Duration of repellency of N,N-diethyl-3-methylbenzamide, citronella oil and cypermethrin against Culicoides species when applied to polyester mesh

The repellent efficacy of 15% N,N-diethyl-3-methylbenzamide (DEET), 0.6% citronella oil, and 0.3% α-cyano-cypermethrin against Culicoides species was compared in three 5 × 5 Latin squares (15 replicates) under South African field conditions. DEET, citronella oil or α-cyano-cypermethrin were applied to polyester meshes that were fitted to down-draught suction 220 V UV light traps which were operated overnight. No significant repellent effect against Culicoides was found for the citronella oil or the α-cyano-cypermethrin. DEET had a significant repellent effect against Culicoides species and C. imicola for all catches made from after sunset to before sunrise.