by Jan Gogarten
The QCBS Excellence Award allowed me to present my work at the International Primatological Society’s XXV Congress in Hanoi, Vietnam, from 11th-16th of August, 2014. At this meeting, over 800 primatologists gathered from around the globe, to not only discuss their research but also partake in a variety of discussions as a community. For example, I was able to partake in the IUCN/SSC Primate Specialist Group’s meeting to determine which species to include on the list of the 25 primates considered to be the most endangered and in need of attention for conservation and research action. Another group met to discuss the future of the Primate Microbiome Project and how best to standardize methods and data sharing.
I was also able to present some new research and get feed back from experts in the field as well as generate a number of new collaborations in the process. As highlighted by the IUCN’s list of 25 most endangered primates, a large number of primate species are currently threated by anthropogenic disturbance, climate change, infectious diseases as well as a myriad of other factors. Unfortunately, many population declines are only noticed well after the fact, and monitoring unhabituated primates is fraught with difficultly. Genetic material ingested by invertebrates is one potentially useful source of information about invertebrates in an ecosystem (e.g., a recent study on leeches suggests they preserve mammalian DNA for several months). Through a collaboration with the Leendertz Lab at the Robert Koch Institute I have been assessing the feasibility of using carrion flies for monitoring primate diversity. We screened carrion flies captured in Taï National Park, Côte d’Ivoire for mammalian mitochondrial DNA (mtDNA) and then attempted genotyping this DNA. Much to our surprise, we detected all nine diurnal primate species in only 201 flies. Taxon-specific PCRs resulted in a four-fold increased detection rate compared to a pan-mammal assay, with over 25% of flies randomly caught in the forest found to contain sooty mangabey (Cercocebus atys) mtDNA. Amplification of seven microsatellite loci from flies caught near a mangabey carcass, resulted in a PCR success rate of ~40%, suggesting these flies might be suitable for individual identification as well, which would be extremely useful for estimating population sizes.
These flies might also contain information about, and even be involved in, disease processes. When we screened flies for anthrax during an outbreak in the mammalian population at Tai, over 7% tested positive using an anthrax specific PCR, suggesting they might be useful for monitoring unhabituated primate populations. Previous studies suggest that flies can play a role in anthrax transmission in non-forest ecosystems, both by contaminating vegetation around a carcass and by biting mammals. To understand how these flies interact with primates in this ecosystem and why such a huge percentage of flies were carrying around mangabey DNA, we studied their interactions with a group of habituated sooty mangabeys (Cercocebus atys). Fly density was higher inside the group than at a distance of 500m and 1000m, although we wondered why there would be more carrion flies in the social group than outside given the lack of carcasses. A brief search of the literature suggested that many species of carrion flies also feed on feces or even blood. When we presented flies reared from larva captured on a carcass with feces, at least some species readily laid larva and fed, suggesting this dietary switching can occur. To see whether flies were simply locally attracted to the primate social group, or really associated and followed a group through the forest we conducted a mark recapture experiment of the fly community (N=1,764 flies marked, 53 recaptured) and found that flies remained with the group for up to 12 days and traveled more than 1.4km from the original point of marking. Further studies are needed to conclusively link these flies to anthrax dynamics in the park, but if flies are actively attracted to and following primates after hatching or feeding on a carcass of an animal that died of anthrax, there is certainly potential for them to be playing a role. Collectively these findings suggest that flies tracking primates can be used as a cost-effective method to monitor wild primate populations and their diseases.
While in Vietnam I was able to visit a number of potential field sites with fellow primatologists following the meeting. This served as an exciting opportunity to discuss research ideas in the field and then to share a beer and mull things over in the evenings. I really enjoyed the experience and thank the QCBS for their generous support.