Author
Submitted to: Journal of Insect Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 11/14/2009 Publication Date: 5/17/2010 Citation: Brent, C.S. 2010. Stage-Specific Effects of Population Density on the Development and Fertility of Lygus hesperus Knight. Journal of Insect Science. 10:49. Interpretive Summary: The Lygus bug is a major pest of cotton and other key economic crops. There is limited knowledge of the environmental factors that affect its growth and development, therefore its sensitivity to high population density was tested in immature and adult stages. Immature bugs reared to adulthood under increasing densities exhibited delays in maturation, heightened mortality, and reductions in body mass and various size parameters. In contrast, reproductive development in both males and females rose with initial density increases. Added food failed to prevent the effects of high density, suggesting that contact frequency rather than competition for limited resources was the primary stress. Unlike nymphs, newly mature adults exposed to increasing population densities did not suffer harmful physiological effects; body mass and egg production were unchanged. However, their rate of survival was much lower than was observed in the immature bugs. Collectively these results indicate that population density can dramatically influence Lygus development, but the specific effects depend on the maturity of the bug. Technical Abstract: The western tarnished plant bug Lygus hesperus Knight, a major pest of cotton and other key economic crops, was tested for its sensitivity to population density during nymph and adult stages. Nymphs reared to adulthood under increasing densities exhibited incremental delays in maturation, heightened mortality rates, and reductions in body mass and various size parameters. In contrast, gonadal activity in both males and females rose with initial density increases. Supplemental nutrients provided to the nymphs failed to offset the negative effects of high density, suggesting that contact frequency, rather than resource partitioning, may be the primary stress. Unlike nymphs, newly eclosed adults exposed to increasing population densities did not suffer negative physiological effects; body mass and patterns of ovipositional activity were unchanged. However, mortality rates increased with population size and to a much greater extent than was observed in nymphs. Collectively these results indicate that population density can dramatically influence Lygus development, but the specific effects are stage-dependent. |