ABSTRACT
Aim: Many crop modelling and climate simulation studies have reported variability in pest and pathogen distribution as well as their interaction with host. These prediction encourages to revisit the pest and pathogen epidemological and distribution studies in light of changing climate. In line with above assumption, the present field study was carried out to study the population dynamics of cowpea aphid (Aphis craccivora) and its influence on BCMV disease incidence. Methodology: In this field experiment, A. craccivora population and BCMV disease incidence data were collected in different standard meteorological weeks of 2013-2014 and 2014-2015. Impact of weather parameters on A. craccivora and BCMV disease incidence was statistically analyzed. Results: The significant change in A. craccivora population and BCMV disease incidence was documented during the study. The maximum aphid population was observed during rabi season and less was observed in kharif and summer season. Whereas, incidence of BCMV was recorded maximum in rabi season. Correlation analysis affirmed, minimum temperature (Tmin) and rainfall had negative impact on A. craccivora whereas weather parameters had non-significant impact on BCMV disease incidence. The regression models developed from the present study explained 41.4 % to 78.8 % and 18.5 % to 46.1% variability (R2) of aphid population and BCMV incidence, respectively. Interpretation: The weather parameters had more impact on A. craccivora population than BCMV disease incidence and merely presence of maximum number of A. craccivora was not a deciding factor for outbreak of virus disease incidence.
ABSTRACT
Different extracts of Mentha spicata L. leaves were investigated for their in vitro antioxidant and antimicrobial activities. In vitro antioxidant activity was evaluated for chloroform, ethanol and aqueous extracts for scavenging of DPPH, Superoxide and FRAP radicals. Antimicrobial activity of the extracts was evaluated against five selected bacterial strains by using cylinder plate assay. Concentration dependent antioxidant activity was observed for all the tested extracts. All the tested extracts of Mentha spicata showed considerable zone of inhibition against the tested bacterial strains. All the extracts showed significant zone of inhibition at a dose of 500μg/ml. Of the three extracts tested the highest zone of inhibition was shown by ethanolic extract against B.subtilis at the dose of 500μg/ml. All extracts exhibited antioxidant and antimicrobial activity in a dose dependent manner.