Colour and odour responses of flying western flower thrips: wind tunnel and greenhouse experiments

The behavioural responses of flying western flower thrips (Frankliniella oc cidentalis Pergande) (Thysanoptera: Thripidae) to the colour yellow and the odour anisaldehyde were examined. In a wind tunnel, upwind flight by femal e thrips was common in an airflow of 0.11 m s(-1) but was impeded at 0.22 m s(-1). In the absence of anisaldehyde, flying female thrips exhibited an o riented response towards a yellow cue in the wind tunnel at a wind speed of 0.11 m s(-1). The main response of females to anisaldehyde in the wind tun nel was flight inhibition. There was no evidence of an odour-induced visual response, an odour-induced anemotactic response or chemotaxis by female th rips to anisaldehyde in wind tunnel bioassays, but chemokinesis was implica ted. With a matrix of yellow or black water traps with and without anisalde hyde in a greenhouse sweet pepper crop, yellow traps with anisaldehyde caug ht more thrips adults than yellow traps without anisaldehyde, black traps w ith anisaldehyde and black traps without anisaldehyde (1.3, 28 and 721 time s for males respectively and 2.4, 9 and 117 times for females, respectively ). Differences between respective traps were statistically significant in a lmost all cases. Trapping experiments using a centre-baited trap design to reduce the interaction of anisaldehyde between baited and unbaited traps we re undertaken in tomato and sweet pepper greenhouse crops. When the spatial distribution of the thrips adult population within the greenhouse was take n into account, yellow water traps with anisaldehyde caught between 11 and 15 times more female and 3 and 20 times more male F. occidentalis adults th an yellow traps without anisaldehyde.