Pink bollworm (Lepidoptera: Gelechiidae): oviposition and larval success on resistant and susceptible cotton plants
1984
Wilson, F.D. | George, B.W. | Szaro, J.L.
Oviposition and larval development of pink boll worm (PBW), Pectinophora Gossypiella (Saunders), on a breeding stock of upland cotton, Gossypium hirsutum L., designated AET-5, was compared to that on a commercial cultivar, 'Deltapine 61' (DPL-61), in greenhouse no-choice and free-choice tests, and in field free-choice tests. The field resistance of AET-5 was caused mainly by lower PBW oviposition. The early-flowering advantage of AET-5 was negated in the greenhouse experiments. In the field, AET-5 exhibited a modest level of internal-boll antibiosis, as shown by its lower ratio of insects per boll recovered for each PBW entrance hole. In the greenhouse, the ratio of entrance holes for every egg laid was lower on AET-5 than on DPL-61. The antibiosis, and the lower number of entrance holes per egg laid may be valuable in transferring AET-5's resistance to improved breeding stocks. Cultivars that are early maturing and carry the other resistance factors would be valuable in short-season, narrow-row production systems because the need for insecticides would be reduced or eliminated. Of the total eggs per plant, 55% of AET-5 and 46% of DPL-61 were laid in clusters at the base of the stem or in the soil around the base of the stem. Mean percentages of eggs laid (above the stem base) on axillary branches, bolls, leaves, and all other plant parts combined (terminals, stems, squares, and flowers)were 41, 42, 13, and 4%, respectively, for AET-5; and 51, 36, 9, and 4%, respectively, for DPL- 61. The total number of eggs per plant was not significantly different on AET-5 than on DPL-61 in the greenhouse, but AET-5 had significantly fewer eggs per plant in the field.
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