Example 28

We tested pyrethrin+perillaldehyde for efficacy against 3- to 5-day old adult Culex quinquefasciatus. For the concentration, 2% of perillaldehyde, and 0.001 μg/mosquito of pyrethrin, and 0.001 μg/mosquito of pyrethrin with 2% of perillaldehyde, at 1 hour we obtained 33%, 10%, and 80% knockdown respectively. At 24 hours we obtained 13%, 7%, and 33% mean mortality respectively. The CO2 control and acetone standard both had 0% knockdown at 1 hour, and 0% mean mortality at 24 hours. Results are shown in Table 18.

TABLE 18
Efficacy of perillaldehyde, pyrethrin, and a combination of both
against adult, virgin, female Culex quinquefasciatus mosquitoes.
% MORTALITY
ACTIVE INGREDIENTCONCENTRATIONAFTER 24 HRS
PERILLALDEHYDE3%13
PYRETHRIN0.001 μg7
OBS.*CALC.**
PERILLALDEHYDE + 3% + 0.001 μg3319.09
PYRETHRIN
*Obs. = observed efficacy
**Calc. = efficacy calculated using Colby (1967) formula
Since the actual insecticidal kill rate exceeds the calculated value, then the action of the combination is super-additive or a synergistic effect is present.

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