K. C. Puzari

Effect of Climatic Parameters on Persistence of Metarhizium anisopliae

Effect of Climatic Parameters on Persistence of Metarhizium anisopliae The work has been done on the study related to the persistence of a potential entomopathogen Metarhizium anisopliae outside of their insect host as there is little or no knowledge about the biology. To resolve this question, the study was conducted in organic and inorganic tea ecosystem of Assam. Results have shown that the entomopathogen remained viable and detectable for 1 year and a month in both soil and air in inorganic tea ecosystem. While it was detectable for 1 year and a month in soil and for approximately 12 months in air in organic tea ecosystem, with negative periods between. M. anisopliae this did not persist as epiphyte in the vegetative cover of both the tea ecosystem even for a month after its application. However, its persistence is highly depended upon all the environmental parameters namely temperature, rainfall, humidity, BSSH, evaporation and wind speed. Moreover, soil biological and physico-chemical properties like soil pH, available NPK, exchangeable cations, soil organic carbon and microbial biomass carbon were found to be increased after its application in the studied area. The results of this study showed that the population of M. anisopliae has the potential of accumulating in the soil and air under proper environmental conditions. Conidia present in these areas decay after one year so, fungal spraying must be done accordingly to achieve a better control. We could not able to detect positive colonies of M. anisopliae as an epiphyte in the vegetative cover of the studied area. If conidia are applied on the abaxial surface of leaves, persistence of the entomopathogen could be enhanced on phylloplanes...

Bioefficacy of Metarhizium anisopliae on Aphis craccivora Koch

Laboratory bioassay studies were carried with nine conidial concentrations of Metarhizium anisopliae (Metchnikoff) Sorokin ranging from 1×103 to 1×1011 conidia/ml against the adults of Aphis craccivora Koch. Mortality was monitored at 24 h (1day) interval up to five days. The mortality data indicated that mortality increased with time, and in the highest concentration (1011conidia/ml) 83.83% mortality was obtained. This was followed by a mortality of 64.72 and 52.96% with 1×1010 conidia/ml and 1×109conidia/ml. However, mortality declined with decrease in concentrations with a lowest (17.65%) at 1×103conidia/ml. The results show that M. anisopliae can be used as a promising biocontrol agent for management of A. craccivora.