ACQUISITION, INCUBATION AND TRANSMISSION OF WATERMELON SILVER MOTTLE VIRUS BY THRIPS PALMI
Acquisition, incubation, and transmission of Watermelon silver mottle virus (WSMoV) by individual Thrips palmi,Karny were investigated by examining symptoms developed on assay host Benincasa hispida (Thumb.) Cogn. An acquisition threshold period of 30 min was required when 5 first instar nymphs as a group were used to transmit the virus. The efficiency of transmission doubled when the acquisition access period increased to 24 hr. Nymphs were able to transmit WSMoV within 2 hr after a 2-hr acquisition access feeding on diseased plants. Of the 64 thrips given a 6 hr acquisition feeding at the nymph stage, about 63% transmitted the virus at either nymph or adult or both stages. Sixteen thrips transmitted the virus on the 1st day. Among transmitters, about one fifth of the insects transmitted only once in their lifetime, and, 22, 5 and 3 individuals transmitted WSMoV 2, 3, and 4 times during their lives, respectively. About 30% thrips transmitted only at the nymph stage, 15% only at the adult stage, and 22% at both stages. About 25% of the transmitters were able to make a successive 2-day transmission. Our data show that, once becoming viruliferous, T. palmi may or may not transmit WSMoV later in life. The results of the study also show an erratic pattern of WSMoV transmission by T. palmi. Our observations suggest that there may be two mechanisms involved in the transmission of WSMoV by T. palmi, a non-circulative stylet-borne transmission at very early stage and the other the propagative-circulative form in later stage.
Chen, C.C., Yeh, S.D. and Hsu, H.T. (2006). ACQUISITION, INCUBATION AND TRANSMISSION OF WATERMELON SILVER MOTTLE VIRUS BY THRIPS PALMI. Acta Hortic. 722, 83-90