Impact of age, sex, and size on the thermal tolerance of the adult black soldier fly (Diptera: Strat

Abstract

Thermal stresses from both environmental conditions and organismal crowding are common in mass production of the black soldier fly, Hermetia illucens L. (Diptera: Stratiomyidae). In this study, upper and lower critical thermal (CT) limits (i.e. knockdown CT_max and CT_min) for the adult black soldier fly were determined. Impacts of size, age, and sex on these critical temperatures were also assessed. The CT_max ranged from 45.0-51.0 °C with larger and older adults having a ~1 °C higher CT_max than smaller and younger adults. However, no differences in the CT_max were found between sexes, regardless of age or size. The CT_min ranged from 8.0 to 13.0 °C with larger and older females having a ~1 °C higher CT_min than males and smaller or younger females. While reporting the upper and lower critical temperatures, this study also revealed the thermal breadth (i.e. the range of body temperatures over which organisms can locomote) for adult black soldier flies across age, sex, and size. Based on these data, and when recognising not all fly populations are the same, mass-rearing facilities should determine the CT_max and CT_min for their fly population in order to optimise mating and fertile egg production, and ultimately maximise profits and sales. One degree of temperature can be the difference between success and failure in industrialised facilities.

Keywords: Hermetia illucens, thermal ecology, critical temperatures, mass production