Safety evaluation of natural products and insecticides to Apis mellifera Linnaeus on mustard.
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Date
2021-10-08
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Palampur
Abstract
The present investigations entitled “Safety evaluation of natural products and
insecticides to Apis mellifera Linnaeus on mustard” were undertaken during the year
2020-21 in Department of Entomology, CSK Himachal Pradesh Krishi Vishvavidyalaya,
Palampur. Intrinsic toxicity of different treatments including natural products viz.,
Agniastra, Brahmastra and Tamar lassi, biopesticide, azadirachtin and insecticides viz.
acetamiprid, clothianidin, imidacloprid and thiamethoxam was worked out for their safety
to A. mellifera workers by contact and oral administration methods. Based on LC50 values
to A. mellifera, clothianidin was found most toxic both by contact method and oral
administration (LC50 value 6.24 and 0.003 ppm, respectively) followed by thiamethoxam
(LC50 value 21.82 and 0.013 ppm) and imidacloprid (LC50 value 239.10 and 0.027 ppm).
The LC50 value of azadirachtin was 8305.17 ppm by contact method. The highest LC50
value was 8550.02 ppm by contact method and 11980.7 ppm by oral administration in
case of acetamiprid. There was no bee mortality in Agniastra, Brahmastra and Tamar
lassi even at 40% concentration of these natural products when tested by contact method.
Under field conditions, sprays of natural products, insecticides and azadirachtin
on mustard were started at 50 % flowering and repeated at an interval of 10 days. On the
basis of 3 sprays, 70.9 per cent reduction in number of bees over untreated check was
observed in thiamethoxam after 1 day of spray followed by imidacloprid spray (66.9 %),
Brahmastra (48.8 %), Agniastra (45.5 %), Tamar lassi (35.1 %) and azadirachtin
(17.4%). In imidacloprid seed treatment there was minimum reduction of 2.7 % in the
number of bees over untreated check. After 7 days of spray, the per cent reduction in the
number of bees was 35.4 % in thiamethoxam followed by Agniastra (23.0 %),
Brahmastra (19.1 %) and imidacloprid spray (16.1 %). The per cent reduction in number
of bees was 7.7 % in imidacloprid seed treatment as compared to 1.8 and 1.2 % in Tamar
lassi and azadirachtin, respectively