Injury to cotton by adult Lygus hesperus (Hemiptera: Miridae) of different gender and reproductive states

Authors: Cooper, William - Rodney; Spurgeon, Dale

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/30/2012
Publication Date: 4/1/2012
Citation: Cooper, W.R., Spurgeon, D.W. 2012. Injury to cotton by adult Lygus hesperus (Hemiptera: Miridae) of different gender and reproductive states. Environ. Entomol. 41:342-348.

Interpretive Summary: The Western tarnished plant bug is an important pest of cotton in the western United States. Feeding by plant bugs causes floral buds (squares) and fruit (bolls) to drop from the plants. In recent studies, we determined that prereproductive adult plant bugs fed more than did unmated or mated reproductive adults. We compared within-plant distributions of adult plant bugs that were prereproductive, reproductive and unmated, or reproductive and mated. Prereproductive adults tended to be located on plant tissues that are susceptible to bug feeding injury (squares, axillary buds, and terminals) whereas both mated and unmated reproductive adults tended to be located on plant tissues that are not harmed by bug feeding (leaves and stems). We also compared levels of feeding injury to cotton plants caused by adult plant bugs of different reproductive states. Compared to reproductive adults, prereproductive adults injured more squares and caused more squares to drop from the plants. These results are consistent with our previous feeding behavior studies, and demonstrate that adult reproductive state is a source of variation that must be controlled in future studies of interactions between plant bugs and cotton.

Technical Abstract: Lygus hesperus Knight (Hemiptera: Miridae) is a key pest of cotton (Gossypium spp.) in the western United States that injures floral buds (squares) and developing fruit (bolls). However, no clear relationship between Lygus population level and plant injury has been established. Age-dependent feeding activity by L. hesperus is a possible source of variation that has not been examined for its influence in studies of the impact of Lygus on cotton. Recent video-based laboratory studies indicated that feeding behaviors and trivial movement varied among L. hesperus adults of different gender and reproductive states (prereproductive, reproductive and unmated, reproductive and mated). We compared within-plant distributions and accumulations of feeding injury to intact cotton plants corresponding to adult L. hesperus of different gender and reproductive states. Adult females, regardless of reproductive state, were observed on squares and axillary buds more often than were males. Additionally, prereproductive adults were observed on squares and axillary buds more often than were mated or unmated reproductive adults, regardless of gender. Plants that were exposed to prereproductive adults exhibited more abscised squares and more squares with injured anthers compared with plants exposed to reproductive adults. However, feeding injury did not differ by insect mating status or gender. These results are consistent with results of our previous video-based assays, and indicate adult reproductive state represents a source of variation that should be controlled in studies to evaluate Lygus-induced injury to cotton and other crop plants.