Morphological characters of resistant and susceptible Ipomoea batatas genotypes to Tetranychus ludeni (Acari: Tetranychidae)

Abstract

Plant morphology has been associated with the resistance or susceptibility to herbivores. The objective was to identify morphological characters involved in resistance genotypes Ipomoea batatas from the germplasm bank of the University Federal dos Vales do Jequitinhonha e Mucuri (UFVJM) to Tetranychus ludeni. Natural infestations of T. ludeni were observed in 54 sweet potato genotypes from the Vegetable Crops sector of UFVJM in a greenhouse. Morphological characters as the number of leaf trichomes, quantity of epicuticular wax on the leaves, leaf area and thickness of the cell wall cuticle and epidermis, were analyzed in five more susceptible (BD 29, BD 08, BD 57, BD 17 e Espanhola) and the five less susceptible (BD 03, BD 31 TO, Brazlândia, Branca, Marmel e BD 33) sweet potato genotypes to this mite. The genotypes, except the BD 29, showed glabrous leaves. The quantity of wax extracted from more susceptible to T. ludeni was lower. The wax of resistant plants may reduce feeding by T. ludeni. The thickness of the cuticle and cell wall of the leaves is not involved in the selection process. Glabrous leaves with lower leaf area and greater quantity of wax epicuticular per leaf increase resistance of this plant to T. ludeni.