A novel juvenile hormone analog, S-methobutene, with enhanced activity and efficacy against <i>Aedes aegypti</i> and <i>Aedes albopictus</i> (Diptera: Culicidae)

Mosquito control interventions are constrained by the limited availability of active ingredients. While there are already very few, the development of pesticide resistance further constrains the options. Innovation in biorational active ingredients is therefore critical for managing invasive vector mosquito species such as Aedes aegypti (L.) and Ae. albopictus (Skuse). Laboratory and semifield evaluations were conducted to compare the effectiveness and efficacy of the novel compounds S-methobutene with S-methoprene against these species. Laboratory bioassays showed that technical grade S-methobutene was 5.7- to 11.5-fold more active than S-methoprene against Ae. aegypti, and 7.5- to 12.7-fold more active against Ae. albopictus. When compared at equivalent active ingredient levels, S-methobutene granules exhibited 5.7- to 10.2-fold greater activity against Ae. aegypti and 5.8- to 12.3-fold greater activity against Ae. albopictus than S-methoprene granules. In semifield microcosm trials, 1.0% S-methobutene granules achieved efficacy comparable to that of 4.25% S-methoprene granules at the same application rates, confirming the superior performance of S-methobutene at lower concentrations as observed in the laboratory assays. Enhanced bioactivity of the technical grades in laboratory bioassays and the field efficacy of the granular formulations in microcosm tests demonstrated that the novel S-methobutene outperformed S-methoprene against mosquito species Ae. aegypti and Ae. albopictus.