Two separate but related studies were conducted regarding management of Anopheles quadrimaculatus larval populations in commercial rice fields near Cleveland, MS, in 2004. Study 1 was to evaluate the effectiveness of 2 treatments of aerially applied ultra-low volume applications of Bacillus thuringiensis var. israelensis (Bti) against An. quadrimaculatus larvae in dense, high-canopy mid- to late-season rice crop. Study 2 was to investigate the effect of preflood treatments of lambda-cyhalothrin (Karate), which is commonly used against rice water weevil (Lissorhoptrus oryzophilus), on An. quadrimaculatus larvae. Excellent initial, but short residual control (>99% control 1 day after treatment) was observed in the Bti-treated fields in both mid- and late-season rice. Little or no effect on mosquito larvae was observed in the lambda-cyhalothrin-treated fields. Results indicate that Bti can be effectively used by mosquito management personnel to control larval populations of An. quadrimaculatus in late-season rice fields; however, lambda-cyhalothrin did not effectively control larval An. quadrimaculatus when applied preflood to rice fields.

Optimized aerial applications were conducted to assess the efficacy of 2 formulations of resmethrin (Scourge 18-54, Aqua-Scourge 10-30) for control of caged adult Anopheles quadrimaculatus. Micronair AU4000 rotary atomizers were employed to apply the chemical. Both compounds were applied at 0.0035 lb AI/acre (3.92 g AI/ha) with the use of the AGDISP computer model to predict appropriate flight offsets (up to 1,219.2 m). Efficacy was based on bioassays with caged An. quadrimaculatus adults and assessment of impinger-collected droplets. Both compounds provided effective mosquito control. Mean mortality at 24 h posttreatment averaged 80.4% for Scourge, and 80.7% for Aqua-Scourge. Mean droplet sizes, Dv0.5 = 26 microm and 38 microm, and mean density, 74 droplets/cm2 and 41 droplets/cm2, for Scourge and Aqua-Scourge, respectively, were consistent with the bioassay results. Analysis of droplet deposition and mortality failed to reveal a statistical correlation between mortality and deposit volume.