Helen Esser


My name is Helen Esser and I’m a third year PhD student at the Resource Ecology Group and the Forest Ecology & Forest Management Group at Wageningen University. I’m also a Fellow at the Smithsonian Tropical Research Institute in Panama.

I study the community ecology of ticks, their vertebrate hosts, and microbes in Panama. Using network analysis, I found that the ticks in Panama are highly host-specific. Specifically, most tick species parasitize a very limited number of host species that are phylogenetically closely related. Only few tick species are truly generalists and feed from a wide variety of vertebrate hosts. High host specificity renders ticks vulnerable to (local) coextinction with their hosts. Indeed, the results from a fragmentation experiment that I carried out on the islands and peninsulas of the Panama Canal showed that with declining wildlife diversity and abundance, tick diversity and abundance declined as well. Although fewer ticks may sound as good news, the surviving ticks were host-generalists. In degraded environments, these generalist ticks feed proportionally more from small mammals such as rodents and opossums, which are often disease reservoir hosts and hence may infect the ticks that feed from them. It has therefore been suggested that loss of wildlife diversity may result in higher disease prevalence in ticks. As such, high wildlife diversity could be regarded as an ecosystem service by buffering against disease emergence. To test this hypothesis, I have collected ticks from small mammals across a strong gradient of wildlife diversity (as determined by camera trapping). At this moment, these ticks are being sequenced in order to identify the microbial species that they carry, and whether the prevalence of pathogenic species increases with wildlife diversity loss. I can’t wait to see the results!!