Open Access Senior Thesis
Bachelor of Arts
© 2023 Finley W Melnikoff
Helminths are some of the most common parasites in the world, infecting anything from humans to plants to mice. These parasites can play a massive role in determining a host's fitness and ultimately can have consequences on their body condition, reproductive ability, and infection transmission potential. Many factors influence the potential burden helminths have on their hosts–from host traits to environmental conditions–yet helminth fecundity and length have been studied very little in relation to these factors. Helminth fecundity–or how many eggs each female worm has in its ovaries–determines the transmission of the parasite, and helminth length is correlated with fecundity, however, it is currently unknown to what extent particular host and environmental factors affect both. In our study we examined how and to what extent host sex, occasion (month in which the host was culled), anthelmintic treatment, and food supplementation affected helminth length and fecundity in two species of intestinal nematodes. We trapped Bank voles (Myodes Glareolus) from May through August at twelve study sites in southern Finland. Each site was randomly assigned a food supplementation status (supplement or control) and a deworming treatment status (treatment or control). We sacrificed and dissected 26 voles, looking for helminths in their G.I. tracts and found two helminth species, Heligmosomoides glareoli (Hg) and Heligmosomum mixum (Hm). These helminths’ fecundity and lengths were measured in order to determine if they were impacted by host sex, supplementation and treatment status using a general linear mixed effects model. We found no evidence of an effect of sex on either factor. However we did find evidence that occasion and treatment combination (deworming and supplementation) had a significant impact on average fecundity in one of our two helminth species and that length and fecundity were both not independent and positively correlated in one of our species. Our results suggest that transmission potential is highest in the late summer when the host population is the largest and that supplementation has the greatest ability to decrease fecundity as the host has more resources to devote to mounting an immune response.
Melnikoff, Finley, "Can Host Traits and Environmental Conditions Predict Helminth Fecundity and Length?" (2023). Pitzer Senior Theses. 168.
Available for download on Monday, December 15, 2025