Caste Abundance of Philophthalmus sp. in Cerithium stercusmuscarum

Abstract

Trematode-snail systems are used in a variety of ways to test large-scale ecological phenomena. For example, optimal allocation theory predicts that organisms will invest resources to defense and reproduction under specific contexts. Previous studies have used eusocial trematodes to test this theory because of the morphological differences in caste members and their inducibility under certain conditions. The proportion of soldiers to reproductives can vary across spatial scales that possess different levels of infection. Using the eusocial trematode Philophthalmus sp, which infects Cerithium stercusmuscarum, allowed for the testing of soldier allocation across finer spatial scales and on a different snail-trematode system than previously done. This study engages with previous work on soldier allocation and invasion threat. My results demonstrated that there was not a statistically significant relationship between the average proportion of soldiers and tide pool infection level prevalence. In addition, this study also investigates whether soldier allocation depends on the potential type of infection present across the tide pools. I found that there was not a statistically significant difference between the mean proportion of soldiers across the tide pools. I offer several other factors that may influence soldier allocation such as the snail immune system and microbial communities in both the host and parasite. These findings add to the literature of eusocial parasitic trematode behavior as well as insight on defense allocation in eusocial organisms. There are also numerous other applications of this research and ecosystem level implications of these small-scale dynamics.