PS 16-223 - Comparing the distribution and diversity of an entomopathogenic virus infecting lepidopteran larvae in temperate and tropical forests

Abstract: Studying the effects of tritrophic interactions on the distribution and composition of communities is a core theme in ecology. In particular, plant-insect-natural enemy interactions have proven to be a tractable system for understanding how species interactions vary across different communities. In this study, we focused on an entomopathogenic virus that infects lepidopteran larvae and documented the variation in viral prevalence and caterpillar host assemblages across four locations and eight communities. The entomopathogen, Junonia coenia densovirus (JcDV; Densovirinae), has been found to infect multiple species of Lepidoptera in the United States. However, the global distribution of this virus is currently unknown. Detection of the virus across different geographic regions can provide insight into the assemblages of lepidopteran hosts and host plant landscapes in which the virus is prevalent. Using the non-destructive method of collecting frass, samples were collected over three years by citizen scientists, research technicians, and students in North, Central and South America. Frass samples were screened for the presence of JcDV using quantitative PCR, with primers specific to the VP4 capsid protein gene of JcDV. We then amplified the viral DNA using PCR and sequenced the viral capsid gene to characterize genetic differentiation of the virus across its distribution. The viral pathogen was found in the frass of caterpillars belonging to 11 families of Lepidoptera, which were found on host plants from 13 different families, across the Americas. We detected JcDV in communities ranging from Vermont and Massachusetts to Arizona and New Mexico in the United States, and as far south as the Eastern Andes of Ecuador. These results provide novel insight into the geographic range of JcDV and indicate that diverse assemblages of Lepidoptera may be exposed to this virus during larval development. The genetic diversity of JcDV across its distribution will be important to understand interspecific differences in responses to the virus as well as varying infection (i.e., speed of kill, mortality, viral load) and responses (i.e., immunity) within a species based on host plant, geographic location, and climate.