The Function of Complexity in the Courtship of the Grasshopper Myrmeleotettix Maculatus

Abstract

Males of the grasshopper Myrmeleotettix maculatus have a courtship which is more complex than that of many other grasshopper species in terms of the number of body parts and different movements involved. The courtship consists of four distinct phases which are described in detail. The female may respond by either ignoring the male, by rejecting him or by calling back. Only females which call back are mated. In laboratory cages where male and female grasshoppers were brought into contact for the first time, 1610 courtship initiations were observed. Only 32% of these proceeded beyond the first phase, and 10% actually reached the last phase of the courtship sequence. Males were often persistent courters with a trend for succeeding courtships to one female to reach the same or a later phase. Females may respond, by calling, at any phase of the male courtship. A male may attempt to mate with a female at any phase of his courtship, but his success is higher if the female has called first. A male will almost always attempt to mate with a female once he has reached the final courtship phase, but he rarely succeeds. These observations are used to examine hypotheses to account for the significance of complexity in the courtship of this species. It is unlikely to serve as a species specific signal, an indicator of male fitness, an advertisement for mates over distance, or a mechanism to prepare males for copulation. Complexity might serve to convert females from a semi-receptive to a fully receptive state. If females could be prepared in this way, it would allow them to continue eating when not being courted. This would be advantageous because it would allow the maximum accumulation of reproductive material in the female. The behaviour might have arisen through sexual selection and have been then given this alternative function. Males of the grasshopper Myrmeleotettix maculatus have a courtship which is more complex than that of many other grasshopper species in terms of the number of body parts and different movements involved. The courtship consists of four distinct phases which are described in detail. The female may respond by either ignoring the male, by rejecting him or by calling back. Only females which call back are mated. In laboratory cages where male and female grasshoppers were brought into contact for the first time, 1610 courtship initiations were observed. Only 32% of these proceeded beyond the first phase, and 10% actually reached the last phase of the courtship sequence. Males were often persistent courters with a trend for succeeding courtships to one female to reach the same or a later phase. Females may respond, by calling, at any phase of the male courtship. A male may attempt to mate with a female at any phase of his courtship, but his success is higher if the female has called first. A male will almost always attempt to mate with a female once he has reached the final courtship phase, but he rarely succeeds. These observations are used to examine hypotheses to account for the significance of complexity in the courtship of this species. It is unlikely to serve as a species specific signal, an indicator of male fitness, an advertisement for mates over distance, or a mechanism to prepare males for copulation. Complexity might serve to convert females from a semi-receptive to a fully receptive state. If females could be prepared in this way, it would allow them to continue eating when not being courted. This would be advantageous because it would allow the maximum accumulation of reproductive material in the female. The behaviour might have arisen through sexual selection and have been then given this alternative function.