Journal of the Saudi Society of Agricultural Sciences (Feb 2022)
Population assessment of Bemisia tabaci (Gennadius.) and disease occurrence of Begomovirus in okra, Abelmoschus esculentus L
Abstract
Okra [Abelmoschus esculentus (L.) Moench] is an essential vegetable cultivated primarily for its delicious green pods. Whitefly, Bemisia tabaci (Genn.) attacks it and damages the foliage by sap-sucking, and also, it transmits Phyto-viruses like Okra Yellow Vein Mosaic Virus and Okra Leaf Curl Virus. The okra production losses due to Whitefly and transmitted viruses are prodigious. This research investigated the population fluctuations of whitefly and the Begomoviruses Percent Disease incidence (PDI) and Disease Severity Index (DSI) in different okra varieties. The Whitefly population's first incidence was recorded in early May, while it peaked in July and vanished in August. The highly susceptible variety was the native Peshawar-local (3.37 Whitefly/ 3 leaf), and the most resistant variety was Sabz-Pari (1.00 Whitefly/3 leaf). The highest disease incidence and severity were recorded on Peshawar-Local (PDI = 72.6, DSI = 69.0), followed by Ganga (PDI = 66.0, DSI = 54.8), while the most resistant variety against the virus infection was Sabz-Pari having lower PDI = 6.00 and DSI = 1.20. The viral infection is characterized by Polymerase Chain Reaction (PCR) through specific primers. Okra Yellow Vein Mosiac Virus was found to be the most prevailing and was amplified (800 bp) in all varieties apart from two resistant one’s, Peshawar-Local and Swat-Green, while Okra Leaf Curl Virus found to be the milder strain, and infection amplified (1600 bp) only in two varieties (Rama-Krishna and Peshawar-Local). The current finding insinuates that due to frequent use of the Peshawar-Local variety, it becomes susceptible to the whitefly and associated viruses; thus, this variety cultivation should be replaced by a resistant variety Sabz-Pari alongside proper monitoring of whitefly masses for expedient management.
