Preparation, sustained release and field mating disruption of Grapholitha molesta sex pheromone microcapsule

Objective  The preparation ofGrapholitha molesta sex pheromone microcapsule was investigated, and the sustained release effect of the microcapsule under indoor conditions was evaluated.

Method  Adopting G. molesta sex pheromone (E8-dodecenyl acetate) as core material, octenylsuccinate starch sodium, emulsifying starch-809, maltodextrin, ß-cyclodextrin and gelatin as wall materials, G. molesta sex pheromone microcapsule emulsion was prepared. The factors that affect the particle size distribution and encapsulation rate of the microcapsule emulsion, including the different proportions of the core material and the wall material, the sustained release ratio under indoor conditions and the mating disruption under field conditions were studied.

Result  The optimum wall material formula (mass ratio) of microcapsule emulsion was octenylsuccinate starch sodium∶ emulsifyingstarch-809∶gelatin∶maltodextrin∶β-cyclodextrin=5∶15∶0∶3∶2. The optimum preparation conditions were as follows: The mass ratio of wall material and core material was 10∶1, the shear velocity was 10 000 r/min, the shearing time was 2 min, the high pressure homogenization pressure was 20 MPa, the homogeneous time was 2 min; During the second homogeneous, 10 g liquid paraffin was added, the homogenization pressure was 20 MPa and the second homogeneous time was 4 min. The indoor sustained release experiments were conducted under 30, 40 and 50 ℃. The sex pheromones released from the microcapsules could be detected on the 91st day, whereas the unencapsulated sex pheromone was no longer detectable after 5 h. Field mating disruption study showed that microcapsule emulsion efficacy could last for 80 d and the effects of four sex pheromone dosages of 45, 75, 120 g/hm² and 75 g/hm² (refrigerating for one year) had no significant difference.

Conclusion  The G. molesta sex pheromones microcapsule emulsion significantly prolongs the duration period, and can be applied for the large-scale mating disruption control of G. molesta.