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

This work describes the optimization of an alginate/chitosan microsphere preparation for the encapsulation of a sexual pheromone, 6-methyl-5-hepten-2-ol (sulcatol), to realize a slow-release device for the biological control of the Megaplatypus mutatus pest. To evaluate and select the best encapsulation/release conditions three parameters were studied: alginate concentration, pH of gelling solution and Ca2+/COO- ratio. The preparation was optimized using biopolymers with improved mechanical properties and swelling behavior. The obtained microspheres were characterized using Fourier transform infrared spectroscopy, scanning electron and optical microscopies, swelling degree, mechanical properties and in vitro release of encapsulated pheromone. The microspheres performed best when they were synthesized using an alginate concentration of 4% 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, sulcatone and 3-pentanol). The formulation can be considered as an efficient slow-release biological control system, with no negative environmental impact. (C) 2015 Society of Chemical Industry