Biorational approaches for the management of fruit borer, Helicoverpa armigera (Hübner) in bell pepper
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Date
2014
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Punjab Agricultural University, Ludhiana
Abstract
The studies on biorational approaches for the management of fruit borer, Helicoverpa
armigera (Hübner) in bell pepper were conducted in Biological Control Laboratory and at
Entomological Research Farm, Department of Entomology, Punjab Agricultural University,
Ludhiana during 2012 and 2013. Toxicity and efficacy of six biorational insecticides against
this pest and their impact on natural enemy‟s fauna in bell pepper ecosystem was evaluated.
In leaf dip bioassay, on the basis of LC50 values against 3rd instar larvae of H. armigera, the
order of toxicity of tested insecticides was emamectin benzoate > azadirachtin > spinosad > B.
thuringiensis > B. bassiana > HaNPV. The respective LC50 values for these insecticides were
0.00015, 0.00016, 0.00143, 0.00144, 0.00277 per cent and 2.39x105 PIB ml-1, respectively.
However, field doses calculated on the basis of LC50 were recorded with highest cumulative
mortality of 3rd instar larvae in emamectin benzoate 5 SG (60.51%) and spinosad 45 SC
(56.24%). For per cent pupation of surviving larvae, emamectin benzoate (22.37%) and
spinosad (26.66%) showed significantly lowest pupation. Similar pattern was observed in
pupal weight and healthy pupae. Maximum adult emergence was in control (90.00%)
followed by HaNPV (37.24%). Azadirachtin 1 EC had the latent effect on hatchability of eggs
laid by recovered adults by significantly reducing egg hatching. In ovicidal tests, lowest
hatchability of eggs 72 h after treatment was recorded with spinosad (23.66%) and emamectin
benzoate (30.53%). Under field conditions, spinosad (29.67 plant-1) and emamectin benzoate
(27.67 plant-1) were most efficient in reducing larval population and per cent fruit infestation
with highest number of healthy fruits in these treatments. The highest marketable fruit yields
and B: C ratio was again recorded in plots treated with spinosad (44.86 t ha-1; 1:2.78) and
emamectin benzoate (42.96 t ha-1; 1:2.69). The different biorational pesticides had little effect
on population of coccinellid beetles (0.34 to 0.50 plant-1) and chrysopids (0.54 to 0.74 plant-1).
Studies on disruptive influence of different biopesticides on T. chilonis revealed that
emamectin benzoate @ 0.60 g L-1 affected the adult emergence (77.41% emergence) most
followed by spinosad @ 0.64 ml L-1 (75.80% emergence) and azadirachtin @ 3.20 ml L1
(81.15%). HaNPV was least disruptive to adult emergence (87.25%) followed by B. bassiana
(87.10%) and B. thuringiensis (85.50%)
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Keywords
bell pepper