EFFECT OF VISUAL CUES AND A MIXTURE OF ISOTHIOCYANATES ON TRAP CAPTURE OF CABBAGE-SEED-WEEVIL, CEUTORHYNCHUS-ASSIMILIS

The effect of trap design, trap color, and a mixture of isothiocyanate s on the capture of Ceutorhynchus assimilis (Paykull) was studied in a series of field experiments. Unbaited yellow water traps, a yellow st icky box trap, and a yellow sticky card trap, mounted vertically, or a t 45 degrees to the vertical with the yellow card facing upwards were effective for capturing seed weevils, but a horizontal yellow sticky c ard trap caught few. White, green, and black traps were unattractive. During migratory periods, trap catch could be enhanced two to four tim es with a lure consisting of a mixture of allyl, 3-butenyl, 4-pentenyl , and 2-phenylethyl isothiocyanates, but this bait did not attract in a trap with ineffective design. The sticky card trap, mounted at 45 de grees to the vertical and baited with the isothiocyanate mixture, may be useful for monitoring movement of C. assimilis during migratory per iods. However, during the colonization phase, lures of either a mixtur e of isothiocyanates or of allyl isothiocyanate alone were not attract ive.