05_Entomo E

Novaluron, a new chitin synthesis inhibitor type of insect growth regulator, was evaluated in the laboratory and field against larvae of the mosquito Aedes aegypti (L.). In the laboratory, the technical material showed a high level of activity against 2nd and 4th instar larvae. The inhibition of emergence (IE) was 100% at concentrations of 0.25 to 1.0 μg/L. Second instars were slightly more susceptible than fourth instars. At the high concentration (1 ppb), most of the mortality occurred in the larvae, but at sublethal concentrations (for larvae) mortality also occurred in pupae and adults (incomplete eclosion). An EC10 (emulsifiable concentrate containing 10% active ingredient) formulation of novaluron was evaluated against Ae. aegypti in waterstorage containers in the field in Thailand. Two tests at high (0.05 to 1 mg/L) and low (1 to 20 μg/L) concentrations were carried out in clay jars (200 L) and plastic pails (75 L). At high concentrations in clay jars, we obtained 86-96% inhibition of emergence (IE) for about 190 d, but the mortality declined at low concentrations after 190 d. At much lower concentrations, in jars and plastic pails in the second experiment, the IE was 80-100% for 2 mo. The highest concentrations of this series (10 μg/L in jars and 20 μg/L in pails) were active for 75 and 68 d respectively, losing efficacy by 82 d post-treatment. In the experiment using low concentrations, all treatments in jars and plastic pails failed to provide adequate control 90 d after treatment. These studies show * These studies were carried out in collaboration with WHO Pesticide Evaluation Scheme (WHOPES). Mention of specific companies or products does not imply that they are recommended or endorsed by WHO or the University of California, Riverside, in preference over others that are not mentioned.