Sweepnet Captures of Lygus hesperus (Hemiptera: Miridae) Adult Genders and Age-Classes in Cotton

Abstract

Management of the western tarnished plant bug, Lygus hesperus Knight, in cotton usually relies on population estimates obtained using the sweepnet. Recent studies indicated adult L. hesperus gender and physiological age influence feeding behavior, within-plant distribution, and injury to cotton. Whether these differences in behavior also influence capture by the sweepnet is not known. We evaluated the sweepnet for sampling L. hesperus adults of known gender and age class in Pima and Acala Upland cotton. Adults of 4 classes (females, prereproductive or reproductive; males, prereproductive or reproductive) marked with fingernail polish to prevent flight were released into assigned sample rows. Captures of marked adults declined seasonally in all experiments. In Pima cotton, the sweepnet was least effective for sampling prereproductive female L. hesperus, and most effective for collecting reproductive males. Captures of reproductive females and prereproductive males were intermediate. We suggest the influence of adult gender and age class on sweepnet captures in Pima cotton corresponds to a propensity for prereproductive adults to reside within plant terminals substantially shielded by foliage. Similar differences in Upland cotton were not observed, probably because the comparatively open structure of the Upland terminal minimized the effects of gender and age class on collection efficiency. Finally, dissection of native L. hesperus indicated an age structure dominated by reproductive maturity. Therefore, future mark-release-recapture studies of factors influencing sweepnet sampling for L. hesperus adults in cotton may maximize relevance by focusing on reproductively mature adults.