Male choice

Summary

Male preference for large females as mates was demonstrated in the wood-boring weevil, Brentus anchorago (Coleoptera: Brentidae) by observation and by mate choice experiments in which the complicating factor of male rivalry was eliminated. Adult weight varied at least 23-fold in a large breeding aggregation in Panama. Drilling females guarded by males were larger than unguarded drilling females, and the number of males attending a drilling female increased with length of the female. Thus despite a sex ratio of about 1:1, males were unevenly distributed among the females. A male attending a female had on average about 1 rival male in his vicinity (Lloyd's Index of Mean Crowding). Male preference for large females in the absence of rival males was directly tested in choice arenas on the surface of the host tree. When a large and a small female were simultaneously presented, large and small males alike mated first with the large female. Male choice of large females is probably adaptive in Brentus anchorago because larger females lay larger eggs, which produce larger offspring in a competitive larval environment. Male choice in this species is associated with high male mating investment and time commitment per female, and not with high male parental investment.