If parasitism results in an increased metabolic burden on the beetle host, then the beetle could easily compensate by increasing its food intake. Thus, we hypothesize that infected beetles of both sexes will increase their food intake while their body weights will either decrease or remain the same. We compared beetle weight change and food intake of infected and uninfected beetles over 16 days to ascertain the degree and direction of pathology in male and female beetles. A pellet of dry, rodent chow was weighed and placed in the vial with the beetle. After 24 hours, each beetle and food pellet was re-weighed and the amount of frass present in the vial was counted.
Results show that the two sexes respond differently to infection.
Infected female beetles consumed more food and gained more weight than uninfected females. There was no difference in beetle weight or food consumption between infected and uninfected male beetles. The metabolic drain on resources involved in egg production and the difference in hormone levels are discussed as possible explanations for the differential response between the two sexes. This study illustrates the importance of sex specific studies when examining the pathological effects of parasitism and points to further, more comprehensive studies involving both nutrition and reproduction in the assessment of pathology.