Responses of whitefly and poinsettias to insecticidal controlled atmospheres

Eggs, larvae, pupae, and adult stages of greenhouse whitefly (Trialeurodes vaporarium Westmood) and silverleaf whitefly (Bemisia argentifolii Bellows & Perring) were exposed to insecticidal controlled atmospheres at 20 degree s C or 30 degrees C, Mortality data were calculated for each stage and resu lts demonstrated that reduced-O-2 atmospheres (an O-2 level of <2 mu L . L- 1 balance in N-2) resulted in faster and higher mortality than elevated-CO2 atmospheres (25 % or 50 % CO2). Responses, from the least to most tolerant stage was adult < larvae < eggs = pupae, regardless of the species of whit efly and treatment temperature. At 20 degrees C, treatment time required to kill >90% of adults, larvae, and eggs and pupae was 2, 4, and 8 hours, res pectively. Increasing the treatment temperature from 20 to 30 degrees C red uced the treatment time to one-half that of 20 degrees C, Treatment time re quired to achieve complete elimination of the insects also caused phytotoxi city symptoms on poinsettias (Euphorbia pulcherrima Willd. es Klotzsch), th us, limiting use of insecticidal controlled atmospheres as the sole means f or managing whitefly.