Thermogenesis in the Southern Masked Chafer, Cyclocephala signaticollis.

ZERMOGLIO, P.F.; CASTELO, M.K.; LAZZARI, C.R.

York

Congreso; 10th European Congress of Entomology; 2014

Royal Entomological Society

P { margin-bottom: 0.21cm; direction: ltr; color: rgb(0, 0, 0); widows: 2; orphans: 2; } Temperature constitutes a main factor affecting the life of insects. Despite their poikilothermic nature, some insects are able of partially regulating their body temperature. The occurrence of thermogenesis has been reported in scarab beetles associated with flight, but also with other activities or even rest. While keeping a higher body temperature in cold environments has a direct effect on the individual performance, its energetic cost is high. So, the advantages of such an increment on temperate species remain unclear. We investigated the occurrence of thermogenesis in a temperate scarab, Cyclocephala signaticollis, an agricultural pest in American grasslands. Thermographic images were taken from adult beetles subjected to 12h:12h L/D or constant darkness regimes and the temperatures of the head, thorax and abdomen were measured along several days. Beetles exposed to 12h:12h L/D regime showed marked cycles of endothermy, warming up their thorax during the early night. This increase reached up to 11.8 °C over the ambient, producing a marked heterothermy. Beetles exposed to constant darkness regime, although they remained active, ceased to exhibit thermogenesis after the first night of experimentation. These results unravel the existence of a thermogenesis rhythm that is exogenously regulated by light in a temperate scarab species. P { margin-bottom: 0.21cm; direction: ltr; color: rgb(0, 0, 0); widows: 2; orphans: 2; Temperature constitutes a main factor affecting the life of insects. Despite their poikilothermic nature, some insects are able of partially regulating their body temperature. The occurrence of thermogenesis has been reported in scarab beetles associated with flight, but also with other activities or even rest. While keeping a higher body temperature in cold environments has a direct effect on the individual performance, its energetic cost is high. So, the advantages of such an increment on temperate species remain unclear. We investigated the occurrence of thermogenesis in a temperate scarab, Cyclocephala signaticollis, an agricultural pest in American grasslands. Thermographic images were taken from adult beetles subjected to 12h:12h L/D or constant darkness regimes and the temperatures of the head, thorax and abdomen were measured along several days. Beetles exposed to 12h:12h L/D regime showed marked cycles of endothermy, warming up their thorax during the early night. This increase reached up to 11.8 °C over the ambient, producing a marked heterothermy. Beetles exposed to constant darkness regime, although they remained active, ceased to exhibit thermogenesis after the first night of experimentation. These results unravel the existence of a thermogenesis rhythm that is exogenously regulated by light in a temperate scarab species.