Nanoencapsulation of Permethrin in Polylactic Acid to Enhance Insecticide Persistence for Scolytinae Pest Control

Abstract

Nanotechnology can be used to protect plants against Fusarium Dieback and the Laurel Wilt, that are new and lethal insect-vectored diseases that can host over 300 tree species, including avocado trees. The vectors of these diseases are beetles members of the Scolytinae subfamily, notoriously difficult to control because they spend most of their lives hidden within galleries. Nevertheless, when tested on avocado bolts, some insecticides (including permethrin) provided a reduction in the number of entrance holes or beetle emergence, but the persistence of pesticide residues might have been influenced by factors like rainfall and sunlight. The present study aims to encapsulate permethrin in polylactic acid nanospheres, conferring protection against losses by physic and chemical factors, ultimately increasing its persistence. The particle size, zeta potential, and encapsulation efficiency obtained were 393nm, -32mV, and 27%, respectively. After 96 h of exposure to UV-A light, the insecticidal activity of unencapsulated permethrin was severely diminished, having a reduction in mortality in scolytinae beetles from 80% to 40%, while the nanoencapsulated permethrin retained a 70%. The study has concluded the potential advantage of formulating permethrin into nanometric biodegradable spheres, enhancing the persistence of the insecticide while removing the use of toxic organic solvents as vehicle for the active ingredient, reducing the environmental impact.)