Ecological impact of neonicotinoids on arthropod fauna of Bt cotton
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Date
2017
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Punjab Agricultural University, Ludhiana
Abstract
The studies on ‘Ecological impact of neonicotinoids on arthropod fauna of Bt cotton’
confirmed presence of 78 species of arthropods comprising predators, non-target, casual
visitors, sucking pests and pollinators (33.33, 25.64, 19.23, 12.82 and 8.98%) at Bathinda.
During 2015, diversity of sucking pests was higher in acetamiprid 20SP and dinotefuran
20SG while it was higher in imidacloprid 17.8SL and thiamethoxam 25WG; acetamiprid
20SP, dinotefuran 20SG and clothianidin 50WDG in 2016 after first, second and third spray.
Diversity was lower in imidacloprid and thiamethoxam in both years. In predatory fauna and
non targets, higher diversity was recorded in imidacloprid 70WS and thiamethoxam 30FS as
compared to other treatments. Diversity of pollinators was higher in imidacloprid 70WS and
thiamethoxam 30FS and in recommended doses of other neonicotinoids while it was lower in
double doses of neonicotinoids. Mean population of whitefly, thrips, red cotton bug, dusky
cotton bug and predatory species was minimum in acetamiprid @ 100 g/ha while jassid was
minimum in dinotefuran 20SG @ 250g/ha and pollinators in clothianidin 50 WDG @ 60g/ha.
The experiment on development of Chrysoperla zastrowi sillemi revealed longer larval period
in acetamprid 20SP @ 50 g/ha when fed on neonicotinoid treated jassid (13.89 and 13.83
days) and whitefly (13.61 and 12.95 days) while it was minimum in imidaclorpid 70WS
during 2015 and 2016, respectively. The number of jassid nymphs and whitefly adults
consumed by larva was maximum in imidacloprid 70WS (286.40, 302.13 and 264.93 and
273.20), respectively in both the years whereas it was minimum in acetamprid 20SP @ 50
g/ha (250.47, 278.80 and 224.07, 246.20). The third experiment on ‘Residual effect of
neonicotinoids on development of Bemisia tabaci’ revealed significantly higher fecundity in
imidacloprid 17.8SL @ 50 g/ha (79.20 and 82.33 eggs/2 pairs) and lower in dinotefuran 20SG
@ 125 g/ha (43.13 and 49.07 eggs/2 pairs) during 2015 and 2016, respectively. Minimum
nymphal duration was recorded in imidacloprid 17.8SL @ 100 g/ha (12.99 and 12.06) and
maximum in dinotefuran 20SG @ 125 g/ha (15.43 and 14.41 days). The growth index was
significantly lower in dinotefuran 20SG @ 100 and 125 g/ha (4.26, 4.24 and 4.35, 4.12)
during 2015 and 2016, respectively.
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