Larvicides based on Bacillus thuringiensis israelensis, Lysinibacilus sphaericus (formerly Bacillus sphaericus), Saccharopolyspora spinosa and insect growth regulators such as methoprene, and a few others are the most commonly used mosquito control products in the United States and elsewhere because of their relative specificity and high effectiveness against target organisms, safety to nontarget species, and compatibility with the environment. Using standard laboratory bioassay, we have evaluated the loss of larvicidal activities of various formulations after being exposed to different storage and handling temperatures. Transportation of products under outdoor conditions for an extended period of time caused more activity loss compared with other conditions. Results are discussed based on their active ingredients as well as physico-chemical properties of the formulations reported. Recommendations are made for proper inventory control, storage, and handling of larvicides to minimize loss of larvicidal activity.
Keywords: mosquito larvicide; product stability.