Feeding Injury to Cotton Caused by Lygus hesperus Adults of Different Reproductive States

Lygus hesperus is a key pest of cotton in the western United States.  Injury caused by lygus is highly variable, and there is no clear relationship between lygus population levels and plant injury despite decades of research.  A likely explanation for the high variation in previous studies is failure to explicitly account for important sources of biological variation.  Recent behavior studies indicated that feeding behaviors and trivial movements differed among adult lygus of different reproductive states (pre-reproductive, reproductive and unmated, and reproductive and mated).  Specifically, pre-reproductive adults exhibited less trivial movement and fed more compared with mated and unmated reproductive adults.  Using greenhouse assays, we assessed the feeding injury to cotton plants caused by lygus adults of different genders and reproductive states.  Cotton plants were grown in single rows within 680-l planters (blocks) and experimental plants selected at the ‘matchhead’ square stage.  Genders were assigned to blocks, and reproductive states assigned to plants within blocks.  Plants were enclosed within acrylic/mesh cages and infested with 1 bug/plant.  Lygus were removed from the cages after 1 wk, and feeding damage to plants was assessed 1 wk after the removal of lygus.  Feeding injury was evaluated by counting the number of missing positions and squares with discolored and shriveled anthers.  Pre-reproductive adults caused significantly more damage to cotton plants compared to reproductive adults.  Results from these assays indicate that variations in feeding behaviors reflect variations in injury caused by lygus adults of different reproductive states.