Catch basin ecosystems and effects of the mosquito larvicide methoprene

Mari Butler, University of Rhode Island

Abstract

The mosquito larvicide methoprene is a juvenile growth hormone mimic that is widely used to control mosquitoes. This chemical disrupts normal mosquito development, drastically inhibiting emergence from the pupal to the adult stage. Methoprene is active at extremely low levels and is widely used; so it could affect arthropods, other than mosquitoes, that have similar endocrine systems. This study evaluates the efficacy at controlling mosquitoes in storm water drainage catch basins and potential nontarget effects of methoprene. Secondly, whether methoprene attracts or deters mosquitoes likely to oviposit in catch basins was examined. Thirdly, the catch basin community was described and environmental factors were used to model mosquito larval abundance; and lastly methoprene's effects on the communities that live in catch basins were measured. ^ Methoprene formulated as 30-day slow release Altosid® pellets effectively controlled mosquitoes for about a month under field conditions and substantially longer under laboratory conditions when applied at a dose of 3.5 g pellets per average-sized catch basin. Methoprene formulated as liquid larvicide did not affect oviposition of either Culex spp. or Ochlerotatus japonicus. ^ Catch basin environment organisms are, for the most part, detritivores that can withstand low levels of oxygen and periods of drought. They tended to increase in abundance as summer progressed with the exception of mosquitoes that dominated communities earlier in the season (July). Mosquito larvae were most likely to be found in catch basins with shallow stagnant water that had relatively low levels of dissolved oxygen and pH and relatively high levels of total suspended solids and carbon and nitrogen in the water. ^ The concentration of methoprene currently used for mosquito control is 0.5 ppb and lower, orders of magnitude below what has been determined as detrimental to other organisms. Neither community indices nor abundances of organisms in the field or in laboratory trials were consistently affected by methoprene. ^

Subject Area

Biology, Ecology|Biology, Entomology

Recommended Citation

Mari Butler, "Catch basin ecosystems and effects of the mosquito larvicide methoprene" (2005). Dissertations and Master's Theses (Campus Access). Paper AAI3186895.
http://digitalcommons.uri.edu/dissertations/AAI3186895

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