Abstract: The response of female Encarsia bimaculata Heraty et Polaszek to its host, Bemisia tabaci (Gennadius) nymph, exuviae or adult extractions was bioassayed in a petri dish arena. The tested materials were extracted by hexane, ethanol and water. The data show that females spent much longer times searching in treated patches than controls. The parasitoids intensified their search in the treated patches and exhibited both orthokinetic and klinotaxic responses. The highest mean of the retention time in the treated patches was in those treated with material extracted from nymphs with water (111.23 seconds), otherwise parasitoids spent equal time in treated patches irrespective of the concentrations of the tested materials. Such kairomones might enhance female searching efficiency and guide them to hosts.

Key words: Encarsia bimaculata, Bemisia tabaci; parasitoids, kairomones, arrestment response, host location