Date of this Version
Tiger beetles are common predators in open habitats throughout the Great Plains, including the eastern salt marshes. Adult tiger beetles are active searchers that attack and eat small insects. By contrast, their larvae are sit-and-wait predators that form permanent burrows and depend on prey moving within striking distance. We hypothesized that adults and larvae of the tiger beetle, Cicindela togata globicollis Casey, would differ in their utilization of lipid (fat) energy reserves, such as fatty acids, based on differences in the likelihood of starvation. To investigate this, we determined the fatty acid profiles from larvae and adult tiger beetles. We found that normally-feeding adults and larvae did not differ substantially in their fatty acid profiles. But, after fasting for a two-week period, larvae selectively used their lipid reserves while adults did not. Moreover, in contrast to all other insect species studied, we found that larval tiger beetles were not able to biosynthesize fatty acids from acetate. Our findings suggest that larvae optimize the use of fatty acids to allow for a lengthy larval developmental period in environments, such as the Great Plains, that provide unreliable and unpredictable food resources.