Investigation on the Biological Characteristics and Thermal Requirements of Egg Parasitoid Trichogrammatoidea bactrae on Eggs of Cotton Pink Bollworm

The biological traits and thermal needs of Trichogrammatoidea bactrae Nagaraja was assessed on the eggs of the Pink bollworm, Pectinophora gossypiella to predict the ideal temperature for the release of the parasitoid. A card with 300 P. gossypiella eggs was offered to T. bactrae adults in a 5:1 ratio at temperatures 18, 20, 22, 24, 26, 28, 30, 32, 34 and 36 oC. All developmental stages of T. bactrae were monitored at each temperature, however, no parasitism or development occurred at temperature 36°C. The highest parasitism rate was observed at 28°C (76.03%), and emergence rates exceeded 85.65% between 18 and 30°C. Temperature variations affected both the development duration and adult longevity, with higher temperatures leading to shorter development times and reduced lifespan. The highest proportion of female offspring was recorded at 20°C (73.67%). The total heat requirement for complete development was calculated to be 136.98 degree-days (K), with a lower threshold temperature identified at 11.75°C.