Studies on molecular variability in whitefly, Bemisia tabaci (Gennadius) population in cotton and its management
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Date
2019-06
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CCSHAU, Hisar
Abstract
The present investigation was carried out at CCS Haryana Agricultural University, Hisar
during Kharif seasons of 2017 and 2018. A survey of cotton growing areas was done in north region of
India viz. Haryana, Punjab and Rajasthan and whitefly samples were collected to find out the molecular
variation among whitefly. MtCOI gene specific primers were used to amplify the mtCOI gene segment
of extracted DNA of whitefly. Screening of forty cotton genotypes were done against whitefly and
level of resistance was further correlated with different biochemical and morphological traits. Different
crops like sorghum, bajra, pigeon pea, cowpea and sesame were grown as intercrops with cotton to
know their effects on whitefly population. Efficacy of different pesticides were tested against whitefly.
For this two spray were done at ETL and data was recorded before spray and 1st, 3rd, 7th and 10th DAS.
Results revealed that in all the samples mtCOI gene segment were amplified at 1000bp band.
Sequences were generated from these samples and aligned along with reference sequences all over the
world representing seven different clades of B.tabaci to analyse phylogenetic relationship. It was found
that our sequences belong to Asia II-1 and clustered in clade of representing Asia II-1 biotype from
Northern region of India. During both the years population of whitefly commenced in month of June
(24th SMW) and continued till harvest of crop (41st SMW) with two peaks. Observations during Kharif
2017, 2018 and pooled analysis of both the years showed that maximum population was recorded in
ARBH 1601 (15.81, 9.76, 12.79 adults/leaf) and minimum in HS 286 (10.03, 5.21, 7.62 adults/leaf),
respectively. Whitefly population showed significant negative correlation with maximum temperature
and significant positive with morning relative humidity. Population of whitefly showed significant and
positive correlation with total sugar content, trichomes density while non significant and positive with
protein and chlorophyll content. Significant and negative correlation with phenol, tannin and leaf
thickness. Intercropping system revealed significant suppression in all the intercropped treatments over
the sole cotton crop. Pooled mean of both the years revealed that minimum population was recorded in
cotton intercropped sorghum (3.69 adults/leaf) and maximum in sole cotton (10.82 adults/leaf). Pooled
mean of both the years 2017 and 2018 showed that the flonicamid 50% WG @ 150 g/ha (68.65%) was
the most effective insecticide while Verticilium lecanii 1.15WP @ 2.5kg/ha (41.11%) was least
effective.