Meeting Abstract
Pollination services provided by managed and wild bees are essential for agricultural and natural ecosystems. However, threats to pollinator health leading to population declines put these services in jeopardy. Several potential causes of declines have been suggested, including exposure to pathogens and agro-chemicals. Although individual effects are widely studied, interactions between pesticides and immunity may exacerbate the negative effects of individual exposures in environments where they co-occur. In bumble bees (Bombus spp.), a landscape analysis demonstrated a correlation between local use of the fungicide chlorothalonil and infection loads of the microsporidian pathogen Nosema bombi in declining species. This is suggestive of an interaction, but causation still needs to be established. By exposing microcolonies of B. impatiens in a fully reciprocal design to chlorothalonil and/or Nosema, we test if a sublethal dose of chlorothalonil influences N. bombi infection and exacerbates its negative effects. We predict that chlorothalonil will reduce immune function, leading to increased infection loads and transmission potential, with associated negative effects on health. This study will be the first to experimentally assess the combined stressors of N. bombi and chlorothalonil in bumble bees, and will provide information on how bumble bee health will be affected by variability in agro-chemical and pathogen environments.
