Mungbean yellow mosaic virus: host range and relationship with the vector, Bemisia tabaci Genn.

Mungbean yellow mosaic virus: host range and relationship with the vector, Bemisia tabaci Genn.

Pantnagar G. B. Pant Univ. of Agric. & Tech. India

1972

93p.

Ph.D. (Plant Pathology)

SB205.M8R3

Some studies on the mungbean yellow mosaic virus were carried out. The aspects included were (i) Host range of the virus (ii) Influence of different host plant combinations on virus-vector relationship, and (iii) Relationship of the virus with its vector, Bemisia tabaci. The results of experiments have been summarized below: The host range of MYMV was studied by testing ninety-eight varieties of fify-three plant species belonging to fifteen families. Two plant species; i.e., Cosmos bipinnatus (Mandarin-Fiesta) and Phaseolus vulgaria var. Manitov were found to be the additional hosts of MYMV. The minimum acquisition and inoculation feeding periods, using different source-test plant combinations, varied from 15 to more than 60 minutes and 10 to more than 60 minutes, respectively. The minimum incubation period of MYMV in the vector varied between 3 to 8 hours in differnt source-test plant combinations. The host plants which show "yellow mottle" reaction (Mahaillupalam-1, urd bean and Jalgaon-781 mungbean), were found to be the better sources of MYMV as well as highgly susceptible to it as compared to host varieties which show "necrotic mottle" reaction (T-9 urd and T-44 mungbeans). The adults required longer acquisition and inoculation feeding periods to infect soybean var. Bragg (from and to soybean) and pigeon pea var. T-21 (from and to pigeon pea) as compared to urd and mungbeans. The virus was readily transmissible between Mahaillupalam-1 urd bean and Jalgaon-781 mungbean. The virus was transmissible from soybean (Bragg) to urd bean (Mahaillupalam-1) with a shorter feeding period as compared to the transmission from urd ben (Mahaillupalam-1) to soybean (Bragg). When the pigeon pea (T-21) was used in transmission tests (from urd bean to pigeon pea to infect the test plants in 60 minutes of acquisition and inoculation feeding periods. The female whitefly adults preferred the healthy green leaves of urd bean for oviposition as compared to diseased leaves showing clear symptoms of "yellow motte". The MYMV persisted in female and male adults of B. tabaci for a maximum of 10 and 5 days, respectively, but not throughout the life span of the vector. The transmission efficiency of female adults as the vector of MYMV was more than three times higher as compared to male adults. The female adults also remained alive for a longer time as compared to males. The results of the experiment on transovarial transmission were negative, indicating that there is no transovarial transmission of MYMV. The MYMV appears to be a circulative type virus. The whitefly adults were able to acquire MYMV from inoculated Mahaillupalam-1 urd bean plants one to three days before these plants actually showed initial symptoms. Attempts to transmit the virus by allowing the adults to feed on diseased leaf extracts through parafilm-membrane were unsuccessful. [AS]

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