Project description:The whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), and the viruses it transmits, are a major constraint to vegetable crops, worldwide. Although the whitefly is usually controlled using chemical pesticides, biological control agents constitute an important component in integrated pest management programs. One of these agents is the wasp Eretmocerus mundus (Mercet) (Hymenoptera: Aphelinidae). E. mundus lays its egg on the leaf underneath the pupa of B. tabaci. First instars of the wasp hatch and penetrate the whitefly larvae. Initiation of parasitization induces the host to form a cellular capsule around the parasitoid. Around this capsule, epidermal cells multiply and thick layers of cuticle are deposited. The physiological and molecular processes underlying B. tabaci-E. mundus interactions have not been investigated so far. We have used a cDNA microarray containing 6,000 expressed sequence tags (ESTs) from the whitefly genome to study the parasitoid-whitefly interaction. We compared RNA samples collected across two time points of the parasitization process: when the parasitoid first instar started the penetration process and once it had fully penetrated the host. The results clearly indicated that genes known to be part of the defense pathways described in other insects are also involved in the response of B. tabaci to parasitization by E. mundus. Some of the responses observed included the repression of a serine protease inhibitor (serpin) and the induction of a melanization cascade. A second set of genes that strongly responded to parasitization included bacterial genes encoded by whitefly symbionts. Quantitative real-time PCR and FISH analyses showed that proliferation of Rickettsia, a facultative secondary symbiont, was strongly induced following the initiation of the parasitization process, a result that supported previous reports suggesting that endosymbionts may be involved in the insect host resistance to various environmental stresses. This is the first study examining the transcriptional response of a hemipteran insect to the attack of a biological control agent (Hymenopterous parasitoid), using a new genomic approach developed for this insect pest. The defense response in B. tabaci seems to resemble that of model organisms such as Drosophila melanogaster. Moreover, endosymbionts of B. tabaci seem to play a role in the response to parasitization, and this is supported by previously published results from aphids. Keywords: time course
Project description:To investigated the stage-specific gene expression response to thiamethoxam in the Bemisia tabaci, we have designed the Agilent eArray platform to identify stage-regulated gene expression towards thiamethoxam exposure. All the B biotype Bemisia tabaci were maintained on cabbage. Thiamethoxam susceptible (TH-S) was cultured without exposure to any chemical insecticides, Thiamethoxam resistance (TH-R) strain exhibited >70-fold resistance to thiamethoxam in comparision to the TH-S strain. Eggs were incubated in 24hours collected as one sample. The fourth nymphs were collected as another sample. The one-day-old unmated adult females were collected as the third samples. Both of the samples were collected from the TH-R, TH-S strains, respectively
Project description:We investigated the transcriptional response to thiamethoxam in the Bemisia tabaci using Illumina sequencing technology. A total of 1,338 genes were differently expressed in the thiamethoxam-resistant whiteflies.
Project description:The saliva from Bemisia tabaci (MED biotype) adults was collected using an artificial feeding system and analyzed using an LC-MS/MS proteomics analysis.
Project description:To investigated the stage-specific gene expression response to thiamethoxam in the Bemisia tabaci, we have designed the Agilent eArray platform to identify stage-regulated gene expression towards thiamethoxam exposure.