Whitefly (Bemisia tabaci Gennadius) is a plant sap-sucking insect and transmits begomovirus, tomato leaf curl New Delhi virus-potato (ToLCNDV-potato) causing potato apical leaf curl disease has been posing serious threat to potato production in Northern India. Therefore, a field survey was conducted in Northern India during 2013-14 and 2014-15 potato offseason to identify the host plants, activity of whitefly on these plants with confirmation of ToLCNDV-potato through PCR. The presence of whitefly and PCR results revealed that cultivable host plants Abelmoschus esculentus, Capsicum annum, Dahlia pinnata, Luffa cylindrica, Solanum melongena, Tagetes erecta, Vigna radiata and non-cultivable host plants Phyllanthus niruri, Trifolium repens, Acalypha indica and Commelina benghalensis acquired ToLCNDV-potato in due course of time, however some of the alternate host plants were found negative, while whitefly collected from these plant showed positive reaction or vice versa. The findings of this study would help in studying the movement of whitefly and survival of ToLCNDV-potato on alternate host plants for better management of this disease in potato. As a precaution, a care should be taken to remove these plants in the vicinity of potato breeder seed crop in whitefly endemic area for the effective management of apical leaf curl disease of potato.

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In India, more than 85% of the total potato production is realised from the subtropical Indo-Gangetic plains where potato is cultivated during winter. The cotton whitefly, B. tabaci is a major pest of potato as it transmits the Tomato leaf curl New Delhi virus (potato) causing the Apical leaf curl disease which leads to huge yield losses. The population dynamics of cotton whitefly was studied at 12 locations across the northern plains of India from 2015–17. It was observed that the cotton whitefly appears on potato immediately after crop emergence. The whitefly adults exhibited four different patterns of population dynamics at different locations. Whiteflies remained on the potato crop as long as minimum daily temperature was above 10–12ºC after which the whiteflies either disappeared from the crops or their flight activity was considerably reduced as indicted by the yellow sticky trap catch data. The whitefly incidence was higher at locations where potato is preceded by crops preferred by whitefly such as cotton, broad beans, groundnut etc. Perusal of the data on number of eggs laid and ensuing nymphs per plant indicated that the contribution of immigrating adults to the whitefly population is much higher than that of the colonising population for major part of the crop period. Thus, in addition to temperature, cropping sequence acts as a major factor in shaping the pattern of whitefly infestation. The results will help in deciding cropping pattern and better timing of insecticidal applications for healthy seed potato production.

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