Interkingdom Cues by Bacteria Associated With Conspecific and Heterospecific Eggs of Cochliomyia Macellaria and Chrysomya Rufifacies (Diptera: Calliphoridae) Potentially Govern Succession on Carrion

Deciphering mechanisms that regulate succession on ephemeral resources is critical for elucidating food web dynamics and nutrient recycling. Blow fly (Diptera: Calliphoridae) colonization and use of vertebrate carrion serve as a model for such studies, since they are the primary invertebrates that recycle this ephemeral resource. Initial colonization by blow flies often results in heightened attraction and colonization by competing conspecifics and heterospecifics, thereby regulating associated arthropod succession patterns. Because Ch. rufifacies is facultatively predacious and cannabalistic, the current study hypothesized that adults would recognize the presence of conspecific and heterospecific eggs, thus avoiding potential predation and competition. Using a Y-tube olfactometer, researchers measured the residence time response of C. macellaria and Ch. rufifacies to conspecific and heterospecific eggs of three different age classes (fresh to 9-h-old). Fly responses to surface-sterilized eggs and to an aqueous solution containing egg-associated microbes were then examined. High-throughput sequencing was used to survey egg-associated bacteria from both species. The study found that C. macellaria and Ch. rufifacies exhibited differential responses to eggs of conspecifics and heterospecifics, which appear to be a result of microbial volatile-related odors. These behaviors likely influence predator-prey interactions between species. Preliminary high-throughput sequencing revealed Ch. rufifacies had a similar egg-associated fauna as C. macellaria, which may serve as a form of camouflage, allowing it to colonize and thereby attract C. macellaria, a common prey for its larvae. (Publisher abstract modified)