Resistance of string beans genotypes to the attack of Zabrotes subfasciatus (Bohemann, 1833) (Coleoptera: Chrysomelidae)

Abstract

The string bean (Phaseolus vulgaris L.) can be attacked by worms of species such as the Zabrotes subfasciatus (Bohemann, 1833) (Coleoptera: Chrysomelidae), which directly affects the pods and seeds quality, making them unsuitable for consumption and commercialization. In order to find out an alternative way of controlling this insect, string bean genotypes and resistance levels to the Z. subfasciatus attack were evaluated, by using free and no-choice tests. The genotypes used were the UEGD7, UEG05, UEG06, UEG11, UEG13, UEG15, UEG18, UEG19 and UEG26, with four replications. In the free-choice test, the number of total, viable and unviable eggs and the attractiveness of adults by genotypes were evaluated. In the no-choice test, the number of total, viable and unviable eggs, dry weight consumption and dry weight consumption per insect, adult insect weight and longevity, period from egg to adult, sex ratio and number and percentage of insect emergence were evaluated. It was observed that the UEG05 genotype was the less preferred for oviposition by Z. subfasciatus, in the free-choice test. The UEG13 genotype showed to be highly resistant and the UEG05, UEG15 and UEG19 were moderately resistant. The UEG18 genotype was considered susceptible and the other ones highly susceptible to Z. subfasciatus.