Lack of correlation between host choice and feeding efficiency for the B and Q putative species of Bemisia tabaci on four pepper genotypes

The B and Q putative species of Bemisia tabaci are among the most invasive pests in the world. In China, Q is displacing B. Although this displacement is often attributed to the higher resistance of Q to insecticides, a higher tolerance of Q to low-quality host plants may also be important. In this study, we first determined the contents of main secondary insect-resistant compounds (total phenol and flavonoids) and nutrients (total amino acid, free protein, total nitrogen, phosphorus, and potassium) in four genotypes pepper (Capsicum annuum). We then conducted host choice and feeding behavior (EPG) experiments with B and Q on the four pepper genotypes. Zhongjiao4 was found to be the high-quality genotype (it had low levels of insect-resistance substances and high levels of nutrients), and Zhonghuahong was found to be the low-quality genotype (it had high levels of resistant compound and low levels of nutrients). EPG data indicated that both B and Q females fed more efficiently on high-quality Zhongjiao4 than on the other three pepper genotypes. In terms of settling and oviposition, however, B preferred the low-quality Zhonghuahong, and Q showed no preference among the four genotypes. We suggest that the lack of correlation between the results for feeding efficiency and settling/oviposition might be explained by repellent plant volatiles whose effects differ depending on pepper genotype and whitefly species.