Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/7/2010
Publication Date: 4/29/2010
Citation: Cooper, W.R., Spurgeon, D.W. 2010. Use of video assays to assess feeding behavior by Lygus hesperus Knight (Hemiptera: Miridae). National Cotton Council, Memphis, TN. pp. 1306-1311. Interpretive Summary: The western tarnished plant bug is a key cotton pest in the western United States. Feeding by plant bugs injures developing flower buds (squares) and causes them to drop from the plant. However, previous reports indicate that the level of damage caused by plant bugs is often much lower, or higher, than expected based on their numbers. This inconsistency increases the difficulty of making management decisions, and of interpreting results of studies to investigate plant bug damage. A potential explanation for these inconsistencies might be variation in feeding behavior among plant bugs of different life stages or genders. We developed video-based methods to monitor behaviors of individual plant bugs. Using these methods we compared the frequency of movement on or off of cotton squares, and the time spent feeding, by adult plant bugs of different genders and reproductive states (pre-reproductive, reproductive and mated, and reproductive and unmated). Pre-reproductive bugs, regardless of gender, fed for longer intervals and tended to stay on squares longer compared with reproductive bugs. Behaviors of reproductive plant bugs differed between genders, and the effects of mating status were generally opposite for males and females. Unmated reproductive females left squares less frequently and fed for longer intervals compared with mated females. Unmated reproductive males left squares more frequently and fed for shorter intervals compared with mated males. Our results document previously unrecognized sources of variation in adult western tarnished plant bug feeding behavior. This information should prove useful to efforts to develop a better understanding of the damage caused by plant bugs.
Technical Abstract: Lygus hesperus Knight (Hemiptera: Miridae) is a key cotton pest in the western United States that injures and induces abscission of squares and small bolls. Feeding behavior varies among individual lygus, and this variation complicates interpretation of studies to elucidate lygus/cotton interactions. We developed video-based methods to monitor lygus activities and investigate factors that influence feeding behavior. We compared times allocated to feeding and trivial movement between male and female adult lygus of three different reproductive states: pre-reproductive, reproductive and mated, and reproductive and unmated. Pre-reproductive adults spent more time probing/feeding compared to reproductive adults, but there were no differences between genders of pre-reproductive adults. Behaviors of reproductive adults were influenced by both gender and mating status; the effects of mating status on trivial movements and time spent probing were roughly opposite for the two genders. Unmated reproductive females exhibited less trivial movement and fed with longer probing intervals compared to mated females. Conversely, unmated males exhibited more trivial movement and spent less time feeding compared to mated males. Mated females also tended to exhibit more trivial movement than mated males, but their durations of probing were similar. In contrast, reproductive unmated females exhibited less trivial movement and spent more time probing than unmated males. This initial study documents previously unrecognized sources of variation in adult lygus behavior that may prove useful in developing a better understanding of variation in square loss induced by adult lygus.