Biology of Coccinella repanda Thunb. an important predator of mustard aphid Lipaphis erysimi (Kltb.) in Assam.
A laboratory and field study was carried out in India on the biology of Coccinella repanda Thnb., an important predator of Lipaphis erysimi (Kalt.) on mustard in Assam. Each female laid an average of 167 eggs; oviposition was not continuous, eggs being laid in phases. All stages of C. repanda preferred 1st-instar nymphs of L. erysimi as food. Fourth-instar larvae of the coccinellid consumed more prey than any other stage. Eggs laid in mustard fields were difficult to find. The population build-up of the predator began in January. Following harvest in March, adults of C. repanda emerging from pupae moved to adjacent wheat fields, and this was thought to be influenced by the presence of Sitobion miscanthi (Tak.) (Macrosiphum miscanthi) on the wheat. A species of Tetrastichus parasitised the pupae of the predator, but it did not appear to be a major threat in the study area.