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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.

The defensive characteristics of the sawflies have received special attention due to the involvement of toxic compounds obtained from host plants. In this context, the haemolymph-based defense is one of the strategies known in sawflies to dissuade the attack of predators. Aneugmenus merida is a neotropical sawfly whose larvae are herbivorous on the toxic bracken fern Pteridium spp. The present study examines the defensive properties of the A. merida larval haemolymph and its possible link with the chemistry of its host plant. We report the behavior of the solitary hunter ant Odontomachus chelifer towards A. merida larvae under laboratory conditions. In addition, we studied the liquid intake behavior of the ants provided with solutions of crude haemolymph, bracken extracts, and its fractions. A. merida larvae showed a marked defensive capacity against the ants. The inhibition of the attack was observed during the stages of antennal contact and mandibular blow, suggesting that larval defensive capacity is due to factors present in the integument and haemolymph. Aqueous and methanolic fractions of haemolymph and bracken also deterred feeding. Although some common compounds were detected in the haemolymph and bracken fractions, they were in very small quantities, suggesting that they are not responsible for the bioactivity. Therefore, the hypothetical connection between the host plant chemistry and larval defensive capacity could not be evidenced. We suggest that the deterrent compounds present in the haemolymph and integument could be jointly acting in the sawfly’s defensive strategy.

Resin bugs are a group of reduviids which collect viscous substances from plants with their legs and use them as an aid in prey capture and to protect eggs against predators. We designed the present investigation to examine aspects of the natural history and biology of Heniartes stali (Wygodzinsky) in association with Rubus cf. adenotrichos (Schltdl.), an Andean wild blackberry covered with trichomes that secrete a sticky fluid. We surveyed the occupancy of this plant by the bugs in five localities in the Venezuelan Andes and the sticky material source was determined. Nymphs, and in minor proportion, adults were frequently found on the blackberry plants. We also document the harvesting and handling of this exudate by H. stali under laboratory conditions. The bugs invested several hours to gather the sticky material using the forelegs, transferred it to the midlegs, and subsequently stored it in a conspicuously hairy area of the hindlegs. Portions of the accumulated material were smeared on the genital are...