Preparation and evaluation of alginate/chitosanmicrospheres containing pheromones for pest control of Megaplatypus mutatus Chapuis (Platypodinae: Platypodidae)

Abstract

This work describes the optimization of an alginate/chitosan microsphere preparation for the encapsulation of a sexualpheromone, 6-methyl-5-hepten-2-ol (sulcatol), to realize a slow-release device for the biological control of the Megaplatypusmutatus pest. To evaluate and select the best encapsulation/release conditions three parameters were studied: alginateconcentration, pH of gelling solution and Ca2+/COO− ratio. The preparation was optimized using biopolymers with improvedmechanical properties and swelling behavior. The obtained microspheres were characterized using Fourier transform infraredspectroscopy, scanning electron and optical microscopies, swelling degree, mechanical properties and in vitro release ofencapsulated pheromone. The microspheres performed best when they were synthesized using an alginate concentration of4% w/v, at pH=9 and with a Ca2+/COO− ratio of 3.5. The attractiveness of the alginate/chitosan microspheres towards M.mutatus was demonstrated by behavioral bioassay with the completed pheromonal blend of the species (sulcatol, sulcatoneand 3-pentanol). The formulation can be considered as an efficient slow-release biological control system, with no negativeenvironmental impact.