Diagnostic dose of synergized d-phenothrin for insecticide susceptibility testing by bottle bioassay.

The diagnostic dose of d-phenothrin synergized 1:1 with piperonyl butoxide for testing insecticide susceptibility of mosquitoes by bottle bioassay is reported for 2 mosquito species, Culex quinquefasciatus and Ochlerotatus taeniorhynchus. The diagnostic dose was defined as 2 times the 95% lethal concentration (LC95). LC50, LC90, and LC95 were estimated by probit analysis of dose response data. Procedures for diluting the commercial-grade off-the-shelf pesticide in acetone, treating the bottles, and calculating baseline data for insecticide-susceptible mosquito populations are described. The advantages and disadvantages of testing off-the-shelf commercial-grade pesticides that are maintained on premises by mosquito control programs, in contrast to using reagent-grade chemicals purchased from a chemical supply house, are also discussed. Data obtained by this method can be invaluable in making timely management decisions about the choice of pesticides in a control program.