Entomological Research最新文献

Mosquito-borne diseases remain a significant health concern amidst current microbial outbreaks. Phytochemicals offer environmentally safe, biodegradable, and targeted pest management. Nanostructure lipid carriers (NLCs), a second generation of solid lipid nanoparticles, are gaining attention as potential diagnostic and therapeutic tools. Sesbania leaves, rich in fatty acids, phenolics, and terpenes, were analyzed using gas chromatography–mass spectrometry. Magnetic nanoparticles (Se-NLC-MNPs) modified the surface of Sesbania extract, encapsulated in the NLC. The resulting nanoparticles were 129.2 and 218.5 nm in size, with zeta potentials of −6.20 and 43.9 mV, respectively. Transmission electron microscopy showed spherical and oval shapes. XRD patterns confirmed the successful decoration of the NLC with the magnetic nanoparticles. The Sesbania extract (Se) and its nanoparticle conjugates were tested for larvicidal efficacy against Culex pipiens and Musca domestica larvae, at doses ranging from 50 to 1500 ppm and 0.1 to 5 mg/mL. Se-NLC-MNPs showed higher larval mortality rates compared to their Se formulation extracts, achieving 100% mortality in third-instar larvae. Sesbania methanol extract contained more terpenes, fatty acids, and other organic compounds than the aqueous extract, making it more harmful to insect larvae. In terms of relative toxicity, Se-NLC-MNPs were more effective than Se-NLC. An in vitro cytotoxicity assay against the WI38 cell line indicated the cytotoxicity assay, suggesting the potential for these nanoparticles to develop into high-performance, environmentally acceptable therapeutics for mosquito-borne diseases.

Various miticides are being applied to apiaries to prevent mites. However, abuse of miticides could seriously damage bee health. To understand the physiological response of honey bees caused by inappropriate exposure to miticides, it is necessary to identify the marker genes whose expression alters in honey bees following exposure to miticides. Although quantitative real-time polymerase chain reaction (qRT-PCR) is widely used for gene expression analysis, selecting appropriate stably expressed reference gene(s) across various conditions is essential for accurately determining target gene expression levels. Therefore, this study assessed the expression stabilities of 10 candidate reference genes (RPS5, RPS18, GAPDH, ARF1, RAB1a, PPI, PGK, SDH, TBP, and EF1) using C_q distribution and four algorithm programs (NormFinder, BestKeeper, geNorm, and RefFinder). Subsequently, we validated various normalization methods using each of the 10 reference genes and a combination of multiple genes by calculating the expression of the target gene (SOD2). Based on the various analysis methods used in this study, RPS5 is suggested as the most optimal reference gene for qRT-PCR analysis in honey bees under multiple conditions of miticide exposure.

This study investigates the influence of microenvironmental factors on carcass decomposition and insect colonization, emphasizing the detailed analysis of insect communities. The research involved placing two pig carcasses in contrasting environments: one in a sunlit open field and the other in a shaded forest area. Over 10 days, we observed variations in decomposition rates, with the carcass in the sunlit area decomposing faster than the one in the shade. This research applies Symbolic Aggregate approXimation to transform the daily measurements of carcass weight into symbolic sequences, enabling a comparison of temporal patterns in insect colonization and decomposition dynamics between the environments. Additionally, we utilized alpha and beta diversity assessments to explore the composition and behavior of the insect populations. Our findings revealed dynamic shifts in insect diversity in the sunlit area, marked by a rapid increase followed by a decline, contrasting with steadier, gradual changes in the shaded area. These shifts underscore the sensitivity of insect communities to subtle differences in sunlight and temperature exposure. Our study confirms the significant impact of these environmental factors on both decomposition rates and insect community dynamics, highlighting their potential to refine post-mortem interval estimations in forensic entomology. This enhances our understanding of how environmental conditions directly influence insect colonization, offering valuable insights for forensic applications.

In the web construction of the garden spider, Argiope bruennichi, the decoration known as the stabilimentum forms a zigzag band after completing the orb web. Based on ecological observations, the spider A. bruennichi was observed to consistently maintain an inverted posture on the stabilimentum of the web, with its position consistently fixed on the open side of the web. The stabilimentum of the spider web can be basically divided into a hub region and a band region; the hub region measures approximately 2.5 times the spider's body length, while the band region measures approximately 2.7 times the spider's body length. The hub silk is constructed after the formation of band silk from periphery towards the center, and that the silk in the hub and band regions originate from numerous pairs of aciniform gland spigots on the median and posterior spinnerets. Our fine structural analysis revealed significant differences in the silk morphological properties between stabilimentum band silk in closed and open sides. Particularly, the silks of the stabilimentum were found to be dried fibers less than 500 nm in diameter, devoid of adhesive substances commonly found in prey capture. Moreover, the zigzag band pattern of the stabilimentum silk fibers is expected to play a role in attracting prey animals through light scattering by forming light dispersion at various angles from the light source.

The tribe Gymnopleurini is a well-known group within Scarabaeinae, characterized by its diurnal ball rolling behavior. Although mitochondrial genomes have been reported for numerous Scarabaeinae species, those of Gymnopleurini remain unexplored. In this study, we document for the first time the mitochondrial genome sequences of two ball-rolling dung beetles, Gymnopleurus mopsus (Pallas, 1781) and Gymnopleurus geoffroyi (Fuessly, 1775), from the tribe Gymnopleurini and infer the tribe's position within Scarabaeinae, whose phylogenetic relationships remain largely unresolved. Their mitochondrial genomes are circular DNA molecules, 15,591 and 15,460 bp in size, respectively, and consist of 37 genes, with an identical gene order in Scarabaeinae. Mitochondrial phylogeny, based on the sequences of 13 protein-coding genes (PCGs) from 72 Scarabaeinae species, recovered monophyly of Scarabaeinae and a sister relationship between Gymnopleurus (Gymnopleurini) and Sarophorus. This finding is the first to suggest a potential sister relationship between two groups, but like previous studies, the lack of strong synapomorphic characters implies further phylogenomic analysis is needed to confirm their relationship. Notably, the monophyly of the Onthophagini + Oniticellini lineage was supported, reflecting its biogeographic history and highlighting the need for a taxonomic revision of this species-rich and cosmopolitan group, incorporating additional suprageneric groups. The mitochondrial genome information of two Gymnopleurini species, G. mopsus and G. geoffroyi, not only helps fill the gap in the missing mitochondrial genome data for the Gymnopleurini tribe but also contributes to future conservation efforts by providing insights into the genomic diversity and population structure of these two threatened species.

Various strains of entomopathogenic fungus Metarhizium flavoviride are potential insect control agents. However, there are few systematic studies on their pathogenicity against larvae of pests in the family Scarabaeidae. This study evaluates the pathogenicity of M. flavoviride Ma130821 against larvae of Metabolus flavescens Brenske feeding on maize and tobacco, respectively, and examines the infection process and aspects of the host immunological response. The present results showed that M. flavoviride Ma130821 caused 76.67%–100.00% mortality of M. flavescens larvae within 18 days. When hyphal bodies infected the hemocoel of a host, this strain inhibited the normal protein metabolism through the consumption of protein nutrients and then activated the immunity by increasing the amounts of hemocytes. The infection also initiated the humoral immunity response by increasing the content and enzymatic activity of phenoloxidase (PO). After inoculation, the content and enzymatic activity of PO presented a significant increase and reached the peaks at 72 or 96 h after inoculation (HAI), indicating that immune responses of hemolymph in infected larvae were more intensive at middle/late stage of infection. However, the growth of hyphal bodies was not recognized by the host's immune system as invaders when they reached a high density. The amount of total hemocyte and the content and enzymatic activity of PO all decreased significantly. M. flavoviride Ma130821 appears to affect the larvae's immune system and results in decreased immunity. Our results demonstrate that M. flavoviride Ma130821, with high virulence to larval M. flavescens by immune responses of hemolymph, could be provided efficient entomopathogenic fungi for pest control.

The pin oak (Quercus palustris Münchh.), a species introduced from North America, has recently seen an increase in nationwide planted as ornamental trees, including streets, parks, etc., in South Korea. The aims of this study are to investigate the distributional characteristics of insect communities on pin oaks across different regions with different environments and to describe injury characteristics of major insect pests. From 2022 to 2023, we conducted investigations at 15 locations where pin oak trees were planted. We performed visual inspections on branches and trunks within 5 m height of trees to record insect pest presence and damage characteristics, using pruning poles to sample branches when needed. As a result, various taxa, mainly Lepidoptera, Hemiptera, and Coleoptera, were identified, and densities of pests varied depending on the planted environment. In the central region of South Korea, the predominant or important species were wood-boring insect pests such as clearwing moths (Cossidae) and longhorn beetles (Cerambycidae). In contrast, the southern region exhibited a higher prevalence of folivorous Lepidoptera. Among six different environments, the largest number of pests was found in parks and followed by street, riverside, tree market, etc. These results suggest that pest monitoring and management strategies tailored to specific regions and environments are necessary when planting pin oak trees. In future, pest control in pin oak trees is more challenging based on this study. Consequently, forest pests are causing damage not only to forests but also to street trees in urban areas, highlighting the need for countermeasures.

Coffee grounds, a solid residue left after coffee extraction, are often discarded in landfills or incinerated, posing environmental concerns. To promote sustainability, this study explores the potential use of coffee grounds as a feed source for Tenebrio molitor (TM) larvae. The growth performance, survival rates, and nutritional properties of TM larvae were evaluated using three feed groups: wheat bran, coffee grounds, and a blend of the two. TM larvae (2 g of 3rd instar per group) were randomly assigned to one of three treatments in a completely randomized design: (1) 100 g wheat bran, (2) 100 g of a wheat bran and coffee grounds blend, or (3) 100 g coffee grounds. Results revealed that the blend of wheat bran and coffee grounds yielded the highest growth and survival rates, followed by wheat bran, with coffee grounds alone showing the least favorable outcomes. Nutritional analysis indicated that larvae fed on the blended diet exhibited enhanced crude protein content and reduced crude fat compared to larvae fed on wheat bran or coffee grounds alone. These findings suggest that the blend of wheat bran and coffee grounds serves as a promising feed additive for TM larvae, improving growth, survival, and nutritional quality while supporting the sustainable use of coffee byproducts.

Aedes albopictus overwinters as eggs and lays diapause eggs under conditions of low temperatures, low humidity, and short photoperiods. We compared the hatchability of diapause and nondiapause eggs in response to cold stress. Nondiapause eggs were acquired at 27°C ± 1°C, 70% ± 5% humidity, and 16:8 (L:D) photoperiod, and diapause eggs were acquired at 21°C ± 1°C, 40% ± 5% humidity, and 8:16 (L:D) photoperiod. The obtained eggs were dried under the same conditions and then exposed to low-temperature stress for each temperature and time. After that, eggs were transferred to a thermostat to induce hatching at room temperature, and the hatching rate and the time required for hatching were measured and analyzed by two-way ANOVA and multiple regression analyses. When exposed to low temperatures for 1–24 h at a temperature of 0°C to −10°C, the diapause eggs had a hatching rate higher than that of nondiapause eggs in all sections. The difference in hatching rate according to temperature, exposure time, and diapause status was all considered significant at −6°C or less (two-way ANOVA). A significant regression equation was calculated to estimate the hatching rate, a dependent variable (R² = 0.439, p < 0.000). We found a significant difference in hatching rates for low-temperature stress between diapause eggs and nondiapause eggs of Ae. albopictus, which may explain why Ae. albopictus spreads in high-latitude regions. The morphological differences between diapause and nondiapause and variables such as dryness and light intensity should be studied to understand the overwintering of Ae. albopictus.

The small brown planthopper, Laodelphax striatellus, is a major pest and the primary vector of the rice stripe virus, a harmful pathogen that significantly affects rice production across East Asia. This study aims to investigate the effects of different temperatures (24°C, 27°C, and 30°C) on the developmental period, rice stripe virus infection rates, and virus transmission efficiency of small brown planthopper at various developmental stages. Higher temperatures significantly shortened the developmental period of small brown planthopper. The time from egg to adult was approximately 5 days shorter at 30°C than at 24°C. The rice stripe virus infection rate gradually increased, peaking after the third instar nymph, with no significant differences observed between 24°C and 27°C. However, at 30°C, the infection rates in the second to fifth instar nymphs were lower compared to those at the other temperatures. Tissue-specific analyses indicated that the thorax, midgut, and ovary serve as primary loci for rice stripe virus proliferation. Temperature significantly affects small brown planthopper development and rice stripe virus epidemiology. Accelerated development rates at higher temperatures may result in increased population turnover, whereas reduced rice stripe virus transmission efficiency under these conditions could alter viral spread dynamics. These findings are vital for developing pest management strategies that consider temperature fluctuations and climate change.