Suppression of pink bollworm and effect on beneficial insects of a nectariless okra-leaf cotton germplasm line

• Published in: Bulletin of entomological research 1991-12, Vol.81 (4), p.379-384
• Main Authors: Flint, H.M., Wilson, F.D., Parks, N.J., Reynoso, R.Y., Stapp, B.R., Szaro, J.L.
• Format: Article
• Language: English
• Subjects: beneficial insects; cultivars; Gelechiidae; genetically modified organisms; germplasm; Gossypium; Gossypium hirsutum; insect control; insecticides; Lepidoptera; lines; Lygus; Miridae; Original Articles; oviposition; Pectinophora gossypiella
• ISSN: 0007-4853; 1475-2670
• DOI: 10.1017/S000748530003193X

Infestations of pink bollworm, Pectinophora gossypiella (Saunders), (Lepidoptera: Gelechiidae), and numbers of beneficial insects in two cottons, Gossypium hirsutum, were compared at Maricopa, Arizona, and Brawley, California, during the 1986–1988 seasons. Plots (0.8 ha) of WC-12NL (nectariless, okraleaf, and early maturing) had significantly lower boll infestations than DPL-61 (nectaried, normal leaf, and later maturing) for each location and year. The three year average (range) PBW/100 bolls for WC-12NL and DPL-61 at Maricopa were 6.8 (5.7–10.7) compared to 11.2 (6.8–15.7), respectively. At Brawley the averages were 18.9 (9.3–27.6) compared to 39.2 (15.5–52.5), respectively. With the exception of 1986 at Maricopa, the percentage of bolls with eggs was significantly greater for DPL-61 (average 8.1, range 3.4–16.0) than for WC-12NL (average 4.2, range 1.1–12.1) for each location and year. Both cottons averaged about four eggs per oviposited boll; not significantly different. The numbers of Lygus spp. and three beneficial species of insects were not different in the two cottons. Collops vittatus (Say) (Coleoptera: Melyridae) was collected in significantly greater numbers in WC-12NL (1.0 per 50 sweeps compared to 0.9 for DPL-61), while Hippodamia convergens (Guérin-Ménéville) (Coleoptera: Coccinellidae) was collected in greater numbers in DPL-61 (0.6 per 50 sweeps compared to 0.3 for WC-12NL). WC-12NL is the culmination of a 20-year breeding programme for resistance to P. gossypiella and has characteristics attractive for cotton production in areas where a shorter growing season is desirable.