Oviposition site preference of Pectinophora gossypiella (Lepidoptera: gelechiidae) on cotton and its effects on boll development

Abstract

Pectinophora gossypiella (Saunders) eggs were distributed over all parts of cotton plants with usually one per site. During early season (July–August) females preferred to oviposit on CIM-70, CIM-109 and NIAB-78 which flowered earlier than the late maturing varieties, Alseemi-515 and CIM-135. On medium maturing varieties, 77% more eggs were laid in September and 14% in October. On late maturing varieties, 85% and 46% more eggs were laid during the corresponding period compared with CIM-70. Most oviposition on flower buds was during August (72.5%) and on bolls during September (70.6%) and October (85%), when few eggs were laid on vegetative parts. Females from diapause larvae lived on average 7.3 days with lower fecundity (75 eggs/female) compared with the non-diapause generation (9.0 days; 125 eggs/female). Females preferred half grown flower buds (7–10 days old) for oviposition, laying 82–94% of the total eggs compared with 7–11% on large flower buds. More bolls from rosette and healthy flowers during August were shed compared with September and October with significant differences between months. Shedding was minimum in CIM-70 and Alseemi-515 but the differences were non-significant. However, differences between these two varieties and NIAB-78, CIM-109 and CIM-135 were significant. Shedding of bolls was between 2nd and 12th day of boll formation, the maximum being from 4th to 6th day. More than 64% of bolls that developed from rosette flowers were shed, whereas, 8–10% were shrivelled on one side and the rest were normal. Bolls that developed from rosette flowers had fewer seeds and less lint than those which developed from healthy flowers.