Respostas biológicas de Sipha flava (Forbes, 1884) (Hemiptera: Aphididae) alimentados em diferentes genótipos de capim-elefante

Abstract

This work aimed to evaluate the effect of genotypes of elephant grass, Pennisetum purpureum Schum, on some biological aspects of Sipha flava (Forbes). Foliar disks of 15 elephant grass genotypes were used, on which individual nymphs up to 12 hours old were placed in dishes and kept at 25 ºC, RH of 70 ± 10% and 12-hour photophase. We evaluated the number of instars, duration and survival of each instar and the entire nymphal period, duration of the pre-reproductive, reproductive and post-reproductive period, daily and total nymph production capacity and longevity of the adults and biological cycle (nymph-adult). The nymphs passed through four instars on all the elephant grass genotypes studied. There were no significant differences in the duration of the first and last nymph stages on the different genotypes, unlike observed for the intermediate instars and nymphal period. The biological parameters of the adult phase of the aphid, such as pre-reproductive, reproductive and post-reproductive period and longevity, were also affected by the genotype. Cameroon de Piracicaba and Guaçu IZ2 were the most suitable genotypes for development of the aphids, providing higher values for overall production of nymphs/female, daily production of nymphs/female, reproductive period and adult longevity. On the other hand, the Sem Pêlo genotype was the least suitable for the aphids’ development and reproduction according to the biological parameters studied.