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Subject: Agricultural Entomology × Author: SHARMA, ARUSHI × Start date: 1980 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Bioefficacy of natural products against cabbage aphid, Brevicoryne brassicae Linnaeus in rapeseed
    (Palampur, 2021-11-03) SHARMA, ARUSHI; Kumar, Surjeet
    Six natural products viz., Agniastra, Brahmastra, cow urine, Darekastra, Dashparni and Eupatorium extract in cow urine were evaluated for their biological activity against Brevicoryne brassicae and for their effect on the population build-up of the aphid on Gobhi Sarson var. GSC-7 under laboratory and field conditions, respectively. The biological activity of natural products was studied by determining their toxic and repellent activity against fourth instar nymphs of cabbage aphid by using standard leaf-dip method of bioassay and effects on its biology. The order of toxicity of natural products to fourth instar nymphs of B. brassicae based on LC50 values in decreasing order was Brahmastra (9.11 %) followed by Agniastra (12.79 %), Dashparni (18.14 %), Eupatorium extract in cow urine (19.04 %), cow urine (19.29 %) and Darekastra (20.87 %). All natural products exhibited moderate level of repellence against the aphid. The repellence index (RI) calculated for different natural products at 10 per cent concentration against fourth instar nymphs of B. brassicae varied from 0.57 to 0.77, minimum and maximum corresponding to Brahmastra and Agniastra. When these products were tested at 10 per cent concentration for their effect on developmental biology of the aphid, Brahmastra was recorded to prolong the total nymphal period (9.97 days) by 3.90 days as compared to untreated check (6.07 days). Among natural products, nymphal growth index varied from 4.44 to 9.19 and highest growth index was recorded in untreated check (14.28). An increase in pre- and post-oviposition periods was recorded whereas oviposition period was found to decrease. All natural products were found to significantly reduce the fecundity of the aphid as compared to untreated check. The adult longevity was reduced but the results were found to be non-significant. Under field conditions, five sprays at regular intervals (10 days) of all natural products @ 10 per cent checked the population build-up of cabbage aphid, however, the extent of reduction over that of untreated check was low. Maximum per cent reduction over untreated check (29.31 %) was recorded in plots treated with Brahmastra followed by Agniastra (28.19 %). Darekastra was found to record minimum per cent reduction (21.62 %) followed by Eupatorium extract in cow urine (21.87 %). Overall, it can be concluded from the present study that all natural products, particularly Brahmastra, exhibited significant biological activity against cabbage aphid both under laboratory and field conditions and therefore, can further be investigated for inclusion in integrated pest management strategy against the aphid on rapeseed.