Intrasexual mounting in the beetle Diaprepes abbreviatus (L.)

The weevil Diaprepes abbreviatus shows three kinds of same-sex mountings: m ales mount other unpaired males, males mount males already engaged in copul ation and females mount other females. Four hypotheses were evaluated in or der to explain same-sex matings by males: ii) female mimicry by inferior ma les, iii) dominance of larger males which affects the behaviour of small ma les, (iii) sperm transfer in which smaller males gain some reproductive suc cess by 'hitchhiking' their sperm with the sperm of larger males, and (iv) poor sex recognition. Data from mate choice and sperm competition experimen ts rejected the female mimicry, dominance and sperm transfer hypotheses and supported the poor sex recognition hypothesis. Mic tested three hypotheses in order to explain female mounting behaviour: ii) females mimic male beha viour in order to reduce sexual harassment by males, (ii) females mount oth er females in order to appear larger and thereby attract more and larger ma les for mating, and (iii) female mimicry of males. The results of our mate choice experiments suggested that the female mimicry of males hypothesis be st explains the observed female mounting behaviour. This result is also con sistent with the poor sex recognition hypothesis which is the most likely e xplanation for male and female intrasexual mating behaviour in many insect species.