The Toxicity of Used Coffee Grounds to the Larvae of Ochlerotatus (Finlaya) notoscriptus (Skuse) (Diptera: Culicidae)

The exotic Ochlerotatus notoscriptus is the most widespread container-breeding mosquito species in anthropic habitats in northern in New Zealand, and also a potential disease vector. We tested the toxicity of used coffee grounds, a recently proposed larvicide, to the species’ larvae, which is known to be tolerant to a wide range of water quality levels. High concentrations of used coffee grounds induced very large larval mortality within a few days. However, large mortality occurred in the controls after two weeks, and there was an apparent boost to larval survivorship in treatments with low to medium concentrations of coffee grounds. Although the results suggest that used coffee grounds could constitute a cost-free and environmentally sound alternative to less desirable insecticides, we believe that extensive field trials are necessary before their use as a larval control method is advocated.