Incidence of Trialeurodes vaporariorum (Hemiptera: Aleyrodidae) and defense mechanisms in Gerbera hybrida

Abstract

The existence of natural variation at different levels of whitefly infestation (Trialeurodes vaporariorum) in gerbera genotypes (Gerbera hybrida) allows the existence of different levels of resistance or susceptibility to the insect. In this investigation the natural variation of gerbera was evaluated at the incidence of T. vaporariorum. In a randomized complete block design, ten gerbera genotypes were analyzed in different phenological stages without incidence (SI) and with incidence (CI) of whitefly. Nymphs were counted, in a cm2 at the center of the underside of the leaves and total adults per leaf. The relative content of chlorophyll (USPAD), the content of phenolic compounds (Cf), the enzymatic activity of peroxidases (AePOX) and the antioxidant capacity DPPH (Caox) were measured. Gerbera genotypes showed significant differences in the incidence of whiteflies (p≤ 0.01), as well as in Cf, AePOX and Caox, both in SI and CI (p≤ 0.01), which suggests differences in insect preference a its host and the ability of genotypes to respond to whiteflies. In CI with respect to SI, they increased the content of Cf (1.4 times), AePOX (4 times) and Caox (12 times). USPAD decreased in the genotype with the highest incidence of the insect (-4%). The significant correlations between the number of insects (nymphs) with Cf (-0.71**) and AePOX (-0.65**) and Caox with Cf (-0.73**) and AePOX (-0.76**), showed that the feeding of the insect interferes with the metabolism of its hosts and triggers integral responses in the defense mechanism of plants, with differences in resistance that can be used in genetic improvement.