Natural Pyrethrum Extracts Photo-stabilized with Organo Clays

Abstract

Botanical pesticide use in agricultural sector over synthetic pesticide would ensure less pest resistance and reduced environmental pollution. Natural Pyrethrum Extracts (NPE) are effective, environmental friendly pesticides, but are photo-labile, limiting their use in pest control. In the present study, naturally occurring montmorillonite (MMT) clay was purified following established procedures. Organo-clays were prepared by treating the purified clay with Hexadecyltrimethylammonium Bromide (HDTMA) and Trimethylphenylammonium Bromide (TMPA) organic cations. NPE molecules were loaded into these organo clays by simple immersion using NPEs solution to obtain NPE-organo clay composites. The samples were characterized using Fourier Transform Infrared (FT-IR) spectrophotometry and X-ray Diffractometry (XRD) techniques. In situ photo-stability tests conducted by exposing the NPEs-clay composites to sunlight for four hours revealed ~52% stabilization of NPEs by HDTMA modified clays. The findings demonstrated a great potential of clay to photo stabilize NPE and consequently improve the versatility of NPE-based pesticides. Bio-assay test on maize weevils revealed 100% mortality rate on NPE HDTMA-clay treatments at 120 hrs while the un-protected NPEs exhibited 18% mortality rate for the same duration of time. Clay synergizes NPE; acting as a carrier, photo- protector and desiccant to NPE pesticide in weevils’ eradication. Embrace of this effective technology shall ensure enhanced food security and more income to the pyrethrum growing farmers.