Entomological Research最新文献

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.

Sand flies called Phlebotomus papatasi are the primary vector of cutaneous leishmaniasis, which is an endemic disease in Al-Madinah Al-Munawarah, Saudi Arabia. The molecular characterization of sand fly species is a helpful tool because genetic variability and population structure within and between populations might influence vectoral capability, necessitating the assessment of management strategies to control the spread of cutaneous leishmaniasis. Therefore, in this study, the structure of the P. papatasi population in Al-Madinah region was investigated. The samples of P. papatasi were collected from Al-Madinah region, identified, and subjected to mitochondrial cytochrome b (Cytb) gene sequencing (n = 45). Analysis of the sequences revealed 13 substitutions. There were 12 different haplotypes identified. Nucleotide diversity and haplotype diversity were low estimated to be 0.0017 and 0.574, respectively. The neutrality indices determined using Tajima's D and Fu and Li's F* were all negative and statistically significant. This indicated that the population has an excess of singletons and low-frequency variations. Network analysis showed one main haplotype and shared haplotypes at different nodes. According to this study, the P. papatasi population in the Al-Madinah region is homogeneous. The knowledge obtained in this study contributes to a better understanding of the genetic geographic distribution of P. papatasi populations in relation to the location of Leishmania major foci, which could aid in the development of control strategies.

Mosquitoes act as biological carriers spreading numerous vector borne diseases globally. The present research aimed to study the effect of essential oils (EOs) from Pentanema indicum (L.) Y. Ling and Chromolaena odorata (L.) R.M. King & H. Rob against Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus mosquitoes. Concentrations of 3.125, 6.25, 12.5 25 and 50 ppm were tested for their mosquitocidal properties. The essential oil (EO) from P. indicum demonstrated promising ovicidal activity, achieving 100% efficacy against Ae. aegypti and Cx. quinquefasciatus and 76% efficacy against An. stephensi at a concentration of 50 ppm within 24 h. Similarly, C. odorata exhibited significant activity at higher concentrations, with ovicidal rates of 72% for Ae. aegypti, 79% for An. stephensi and 64% for Cx. quinquefasciatus at 300 ppm after 72 h. In terms of larvicidal activity, P. indicum showed potent toxicity with LC₅₀ values of 4.28 ppm for Ae. aegypti, 14.01 ppm for An. stephensi and 5.47 ppm for Cx. quinquefasciatus. Additionally, C. odorata exhibited considerable mosquito larvicidal activity at higher concentrations, with LC₅₀ values of 95.28 ppm for Ae. aegypti, 98.95 ppm for An. stephensi and 89.05 ppm for Cx. quinquefasciatus after 24 h. However, no significant pupicidal activity was observed for both EOs. GC–MS analysis identified β-Pinene (14.31%), D-Limonene (13.48%) and Caryophyllene (25.48%) as the main components in P. indicum. The EO from C. odorata contained α-Pinene (12.10%), Geijerene (11.62%) and Caryophyllene (10.64%) as the primary components; probably these compounds were responsible for the observed activities. Toxicity studies indicated that the EOs from both plants had no adverse effects on natural predators. The EOs were then formulated for field application and tested in a laboratory setting; they demonstrated promising mosquitocidal activity without harming natural predators. This study suggests that EOs from P. indicum and C. odorata offer an effective alternative to synthetic pesticides.

This study analyzed the biodiversity of entomopathogenic fungi Metarhizium species isolated from Korean soil samples and insect cadavers. Morphological characteristics and molecular phylogenetic analyses were used to analyze Korean species diversity. Concatenated datasets of three genes, the translation elongation factor 1-a (TEF), DNA-directed RNA polymerase II (RPB1), and internal transcribed spacer (ITS), were used for phylogenetic analyses using the following three methods: maximum parsimony (MP), Bayesian inference (BI), and maximum likelihood (ML). In addition, the TEF gene was used for molecular identification. As a result, five species were identified: Metarhizium pinghaense, Metarhizium robertsii, Metarhizium rileyi, Metarhizium pemphigi, and Metarhizium lepidiotae. In particular, M. robertsii and M. lepidiotae were identified in Korea for the first time in this study. The TEF gene was useful for species identification of Metarhizium species especially M. pinghaense and Metarhizium anisopliae. Among these fungi, only M. lepidiotae showed high pathogenicity against cotton aphids (Aphis gossypii) and lesser mealworm (Alphitobius diaperinus).