ABSTRACT
As such in search of alternative to chemical insecticides against insect pest of rice resulted in identifying white muscardine fungus, Beauveria bassiana an entomopathogen out of several entomogenous fungi prevalent in rice ecosystem as the potential mycoinsecticides. The fungus has 78-87% virulence against rice hispa with LC 50 value of 90.16. Under field situations it is required that the effectiveness of the bioagents is enhanced by combining them with compatible pesticides. A sublethal dose of a pesticide would make the insect physiologically weak which makes it much more susceptible to the attack of the entomogenous organisms. In view of this, compatibility test was conducted with 14 different commonly applied insecticides at two different doses i.e., recommended and half of the recommended dose. In small scale field trial chloropyriphos at half of the recommended dose along with B. bassiana was the best treatment in controlling the pest along with increased yield of the crop consecutively for two years. Similarly, in multilocational field demonstration trial conducted in hispa endemic areas of Assam viz., Sibsagar and Jorhat covering six different localities B. bassiana (@ 10 million spore/ml dilution) and half of the recommended dose of chlorpyriphos proved superiority then the commonly applied insecticides in decreasing the pest population with increased yield of crop.
ABSTRACT
Liquid bioformulation of Metarhizium anisopliae amended with oils and adjuvants was prepared. Six oils viz., sunflower, safflower, soybean, mustard, arachnid and coconut oils at three different concentrations, 0.1, 0.5 and 1.0 per cent and three adjuvants viz., glycerol @ 5, 8 and 10 per cent; tween-80 @ 0.02, 0.04, 0.06 and 1.0 per cent and arachnid oil @ 1, 5 and 10 per cent were tested to see their effect on growth and development of M. anisopliae in the bioformulation. Liquid bioformulation of M. anisopliae amended with Glycerol (10.0%) + Sunflower oil (0.5%) was found significantly effective which showed 84.33 per cent and 94.93 per cent higher surface area covered and biomass production respectively than the control. Efficacy of the bioformulation was tested against cow pea aphid, Aphis craccivora in pot as well as field condition. Liquid formulation of M. anisopliae supplemented with Glycerol (10.0%) + Sunflower oil (0.5%) was found to be significantly effective causing aphid mortality of 80 per cent at 30 days after spraying with protection of secondary spread of cow pea mosaic disease up to 100 per cent and 96.03 per cent in pot and field condition respectively. Spraying liquid formulation of M. anisopliae amended with Glycerol (10.0%) + Sunflower oil (0.5%) at 15 days interval for twice proved to be the best treatment with highest yield of 24.03 t/ha with a cost benefit ratio of 1:7.95 as compared to control (11.20 t/ha).