Christina Anaya, PhD student at Oklahoma State University and 2017-2018 Fulbright/NSF Student Fellow at Hólar University College, will present her research at the Biology Seminar:
Parasites are often ignored in ecological studies despite their ability to affect hosts at distinct levels (e.g. individuals, populations), in different contexts (e.g., behavior, physiology) and at various levels of the food web. Hairworms (Phylum: Nematomorpha) are an excellent organism for ecological studies because they are an understudied group of parasites with complex life cycles that infect crickets and other arthropods to complete their life cycle. However, most research focuses on hairworm biodiversity and phylogenetic relationships therefore, their impact on host biology and their life cycle ecology is not well understood. For my dissertation, one focus is on the survivorship and reproduction of infected crickets. Contrary to anecdotal evidence that “crickets commit suicide” when they release hairworms in aquatic systems, results indicate that house crickets infected with P. varius in the laboratory were capable of surviving infection. In fact, although infected female crickets contained no eggs at the time of hairworm emergence, these female crickets produced eggs post-infection at a quantity that was not significantly different than uninfected control crickets. I also focus on life cycle strategies of hairworms. My results indicate Gordius cf. robustus Oklahoma is the first terrestrial species of the phylum. Field surveys and laboratory experiments over three years found this species emerges and mates in terrestrial systems, burrows into soil, and contains a double-membrane egg unlike any species of hairworm. I also examine transmission strategies of hairworms and host use. Results show that terrestrial earthworms, like aquatic snails, are viable indicator species for hairworm biodiversity studies because in locations where adult terrestrial hairworms are found, the cyst stage is commonly found in terrestrial earthworms. Comparatively, no cysts of aquatic species were found in terrestrial earthworms. This research contributes to the growing body of evidence that hairworm life cycles are variable within the phylum making them excellent models for ecological studies. Finally, I am examining the biodiversity of hairworms in Iceland, a location where no hairworms have been described. My preliminary data shows a species in the genus Gordionus is I am currently undertaking morphological and genetic analyses to determine the species. By examining the biology and life cycle strategies of different species of hairworms, we can now begin to answer question about the evolutionary paths the phylum has taken.