Spreadable dispersion of insect sex pheromone capsules, preparation via complex coacervation and release control of the encapsulated pheromone component molecule

Abstract

Using insect female pheromone to disrupt their mating process is a new technology, which has been applied as environment friendly pesticides in agricultural and forestry industries to control pest infestation. Dodecanol (C₁₂OH), as one of the simple pheromone component, was chosen and encapsulated as core material using gelatin (GE) and acacia gum (AG) as wall materials via complex coacervation. Through variations in capsule preparations, particularly the crosslinking density of the wall materials, release controllability of C₁₂OH was studied. A series of C₁₂OH-containing capsules were prepared with different concentrations of GE and AG and different crosslinkings. Crosslinking and C₁₂OH encapsulation were enhanced when more crosslinker, either formaldehyde or glutaraldehyde, were used. At same level of crosslinker, lower crosslinking and higher C₁₂OH encapsulation were obtained in microcapsules done with formaldehyde than those with glutaraldehyde. Constant release of C₁₂OH was achieved in capsules prepared with glutaraldehyde. Mechanisms of C₁₂OH release were discussed based on the results. Scanning electron microscopy was used to characterize the structure and morphology of the microcapsules, which seemingly confirmed existence of a core–shell structure in the capsules, with the coacervated polymers as the shell and C₁₂OH the core.