P-13 - Developing a cohort of active tree holes for La Crosse virus interventions

Abstract: La Crosse virus (LACV), the most common cause of pediatric neuroinvasive arboviral infection in the United States, is primarily vectored by the eastern tree hole mosquito, Aedes triseriatus. Despite its role as the principal vector, evidence-based interventions (i.e., larval control) for LACV vectors in tree holes are lacking. With future intervention studies in mind, we located, mapped, and characterized 40 tree holes with known larval mosquito presence in a La Crosse endemic region (Western North Carolina). The presence of Ae. triseriatus was confirmed from all but one tree hole.

Immature LACV vectors (convenience sampling) were pooled and submitted for virus testing (results pending). Of the 748 LACV vectors reared to adults, Ae. triseriatus was the most common (75.5%; 95% CI: 72.1%-79.0%) species observed. Two invasive LACV vectors, Aedes japonicus (21.2% [95%CI: 17.7%-24.6%) and Ae. albopictus (3.3% [95%CI: 2.9% -3.8%) were less common. Active tree holes were observed in diverse tree species, including tulip poplar, sycamore, willow, Japanese maple, false dogwood, white oak, birch, red maple, and white ash. Taken together, our findings suggest a high prevalence of LACV vectors in active and diverse tree holes. These observations will be further contextualized in terms of future larval control interventions.