M Burns1, D Herrera2, T Brosius2, T J Muir2. 1. Department of Biology, Augustana College IL, Rock Island, IL; Department of Biology, Miami University, Oxford, OH, USA. burnsmp3@miamioh.edu. 2. Department of Biology, Augustana College IL, Rock Island, IL, USA.
Abstract
BACKGROUND: Tiger beetles are a widely distributed group including species that may be exposed to sub-freezing temperature overwinter. Despite being well studied, little is known about tiger beetle cold tolerance. OBJECTIVE: We investigated seasonal changes in cold hardiness of two northerly distributed tiger beetle species (Cicindela repanda and Cicindela limbalis). MATERIALS AND METHODS: We monitored the supercooling point (SCP), glycerol concentration, and hemolymph osmolality of adult tiger beetles during a 3.5-month acclimation to winter. RESULTS: SCP decreased during winter acclimation for C. repanda, but not for C. limbalis. Both species modestly increased glycerol concentration, and C. repanda increased hemolymph osmolality by 38%. CONCLUSION: This initial investigation into the cold-hardiness of adult tiger beetles suggests that they are capable of lowering their SCP as winter approaches, which may help them survive sub-freezing winter temperatures. Further assessment of their chill and freeze tolerance and of their overwintering conditions in the field is needed to better understand their winter physiology.
BACKGROUND:Tiger beetles are a widely distributed group including species that may be exposed to sub-freezing temperature overwinter. Despite being well studied, little is known about tiger beetle cold tolerance. OBJECTIVE: We investigated seasonal changes in cold hardiness of two northerly distributed tiger beetle species (Cicindela repanda and Cicindela limbalis). MATERIALS AND METHODS: We monitored the supercooling point (SCP), glycerol concentration, and hemolymph osmolality of adult tiger beetles during a 3.5-month acclimation to winter. RESULTS: SCP decreased during winter acclimation for C. repanda, but not for C. limbalis. Both species modestly increased glycerol concentration, and C. repanda increased hemolymph osmolality by 38%. CONCLUSION: This initial investigation into the cold-hardiness of adult tiger beetles suggests that they are capable of lowering their SCP as winter approaches, which may help them survive sub-freezing winter temperatures. Further assessment of their chill and freeze tolerance and of their overwintering conditions in the field is needed to better understand their winter physiology.