Poster Session 5, 3:15 PM - 4:00 PM: Concourse [B14]

The Influence of Bee Host Community Context for In Vitro Growth Parameters of a Trypanosomatid Parasite

Presenter: Emma Lynne Piedade

Faculty Sponsor: Lynn Adler

School: UMass Amherst

Research Area: Biology

ABSTRACT

Host community diversity can limit multi-host parasite transmission and virulence, with positive effects for hosts. Crithidia bombi is a unicellular multi-host trypanosomatid bee gut parasite primarily infecting bumblebees (primary host), decreasing bumblebee host fitness, but replicating also in some non-bumblebee bee species (alternative hosts). Infection by C. bombi differs between hosts, and in vitro techniques are key to isolating effects of selection in multi-host networks on intrinsic parasite traits. We hypothesize that host community traits, including primary host encounter rates, will impose selection on C. bombi growth parameters that can be detected in vitro due to differences in the efficiency of resource use. We predict that increased likelihood of C. bombi encountering its primary host will select for strains with increased maximum growth rate and carrying capacity. Twenty-four C. bombi strains were collected and isolated from B. impatiens workers from 14 bee communities differing in B. impatiens relative abundance, bee genera richness, and network modularity; these metrics were chosen to estimate the likelihood of encountering the primary host, B. impatiens. For each strain, growth was measured over a 10 day period using spectrophotometry. Maximum growth rate and carrying capacity were calculated for each strain. Carrying capacity was positively associated with the whole season network modularity, indicating that environments with more isolated interactions between subgroups may select for more efficient resource use by C. bombi. Understanding how pollinator host community traits affect intrinsic traits of parasites is key for determining impacts of bee community diversity loss.

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