Structure-activity relationships in diphenyl ethers for insect growth regulating activity against mosquitoes

Out of the 30 substituted diphenyl ethers synthesized and tested for insect growth regulating (IGR) activity against mosquitoes, three compounds viz., DPE-16, 19 and 28 showed promising IGR activity. While DPE-16 and 19 were found to be effective against all three vector species tested viz., Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi, with the respective EI50 values of 0.1485, 0.3650, 0.2225 mg/l and 0.1474, 0.1392, 0.1145 mg/l, DPE-28 was found to be highly effective against C. quinquefasciatus with an EI50 value of 0.0022 mg/l. The structure-activity relationship in the diphenyl ethers with respect to their octanol-water partition coefficients showed an increase of lipophilicity when both the ortho positions of the phenolic moiety are substituted by tertiary butyl group. The simulated field trial carried out with DPE-16, 19 and 28 showed that these compounds were effective for 7, 7 and 9 days respectively at 0.1 mg/l against C. quinquefasciatus.