Resistance of white potato (Solanum spp.) to Thrips palmi karny (Thripidae: Thysanoptera) and analysis of the mechanism involved
1994
Fernandez, E.C. | Bernadol, E.N. (Philippines Univ. Los Banos, College, Laguna (Philippines). Inst. of Plant Breeding)
In mass rearing the thrips on potted plants, it was found necessary to provide a thin soil layer for pupation, water the plants from below, ward-off the attack of foraging ants, and prevent increase in greenhouse summer temperature beyond 32 deg C. It was more practical to use eggplant than cucumber seedlings. To enhance thrips population build-up in low-elevation fields for adequate pest pressure on the test genotypes, the materials should be planted in January and sprayed with selective pesticide 7 and 14 days after planting to kill the natural enemies. Evaluation for thrips resistance should be done 2 months after plant emergence based on leaf damage rating. Through this elevation method, 2 wild potato species (Solanum chacoense and S. kurtzianum) and 8 S. tuberosum clones were selected as the most resistant among 440 genotypes tested. The mechanisms of resistance observed were ovipositional and feeding non-preference (antixenosis) and antibiosis manifested as increased thrips mortality, lengthened developmental period, reduced fecundity and shortened adult life. There was no consistent association between thrips resistance and trichome density, total ash, fiber or nitrogen content of the entries studied, suggesting the need to consider the specific chemical components instead. Most of the resistant entries have higher total glycoalkaloid content in the leaves. There were indications that other compounds are responsible for resistance in some genoytypes
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