Journal of Applied Entomology最新文献

Halyomorpha halys is an invasive stink bug, native to east Asia, responsible for extensive economic loss in numerous crops. Since several factors can influence the severity of the recorded injury level, we performed field and semi-field experiments in commercial apple orchards to monitor their interaction. To establish how position (both in the orchard and on the canopy), management and cultivar interact in determining pre-harvest injury levels, more than 100,000 apples, distributed over 106 orchard blocks, were examined in the field. Apples located higher in the canopy, on edge rows and in orchards with organic management had a higher number of external injuries and such factors were more relevant when occurring in combination, and on mid and late-season cultivars. Exclusion cages were used to assess if the injury severity changed with the apple growth stage and with the life stage of H. halys, exposing Red delicious apples to adults and nymphs for 48 hours, from May to July. Early-season injuries did not evolve in distinct depressions nor in wide areas with necrotic tissue. Later in season, the injury severity was higher and similar for adults and older nymphs (fourth and fifth instars), with the development of depressions externally and necrotic tissue internally. Thus, even a low number of individuals could cause severe damage, over a short exposure period, when it happened near full maturation. The combined results offer new insights to support the development of informed and sustainable control strategies.

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), is an invasive pest species that has incurred massive economic damages in areas cultivating economically important crops like corn, rice, cotton and many others. Known to be a native of the Western Hemisphere, FAW has since then established itself in many parts of Africa, Asia and Australia and Oceania. The Philippines had been among the Asian countries vulnerable to FAW invasion, which was validated in June 2019. This study aims to characterize the existing strains and haplotypes of FAW and describe the genetic structure and the signature of its recent demographic history nationwide. COI sequences reveal the predominance of rice-strain over the corn-strain FAW, while Tpi sequences are more accurate in defining the corn-strain found in corn and sugarcane. Discordant COI-Tpi configurations frequently occur the most in the entire FAW population at 65.29%. Nucleotide and haplotype diversity are low with an average of 0.005976 and 0.4019 respectively. In addition to non-significant values in neutrality tests suggesting neutral evolution, the low nucleotide and haplotype diversity indicate population contraction from founder effect. Variations are mostly found within regions, and genetic structure is moderate among regions (F_ST = 0.14375). These results can be attributed to low selective pressures accompanying its establishment, or more likely due to recent migration and/or human-assisted factors such as trade. Implications on pest management and prospective studies in the future are also discussed in this study.

The Oriental fruit fly, Bactrocera dorsalis, is a pest of significant economic interest that damages horticulture and causes major economic losses worldwide. The main control measures are based on insecticides, which are being increasingly restricted due to the development of genetic resistance. Therefore, there is a crucial need for a novel, sustainable, and environmentally safe means of controlling this pest. Advances in genome editing, aided by the discovery of CRISPR-Cas9 tools and the development of gene drive systems, offer new alternatives for combating insect pests and vectors. Genetic suppression tools targeting key parameters could become powerful assets within the AW-IPM programme for controlling B. dorsalis. This literature review provides an overview of currently characterized genes that could be targeted for genetic suppression of B. dorsalis.

Tetranychus cinnabarinus (Boisduval), a worldwide acarine pest, has garnered significant attention in recent studies, particularly regarding the role of ecdysteroids. Ecdysteroids (moulting hormone) played key roles in regulating the important physiological processes of arthropods, such as ecdysis, metamorphosis reproduction and immunity. However, the underlying mechanisms of ecdysteroid biosynthesis and signalling have not been elucidated in T. cinnabarinus. Therefore, in this study, we utilized RACE technology in conjunction with RT-PCR to obtain the complete sequence of three Halloween genes disembodied (dib), shadow (sad), shade (shd) and ecdysone receptor (EcR). Moreover, we analysed the expression level of these target genes in T. cinnabarinus, which was found to be expressed at all developmental stages. When using sublethal concentration of chromafenozide for bioassay on nymph of T. cinnabarinus, as the concentration increased, the ecdysis rate, mortality and ecdysteroid content were increased, and the moulting duration was decreased. We also characterized the expression on nymph of T. cinnabarinus after treatment with sublethal concentrations of chromafenozide, which were up-regulated. Based on these findings, we concluded that the treatment of sublethal chromafenozide enhanced Halloween gene and nuclear receptor gene expression, aided in the investigation of the molecular regulatory mechanism for moulting of T. cinnabarinus, and provided a theoretical basis for new agents.

The present study was carried out for the first time in Morocco to valorise plant species of the Artemisia genus. Its aim was to evaluate the larvicidal activity of essential oils from six Artemisia plants (A. herba alba, A. absinthium, A. campestris L., A. negrei, A. pontica, and A. arborescens) against Culex pipiens mosquitoes, which are recognised as potential vectors of West Nile virus. Bioinsecticides derived from EOs have shown promise as effective mosquito control agents. The EOs were analysed using GC–MS and GC-FID and were obtained by hydrodistillation from the aerial parts of the plants. Besides, the experiment was carried out according to the standard WHO protocol. Thujone and camphor were identified as the predominant compounds in all six Artemisia plants. A. herba alba demonstrated the highest larvicidal activity with LC₅₀ and LC₉₀ values of 4.85 and 15.39 μg/mL, respectively. Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were employed to explore the correlation between major EO compounds and larvicidal efficacy. The results suggest that these findings could pave the way for the development of tailored biocides that specifically target important disease vectors.

Entomopathogenic nematodes (EPNs), especially Heterorhabditis bacteriophora, are promising candidates for biological control of Popillia japonica larvae. Thus, there is a need to study native strains to ensure biological agents adapted to specific environmental conditions to improve their effectiveness in field applications. This work aimed to test the pathogenicity of five Azorean isolates of H. bacteriophora strains to third-instar larvae of P. japonica under laboratory and semi-field conditions. All EPNs were able to quickly infect larvae with LT₅₀'s ranging between 3.66 and 4.54 days in controlled laboratory conditions. The semi-field experiment consisted of an EPN application in buried tubes containing five larvae each in May and October. After 15 days, larvae were recovered and confirmed for nematode parasitism. In May, Az29, Az148, Az170, and Az171 displayed a mean of 37% infected larvae per tube. In contrast, EPNs showed a lower infection ability during the experiment in October, and only Az148 maintained the number of parasitized larvae, with a proportion of 40% of infectivity. The results suggest that native EPNs, like Az148, could be better adapted to climatic and edaphic conditions to control P. japonica larvae.

Apiculture provides better livelihoods for about 144,000 men, women and youth in Kenya. However, various challenges and barriers are available that prevent the industry from flourishing. One of these challenges is the low hive colonization rate reported by Kenyan beekeepers, who mainly depend on swarm catching to increase colony numbers within their apiaries. Many different traditional plants are used to attract bee swarms, although they have not been tested and compared scientifically with the most used and cost-effective bait in Africa, the beeswax, for improving swarm catches. To fill this knowledge gap, an ethnobotanical survey was carried out in Kenya to gain an in-depth understanding of traditional apicultural practices used for hive baiting to attract swarms. Additionally, the volatile composition of traditional plants used as swarm lures was examined using gas chromatography–mass spectrometry (GC–MS), and their effectiveness in catching swarms was evaluated in comparison to beeswax in the field. The survey results revealed that Ocimum kilimandscharicum, Cymbopogon nardus and Elaeodendron buchananii are the three commonly used traditional plants for baiting, chosen based on their aroma, abundance, ease of processing and durability. Notably, the volatiles emitted by O. kilimandscharicum plus beeswax attracted significantly two and half-fold more bee swarms than the control (beeswax alone), whereas those of E. buchananii were the least attractive and similar to those of the control. These discrepancies may be partly due to the presence of small amounts of geraniol and citral in the essential oils of O. kilimandscharicum, which are characteristic compounds of the Nasonov gland pheromone from workers honey bees known to attract bee swarms. Overall, our findings suggest that adding O. kilimandscharicum to beeswax may significantly enhance bee swarm catches in the field.

Host diet is one of the key factors that shapes insect associated microbial communities, and the impact of dietary shift on abundance of microbial communities and insect fitness is poorly understood. Cigarette beetle (Lasioderma serricorne (F.)) are in close association with yeast symbionts for nutritional and defence benefits. The present study highlights that dietary source determines the yeast abundance in cigarette beetle and any change in diet induces a shift in yeast abundance. A general trendline of increase in yeast abundance during larval and pupal stage followed by a drop in adult stages of cigarette beetle was observed among all diet sources. The yeast abundance varied among diet sources and was significantly higher on natal (wheat) and reverted colonies compared to other exposed dietary sources. Yeast abundance in reverted colonies of soybean and bengal gram increased to the levels of those that were originally feeding on wheat suggesting a similar microbial structure among those diet sources. The correlation between yeast abundance and beetle biomass among diet guilds suggest a predictable relationship between yeast symbionts and diet source. The investigation can provide further insights on yeast symbiont abundance and food source specificity in cigarette beetle biology and management.

Nesidiocoris tenuis (Reuter) (Heteroptera Miridae) is a key biological control agent of the tomato leaf miner Tuta absoluta (Meyrick). However, in cases of prey scarcity, this predator switches into a phytophagous pest causing ring injuries in stems of tomato plants. The aim of this study was to assess the side effects of dry residues and explore the presence of target site resistance mutations of 10 insecticides, two bioinsecticides, an acaricide and a fungicide widely applied in IPM, on adults of N. tenuis collected from two different regions of Crete; the Western and the Eastern side of the island during two successive years. Lethal toxicity trials were performed on sprayed tomato stems and toxicity of adults of N. tenuis was recorded 2 h, 7 and 14 days after exposure. At both populations, chlorpyrifos, acetamiprid and thiamethoxam were moderately harmful at the application day and slightly harmful 7 days after the application. Only chlorpyrifos maintained its toxicity for more than 7 days. All the rest tested pesticides (emamectin benzoate, abamectin, chlorantraniliprole+abamectin, chlorantraniliprole, deltamethrin, tebufenpyrad, spinosad, Bacillus thuringiensis var kurstaki, metaflumizone and myclobutanil) were classified as harmless. Additionally, analysis of insecticide target site sequences indicated the absence of resistance mutations in both populations. Overall, our findings illustrate the impact of 15 pesticides and their residual toxicity on the mortality rates of N. tenuis adults.