THE POTENTIAL OF FLOWER ODORS FOR USE IN POPULATION MONITORING OF WESTERN FLOWER THRIPS FRANKLINIELLA-OCCIDENTALIS PERG (THYSANOPTERA, THRIPIDAE)

Sticky blue traps are a suitable and important tool for Western Flower Thrips population monitoring in greenhouses. They can be used in vege tables and in ornamentals, and provide important information on the cu rrent status of the pest population. However, such traps cannot be use d in some susceptible plant species when they are flowering because at that stage the plants are more attractive to Western Flower Thrips th an the traps. We therefore tried to increase trap attractiveness by co mbining the colour cue with an attractive odour cue. In laboratory exp eriments, we found a significant additive effect on attractiveness for two odours in traps provided with both the visual and the olfactory c ues as compared to traps with either cue alone. However, these results could not easily be reproduced in greenhouses. The main factors respo nsible for this failure seem to be (1) the only moderate, additive inc rease of trap attractiveness when using combined visual and olfactory cues, and (2) the problems associated with odour diffusion. Unless a m ore attractive odour is found and a suitable odour dispenser is availa ble, the use of odours to enhance sticky blue trap attractiveness for Western Flower Thrips cannot be recommended and, given the added cost for the trap, may not be affordable for growers.