Edible love gifts may influence female behaviour
Male crickets offer nuptial gifts to their mating partners which may alter the females’ reproductive physiology and make them less likely to mate with other males
Many insects mate by transferring their sperm in a capsule, or ampulla. In decorated crickets, Gryllodes sigillatus, an additional edible present, a spermatophylax known as a nuptial gift, is offered to the female during mating in the form of a large gelatinous ball of protein attached to the ampulla which the female eats while the sperm are being transferred. The scientists believe that some of the proteins contained in the nuptial gift prevent digestive enzymes in the female’s gut from breaking down other active proteins in the gift. These protected proteins may then alter her reproductive physiology and make her less likely to mate with further males.
Yannick Pauchet from the Max Planck Institute for Chemical Ecology explained: “It has long been thought that these edible love gifts were packed with feeding stimulants making them appealing to the female. However, our study revealed that these gifts are also composed of proteins which function to feed the female but which may also have an effect on her behaviour.”
The researchers analyzed the proteins contained in the nuptial gift to determine their molecular structure and function. They found that not only are some of the proteins protected from being broken down by enzymes, but they bear a striking resemblance to growth factor proteins known to exist in other insects. This similarity suggests that the proteins could promote cell growth and development in target tissue within the female’s body and as a result influence female reproductive behavior.
“Our analysis of the composition of the Gryllodes sigillatus spermatophylax proteome represents a milestone in our understanding of the evolution of nuptial food gifts in insects and opens up exciting new research avenues,” Yannick Pauchet said.
Nuptial gifts occur in several insect species in various forms including nicely wrapped dead bugs collected by males, various body secretions, body parts or even the male’s entire body. In the decorated cricket, the female detaches the gelatinous nuptial gift, which is made by the male, from the sperm capsule and feasts during sperm transfer. When she has finished eating the gift she then consumes the sperm capsule itself and in doing so terminates sperm transfer.
There is a direct correlation between the time needed for a female to consume the nuptial gift and the time required for complete transfer of sperm from the ampulla to the female’s sperm storage organ. The larger the gift, the longer the ampulla attachment time and so the greater the male’s chance of paternity.
Future research will investigate the exact role that the proteins in the nuptial gift may play in altering the reproductive physiology of the female decorated cricket. More work is needed to determine whether the nutritional composition of the gift could make her less receptive to further matings or could in some way ensure that fertilization occurs.