Biological and phylogenetical studies of whiteflies from north-western Himalayan region
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Date
2021-03
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
An integrated approach was carried out to explore the diversity of reproductive host plant, along with the seasonal incidence, host preference and biotic potential, taxonomic identification using molecular and morphological tools and use of essential oils for the management of whiteflies in Uttarakhand Himalayan region. Extensive surveys were conducted in 45 locations of 4 district of Uttarakhand during 2017-2019 to record the potential reproductive host associated with Bemisia tabaci and Trialeurodes vaporariorum and total 118 host plant species belonging to 49 families were documented. Host plants belonging to family Asteraceae, Fabaceae, Solanaceae, Cucurbitaceae, were found as most preferred host plant by both B. tabaci and T. vaporariorum. Whitefly (B. tabaci) was present on brinjal and tomato throughout the cropping season at Vegetable Research Centre, Pantnagar during 2017-2019 and its peak activity was observed on last week of December in both the crops. Whitefly population had significantly negative correlation with maximum temperature (r= -0.50** and r= -0.53**), minimum temperature (r= -0.61** and r= -0.57**) and evaporation (r= -0.64** and r= -0.66**) while non significant correlation was observed with sunshine hours in both the years on tomato and brinjal plants. The feeding and oviposition preference and biotic potential studies proved that among all brinjal was the most preferred host for feeding and oviposition followed by tomato and cabbage for B. tabaci and T. vaporariorum while the least preferred host recorded was bottle gourd and chilli for B. tabaci and T. vaporariorum respectively. Similarly, the preimaginal developmental period of immature stages of B. tabaci and T. vaporariorum was faster on brinjal (19.40 days and 21.57 days) than on tomato (22.40 days and 24.03 days). The survival rate was also maximum in brinjal plants for both the species as compared to tomato. The comparative morphological studies of life stages of B. tabaci and T. vaporariorum showed distinct differences in morphological features such as the no. of marginal setae, vasiform orifice, ligula, antennae and eyes. Morphological and morphometric features of both whitefly species were imaged and illustrated in detail for correct field level identification. The molecular diversity of B. tabaci and T. vaporariorum using mt COI markers followed by sequencing revealed the preponderance of genetic diversity in whitefly species. In case of B. tabaci, five different types of biotypes were found i.e., Asia II-1, Asia I, Asia II-5, MEAM 1 and Uganda. In case of T. vaporariorum the obtained phylogenetic tree revealed that there was no variation in the collected samples. Various plant essential oils were tested for repellency and ovipositional deterrent effect against B. tabaci. Among all the essential oils, mint oil showed maximum repellency and ovipositional deterrence, followed by tulsi and citronella oil while, significantly low repellency and ovipositional deterrent effect was recorded in lemongrass oil