Bacterial Interactions with Necrophagous Flies

Animal remains represent ephemeral resources that provide nutrients to a wide range of organisms. On death, vertebrate carrion is immediately colonized with a variety of microorganisms (typically obligate or facultatively anaerobic bacteria from the air, from insects, or from the corpse itself), which produce odors through the breakdown of tissues, the alteration of volatile chemicals present in the environment, or both. Within minutes, certain necrophagous flies are attracted by these chemical signals, resulting in waves of oviposition and larviposition activity. Although there are certainly detrimental (pathogenic) bacteria in the milieu, there is significant evidence suggesting that the presence of bacteria in or on the corpse seems to aid in larval development and pupariation. This may be because of a change in larval nutrition, with the bacteria either being used as a food source themselves or making nutrients more available to larvae. Maggots also produce and secrete or excrete antimicrobial molecules that are effective in killing certain bacteria. It is unclear whether this is a defensive mechanism, a selective measure to enhance the survival of bacteria beneficial to the larva, or a combination of both. Significant research is still needed to fully appreciate the potential role that these bacteria-insect interactions have in conferring a competitive advantage for surviving in a carrion community.