Project description:The role of plant-derived food sources in plant-herbivore-carnivore interactions is an essential topic in basic ecology, and it is directly linked to the applied discipline of biological pest control. Honeydew, which phloem-feeding hemipteran insects excrete, constitutes a rich source of carbohydrates and proteins for beneficial insects in ecosystems. However, the quality of this plant-derived food source depends on its composition. Here we demonstrated that plant proteins in honeydew increase the fitness of a parasitic wasp (member of the third-trophic level).
Project description:In this study, NanoString technology gene expression quantification platform was used to study the expression of toxin genes causing infections from Bacteria (Photorhabdus and Xenorhabdus), Nematode (H.indica, S.riobrave , S.carpocapsae) specific genes for detection and Immune related genes from the infected insects (Spodoptera frugiperda and Galleria mellonella). The study revealed the expression of different immune related genes from the infected insects (Spodoptera frugiperda and Galleria mellonella) and helped in understanding the trend of expression of gene in the samples from the healthy condition to the death stage. Variations in gene expression were seen as per the expectation.
Project description:Certain phytophagous insects can induce leaf curling in their host plants that may provide protected and nutrient-rich habitats. However, the mechanisms of this induction remain poorly understood. The cassava mealybug, Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae), is a serious pest of the cassava and causes leaf curling. To reveal the mechanisms of leaf-curl induction, we first inoculated varying numbers of mealybugs in different locations, namely, the apical meristem and the stem, on cassava seedlings. Second, we performed transcriptome analysis using the total RNA extracted from leaves. The results showed that a single insect was able to induce leaf curling, but the intensity and frequency of the leaf curling were positively correlated with the number of insects. Furthermore, the leaf curling occurred when the mealybugs fed on or close to the apical meristem but not when they fed on the stem. Transcriptome analysis identified a total of 3,931 differentially expressed genes (DEGs) from intact plants and the plants inoculated with mealybugs at different time points. GO analysis of the biological processes revealed that the DEGs contained a series of factors for leaf development of the adaxial–abaxial axis, and auxin biosynthesis and polarity. This suggests that alterations in these functions may cause leaf curling.
Project description:Despite considerable speculation for the role of cytosine (DNA) methylation in biological and molecular processes in insects, direct functional tests are lacking. Here we provide evidence for the functional role of the maintenance DNA methyltransferase 1 (Dnmt1) in an insect using experimental manipulation. Through RNA interference (RNAi) we successfully post-transcriptionally knocked down Dnmt1 in ovarian tissue of the hemipteran Oncopeltus fasciatus (the large milkweed bug). Individuals depleted for dnmt1, and subsequently DNA methylation, failed to reproduce. Manipulating the levels of DNA methylation did not result in changes in overall gene expression. Furthermore, reductions in levels of DNA methylation at transposable elements (TEs) did not lead to large-scale reactivation of TE transcription. Despite the lack of a causal relationship between reduced DNA methylation and gene expression in the tissue we surveyed, eggs were inviable revealing an important function of DNA methylation in O. fasciatus. Our work provides direct experimental evidence for a functional role of Dnmt1 and DNA methylation in insects and presents O. fasciatus as a tractable model for further exploration of the function of DNA methylation in other tissues and life history circumstances for insects.
