Response of Bemisia argentifolii (Homoptera: Aleyrodidae) to water and nutrient stressed cotton

Abstract

Water stress usually increases plant susceptibility to the whitefly Bemisia argentifolii Bellows and Perring, whereas nutrient stress generally reduces the level of whitefly infestation. This study examined the effect of water and phosphorus stress on plant physiological traits to help explain the response of B. argentifolii to host plant conditions. Host preference was determined by examining oviposition rates on water- and phosphorus-stressed cotton, Gossypium hirsutum L., in the greenhouse, and by studying the effect of irrigation frequency on oviposition and B. argentifolii developmental rate in the field. In the greenhouse oviposition was reduced 9% (P = 0.09) by water stress but was not affected by phosphorus deficiency. In the field, oviposition was 6 times greater in the biweekly compared with weekly irrigated plots. In nochoice experiments, however, oviposition was inaffected by irrigation frequency, with the exception of lower leaves in the canopy with had been previously damaged by B. argentifolii, where oviposition was reduced 63% in the biweekly plots where damage was the greatest. Irrigation frequency had no effect on developmental rate from egg to adult. In the greenhouse, oviposition was affected most by leaf position on the plant, and was >2 times as great on the youngest compared with the oldest leaf on a 4-leaf seedling. Multiple regression analysis suggested that oviposition was not independently affected by transpiration rate or leaf temperature. Leaf water potential, sucrose concentration, and amino acid concentration made the greatest contribution to B. argentifolii host selection, with oviposition being greatest on leaves with low water potential and low bulk leaf sucrose and amino acid concentrations.