1Division of Entomology and Nematology, Indian Institute of Horticultural Research, Hessaraghutta Lake Post, Bangalore-560 089 (India).
2Department of Zoology, Bangalore University, Bangalore-560 056 (India).
Zygogmmma bicolorata Pallister, introduced for biological control trials against the noxious weed, Parthenium hysterophorus L., was capable of breeding at constant temperatures ranging fFom 15 to 35°C in the laboratory. The temperature range between 20 and 30°C was most suitable, the total development being completed in 46.63 and 20.75 days, respectively. Eggs failed to hatch at 40°C and only 4 and 16% hatching was obtained at 15 and 35°C, respectively. The adults diapausing within the soil could tolerate continuous exposure to 40 and 45°C for only 10 days and 21 hours, respectively. This suggests that the beetle is unlikely to survive in a state of diapause, in parts of the country where the temperature exceeds 45°C during summer.
