Laboratory evaluation techniques to investigate the spatial potential of repellents for push and pull mosquito control systems.

A protocol has been developed for the indoor evaluation of candidate spatial repellents intended for use in push and pull systems. Single treatments (catnip oil, 1-methylpiperazine, and homopiperazine) and a mixture of catnip oil and homopiperazine were tested with yellow-fever mosquitoes (Aedes aegypti) in Y-tube olfactometers to determine 1) if these compounds inhibited mosquito host-seeking at short distances and 2) if results obtained in olfactometer tests can be correlated with a larger scale set-up, that is, a room test. All test materials significantly decreased the ability of mosquitoes to find host odors (from a human finger) by up to 96.7% (2.5% catnip and homopiperazine mix). Similar effects could be observed within a new room test set-up, which involved a repellent dispensing system and an attractive trap (BG-Sentinel). Mosquitoes captured by the BGS trap had to fly through a treatment-containing air curtain created by the dispensing system. Compared with the use of a control (ethanol solvent without candidate repellent), trap catch rates were significantly reduced when 5% catnip, 5% 1-methylpiperazine, and 5% homopiperazine were dispensed. Homopiperazine produced the greatest level of host-seeking inhibition with a 95% reduction in the trap catches. The experimental set-up was modified to test the viability of those technologies in a simple push & pull situation.. The combination of BGS trap and a 10% mix of catnip and homopiperazine helped to reduce human landing rates by up to 44.2% with a volunteer sitting behind the air curtain and the trap running in front of the curtain.