Influence of some polygonaceous plants on biology of Galerucella placida baly (Coleoptera: Chrysomelidae)

Biology of leaf beetle, Galerucella placida Baly was studied on eight polygonaceous plants, which indicated that body length and width of 1^st-3^rd instar larvae was maximum on Polygonum hydropiper (L.) Spach. and minimum on Polygonum perfoliatum L. Pupal length and width was maximum (4.58 mm and 2.37 mm) on P. hydropiper (L.) Spach. and minimum (4.10 mm and 2.05 mm) on P. perfoliatum L. The maximum length and width of male (5.60 mm and 2.35 mm) and female (6.25 mm and 2.50 mm) was recorded on P. hydropiper (L.) Spach. and minimum (5.10 mm and 2.00 mm) for male and (5.50 mm and 2.15 mm) for female on P. perfoliatum L. Similarly, shortest larval (13.12 days) and pupal duration (4.46 days), and highest fecundity (431.60 eggs/female) was recorded on P. hydropiper (L.) Spach. The maximum larval (17.25 days) and pupal duration (4.76 days), and lowest fecundity (163.00 eggs/female) were observed with P. perfoliatum L. These observations indicate the scope for use of G. placida as a biocontrol agent against P. hydropiper, since it was found the most suitable host plant in comparison to other polygonaceous plants.