Sex and dung and phenoloxidase: Resource allocation, reproduction and immunity in scarab beetles

Because they develop in discrete balls of food provided by their mothers, dung beetles are excellent model systems for investigating how animals parcel out the resources available to them. The brood ball can be manipulated so that the larva gets more or less food than its mother intended, and adult reproductive allocation can also be quantified by measuring how many brood balls a female makes and how large they are. Many species of dung beetle are also strongly sexually selected, with horned males who fight for access to females. I will review a series of experiments we have carried out using the South African species Euoniticellus intermedius to ask questions about the evolutionary ecology of insect immunity, concentrating on how females should change their reproductive investment after an immune challenge and how resource availability, horn length and immunity interact in males.