Sticky trap predation in the Neotropical resin bug Heniartes stali (Wygodzinsky) (Hemiptera: Reduviidae: Harpactorinae)

Certain species of assassin bugs have evolved the sticky trap strategy to capture prey using adhesive substances on their legs. The resin bug Heniartes stali collects a sticky exudate from the trichomes of a blackberry plant and smears its legs with it through an intriguing gathering process. We report laboratory experiments aimed at understanding the capture behavior of H. stali when it encountered three insect prey species with different mobility: the coleopteran larvae of Tribolium castaneum, a slow-moving organism; workers of the aggressive and highly mobile ant Camponotus rufipes; and winged prey, the fly Drosophila sp. Bugs stalked prey approaching within reach of their forelegs. After the bug threw forwards its forelegs, the prey became stuck and was subsequently held firmly by clutching with the aid of the middle legs, also smeared with trichome exudate. The bugs took longer to catch ants and immobilize them than larvae. Attacks on flies were unsuccessful because of flight escape before contact with H. stali occurred. A clear association between exudate harvesting and prey-capture behavior was unequivocally demonstrated. This is the first detailed description of a sticky leg trap from harvested plant exudate in Heniartes and related prey-capture behavior.