Biotic Potential of Three Coccinellid Predators on Various Diaspine Hosts

Biotic potential of three Coccinellid predators viz., Chilocorus bijugus (Muls), Chilocorus nigritus (Fab.) and Sticholotis madagassa (Weise) were studied on various diaspine scales. C. bijugus and C. nigritus accepted all the hosts provided whereas, S. madagassa accepted only three hosts. When aqueous extract of sugarcane scale insect was sprayed over non-preferred host, S. madagassa could develop on two additional hosts. Developmental period on different hosts in case of C. bijugus and C. nigritus ranged from 33.5 to 41.4. and 32.3 to 35.1 days respectIvely, whereas S. madagassa developed faster on Melanaspis glomerata (Green) (33.4 days) than on other hosts. S. madagassa was also found to be more fecund on M. glomerata. C. bijugus showed relative preference for Quadraspidiotus perniciosus (Comst.), lived longer and produced larger progeny. C. nigritus fed and bred equally well on all the bosts provided, showing its wide acceptability and polyphagous nature. C. nigritus was found to be more promising on biotic parameters followed by C. bijugus and S. madagassa.