Effects of relative humidity on egg hatching success of blow flies (Diptera: Calliphoridae)

Abstract

Humidity can influence oviposition decisions by females and the development and survival of offspring. We measured the impact of relative humidity on egg eclosion of three forensically relevant blow fly species: Lucilia sericata (Meigen), Phormia regina (Meigen) and Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae). Egg masses were placed into glass jars lined with filter paper and placed into growth chambers at 25°C with 12:12 L:D, across six levels of relative humidity (30, 40, 50, 60, 70, and 80%). Eggs were observed every six hours for eclosing larvae to measure the effect of humidity on time to egg eclosion. As relative humidity increased, time to eclosion decreased for all three species. Calliphora vicina hatching success was the least affected by humidity, maintaining greater than 60% hatching success even at 30% relative humidity. In contrast, L. sericata required at least 50% relative humidity to have hatching success above 60%. Phormia regina was the most affected by humidity, requiring relative humidity to be above 70% to reach hatching success above 60%. Given the differential effect of relative humidity on egg hatching, these results may have implications for oviposition decisions made by female blow flies.