DEVELOPMENTAL THRESHOLDS AND THERMAL REQUIREMENTS NEEDED FOR THE COTTON PINK BOLLWORM PECTINOPHORA GOSSYPIELLA (SAUNDERS)

Abstract

The present study was conducted on the cotton pink bollworm, Pectinophora gossypiella (Saunders.) (Lepidoptera: Gelechiidae) the most devastative insect pest to cotton cultivations in Egypt. It causes great damage and loss in the cotton yield. All experiments were carried out in the laboratory of the environmental study, Department of Plant Protection, Faculty of Agric., Ain Shams Univ. aiming to estimate some biological parameters of P. gossypiella reared on artificial diet at four constant temperatures 18, 20, 25, 30oC with 65±5% RH, then determine threshold of development and thermal constant for each of the developmental stages and complete generation. Obtained results demonstrated that the duration of each developmental stage of P. gossypiella highly affected by the change of temperature. The incubation period of eggs greatly varied at different temperature, these periods were 10.86, 10.29, 6.00 and 4.00 days at 18, 20, 25 and 30oC, respectively. Threshold of development for P. gossypiella egg stage was 12.1oC. The mean of duration for P. gossypiella larvae, pupae were 30.40, 14.10 days and the durations for male, female and generation were 24.72, 26.99 and 57.95 days, respectively. The longest duration of larvae, pupae, male and female moths were 47.61, 20.13, 33.59 and 33.68 days recorded at 18oC while the shortest durations were 16.60, 7.40, 13.75 and 14.64 days recorded at 30oC for larvae, pupae, male and female moths, respectively. The threshold of development for P. gossypiella larval, pupal, male, female stages was 11.6, 12.1, 9.8, 9.5oC, respectively. The threshold of development for P. gossypiella generation was 11.7oC. Based on the estimated threshold of development and duration of each developmental stage at the respective rearing temperature, the average of thermal constant was estimated as 73.59 for egg stage, 298.76 for larvae, 124.98 for pupae, 299.49 for adult male, 338.96 for adult female and 567.80 DDs for P. gossypiella generation.