Bulletin of Entomological Research最新文献

The fruit fly Ceratitis capitata is a successful generalist due to the trade-off between different variables in its life history traits. The present study aimed to assess some life history traits of C. capitata recovered from peach, plum and fig, three key host species, under the climatic conditions of an irrigation oasis in the arid province of San Juan, Argentina. Pupal abundance, sex ratio and morphometric parameters such as pupal and adult weight, pupal volume, wingspan and head-caudal length were influenced by the host in which the larvae were reared. Sexual maturity, measured as the peak of calling (pheromone emission), was homogeneous on the sixth and seventh days after emergence, but males recovered from fig showed early calling activity on the third day after emergence. The plasticity of C. capitata to adapt its life history traits to specific nutrient variations within the larval environment allows it to colonise and establish populations where key hosts, as those studied here, are available. The knowledge of the interactions between host fruit trees and C. capitata populations provides helpful information for planning the management of local orchards and urban fruit plantations within irrigation oases, taking into consideration the concept of key hosts as peach and fig.

Understanding why animals choose one food over another is one of the key questions underlying the fields of behaviour ecology. This study aims to test if ladybird beetle, Propylea dissecta Mulsant (Coleoptera: Coccinellidae) can forage selectively for nutrients in order to redress specific nutritional imbalances to maximise their fitness. We hypothesised that the presence of more food choices leads to bad decisions in terms of their food selection which ultimately negatively affects the mating and reproductive parameters of P. dissecta. To test this, we first manipulated the predator's nutritional status by rearing them in five separate dietary groups from first instar larvae to newly emerged adult stage. Thereafter, we tested their food choice between five different foods, i.e. Aphis craccivora Koch, Aphis nerii Boyer de Fonsclombe, conspecific eggs, heterospecific eggs and mixed pollen grains, equidistantly placed in a Petri dish. Based on the food choice of the newly emerged adults, they were reared on the chosen diet for 10 days. Thereafter, adults were paired with their opposite sex (collected from stock culture reared on A. craccivora) and mating and reproductive parameters were recorded. Our results suggested that the variety of food did not affect the food choice of ladybird beetle, P. dissecta. They tend to choose their natural diet, i.e. aphid in each dietary regime. We found that previous dietary regime, i.e. larval dietary regime, significantly influences the mating and reproductive parameters of both the male and female except for the time to commence mating by the male. Food choices of adult beetles were found to significantly influence the time to commence mating, average fecundity and per cent egg viability in males and only mating duration in females. Our findings suggest that P. dissecta consistently made optimal decisions when facing various food choices. They consistently preferred their natural and preferred food choice over others, indicating a strong food selection behaviour.

Bagrada bug, Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae), is an invasive pest of cole crops in the United States. Because it also feeds on widespread weeds and persists in natural habitats surrounding crop fields, conventional control strategies are often ineffective at providing long-term control. One egg parasitoid, Gryon aetherium Talamas (Hymenoptera: Scelionidae), is a promising biological control candidate because of its ability to parasitise B. hilaris buried eggs. Recently, adventive populations of G. aetherium were recovered from sentinel eggs in California along with a native egg parasitoid, Ooencyrtus californicus Girault (Hymenoptera: Encyrtidae). A better understanding of these parasitoid species' spatial preference for foraging and their possible competitive interactions will help evaluate their host suppression potential. We compared the foraging abilities of these two parasitoid species for eggs deposited below and above ground. We also investigated the effect of interspecific competition on host suppression and the ability of O. californicus to parasitise eggs previously parasitised by G. aetherium. G. aetherium parasitised naturally and manually buried eggs, whereas O. californicus did not. In another experiment, O. californicus parasitised eggs glued to cards, but not in the presence of sand. Results suggest that G. aetherium may be negatively affected by the presence of O. californicus, and there was a slight but significant reduction in total host mortality when the parasitoids were present together. However, the inability of O. californicus to forage in soil likely limits negative interactions between these two species, and the two parasitoids may ultimately complement each other.

Paranosema locustae is an environmentally friendly parasitic predator with promising applications in locust control. In this study, transcriptome sequencing was conducted on gonadal tissues of Locusta migratoria males and females infected and uninfected with P. locustae at different developmental stages. A total of 18,635 differentially expressed genes (DEGs) were identified in female ovary tissue transcriptomes, with the highest number of DEGs observed at 1 day post-eclosion (7141). In male testis tissue transcriptomes, a total of 32,954 DEGs were identified, with the highest number observed at 9 days post-eclosion (11,245). Venn analysis revealed 25 common DEGs among female groups and 205 common DEGs among male groups. Gene ontology and Kyoto Encyclopaedia of Genes and Genome analyses indicated that DEGs were mainly enriched in basic metabolism such as amino acid metabolism, carbohydrate metabolism, lipid metabolism, and immune response processes. Protein-protein interaction analysis results indicated that L. migratoria regulates the expression of immune- and reproductive-related genes to meet the body's demands in different developmental stages after P. locustae infection. Immune- and reproductive-related genes in L. migratoria gonadal tissue were screened based on database annotation information and relevant literature. Genes such as Tsf, Hex1, Apolp-III, Serpin, Defense, Hsp70, Hsp90, JHBP, JHE, JHEH1, JHAMT, and VgR play important roles in the balance between immune response and reproduction in gonadal tissues. For transcriptome validation, Tsf, Hex1, and ApoLp-III were selected and verified by quantitative real-time polymerase chain reaction (qRT-PCR). Correlation analysis revealed that the qRT-PCR expression patterns were consistent with the RNA-Seq results. These findings contribute to further understanding the interaction mechanisms between locusts and P. locustae.

Spodoptera littoralis (Boisd) (Lepidoptera: Noctuidae) is a highly polyphagous insect that significantly reduces agricultural production of several food staples. We evaluated performance of S. littoralis on several meridic diets based on various maize hybrids, including Oteel, Simon, Valbum, SC703, and SC704. Growth, feeding behaviours, and activity of digestive enzymes of S. littoralis were examined under laboratory conditions. In addition, selected biochemical characteristics of maize hybrid seeds were evaluated, including starch, protein, anthocyanin, as well as phenolic and flavonoid contents, to examine relationships between plant properties and digestive performance of S. littoralis. Performance of S. littoralis on maize hybrids, as measured by nutritional indices, was related to both proteolytic and amylolytic activities quantified using gut extracts. Larval S. littoralis reared on SC703 exhibited the highest efficiency of conversion of digested food, while the lowest was recorded in those fed on the Oteel hybrid. S. littoralis reared on SC703 and Oteel also exhibited the highest and lowest relative growth rates, respectively. The highest levels of proteolytic activity in S. littoralis were measured from larvae reared on the SC703 hybrid, while the lowest levels occurred on the Oteel and Valbum hybrids. Amylolytic activity was lowest in larvae reared on SC703 and Valbum hybrids and highest in larvae reared on the Oteel hybrid. Our results suggest that the SC703 hybrid was the most suitable host for S. littoralis, while the Oteel hybrid demonstrated the greatest level of tolerance against S. littoralis of those evaluated. We discuss the potential utility of maize hybrids exhibiting tolerance traits against this cosmopolitan pest with reference to cultivation of tolerant varieties and identification of specific tolerance traits.

Aphis gossypii is one of the most economically important agricultural pests that cause serious crop losses worldwide, and the indiscriminate chemical application causes resistance development in A. gossypii, a major obstacle to successful control. In this study, we selected the up-regulated expression gene AgJHAMT, which was enriched into juvenile hormone pathway though transcriptome sequencing analysis of the cotton aphids that fed on transgenic cotton lines expressing dsAgCYP6CY3 (the TG cotton). The AgJHAMT gene was overexpressed in cotton aphids which fed on the TG cotton, and its expression profile during the nymphs was clarified. Then, silencing AgJHAMT could advance the developmental period of cotton aphids by 0.5 days compared with control groups. The T and t values of cotton aphids in the dsJHAMT treatment group (6.88 ± 0.15, 1.65 ± 0.06) were significantly shorter than that of the sprayed H₂O control group (7.6 ± 0.14, 1.97 ± 0.09) (P < 0.05), respectively. The fast growth caused by AgJHAMT silencing was rescued by applying the JH analogue, methoprene. Overall, these findings clarified the function of AgJHAMT in the developmental period of A. gossypii. This study contributes to further clarify the molecular mechanisms of delaying the growth and development of cotton aphids by the transgenic cotton lines expressing dsAgCYP6CY3.

Gene expression studies in organisms are often conducted using reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR), and the accuracy of RT-qPCR results relies on the stability of reference genes. We examined ten candidate reference genes in Sclerodermus guani, a parasitoid wasp that is a natural enemy of long-horned beetle pests in forestry, including ACT, EF1α, Hsc70, Hsp70, SRSF7, α-tubulin, RPL7A, 18S, 28S, and SOD1, regarding variable biotic and abiotic factors such as body part, life stage, hormone, diet, and temperature. Data were analysed using four dedicated algorithms (ΔCt, BestKeeper, NormFinder, and geNorm) and one comparative tool (RefFinder). Our results showed that the most stable reference genes were RPL7A and EF1α regarding the body part, SRSF7 and Hsc70 regarding the diet, RPL7A and α-tubulin regarding the hormone, SRSF7 and RPL7A regarding the life stage, and SRSF7 and α-tubulin regarding temperature. To ascertain the applicability of specific reference genes, the expression level of the target gene (ACPase) was estimated regarding the body part using the most stable reference genes, RPL7A and EF1α, and the least stable one, SOD1. The highest expression level of ACPase was observed in the abdomen, and the validity of RPL7A and EF1α was confirmed. This study provides, for the first time, an extensive list of reliable reference genes for molecular biology studies in S. guani.

Drosophila suzukii is a pest of global concern due to its great impact on several crops. The entomopathogenic nematode Steinernema carpocapsae was highly virulent to the larvae of the fly although some immune mechanisms were triggered along the infection course. Thus, to understand the gene activation profile we performed a comparative transcriptome of D. suzukii larvae infected with S. carpocapsae and Xenorhabdus nematophila to map the differentially expressed genes involved in the defence response. The analysis exposed the induction of genes involved in the humoral response such as the antimicrobial peptides and pattern-recognition receptors while there was a suppression of the cellular defence. Besides, genes involved in melanisation, and clot formation were downregulated hindering the encapsulation response and wound healing. After the infection, larvae were in a stress condition with an enrichment of metabolic and transport functionalities. Concerning the stress response, we observed variations of the heat-shock proteins, detoxification, and peroxidase enzymes. These findings set a genetical comprehensive knowledge of the host-pathogen relation of D. suzukii challenged with S. carpocapsae which could support further comparative studies with entomopathogenic nematodes.

Panonychus citri is one of the most destructive pests in citrus orchards, exhibiting varying degrees of tolerance to numerous insecticides, such as spirodiclofen. To effectively manage pests, this study explores the response of P. citri to spirodiclofen stress from the perspectives of life history, enzymatic parameters, and reproduction. The effects of two concentrations (LC₃₀ and LC₅₀) of spirodiclofen on the biological parameters of P. citri were evaluated by the life table method. The results showed that the development duration, fecundity, oviposition days, and lifespan were shortened, though the pre-oviposition period of two treatments was prolonged in comparison with the control. A significant decrease was recorded in the net reproductive rate (R₀) and the mean generation time (T) for the two treatments. Nevertheless, the intrinsic rate of increase (r) and the rate of increase (λ) were not significantly affected in the LC₃₀ treatment, whereas they declined in the LC₅₀ treatment. The enzyme activity assay resulted in higher activities of catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), and carboxylesterase (CarE), among the treatments than the control. In contrast, the treatments recorded lower cytochromeP450 (CYP450) and Glutathione S-transferase (GST) activities than the control. Furthermore, the study detected that relative mRNA expression of Vitellogenin (Vg) and Vitellogenin receptor (VgR) for two treatments were lower than the control. In summary, two concentrations of spirodiclofen inhibited progeny growth and fecundity of P. citri. Additionally, the results of this study may support further research on tolerance of P. citri in response to spirodiclofen stress.