Changes in the Foraging Behavior, Within-Plant Vertical Distribution, and Microhabitat Selection of a Generalist Insect Predator: an Age Analysis

Abstract

The foraging behavior, within-plant vertical distribution, and microhabitat selection of 2nd instars and adults of Zelus renardii Kolenati were studied in an organic cotton field. In total, 47 individuals (21 nymphs and 26 adults) were observed foraging freely in the field for a total of 94 h. Both developmental stages of Z. renardii consumed a wide variety of arthropods including herbivores and predators, but predatory insects comprised a greater fraction of the prey of adults compared with nymphs. Adult Z. renardii also fed on larger prey compared with nymphs. Z. renardii recognized most prey from a distance, and the majority of the prey were moving when they were attacked, suggesting that this predator reacts strongly to visual stimuli. Nymphs and adults also were observed feeding on extrafloral nectaries located on the bottom of leaves and at the base of fruiting structures, Activity budgets of nymphs and adults were similar, implying no gross changes in their foraging strategies; however, nymphs spent most of their time in the lower plant strata; the adults, in contrast, foraged primarily in the upper canopy. Nymphs also spent more time on the undersurface of leaves and less time on the petioles and stems compared with the adults. These changes in within-plant vertical distribution and microhabitat selection may influence the prey encounter rates and therefore the diet composition of nymphal and adult Z. renardii .