Submitted to: Journal of Entomological Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/22/1997
Publication Date: N/A
Interpretive Summary: Cotton is an important cash crop in the United States. Early season insects, which must be controlled, include thrips. Thrips resistance in cotton is often associated with extreme pubescence (hairiness). Heavy pubescence is undesirable since plant hairs contribute to trash in lint. Converted race stocks were screened for thrips tolerance in an effort to find sources that did not have heavy pubescence. One race stock was identified that showed promise as a source of tolerance. A genetic study with five genetically different cottons indicated that non-additive genetic variance predominates. This suggests a long term effort would be required to transfer the resistance to acceptable cotton varieties.
Technical Abstract: Thrips (Thysanoptera: Thripidae) resistance or tolerance in cotton (Gossypium hirsutum L.) is often associated with extreme pubescence. This is undesirable since hairy (pubescent) plants tend to have more trash in harvested lint which reduces the price received by growers. Two other possible sources of resistance include gossypol and thick lower epidermal cells; the latter has been found in G. barbadense L. Five G. barbadense genotypes were mated in a North Carolina Design II to 4 upland cultivars to evaluate combining ability. In addition, 90 converted racestocks were screened for tolerance to thrips. Experiments were designed to evaluate tolerance or resistance by comparing plots with and without thrips. Two G. barbadense parents had tolerance to thrips while 2 upland cultivars also exhibited tolerance. In the F1 generation, general combining ability was significant for thrips damage ratings among the G. barbadense parents. In the F2 generation, all characters exhibited specific combining ability. Thus, non-additive genetic variance predominates measures of thrips tolerance.