Resistance screening against the South American tomato pinworm (Tuta absoluta) in tomato by means of a simple bioessay.

A greenhouse bioessay is described for screening resistance against the South American tomato pinworm (Tuta absoluta Meyrick = Scrobipalpuloides absoluta Meyrick) in large tomato populations. Two L. esculentum cultivars and three wild Lycopersicon accessions were evaluated. Young fully expanded leaves of adult plants grown in pots were infested using young tomato leaves carrying neonate larvae. The infestation rate was evaluated 7, 14 and 21 days after the infestation. No differences were found between plants within genotypes. Highly significant differences between genotypes were found twenty one days after the infestation date. The broadsense heritability of the infestation rate at twenty one days was 0.95, indicating the high reproducibility of the bioessay. The current results show that the bioessay is simple, highly reproducible and it allows the discrimination between resistant and susceptible plants in large segregating populations, both in the greenhouse and in the field.

Key words: pest resistance, South American tomato pinworm, Tuta absoluta, tomato, Lycopersicon spp.