BEMISIA-ARGENTIFOLII ADULTS CAUGHT IN CC WHITEFLY TRAPS AT DIFFERENT TRAP HEIGHTS AND TRAP CATCH RELATIONSHIPS TO LEAF-TURN COUNTS ON COTTON

The effects of trap placement on adult Bemisia argentifolii Bellows an d Perring catches in a new whitefly trap (CC trap) in cotton fields we re studied in California and Arizona in 1996 and 1997. In a no-choice study in 1996, more adults were caught in traps placed 15 cm below the top of the cotton canopy compared with traps placed at canopy top or 15 cm above the plant canopy. Traps caught more whitefly adults in the Stoneville 474 and Louisiana 887 plots compared with traps placed in the Deltapline 5415 and 5461 plots, reflecting the same differences in adult populations on the leaves in the plots, as determined using the leaf-turn method. In a no-choice trap study in 1997, trap catches wer e significantly correlated with leaf-turn counts with traps placed at the top of cotton beds, 30, 60, 90 and 120 cm above plant beds. Signif icant correlations occurred from 21 August to 18 September when the le af-turn adult counts were 54 or more adults per ten leaves. In a choic e study in 1997, trap catches from 14 August to 18 September were sign ificantly correlated with the leaf-turn adult counts for traps placed from 30 to 120 cm above cotton beds.