author(s)
S Onkara Naik, GS Kannan, V Venkataravanappa and AK Chakravarthy

abstract
Whitefly is one of the most intractable, highly polyphagous and serious pest on economically important food and fibre crops. It does direct damage to plants by feeding on the sap. Besides it serves as a potent means of virus transmission from plant- to -plant. The whitefly transmitted begomoviruses (YMV) are emerging as a serious threat causing leaf curl and yellow mosaic virus diseases on cucurbit and bitter gourd. The number of whiteflies required for YMV transmission experiment results indicated that, single whitefly transmitted the virus to an extent of 19.5 per cent and with an incubation period of 13.75 days. Fifteen whiteflies transmitted 100 % virus within 6.15 days of incubation. The whiteflies needed a minimum AAFP of 16 min to become viruliferous resulting in 15.65 per cent transmission. An IAFP of 30 min made the whiteflies viruliferous to cause 47.25 per cent transmission; an IAFP of 3h or more resulted in 100 per cent disease transmission. As IAFP increased, the incubation period decreased. The pre-acquisition starvation of whiteflies lasted for 3h or more was resulting in 100 per cent transmission and post-acquisition starvation period of whiteflies did not have any effect in increasing YMV transmission.