Entomological Research最新文献

The flower bugs, Orius maxidentex Ghauri and Orius minutus (Linnaeus), are important natural enemies of agricultural pests such as thrips and aphids. Insect olfactory systems play an important role in chemical communication, aiding them in locating host or prey habitats. To gain a deeper understanding of the role that sensory organs play in the biological behaviors of these flower bugs, the external structures of antennae and antennal sensilla were demonstrated using scanning electron microscopy (SEM). The antennae of the two species are linear in shape and consist of scape, pedicel, and two flagellomeres. The antennae of O. maxidentex were shorter compared to those of O. minutus. Additionally, the total length of the male antennae was longer than that of the female antennae in both species. Four types and four subtypes of antennal sensilla were documented in both species, including sensilla trichodea (ST I and ST II), sensilla chaetica (SCh I and SCh II), sensilla basiconica (SB), and sensilla campaniformia (SCa). Sexual dimorphism was not observed in the type and distribution of antennal sensilla but existed in the abundance of sensilla basiconica. Our findings provide important insights for future studies on defining the olfactory function of flower bug antennae using electrophysiological methods, especially in the heat-resisting species O. maxidentex.

This study evaluated the insecticidal, repellent, and fumigant activities of four plant-derived extracts: Ficus carica (common fig), Eruca sativa (arugula), Portulaca oleracea (common purslane), and Lupinus albus (white lupin) against adult Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae). Gas chromatography–mass spectrometry (GC–MS) analyses identified key bioactive compounds, including unsaturated fatty acids, phytosterols, and tocopherols, which may contribute to their insecticidal and repellent properties. In the residual paper technique, F. carica extract exhibited the highest mortality (22% at 100 mg/mL), followed by E. sativa (14%) and L. albus (6%), while P. oleracea induced only 2% mortality. Repellency bioassays revealed strong deterrent effects, particularly for F. carica and E. sativa. After 3 h, F. carica exhibited 98% repellency at 2 mg/cm², maintaining 66% at 0.5 mg/cm² and 56% at 0.125 mg/cm², indicating broad-spectrum efficacy. E. sativa followed with 64% repellency at 2 mg/cm², sustaining over 50% repellency across all concentrations. Although repellency declined over time, F. carica retained 70% at 2 mg/cm² after 24 h, while E. sativa maintained 64% repellency. In contrast, L. albus and P. oleracea exhibited weaker repellency. These findings highlight the strong repellent effects of F. carica and E. sativa, suggesting their potential as natural alternatives to synthetic insecticides in stored grain pest management. Under fumigation conditions, F. carica, E. sativa, and P. oleracea exhibited minimal insecticidal activity, and L. albus had no measurable effect. These results indicate that the primary potential of F. carica and E. sativa lies in their strong repellency and moderate contact toxicity, rather than fumigation.

Adding black soldier fly (BSF) larvae to animal manure enhances composting and environmental outcomes, producing organic fertilizer. However, the environmental impact of laying hen manure treated with BSF larvae remains poorly understood. This study, therefore, aimed to evaluate the decomposition ability, ammonia production, and proximate composition of laying hen manure at different instar stages of BSF larval treatment. The treatments included (1) 200 g of 2nd instar and (2) 200 g of 3rd instar BSF larvae/2000 g of laying hen manure. BSF larvae had no significant effect on the decomposition ability of laying hen manure during the experimental period. No significant difference in ammonia production was determined between the two groups on days 0 to 10, except on Days 15, 20, 25, and 30, when the differences were statistically significant (p < 0.05). In addition, no significant differences in pH, moisture, TN, CA, or ADF content of laying hen manure were detected between the 2nd and 3rd instar of BSF larvae; however, the NDF content showed significant differences between the two groups (p < 0.05). In terms of environmental impact, the 2nd instar BSF larvae groups increased decomposition ability and proximate composition of laying hen manure or decreased ammonia production compared with the 3rd instar BSF larvae groups. In conclusion, using the 2nd instar of BSF larvae on laying hen manure had a beneficial effect on the environmental impact and enhanced larval development under optimal conditions, which may be associated with pH.

Bactrocera dorsalis (Oriental fruit fly) and Bactrocera zonata (peach fruit fly) are economically important pests of fruits and vegetables. In the current study, the life history traits of B. dorsalis and B. zonata were investigated under cohabitation. The experiment consisted of three treatments: B. dorsalis alone, B. zonata alone, and B. zonata in a shared habitat with B. dorsalis. Data showed that cohabitation had a negative impact on the life history traits of B. dorsalis and a positive impact on the life stages of B. zonata. Significantly more landings, ovipositions, pupal recovery, and adult longevity were observed in co-habited B. zonata, while no difference in these parameters was observed in co-habited B. dorsalis, except for a decrease in adult longevity.

Locusta migratoria eggs use diapause and cold tolerance mechanisms, supporting potential for mass rearing. Long-term cold storage conditions for maintaining egg hatching rates remain understudied. This study aimed to determine optimal cold storage conditions for long-term preservation of L. migratoria egg masses. Eggs were stored at 7.5°C for 1 month starting on Days 1, 3, 6, and 9 after oviposition. The highest hatching rate (96.3%) was observed when storage began on Day 6 after oviposition, and no hatching occurred when initiated on Day 1. Among the temperatures tested (5°C, 7.5°C, 10°C, 12.5°C, and 15°C), 10°C yielded the highest hatching rate at 1 month (74.3%), followed by 7.5°C (69.3%). The lowest hatching rate (26.4%) was recorded at 5°C. Egg masses stored at 7.5°C and 10°C maintained high hatching rates (81.1%–86.9%) over a 10-day observation period, even after 5 months of storage. Regression analysis estimated maximum storage durations for maintaining hatching rates ≥ 90% as 2.8–3.9 months at 7.5°C, 2.3–3.8 months at 10°C, and only 0.6 months at 5°C. Notably, eggs stored at 7.5°C for 4 months beginning on Day 6 after oviposition exhibited a hatching rate > 90%, confirming the condition's suitability for extended preservation. Moreover, prolonged storage was associated with shorter hatching durations, suggesting continued embryonic development during cold storage. Thus, initiating cold storage at 7.5°C–10°C 6-day postoviposition allows effective long-term preservation of L. migratoria egg masses, contributing to the establishment of stable, year-round rearing systems.

Invasive alien species are an international problem because they can pose ecological and economic threats. Red swamp crayfish (Procambarus clarkii) is a representative invasive invertebrate species that has spread to Europe, North America, and Asia and causes ecosystem disturbances in freshwater and damages water management facilities. This study aimed to evaluate the species distribution and potential spread of P. clarkii, which was presumed to have been human-mediated introduced into South Korea. To achieve this purpose, this study predicted the global habitable areas of P. clarkii using a maximum entropy model based on global and South Korea-specific P. clarkii distribution data and five environmental variables. Shared socioeconomic pathway (SSP) scenarios were used to assess the effects of climate change on distribution. The model showed a good predictive performance for occurrence (AUC = 0.9707; TSS = 0.851; F1 score = 0.869). Temperature seasonality and mean temperature of the warmest quarter were the most influential factors for P. clarkii habitat. The model identified most regions with temperate climates and parts with continental and cold semiarid climates as high-risk areas. Under the SSP scenarios, the model predicted that the range might move into continental regions where habitat suitability is lower than that in temperate regions. In South Korea, habitat suitability was predicted to be high in the southern regions and eastern and western coasts. Also, suitability within the country is expected to increase. This study provides perspectives on P. clarkii invasion risk and highlights the need to prevent human-mediated introduction.

Niemann-Pick type C2 protein is a newly discovered odor molecule carrier protein in arthropods and has garnered widespread attention in recent studies. However, its functions in predatory mites remain largely unexplored. In this study, we cloned the coding sequences of nine NPC2 genes from the predatory mite Neoseiulus californicus and designated them as NcNPC2-1 to NcNPC2-9. These genes encode proteins ranging from 146 to 174 amino acids in length, with molecular weights between approximately 15.6 and 19.3 kDa. All proteins possess a conserved ML lipid recognition domain, and their tertiary structures are mainly composed of β-sheets, consistent with the characteristics of the NPC2 protein family. Phylogenetic analysis indicated that these genes are closely related to the NPC2 genes of other mites and spiders. All nine genes were expressed in the olfactory-functional leg I, with NcNPC2-5, NcNPC2-6, and NcNPC2-8 showing higher expression levels in leg I. After excision of leg I or both leg I and the gnathosoma, the expression level of NcNPC2-5, NcNPC2-6, NcNPC2-7, NcNPC2-8, and NcNPC2-9 significantly decreased compared with that in leg I. Next, RNA interference experiments were performed on NcNPC2‑5, NcNPC2‑6, and NcNPC2‑8. Knockdown of NcNPC2‑6 and NcNPC2‑8 did not significantly affect the attack latency of female N. californicus towards Tetranychus urticae eggs compared with the dsGFP control but did significantly reduce their daily predation rate. In contrast, knockdown of NcNPC2‑5 significantly increased attack latency and reduced daily predation rate. Our results support that NcNPC2-5 is involved in the prey recognition and localization process of N. californicus.