Insect Science最新文献

Symbiotic microorganisms are essential for the physiological processes of herbivorous pests, including the pear lace bug Stephanitis nashi, which is known for causing extensive damage to garden plants and fruit trees due to its exceptional adaptability to diverse host plants. However, the specific functional effects of the microbiome on the adaptation of S. nashi to its host plants remains unclear. Here, we identified significant microbial changes in S. nashi on 2 different host plants, crabapple and cherry blossom, characterized by the differences in fungal diversity as well as bacterial and fungal community structures, with abundant correlations between bacteria or fungi. Consistent with the microbiome changes, S. nashi that fed on cherry blossom demonstrated decreased metabolites and downregulated key metabolic pathways, such as the arginine and mitogen-activated protein kinase signaling pathway, which were crucial for host plant adaptation. Furthermore, correlation analysis unveiled numerous correlations between differential microorganisms and differential metabolites, which were influenced by the interactions between bacteria or fungi. These differential bacteria, fungi, and associated metabolites may modify the key metabolic pathways in S. nashi, aiding its adaptation to different host plants. These results provide valuable insights into the alteration in microbiome and function of S. nashi adapted to different host plants, contributing to a better understanding of pest invasion and dispersal from a microbial perspective.

Take-off behavior is crucial to the overall success of insect migration. Although most high-altitude migratory flights commence with mass take-offs around dusk and dawn, little is known about nighttime take-off behavior. The take-off behavior of migratory Sogatella furcifera was investigated in field cages from 2017 to 2019. The species showed a bimodal take-off pattern at dusk and dawn on rainless nights, with mass flight at dusk more intense than dawn flight. However, a higher frequency of take-offs during the nighttime was observed on rainy nights, resulting in the absence of dawn take-offs. Most migratory take-off individuals at dusk and dawn landed on the cage top or the walls above 150 cm, while non-migratory individuals that took off during the nighttime due to rainfall mainly landed on the cage walls below 150 cm. Furthermore, it has been observed that migratory take-off individuals possess stronger sustained flight capabilities and exhibit more immature ovaries compared with non-migratory take-offs. These findings advance our understanding of the take-off behavior of S. furcifera and thus provide a basis for the accurate prediction and management of the migratory dynamics of this pest.

Females of many species are polyandrous. However, polyandry can give rise to conflict among individuals within families. We examined the level of polyandry and paternity skew in the common eastern yellowjacket wasp, Vespula maculifrons, in order to gain a greater understanding of conflict in social insects. We collected 10 colonies of V. maculifrons and genotyped workers and prereproductive queens at highly variable microsatellite markers to assign each to a patriline. Genotypic data revealed evidence of significant paternity skew among patrilines. In addition, we found that patrilines contributed differentially to caste production (worker vs. queen), suggesting an important role for reproductive conflict not previously discovered. We also investigated if patterns of paternity skew and mate number varied over time. However, we found no evidence of changes in levels of polyandry when compared to historical data dating back almost 40 years. Finally, we measured a suite of morphological traits in individuals from the most common and least common patrilines in each colony to test if males that showed highly skewed reproductive success also produced offspring that differed in phenotype. Our data revealed weak correlation between paternity skew and morphological phenotype of offspring sired by different males, suggesting no evidence of evolutionary tradeoffs at the level investigated. Overall, this study is the first to report significant paternity and caste-associated skew in V. maculifrons, and to investigate the phenotypic consequences of skew in a social wasp. Our results suggest that polyandry can have important consequences on the genetic and social structure of insect societies.

The fall armyworm (FAW), Spodoptera frugiperda, has colonized and caused consistent damage in the Eastern hemisphere. The identification of various FAW strains is essential for developing precise prevention and control measures. The triosephosphate isomerase (Tpi) gene is recognized as an effective marker closely linked to FAW subpopulations. However, most current studies primarily focus on the comparison of variations in specific gene sites of this gene. In this study, we conducted full-length sequencing of the Tpi genes from 5 representative FAW groups. Our findings revealed that the Tpi genes varied in length from 1220 to 1420 bp, with the primary variation occurring within 4 introns. Notably, the exon lengths remained consistent, at 747 bp, with 37 observed base variations; however, no amino acid variations were detected. Through sequence alignment, we identified 8 stable variation sites that can be used to distinguish FAW strains in the Eastern hemisphere. Additionally, we performed strain identification on 1569 FAW samples collected from 19 provinces in China between 2020 and 2021. The extensive analysis indicated the absence of the rice strain in the samples. Instead, we only detected the presence of the corn strain and the Zambia strain, with the Zambia strain being distributed in a very low proportion (3.44%). Furthermore, the corn strain could be further categorized into 2 subgroups. This comprehensive study provides a valuable reference for enhancing our understanding of FAW population differentiation and for improving monitoring and early warning efforts.

Aggregations of juveniles are dominant forms of social life in some insect groups. Larval societies are shaped by competitive and cooperative interactions of the larvae, in parallel with parental effects. Colonies of necrophagous larvae are excellent systems to study these relationships. Necrodes littoralis (Staphylinidae: Silphinae), a carrion beetle that colonizes cadavers of large vertebrates, forms massive juvenile aggregations. By spreading over carrion anal and oral exudates, the beetles form the feeding matrix, in which the heat is produced and by which adults presumably affect the fitness of the larvae. We predict that exploitative competition shapes the behavior of N. littoralis larvae in their aggregations. However, cooperative interactions may also operate in these systems due mainly to the benefits of collective exodigestion. Moreover, indirect parental effects (i.e., formation of the feeding matrix) probably modulate larval interactions within the aggregations. By manipulating parental effects (present/absent) and larval density (0.02-1.9 larvae/g of meat), we found a strong negative group-size effect on fitness components of N. littoralis, in colonies with parental effects over almost the entire density range, and in colonies without parental effects for densities larger than 0.5 larva/g. This was accompanied by positive group-size effects in terms of development time (it shortened with larval density) and thermogenesis (it increased with larval density). A pronounced positive group-size effect on juvenile fitness was found only in colonies without parental effects and only in the low-density range. These results support the hypothesis that larval societies of N. littoralis are shaped by exploitation competition.

With the increasing development of nanomaterials, the use of nanodiamonds (NDs) has been broadly manifested in many applications. However, their high penetration into the ecosystem indubitably poses remarkable toxicological risks. This paper investigates the toxic effects of NDs on the darkling beetle, Blaps polychresta Forskal, 1775 (Coleoptera: Tenebrionidae). Survival analysis was carried out by monitoring the beetles for 30 d after the injection of four different doses of NDs. A dose of 10.0 mg NDs/g body weight, causing less than 50% mortality effect, was assigned in the analysis of the different organs of studied beetles, including testis, ovary, and midgut. Structural and ultrastructural analyses were followed using light, TEM, and SEM microscopes. In addition, a variety of stress markers and enzyme activities were assessed using spectrophotometric methods. Furthermore, cell viability and DNA damage were evaluated using cytometry and comet assay, respectively. Compared to the control group, the NDs-treated group was exposed to various abnormalities within all the studied organs as follows. Significant disturbances in enzyme activities were accompanied by an apparent dysregulation in the antioxidant system. The flow cytometry results indicated a substantial decrease of viable cells along with a rise of apoptotic and necrotic cells. The comet assay demonstrated a highly increased level of DNA damage. Likewise, histological analyses accentuated the same findings showing remarkable deformities in the studied organs. Prominently, the research findings substantially contribute for the first time to evaluating the critical effects of NDs on B. polychresta, adopted as the bioindicator in this paper.

Changes in diet type and nutrient availability can impose significant environmental stress on organisms, potentially compromising physiological functions and reproductive success. In nature, dramatic fluctuations in dietary resources are often observed and adjustments to restore cellular homeostasis are crucial to survive this type of stress. In this study, we exposed male Drosophila melanogaster to two modulated dietary treatments: one without a fasting period before exposure to a high-fat diet and the other with a 24-h fasting period. We then investigated mitochondrial metabolism and molecular responses to these treatments. Exposure to a high-fat diet without a preceding fasting period resulted in disrupted mitochondrial respiration, notably at the level of complex I. On the other hand, a short fasting period before the high-fat diet maintained mitochondrial respiration. Generally, transcript abundance of genes associated with mitophagy, heat-shock proteins, mitochondrial biogenesis, and nutrient sensing pathways increased either slightly or significantly following a fasting period and remained stable when flies were subsequently put on a high-fat diet, whereas a drastic decrease of almost all transcript abundances was observed for all these pathways when flies were exposed directly to a high-fat diet. Moreover, mitochondrial enzymatic activities showed less variation after the fasting period than the treatment without a fasting period. Overall, our study sheds light on the mechanistic protective effects of fasting prior to a high-fat diet and highlights the metabolic flexibility of Drosophila mitochondria in response to abrupt dietary changes and have implication for adaptation of species to their changing environment.

Under global climate change, high and low temperature extremes can drive shifts in species distributions. Across the range of a species, thermal tolerance is based on acclimatization, plasticity, and may undergo selection, shaping resilience to temperature stress. In this study, we measured variation in cold temperature tolerance of early instar larvae of an invasive forest insect, Lymantria dispar dispar L. (Lepidoptera: Erebidae), using populations sourced from a range of climates within the current introduced range in the Eastern United States. We tested for population differences in chill coma recovery (CCR) by measuring recovery time following a period of exposure to a nonlethal cold temperature in 2 cold exposure experiments. A 3rd experiment quantified growth responses after CCR to evaluate sublethal effects. Our results indicate that cold tolerance is linked to regional climate, with individuals from populations sourced from colder climates recovering faster from chill coma. While this geographic gradient is seen in many species, detecting this pattern is notable for an introduced species founded from a single point-source introduction. We demonstrate that the cold temperatures used in our experiments occur in nature during cold spells after spring egg hatch, but impacts to growth and survival appear low. We expect that population differences in cold temperature performance manifest more from differences in temperature-dependent growth than acute exposure. Evaluating intraspecific variation in cold tolerance increases our understanding of the role of climatic gradients on the physiology of an invasive species, and contributes to tools for predicting further expansion.

The two-spotted spider mite (Tetranychus urticae) is one of the most well-known pesticide-resistant agricultural pests, with resistance often attributed to changes such as target-site mutations and detoxification activation. Recent studies show that pesticide resistance can also be influenced by symbionts, but their involvement in this process in spider mites remains uncertain. Here, we found that infection with Wolbachia, a well-known bacterial reproductive manipulator, significantly increased mite survival after exposure to the insecticides abamectin, cyflumetofen, and pyridaben. Wolbachia-infected (WI) mites showed higher expression of detoxification genes such as P450, glutathione-S-transferase (GST), ABC transporters, and carboxyl/cholinesterases. RNA interference experiments confirmed the role of the two above-mentioned detoxification genes, TuCYP392D2 and TuGSTd05, in pesticide resistance. Increased GST activities were also observed in abamectin-treated WI mites. In addition, when wild populations were treated with abamectin, WI mites generally showed better survival than uninfected mites. However, genetically homogeneous mites with different Wolbachia strains showed similar survival. Finally, abamectin treatment increased Wolbachia abundance without altering the mite's bacterial community. This finding highlights the role of Wolbachia in orchestrating pesticide resistance by modulating host detoxification. By unraveling the intricate interplay between symbionts and pesticide resistance, our study lays the groundwork for pioneering strategies to combat agricultural pests.