PH-responsive eco-friendly chitosan modified cenosphere/alginate composite hydrogel beads as carrier for controlled release of Imidacloprid towards sustainable pest control

Abstract

Efficacious pesticide formulations having prolonged activity with minimal environmental risks is imperative for sustainable agriculture. Control release formulation is a prudent approach towards efficient pesticide utilization with reduced environmental implications. This work embodies an innovative easy-to-prepare pesticide formulation using chitosan (Cht)-alginate (Alg)-cenosphere (Cn) composite hydrogel beads for the sustained release of imidacloprid (IMI) with added advantage of UV safeguarding of pesticide, direct on-field application and upscalability. The IMI@Cht-Alg-Cn beads showed high encapsulation efficiency of around 80%, owing to their hollow structure and porous crosslinked network. Around 80% release of pesticide over a period of 72 hr substantiates a slower release profile under different pH conditions mimicking different soil types. Excitingly, leaching study reveal a two fold slow pesticide loss of 12 % compared to a commercial formulation. Subsequent validations in a model plant system (Vigna unguiculata) signify on-field universal applicability of the efficacious formulation. A long-term safety assessment study involving a human skin cell line (HaCaT), a plant model (Vigna radiata), soil-dwelling bacteria (E. coli and B. subtilis) and a non-targeted aquatic model organism (Daphnia magna) advocates a safe-by-design approach of the hydrogel beads. A 100% efficacy against Aphis crassivora (cowpea aphid) over 48 hrs compared to commercial formulation and technical grade of IMI suggest its suitability for on field application. This work merits sustainable pesticide use by providing application-based proofs and qualifies as a potential pesticide formulation for sustainable pest management.