Assessment of the repellent effect of citronella and lemon eucalyptus oil against South African Culicoides species

Abstract

The use of insect repellents to reduce the attack rate of Culicoides species (Diptera:Ceratopogonidae) should form part of an integrated control programme to combat Africanhorse sickness and other diseases transmitted by these blood-feeding midges. In the presentstudy the repellent effects of a commercially available mosquito repellent, a combinationof citronella and lemon eucalyptus oils, on Culicoides midges was determined. The numberof midges collected with two 220 V Onderstepoort traps fitted with 8 W 23 cm white lighttubes and baited with peel-stick patches, each containing 40 mg of active ingredient, wascompared with that of two unbaited traps. Two trials were conducted and in each trial thefour traps were rotated in two replicates of a 4 x 4 randomised Latin square design. Althoughmore midges were collected in the baited traps, the mean number in the baited and unbaitedtraps was not significantly different. This mosquito repellent did not influence either thespecies composition or the physiological groups of Culicoides imicola Kieffer. The highermean numbers in the baited traps, although not statistically significant, may indicate that thismosquito repellent might even attract Culicoides midges under certain conditions.