Evidence for a short-range sex pheromone in female Maladera matrida beetle.

Laboratory studies with live and frozen Maladera matrida female and male beetles showed that males were attracted to chemical substances emanating from the females at dusk. Beetles exhibited sexual activity (including mating) at dusk towards frozen females but not towards frozen males. Frozen females that had been extracted with methanol together with either hexane or dichloromethane or with a mixture of all three solvents did not elicit male sexual activity. Activity was fully restored when a concentrate of the extract was applied to the previously extracted frozen females. Males also responded with vigorous sexual activity to frozen males to which female extract had been applied. Deterrent chemicals appear to be absent from the male body. Males exposed to females that had been frozen during the morning displayed weak sexual activity, indicating that females lack active semiochemicals. Differences between dusk and morning extracts were found with respect to more than 20 compounds, some of which were present in much higher concentrations at dusk than in the morning, while others were not detected in the morning extract. The active component(s) of the short-range sex pheromone of female M. matrida is (are) presumably to be found among these compounds.