Efficacy of Bio-pesticides and Newer Insecticides against Major Insect Pests of Cauliflower

A field trail Comprising of nine insecticides conducted at farmer’s field in endemic area of pests on cauliflower in Siwan district of Bihar during 2018-19. Data revealed that Indoxacarb 14.5 SC @1.0 ml/L of water was found to be most effective insecticides on major pests of cauliflower i.e. leaf webber (41.06% reduction), tobacco caterpillar (48.91% reduction), Diamond Back Moth (64.40% reduction) and aphid (69.96% reduction) over farmer’s practices (chlorpyriphas 20 EC @ 1.5 ml/L of water) i.e. 24.67% 27.86%, 32.47% and 34.81% reduction of leaf webber, tobacco caterpillar, Diamond Back Moth and aphid, respectively. Similarly, significantly highest yield (144.26 q/ha) produced cauliflower in treatment of Indoxacarb 14.5 SC. However, Cost-benefit analysis revealed that highest cost-benefit ratio of 1:11.15 in treatment of Cartap hydrochloride 50 SP @ 1.0gm/L of water followed by Thiodicarb 75 WP @ 1.0g/L (1:9.39), Indoxacarb 14.5 SC @ 1.0 ml/L (1: 7.96), Emamectin benzoate 5 WSG @ 0.25 gm/L (1:7.22), Novaluran 10 EC @ 1.0 ml/L (1:6.48), Spinosad 45 SC @0.33 ml/L (1:6.34), Avemectin 1.9 EC @ 0.5 ml/L (1:5.57), Azadirachtin 0.15% @ 4 ml/L ( 1:4.10) and farmer’s practices (1:3.10), respectively.

Isolation and characterization of Lepidoptera specific Bacillus thuringiensis strains predominantly from north-eastern states of India.

Both, the tobacco caterpillar Spodoptera litura (Fabricius) and the cotton bollworm Helicoverpa armigera (Hübner), are serious polyphagous pests causing considerable loss to crops. Indiscriminate use of chemical pesticides for controlling them has rather resulted in their resistance development. Microbial pesticides, Bacillus thuringiensis in particular, play an important role in pest management. Here, we isolated Bacillus thuringiensis-like bacteria from the soil samples primarily collected from North East region of India along with some states viz., Haryana, Punjab, Maharashtra, West Bengal and Uttarakhand and studied their toxicity against the above two insect pests at 10 µg/g along with standard strain B. thuringiensis subsp. kurstaki HD-1 and at 1 µg/g Pseudomonas fluorescens based MVPII expressing Cry1Ac toxin and AUG-5. Isolates AUG-5 and GTG-7 proved toxic to more than 75% larvae on the 4th as well as 7th day of the treatment of the neonates of H. armigera. The AUG-5 isolate was also effective against S. litura. Ten effective isolates (AUG-5, GTG-4, GTG-7, GTG-9, GTG-42, GTG-64, GTG-70, GTG-3S, GTG-4S and GTG-6S) were characterized using biochemical and 16S rDNA analysis. Nearly, all the isolates tested positive for utilizing monosaccharides. All selected B. thuringiensis isolates showed resistance to ampicillin and co-trimoxazole except AUG-5 to co-trimoxazole. AUG-5 and GTG-7 were highly toxic to both insects, and possessed cry1, cry1A and cry2 genes. These isolates AUG-5 and GTG-7 also contained high Cry1Ac (104.8 and 88.32 ng/mg) and Cry2Ab (3792 and 1305.9 ng/mg), respectively in their spore-crystal complex. Both, AUG-5 and GTG-7 isolates, could be considered for further development as bioinsecticides. The present study has established the diversity and richness of B. thuringiensis-like isolates in soils collected from north-eastern region of India.