The effectiveness of spinosad for larval mosquito control is summarized based on available published literature and some heretofore unpublished studies. Spinosad is highly active against larvae of all mosquito species tested thus far. It is effective at similar dosages for all larval mosquito instars, with peak cumulative mortality occurring at 72 h posttreatment. More studies are needed to fully define spinosad's ovicidal properties and its impact on the pupal stage. High levels of organic matter and full sunlight are both factors that can negatively impact spinosad efficacy and longevity and should be considered when making use rate and retreatment decisions. Studies clearly show that spinosad technical active ingredient and current crop formulations are suboptimal for larval mosquito control and underrepresent spinosad's true activity. A series of spinosad formulations specialized for larval mosquito control will be sold commercially. Prior to its launch and widespread use, there is a need for additional baseline studies to clarify the natural geographic variation in susceptibility of field mosquito populations. Spinosad represents a new and effective natural product for the integrated management of larval mosquitoes. It possesses a unique mode of action not shared by any other insecticide and is shown to be minimally disruptive to most nontarget species tested thus far at its proposed field use rates.

Field experiments were conducted in 1996 and 1997 to evaluate barnyardgrass (Echinochloa crus-galli) control, rice (Oryza sativa) yield, and grain quality with cyhalofop-butyl applied early postemergence (EPOST) or late postemergence (LPOST) in drained or flooded plots at rates of 0.15 to 0.4 kg ai/ha and standard treatments of molinate or propanil. Control with cyhalofop-butyl at 0.15 and 0.2 kg/ha applied in drained plots was greater compared to propanil and generally increased when treatments were applied EPOST to plots reflooded 2 d after treatment. Barnyardgrass control with cyhalofop-butyl at 0.15 and 0.2 kg/ha applied in flooded plots was similar to or better than the control obtained with molinate. Rice yields generally reflected differences in barnyardgrass control and were greatest with cyhalofop-butyl applied EPOST in drained plots. The 0.4 kg/ha rate of cyhalofop-butyl resulted in rice foliar injury and significant reductions in grain yield. Grain qualitative characteristics (total milling yield, grain vitreosity, grain length, and grain length to width ratio) were better with cyhalofop-butyl applied EPOST in drained plots compared with propanil or molinate.

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