Insect resistance in tomato accessions and their hybrid derivatives in Tamil Nadu, India.
Host plant resistance offers a viable alternative to the use of chemical insecticides for managing insects Infesting tomato. Hence, a study was carried out in Tamil Nadu, India during 1996 to 2004. An exhaustive germplasm comprising 321 tomato accessions including cultivars, wild lines, land races, tribal/native tomatoes was gathered from various sources and screened for resistance against the major pest namely fruit worm, Helicoverpa armigera Hubner (Noctuidae: Lepidoptera). In the field screening, larval population and fruit damage was evaluated while in the glasshouse, foliage and fruit damage was assessed and ten promising accessions were selected. Based on further laboratory studies on the various mechanisms and bases of resistance, four accessions namely, Varushanadu Local, Seijima Jeisei, Ac 238 and Roma were selected and subjected to intercrossing by conventional hybridization, which yielded three viable hybrids. The resistance potentials of these hybrids against the fruit worm, H. armigera, leaf caterpillar, Spodoptera litura Fab. Noctuldae: Lepidoptera), leaf miner, Liriomyza trifolii Blanchard (Agromyzidae: Diptera) and whitefly, Bemisia tabaci Genn. (Aleyrodidae: Hemiptera) were probed both in the field and glasshouse along with their respective parents. The hybrids exerted lesser feeding and ovipositional preference and higher antibiotic effects on insect stages. The density of three types of non-glandular and two types of glandular trichomes and phenol content in the foliage, lycopene and ascorbic acid content in the fruits were the major factors of resistance. Based on these studies, Hybrid 3 (Ac 238 x Roma) and its derivatives were adjudged as potential accessions possessing insect tolerance.
Selvanarayanan
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Department of Entomology, Faculty of Agriculture Annamalai University, 608 002 Tamil Nadu, India.
Muthukumaran
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D000818:Animals; D001205:Ascorbic Acid / Q000032:analysis / Q000494:pharmacology; D002338:Carotenoids / Q000032:analysis / Q000494:pharmacology; D003433:Crosses, Genetic; D004175:Diptera / Q000254:growth & development; D004198:Disease Susceptibility; D006430:Hemiptera / Q000254:growth & development; D007313:Insecta / Q000254:growth & development*; D007915:Lepidoptera / Q000254:growth & development; D000077276:Lycopene; D018551:Solanum lycopersicum / Q000737:chemistry / Q000235:genetics* / Q000469:parasitology*; D010572:Pest Control, Biological / Q000379:methods*
D002338:Carotenoids; D001205:Ascorbic Acid; D000077276:Lycopene