Impact of melon accessions resistant to aphids on the demographic potential of silverleaf whitefly.

Bemisia tabaci (Gennadius) and Aphis gossypii Glover are devastating melon, Cucumis melo L., pests. The geographic areas where they occur overlap, and the same chemicals are used to control both of them. Therefore, to reduce pesticide use, it would be necessary to breed melon lines that simultaneously express a resistance to both insects. Female survival; the time when reproduction starts, peaks, and ends; the number of female offspring at the reproductive peak; and total reproduction (S) were determined under semicontrolled conditions for B. tabaci kept in clip-cages on a susceptible melon genotype Vedrantais, and 12 potential resistant accessions, particularly genotypes expressing the Vat gene controlling resistance to A. gossypii. By using the Lewontin triangular reproductive function and Bootstrapping, the intrinsic rate of increase (r) and its variance were calculated. Statistical analysis showed that the parameter S was as relevant as r for discriminating between the melon accessions. Three genotypes were potential genitors of resistance to the whitefly: PI 161375, PI 414723, and PI 532841. Those possessing the Vat gene were either resistant (PI 161375 and PI 414723) or susceptible (Margot, IsoVat R, and AR 5). This demonstrated the ineffectiveness of Vat against B. tabaci. In this article, we propose a strategy to breed lines that express resistance to aphids and whiteflies on the short-term.