Eco-friendly insecticides for the management of major pests of amaranths

Abstract

There has been increasing reports on health hazards in human beings from the unscientific and intensive use of pesticides in crops, especially vegetables. It was in this backdrop, a scientific investigation was designed to evolve safer and eco-friendly methods in pesticide use to control the major pests of the popular leafy vegetable amaranths. Field experiments were conducted at the college of Horticulture, Vellanikkara during 2000-2001 to identify the safer, eco-friendly insecticides. For the first experiment, thirteen different commercial formulations of neem, microbial and chemical pesticides were evaluated for the control of amaranths leaf webbers viz., H. recurvalis, P. basalis, weevil H. truncatulus and grasshopper A. crenulata. The best six effective components were further screened at lower doses, so as to identify the most promising one in the second experiment. The effect of the tested components on the natural enemies and other bio control agents were also studied.. Organoleptic quality evaluation of cooked amaranths leaves was done to know, whether the applied insecticides have any effect on the taste, appearance, colour, flavour, texture and bitterness. Of the insecticides tested in the first experiment, Econeem, N eem Azal, Halt, Dipel, Delfin and Nuvan were the most effective in controlling the pest population. The results of the second experiment indicated that the plots treated with Dipel @ 0.7 ml r' gave better control of both the leaf webbers. Halt @ 0.7

g r' gave comparably good results for the control of weevil. All the microbial insecticides tested were found ineffective to grasshopper. No disease symptom or deformities were observed in any of the natural enemies and other bio control agents. In the field, though Nuvan was found to control the pests, it was not effective in the long run. All the microbial products were found to protect the crop for a longer period of time. The crop sprayed with Delfin @ O.7g r' gave an yield of 5481 kg green leaves per acre compared to untreated control (2963 kg). Organoleptic quality evaluation of cooked amaranths leaves revealed that, there was no significant difference in qualities of cooked amaranths due to treatments compared to untreated control.