The objective of this study was to survey the possible alterations on the development of Tuta absoluta (Meyrick) larvae fed on leaves of Lycopersicon hirsutum f. glabratum, PI 134417 - resistant to this insect and L. esculentum, 'Santa Clara' - susceptible, treated with formulation of Bacillus thuringiensis var. kurstaki (Btk). In order to obtain larvae in the different instars used in these experiments, neonate larvae were reared on the tested Lycopersicon plants until the desired instar. For each larval ages (unfed neonate, 1st, 2nd, 3rd, and 4th instars), were made a separate bioassays in which larvae fed on tomato leaves of the two genotypes + Btk. Larval developmental time was delayed and larval survival was reduced by both resistant tomato and Btk treatment. There was a significant interaction between these treatments for larval development time when 3rd instar larvae fed on Btk-treated leaves and for larval survival, when 4th instar larvae fed on Btk-treated leaves. The pupal weight was affected more drastically by the genotype that for the pathogen. The application of Btk on tomato genotypes insect resistant/susceptible increased the efficiency of the control of T. absoluta wich depended on the age of larvae and was larger in the first two instares.
Insecta; South American tomato pinworm; plant resistance; entomopathogenic bacterium