Influence of the pigeonpea Cajanus cajan (L) Millsp cultivars on the population density of the spiralling whitefly, Aleurodicus dispersus Russel (Homoptera: Aleurodidae)

摘要

Spiralling whitefly, Aleurodicus dispersus Russel (Homoptera: Aleurodidae) originated from Central America, got recently introduced into India (David and Regu, 1995), is a polyphagous pest infesting many agricultural and horticultural crops. Chemical control is almost impossible due to its very wide host range and poor contact of insecticides due to the presence of heavy waxy coating and threads over its bodies. So the ultimate solution to manage this pest is the alternate methods of evolving and adopting resistant varieties which has been recognised as one of the important method in the IPM programme (Painter, 1968). Hence varietal screening studies to identify the resistant germplasm was carried out. Spiralling whitefly was not a serious pest onpigeonpea until recently, however it may become a serious pest in near future. Keeping these in mind, a survey was conducted on the incidence of the spiralling whitefly on pigeonpea cultivars raised at Agricultural College and Research Institute, Madurai during 2001. Seven cultures (PUSA MS 33, MS Co 5, MS Prabhat DT, MS Prabhat NDT, QMS 1, QMS 288A and GT 288B), five cultivated varieties (ICPL 87, IDT 2, PUSA 928, Co RG 9060 and ICPL 1045) and five F_1 hybrids (QMS 1 X 88027, NDT X Co 5, NDT X APK 1,DT X Co5 and DT X 8403 1) were raised in field in a randomized block design with four replication. Cultivation methods were followed as per crop production guide, (Anon, 1999). In each plot, five plants were selected for recording pest incidence. In theindividual plant, three leaves one each from top, middle and bottom was selected for sampling. In each leaf, number of spiralling whiteflies, both nymphs and adults were observed. For eggs, the leaves were graded from 0 to 5. In each plot, number of total plants and affected plants were counted and per cent infestation was calculated. The data were subjected to suitable transformations, analysed by randomized block design method and the means were separated by DMRT (Gomez and Gomez, 1984).