Attraction of common Australian blowflies to algal affected remains, and the specific effect of algae present in the food substrate on growth and survival of Calliphora stygia

Abstract

ABSTRACT Entomology is a well-established approach for estimating the post-mortem interval (PMI) in terrestrial decomposition, however it is of limited value in aquatic environments due to little research into insect attraction and colonization in aquatic environments. This study aimed to investigate the effect algae in the feeding substrate has on the growth and survival of Calliphora stygia, and on the attraction of a range of common Australian blowfly species. Growth and survival studies were conducted under controlled laboratory conditions, with growth measured through larval length and developmental stage, and survival estimated by percentage of adult eclosion. A walk olfactometer was used to assess attraction to an algal affected substrate, observing that algae was a strong attractant for females of multiple blowfly species. Species of the genus Calliphora had the highest rate of attraction at 95–100%, with Chrysomya rufifacies the lowest at 75%. Both developmental stage and survival of C. stygia were not significantly impacted by the presence of algae. However, larvae fed algae-soaked liver were significantly longer when compared with the controls. This study highlights the potential for skewed PMI estimations in forensic casework where entomologists may rely on larval length for PMI estimations, and the attractive effect of algae on blowflies.