Abstract:
The objective of this work was to evaluate the resistance of Manihot esculenta and its hybrids (M. esculenta x M. esculenta ssp. flabellifolia and M. esculenta x M. esculenta ssp. peruviana) to the whitefly (Aleurothrixus aepim). The trial was carried out in a greenhouse from October to December 2015, and it was based on a completely randomized design with eight treatments (eight genotypes). The evaluated variables and replicates were the following: duration of the developmental phases of the whitefly (nine replicates); nymphal viability (nine replicates); egg viability (five replicates); period of incubation (five replicates); and number of eggs (three replicates). Trichome counting (nine replicates) and the colorimetric analysis (nine replicates) were also performed. The 'Ecuador 72' genotype promoted the lowest value for viability of the immature development phase (44.89%), showing an antibiosis effect on A. aepim. The FLA 003 genotype (a wild accession of M. esculenta ssp. flabellifolia) and the F1 011 (M. esculenta x M. esculenta ssp. flabellifolia) and PE 001 (M. esculenta x M. esculenta ssp. peruviana) hybrids showed resistance by antixenosis and were the less preferred for oviposition. The 'Ecuador 72', FLA 003, F1 011, and PE 001 genotypes can be used as sources to obtain new, resistant cultivars of cassava.
Index terms:
antibiosis; antixenosis; pests; varietal resistance; wild cassava