Dengue fever is a serious problem in Mexico and vector control has not been effective enough at preventing outbreaks.
Malaria is largely under control, but it is important that new control measures continue to be developed.
Novaluron, a novel host-specific
insect growth regulator and
chitin synthesis inhibitor, has proved to be effective against agricultural pests, but its efficacy against larval mosquito vectors under field conditions remains unknown. In accordance with the World Health Organization
Pesticide Evaluation Scheme, phase I, II and III studies were conducted to evaluate the efficacy and residual effect of
Novaluron (Rimon 10 EC, Makhteshim, Beer-Sheva, Israel) on the
malaria vectors Anopheles albimanus Wiedemann (Diptera: Culicidae) and Anopheles pseudopunctipennis Theobald, the
dengue vectors Aedes aegypti (L) and Aedes albopictus Skuse and the nuisance mosquito Culex quinquefasciatus Say. Laboratory susceptibility tests yielded diagnostic concentrations for all five target species. Field trials to identify the optimum field dosage of
Novaluron against Anopheles mosquitoes were carried out under semi-natural conditions in artificial plots and in vessels with wild mosquitoes. Efficacy was measured by monitoring mortality of larvae and pupae and the percentage of inhibition of emergence from floating cages. Dosages of
Novaluron for field tests were based on pupal LC(99) (lethal concentration 99%) of An. pseudopunctipennis (0.166 mg/L) in plots and average pupal LC(99) of Ae. aegypti and Ae. albopictus (0.55 mg/L). At all dosages tested,
Novaluron significantly reduced larval populations of An. albimanus, Culex coronator Dyar & Knab, Ae. albopictus and Cx. quinquefasciatus by approximately 90%, inhibited adult emergence of An. albimanus and An. pseudopunctipennis by approximately 97% for almost 4 months in experimental plots, and inhibited adult emergence of Ae. aegypti and Ae. albopictus by approximately 97% for up to 14 weeks. Recommended dosages of
Novaluron for non-container breeding and container breeding mosquitoes are 0.166 mg/L and 0.55 mg/L, respectively. Overall, the residual effect was more sustained than that of
temephos. The lowest dosage of
Novaluron had less of an impact on non-target organisms than did
temephos. Small-scale field trials in natural breeding sites treated with
Novaluron at 0.6 L/ha eliminated adult emergence of An. albimanus and Cx. coronator for 8 weeks. For phase III studies,
Novaluron was tested at the local and village levels, applying the optimum field rate to all natural breeding habitats within 1 km of a pair of neighbouring villages. Village-scale trials of
Novaluron at 0.6 L/ha reduced An. albimanus larval populations for at least 8 weeks and, more importantly, sharply reduced the densities of adult host-seeking mosquitoes approaching houses. We conclude that
Novaluron is effective and environmentally safer than
temephos.