Routine inspection for mosquito larvae involves counting larvae in water samples taken by a pint-sized “dipper” on a yard-long stick. Mosquito control personnel take hundreds of such samples per day in a haphazard fashion—dipping wherever they suspect larvae may inhabit. Using this approach, field biologists find hotspots effectively, cover a lot of ground, and treat these habitats for larvae as they go.
Where standard larval surveillance provides area-wide treatment of larvae, it fails to describe detailed geographic patterns within neighborhoods. To address this lack of microhabitat mapping, starting in August 2019 we created a systematic approach to mosquito larvae and their mosquitofish predator presence. Field biologists surveyed the entirety of the Tammany Hills neighborhood south of Door-to-door OWTS tank survey Effluent discharged into ditches is not the only source conducive for mosquito production associated with OWTS. Mosquitoes can infiltrate OWTS settling tanks if lids are broken, missing, or other access points allow entry. In 2019, field biologists performed inspections door-to-door in the Tammany Hills neighborhood to understand whether mosquito production was occurring within OWTS tanks. Nearly 10% of OWTS inspected had cracked lids or other entry ports for mosquitoes to lay eggs and rear their offspring directly within the treatment systems. Covington for two days by observing the ditch for the presence of “mosquitoes, fish, both, neither or dry condition” at every tenth pace.
The result is a mosaic map of mosquito larval habitat. This data allowed visiting researcher Mark Meyer to assess the relationship of various geographic variables with observed mosquito and predator presence. As a result, increasing slope was significantly negatively correlated with fish presence (P = 0.009), while total ditch depth was positively correlated with fish presence (P =0.001). Additionally, TDS was again verified to negatively (P = 0.04) influence the likelihood of encountering fish.