BIOEFFICACY OF SOME Bacillus thuringiensis AND NEEM ( Azadirachtin ) FORMULATIONS AGAINST COTTON BOLL WORMS
Loading...
Date
1995
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
AAU, Anand
Abstract
The studies were conducted to evaluate Bacillus thuringiensis var. kurstaki and Azadirachtin based formulations in laboratory as well as field conditions for the management of cotton bollworms on cotton hybrid-6 at Anand Campus, Gujarat Agricultural University during 1993-94 and 1994-95. Laboratory assays ori the comparative bioefficacy of three B.t.k. formulations viz., cutlass, delfin and bactec against neonate larvae of Heliothis armigera (Hub.) and Spodoptera litura (Fab.) revealed that H. armigera is more susceptible to B.t.k. as compared to S. litura. Amongst them cutlass was found most toxic to H. armigera and delfin to S. litura. The respective' LCso values of cutlass and delfin were 124.77 and 348.03 ng/well against H. armigera and S. litura. Field studies were conducted during 1993-94 and 1994-95 in Latin Square Design with six treatments and six replications. During both the years, B.t.k. treatments @1 kg/ha were equally effective as chemical insecticide for management of cotton bollworms. In overall performance to protect the fruiting bodies (bud and green boll), B.t.k. treatments were significantly superior than neem treatment and control. Moreover, B.t.k. treatments remained close to chemical insecticide. Higher sucking pest population was observed in B.t.k. and Azadirachtin based natural pesticides treatments compared to chemical insecticide treatment. Insecticidal treatment was proved to be most toxic to Chrysopa. Coccinellids and predatory spiders. Whereas, B.t.k. and neem were observed to be safer, eventhough neem had showed slight deterrent effect on Chrysopa. During both the years, yield of seed cotton in chemical insecticide treatment was highest followed by B.t.k. treatments viz., cutlass, delfin and bactec, which were also noticed to be higher over neem and untreated check. However, neem was better than control. In B.t.k. persistence study, cutlass, delfin and bactec were found at par for their persistence and the half life time for all the three formulations was two days. Compatibility study of cutlass and cypermethrin indicated synergistic response on test insects, E.vittella and S. litura at conjunction of half the field recommended doses of both the agents.
Description
Keywords
AGRICULTURAL ENTOMOLOGY, A STUDY