Comparison of feeding behaviors among Lygus hesperus nymphs and adults

Lygus hesperus Knight (Hemiptera: Miridae) is a key pest of cotton (Gossypium spp.) in the western United States that injures floral buds and developing fruit. Levels of lygus-induced damage to cotton can vary among lygus stages or gender, and these variations complicate interpretation of studies to elucidate lygus/cotton interactions. Variations in observed injury may reflect different behaviors among classes of lygus. We used high-definition video to compare the behaviors of male and female L. hesperus of different life-stages: third instars, fifth instars, and pre-reproductive adults. The experimental area for video assays was a 100×15-mm Petri plate, in the center of which an excised floral bud (6-mm diameter) was partially embedded in paraffin. Opposing cameras facilitated the unimpeded observation of feeding behaviors and the mapping of stylet-probes on the surface of the floral bud. Estimates of the numbers of stylet-probes, average stylet-probing interval, and residence time on the floral bud were compared among L. hesperus genders and life stages using a mixed-model full-factorial ANOVA. Logistic regressions were used to make comparisons among L. hesperus genders and life stages of relative frequencies of stylet-probing intervals ≤10 s (test probes), >10 to ≤60 s (salivation probes), or >60s (sustained ingestion), and of stylet-probe locations on the floral bud (anthers, ovary, extrafloral nectaries, and peduncle). This study documents previously unrecognized sources of variation in L. hesperus behavior that may prove useful in developing a better understanding of variation in floral bud abscission induced by L. hesperus feeding.