The promise of sex…

2006911311.jpg…can be very deceptive.

Phoretic nest parasites use sexual deception to obtain transport to their host’s nest. Leslie S. Saul-Gershenz & Jocelyn G. Millar. Proc. Natl. Acad. Sci. 10.1073/pnas.0603901103

Advance online publication, Sept. 11th, 2006.

Cooperative behaviors are common among social insects such as bees, wasps, ants, and termites, but they have not been reported from insect species that use aggressive mimicry to manipulate and exploit prey or hosts. Here we show that larval aggregations of the blister beetle Meloe franciscanus, which parasitize nests of the solitary bee Habropoda pallida, cooperate to exploit the sexual communication system of their hosts by producing a chemical cue that mimics the sex pheromone of the female bee. Male bees are lured to larval aggregations, and upon contact (pseudocopulation) the beetle larvae attach to the male bees. The larvae transfer to female bees during mating and subsequently are transported to the nests of their hosts. To mimic the chemical and visual signals of female bees effectively, the parasite larvae must cooperate, emphasizing the adaptive value of cooperation between larvae. The aggressive chemical mimicry by the beetle larvae and their subsequent transport to their hosts’ nests by the hosts themselves provide an efficient solution to the problem of locating a critical but scarce resource in a harsh environment.

The short supplemental film below shows a male H. pallida approaching one of two aggregates of beetle larvae on a wooden rod. The bee comes into contact with one of them, falls to the ground under its weight, then flies away with most of the larvae attached to his back. Watch very closely: