Spatio-temporal mechanisms of urban mosquito coexistence in Baltimore, MD

Abstract

Understanding the interactions governing species distributions and community structure are of fundamental ecological importance. Mosquitoes that utilize container habitats at their larval stage usually engage in strong competition and competitive exclusion is expected; however, numerous container-utilizing mosquito species co-occur in the same individual container habitats and regionally coexist. I investigated spatial and temporal mechanisms governing the distributions and abundances of the competitively superior invasive Aedes albopictus and resident Culex spp. mosquitoes in four neighborhoods with varying socioeconomic status in Baltimore, Maryland. Specifically, I investigated if the findings from both field surveys and field and laboratory experiments were consistent with four spatial and temporal hypotheses for species coexistence that act at different scales: spatial partitioning among neighborhoods and blocks, seasonal condition-specific competition, aggregation among individual container habitats, and priority colonization effects within individual containers. I found modest but important evidence for all hypotheses that could each facilitate Culex spp. coexistence with Ae. albopictus. I found clear neighborhood effects, with low SES neighborhoods supporting higher abundances of mosquitoes than high SES neighborhoods overall, but with the highest abundances of Ae. albopictus in low SES neighborhoods and Culex spp. being more variable among neighborhoods. Culex spp. abundances were higher in the early summer compared to mid-summer peaks in abundance for Ae. albopictus. Laboratory competition trials showed increased aggregation of Ae. albopictus had a slight positive effect on Culex spp. population performance, and aggregation conditions sufficient for coexistence among experimentally placed ovitraps and negative associations of Aedes and Culex genera in resident containers in the field. Lastly, I found that priority colonization of a container leads to stronger population performance for both species, and that resource availability seems to affect Culex spp. more than competition. The results of my dissertation have revealed the role of several ecological mechanisms that may facilitate the regional coexistence of Culex spp. with Ae. albopictus and is among the first bodies of work to do so. Due to their roles in the transmission of human pathogens, future examination of other spatial and temporal mechanisms of coexistence between Ae. albopictus and resident Culex spp. is warranted.