1Division of Entomology and Nematology, Indian Institute of Horticultural Research, Hessaraghatta Lake Post, Bangalore-560 089 (India).
2Department of Zoology, Bangalore University, Bangalore-560 056 (India).
The Mexican beetle, Zygogramma bicolorata Pallister, a promising biological control agent of the noxious weed, Parthenium hysterophorus L. (Asteraceae), required 407 day degrees for completion of its development. By summation of thermal units, it was estimated that the insect completed 5.6 generations under field conditions in Bangalore (India). The theoretical number of generations possible in different parts of the country could be estimated by following this method from mean maximum and minimum temperatures recorded in each area.
