Project Summaries

12-373  Project Manager: P. F. O'Leary


Colin S. Brent, USDA-ARS

This project examined how the western tarnished plant bug, Lygus hesperus, is able to cope with the extreme environmental conditions of the southwestern United States, particularly heat. Relatively little is known about the thermal sensitivity of Lygus and even less is known about the means by which they overcome such environmental challenges. The first step in the research was to determine the overall genetic composition of this species. While producing a full genome would have been cost prohibitive, we were able to generate a transcriptome for adult L. hesperus that identifies the set of genes that are being actively expressed throughout the entire body. The information for almost 20,000 previously unidentified Lygus genes provided by the transcriptome will serve as an important tool for all future research in the molecular biology of this and related species.

The next step in our research was to determine which genes might be responsible for coordinating a response to temperature stress. By identifying genes with key roles in survival, we can promote the development of novel and highly targeted control approaches. We measured changes in gene activity in mature adults after they were exposed to several hours of very low or very high temperatures. The results indicated that a number of genes similar to those known to play a role in the heat stress response of other insects were being turned on or off depending on the conditions experienced. These results suggest that these genes play an important part in temperature tolerance. We are currently verifying these results and determining where in the body these genes are expressed to determine their specific function. This information will be compared to ongoing research on behavioral and physiological responses to temperature stress so that we have a more complete understanding of how Lygus can cope with inhospitable environments.

Currently, we are testing whether rearing environment can precondition an individual for surviving temperature extremes or if instead their response remains highly flexible. Groups of L. hesperus were reared either under cool or warm environments, as would be found in different geographic regions or during different seasons. Gene expression information has been collected and is being analyzed. The results will clarify which genes are responding, the conditions to which they are responding (cold vs. heat), and whether their responses are affected by the conditions in which a lygus bug matures.


Project Year: 2012

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