View Program - 63rd Annual Drosophila Research Conference

The cactophilic Drosophila system of the Sonoran Desert is an excellent model not only to study how organisms may thrive in toxic environments, but also how some taxa are associated with the microbes necessary to decompose plant tissue. Cacti contain toxic compounds that protect them from herbivory. When a cactus is injured, sap exudes from its wounds and microorganisms quickly colonize the sap and begin the decomposition process. Interestingly, several Drosophila species can exploit these substrates as feeding and breeding sites.
While many members of the cactophilic Drosophila repleta species group have been able to transition seamlessly onto a standard cornmeal diet, Drosophila mettleri, is an exception. This is the only known species to breed exclusively in soil soaked with necrotic cactus sap and tissue, allowing it to take advantage of a more toxic and microbially rich niche. This taxon requires cactus-supplemented media to maintain healthy cultures under laboratory conditions. We hypothesized that D. mettleri’s reliance on its host plant and associated microbiome resulted in the loss of its ability to adapt to a novel, more sterile environment.
Our understanding of the physiological processes required for Drosophila to utilize decomposing cactus as a host plant is limited. For example, we currently do not know whether D. mettleri derives nutritional benefit from the decomposing cactus, the saprophytic microorganisms responsible for the decomposition process, or a combination of the two. This study examines D. mettleri to understand how various life stages perform when reared on (1) standard media, (2) standard media + cactus powder, and (3) standard media + sterilized cactus powder. Development rates between each life stage and adult feeding behavior were examined. The results show that cactus has an essential role in ensuring that Drosophila survive the pupation and eclose successfully.

Developmental Effects of Cactus on Drosophila mettleri