Factors of resistance in tomato accessions against the fruit worm, Helicoverpa armigera (Hubner)

Three tomato accessions (Lycopersicon spp.) selected from preliminary field and glasshouse screening of 321 accessions were studied for factors of resistance against the fruit worm, Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) in comparison with a susceptible check at Annamalainagar, Tamilnadu, India. In the field screening, the larval population on foliage and fruit damage was least in the accession Varushanadul Local. Under glasshouse conditions, larval feeding was least on the foliage and fruits of the accessions PT 4287, Varushanadu Local and Seijima Jeisei. These accessions exerted pronounced antibiosis on H. armigera as evidenced by higher larval and pupal mortality; prolongation of larval and pupal tenure; decline in emergence and longevity of adults and also higher malformation in the emerging adults. Among the factors of resistance in these accessions, ortho-dihydroxy phenols, trichome density in the foliage and acidity of the fruits exerted a significant negative correlation on larval feeding. Non-reducing sugars in the foliage had a significant positive correlation with larval feeding.