Bite force, body size, and octopamine mediate mating interactions in the house cricket (Acheta domesticus)

Abstract

Abstract Mating interactions are rife with conflict because the evolutionary interests of males and females seldom coincide. Intersexual conflict affects sexual selection, yet the proximate factors underlying male coercive ability and female resistance are poorly understood. Male combat outcomes are often influenced by bite force, with superior biters being more likely to achieve victory over poorer biters in a range of species, including crickets. If good performers also achieve mating success through sexual coercion, then bite force might play a role in intersexual conflict as well. We tested the capacity of bite force to influence mating interactions in house crickets both directly by measuring bite forces of males and females and by altering male bite capacity through neuropharmacological manipulation. In addition, the invertebrate neurotransmitter octopamine both mediates aggression and underlies motivation to bite in male house crickets. By blocking octopamine receptors through the application of an antagonist, epinastine, we tested the effects of reduced bite force on male mating success. Our results show that male bite capacity, in combination with body size, influences both the likelihood and the outcomes of mating interactions, whereas treatment of males with epinastine eliminates motivation to mate. Our results suggest a functional role for bite force in affecting both sexual conflict and sexual selection and expand our knowledge of the influence of biogenic amines on reproductive behaviour. Abstract Animal functional capacities are relevant to sexual conflict, just as they are to sexual selection. Males orally supplemented with a synthetic neurohormone blocker, epinastine did not successfully mate with females. Control group males were more likely to have successfully mated with females at higher ratios, take a shorter amount of time to initiate mating and have longer spermatophore attachment times to females when they: Had higher bite force measurement than females.Were larger than females.These findings suggest that selection might act on such capacities in both males and females in A. domesticus, not only males.