Comparative Toxicity And Persistence Of Pyriproxyfen, Diflubenzuron, And Temephos Against Aedes Aegypti (L.).
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Date
2014-01
Authors
Loo, Siaw Fang
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Publisher
Universiti Sains Malaysia
Abstract
The effects of the juvenile hormone analogue (JHA), pyriproxyfen, and chitin synthesis inhibitor (CSI), diflubenzuron, in comparison with the conventional organophosphate insecticide, temephos were tested against Vector Control Research Unit (VCRU) strain of Aedes aegypti. Technical-grades were used throughout the study. A laboratory bioassay was conducted following the standard method recommended by World Health Organization (WHO) year 2005. According to the study, pyriproxyfen was found to be the most effective against Ae. aegypti larvae, with the lowest EI50 value of 0.00031 (0.00026 – 0.00036) ppm. While diflubenzuron showed a more tolerant effect with an EI50 value of 0.00144 (0.00129 – 0.00159) ppm. Temephos recorded the highest LC50 value, which is 0.00363 (0.00349 – 0.00375) ppm, showing a lower larvicidal efficacy against Ae. aegypti larvae under laboratory condition. By considering the EI50 or LC50 value for each larvicide, the efficacy of pyriproxyfen was 11.7 times greater compared to temephos while the efficacy of diflubenzuron was 2.52 times greater. A simulated field trial was also conducted to evaluate the residual activity of the insecticide under both replenished and non-replenished regimes. In this study, each larvicide was applied at their respective diagnostic concentration, which is two times that of their LC99 value, against 40 3rd instar larvae placed in a 50 liter plastic container holding 40 liter of seasoned water. A concentration of 0.035 ppm diflubenzuron, 0.015 ppm temephos and 0.013 ppm pyriproxyfen were assessed. Exposed larvae were removed weekly and a new batch of larvae was introduced into the treated container.
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Keywords
Pyriproxyfen, Diflubenzuron , Temephos Against Aedes Aegypti (L.).