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Title: Parasitization by Cotesia chilonis influences gene expression in fatbody and hemocytes of Chilo suppressalis

item WU, SHUN-FAN - Zhejiang University
item SUN, FANG-DA - Zhejiang University
item QI, YI-XIANG - Zhejiang University
item YAO, YAO - Zhejiang University
item FANG, QI - Zhejiang University
item HUANG, JIA - Zhejiang University
item Stanley, David
item YE, GONG-YIN - Zhejiang University

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2013
Publication Date: 9/23/2013
Citation: Wu, S., Sun, F., Qi, Y., Yao, Y., Fang, Q., Huang, J., Stanley, D.W., Ye, G. 2013. Parasitization by Cotesia chilonis influences gene expression in fatbody and hemocytes of Chilo suppressalis. PLoS One. 8(9):e74309.

Interpretive Summary: Long-term agricultural sustainability is severely threatened by widespread use of classical insecticides. Threats include increasing resistance to insecticides and sharply decreasing environmental quality. The concept of biological control of insects is a potentially powerful alternative to classical insecticides. Biological control is based on the idea that direct application of certain insect-specific predators, pathogens and parasites can reduce pest insect populations to a point that the pests exert only negligible economic damage. A major problem, however, is that many insect parasites have a very narrow range of hosts. This limits the usefulness of any given parasite species in biological control programs. In this paper, we examined the relationship of a parasitic insect and its host, a pest insect. We learned that parasitization influences host gene expression, which is essential to the success of the parasite. Scientists who study host/parasite relationships will use this information in future research designed to understand how parasites can be manipulated to broaden the host range of a parasite. Ultimately, this research will benefit growers who produce vegetable crops and the people who consume vegetables.

Technical Abstract: During oviposition many parasitoid wasps inject various factors along with eggs that manipulate the physiology and development of their hosts. These manipulations are thought to benefit the parasites. However, the detailed mechanisms of host-parasitoid interactions are not fully understood. We posed the hypothesis that parasitization by a braconid wasp, Cotesia chilonis, influences gene expression in the fatbody and hemocytes of its host, Chilo suppressalis. We obtained 39,344,452 reads, which we assembled into 146,770 scaffolds, and 76,016 unigenes. Parasitization impacted gene expression in fatbody and hemocyte. Of these, 8096 fatbody and 5743 hemocyte unigenes were down-regulated and 2572 fatbody and 1452 hemocyte unigenes were up-regulated. Gene ontology data showed the majority of the differentially expressed genes are involved in enzyme regulated activity, binding, transcription regulator activity and catalytic activity. qPCR results show that most anti-microbial peptide transcription levels were up-regulated after parasitization. Expression of a methionine-rich storage protein gene and a gene encoding a serine protease inhibitor 7 were up-regulated. The results of this study support our hypothesis that parasitization influences expression of fatbody and hemocyte genes in the host, C. suppressalis. The general view is that manipulation of host metabolism and immunity benefits the development and emergence of the next generation of parasitoids. The accepted beneficial mechanisms include the direct impact of parasitoid venoms and venoms constituents on host tissues (such as cell damage) and, more deeply, the ability of venom constituents to influence gene expression. We infer that insect parasitoids generally manipulate their environments, the internal melieu of their hosts.