acetone extracts derived from various actinomycetes as novel biopesticide candidates. A total of 300 soil-derived actinomycetes were isolated from various sites in Korea, and were screened for their JHD and insecticidal activities against a range of important medical and agricultural pests. Among them, eight extracts showed high levels of JHD activity. The AN120590 strain showed a broad insecticidal spectrum with stably maintained JHD properties. Additionally, the dead larvae of Aedes albopictus and Plutella xylostella treated with acetone extracts of the AN120590 strain displayed morphological deformities similar to those of insects treated with juvenile hormone-based insect growth regulators (IGRs). These findings indicate that actinomycetes represent promising sources of novel IGRs that can be effectively applied as insecticides with a broad insecticidal spectrum.

Insecticide resistance is threatening the effectiveness of efforts to control dengue vectors in Thailand. This study explores the levels of insecticide resistance in Aedes aegypti mosquitoes to deltamethrin. A study was carried out in dengue-endemic areas of Thailand to find the situation of insecticide susceptibility status of dengue vectors. Female Ae. aegypti mosquitoes were collected from 8 districts in different provinces and were exposed to various discriminating concentrations of deltamethrin (1×, 5×, and 10×) using the WHO insecticide resistance intensity bioassay. All tested populations of Ae. aegypti were found to be resistant to the WHO discriminating concentration of deltamethrin (0.03%). Mosquito populations collected from Surat Thani (SUT), Nakhon Si Thammarat (NST) and Ayutthaya (AYU) Provinces were resistant to deltamethrin exposure up to 10× the discriminating concentration suggesting the high resistant intensity. The effect of pre-exposure to the insecticide synergist, piperonyl butoxide (PBO), was also tested at the discriminating concentration of 0.03% deltamethrin. A significant increase in susceptibility to deltamethrin and knockdown percentage was observed in all populations of mosquitoes that were pre-exposed to PBO. These findings indicate that dengue control in Thailand with deltamethrin only could be threatened by high resistance in Ae. aegypti populations. It is recommended that vector control strategies incorporating PBO as an effective synergist can enhance the susceptibility of mosquitoes in the presence of deltamethrin resistance.

During the mating of honeybees (Apis mellifera), the seminal fluid and sperm produced by the drones’ reproductive organs are transferred to the queens’ spermatheca. However, compared to the reproductive organs of the queens, little is known about those of the drones. To identify genes that are differentially expressed in the drones’ reproductive organs during sexual maturation, we conducted a comprehensive transcriptome analysis of the respective organs across various developmental stages. Our investigation identified 20 genes with over a 50-fold enhancement in expression relative to their basal levels upon emergence. Among these genes, 13 had been previously predicted, while 7 had not been characterized. We conducted qRT-PCR to analyze the differential and spatial expression profiles of the identified 20 genes in the testes, seminal vesicles, and mucous glands of the drones. Our findings suggest that certain genes exhibit significantly elevated expressions in the reproductive tissues of the drones, indicating their potentially crucial roles in the reproduction of honeybees.