Population Dynamics of Insect Pests and Management of Aphid in Fenugreek (Trigonella foenum-graecum L.)
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Date
2022-07-25
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Agriculture University, Jodhpur
Abstract
The study on ‘Population dynamics of insect pests and management of aphid
in fenugreek (Trigonella foenum-graecum L.)’ under semi-arid conditions was carried
out in Rabi, 2021-22 at Research Farm, ARS, Mandor, Jodhpur. The infestation of
aphid, Aphis craccivora Koch and leaf miner, Liriomyza congesta (Becker)
commenced in 1st SMW whereas infestation of weevil, Hypera postica (Gyllenhal)
commenced in 5th SMW on fenugreek crop and subsequently the population of leaf
miner, weevil and aphid increased gradually and reached to its peak in the 6th, 9th and
5
th SMW, respectively, thereafter it declined gradually.
The correlation coefficient between larval population of leaf miner showed
non-significant correlation with maximum temperature, minimum temperature,
rainfall, maximum relative humidity, minimum relative humidity and recorded
sunshine hours (r = -0.216, r = -0.349, r = -0.093, r = 0.205, r = 0.197 and r = 0.375,
respectively) with the larval population of leaf miner. The grub population of the
weevil had negative significant correlation with rainfall and recorded sunshine hours
(r = -0.612 and r = -0.676, respectively). The minimum temperature had negative
significant correlation (r = -0.553) whereas maximum relative humidity had positive
significant correlation (r = 0.534) with aphid population.
Out of eleven genotypes screened against the aphid, A. craccivora in
fenugreek, the genotypes RMt-351 and RMt-354 were categorized as less susceptible
against aphid. The highly susceptible genotypes against aphid were AFg-3, RMt-303,
while AFg-1, AFg-2, AFg-4, AFg-5, RMt-1, RMt-143, RMt-305 were categorized as
moderately susceptible for aphids. The plant attributes such as plant height, pod
length, number of branches/plant, number of seeds/pod, number of pods/plant showed
non-significant correlation with mean aphid population.
Out of nine insecticides tested, flonicamid 50 WG was found most effective
against population of aphid, A. craccivora in fenugreek. After two sprays, flonicamid
50 WG was found most effective with no aphid population recorded followed by
cyantraniliprole 10.26 OD (0.67 aphids/5 cm central shoot) and thiamethoxam 25 WG
(1.00 aphids/5 cm central shoot). While the treatments with azadirachtin 10,000 ppm
was least effective against aphid population. The maximum yield (1722 kg/ha) and
net returns (Rs. 74450 per ha) of fenugreek was obtained from the plots treated with
flonicamid 50 WG. The highest benefit-cost ratio was observed in plots treated with
thiamethoxam 25 WG (3.79:1) followed by flonicamid 50 WG (3.57:1).
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Mishra, Shreya