Not All Hypoxia Is the Same: Survival of Immersion Differs from Survival of an Anoxic Atmosphere in Soldier Fly Larvae

Soldier fly (Diptera : Stratiomyidae ) larvae are decomposers that are exposed to severe hypoxia as they develop in manure. They also have great importance in forensic entomology, as they are opportunistic and can be used to determine postmortem interval. However, little is known about how their resistance to severe hypoxia. This study compared survival of larvae of the black soldier fly, Hermetia illucens, exposed to immersion in severely hypoxic water or contained in a pure nitrogen environment at temperatures of 20 °C, 25 °C, 30 °C and 35 °C. The vials were observed for a total of five different times.  Mean time to 50% mortality ranged from 40 hours at 20 °C to 15 hours at 35 °C.  Larvae survived in nitrogen atmospheres longer than in hypoxic water although differences were only significant at 25 °C.  Our results suggest that the atmosphere matters when testing hypoxia survival and that immersion in liquid likely increases metabolism as larvae exclude water from the body cavity.