Physical stability and bio-efficacy enhancement of Neem kernel aqueous extract by optimized amount of botanical synergist for the control of early stages of mosquitoes

Abstract

The aim of present study is to enhance the stability of physic-chemical characteristics of neem kernel aqueous extract by botanical stabilizer system. There are variety of bioactive constituents are present in neem which give broadspectrum of insecticidal activity. Neem aqueous extract is commonly used and found very effective in pest control applications without harming the environment. However, due to hydrolytically unstable characteristics of neem active ingredients which results its lesser bioactivity and limits its usage in aqueous form.  To overcome this un-stability issue oil extracted botanical stabilizer (Prosopis juliflora) were used in various ratios. In 70: 30 ratios, neem aqueous extract was found stable without any turbidity, p H change and fungal growth. Active ingredient, Azadirachtin was found stable with very less degradation i.e only 20-30 % degradation. This may possibly be due to inhibition of hydrolytic reactions. Bio-efficacy evaluation data also showed improved and stable mosquito larvae mortality % i.e 75-90% with 8 µg/g LD50 value. The approach used in this study could be very useful in long term stability of neem kernel extract in various geographical conditions without adding toxic solvents or chemical compositions.