The effect of selected uv absorber compounds on the photodegradation of pyrethroid insecticides applied to cotton fabric screens

Abstract

AbstractUV absorber compounds were tested to reduce the photolytic decomposition of deltamethrin, applied to 100 % cotton fabric, to be used as a target screen for tsetse fly control. In the absence of UV absorbers, over 90% of deltamethrin was degraded after 6 h irradiation under an Osram UV‐sun radiation lamp (equivalent to 96 h sunlight) at 35(±1)°C. The degree of protection increased with increase in the proportion of the U V absorber compound. With a mixture of 2,4‐dihydroxybenzophenone (I) and deltamethrin (3 + 1, by mass) 7% of deltamethrin was degraded. Similarly, I protected alpha‐cypermethrin and cyfluthrin against photolysis, I and 2‐hydroxy‐4‐methoxybenzophenone‐5‐sulfonic acid (IV) both protected deltamethrin from “Glossinex 200” SC formulation against photolysis, but I was more effective than IV.