Infection patterns and molecular data reveal host and tissue specificity ofPosthodiplostomumspecies in centrarchid hosts

Abstract

AbstractPosthodiplostomum minimumutilizes a three-host life cycle with multiple developmental stages. The metacercarial stage, commonly known as ‘white grub’, infects the visceral organs of many freshwater fishes and was historically considered a host generalist due to its limited morphological variation among a wide range of hosts. In this study, infection data and molecular techniques were used to evaluate the host and tissue specificity ofPosthodiplostomummetacercariae in centrarchid fishes. Eleven centrarchid species from three genera were collected from the Illinois portion of the Ohio River drainage and necropsied.Posthodiplostomuminfection levels differed significantly by host age, host genera and infection locality. ThreePosthodiplostomumspp. were identified by DNA sequencing, two of which were relatively common within centrarchid hosts. Both common species were host specialists at the genus level, with one species restricted toMicropterushosts and the other preferentially infectingLepomis. Host specificity is likely dictated by physiological compatibility and deviations fromLepomishost specificity may be related to host hybridization.Posthodiplostomumspecies also differed in their utilization of host tissues. Neither common species displayed strong genetic structure over the scale of this study, likely due to their utilization of bird definitive hosts.