Use of kaolin to minimise B. oleae damage in olive crops

The olive fruit fly, Bactrocera oleae is an olive key pest that causes big economic losses in Mediterranean olive crops. This insect stings olive fruits where it lays its eggs and larvae develop causing fruit drop. The kaolin particle film is a highly refined kaolinic mineral, white, chemically inert, and hydrophilic. Kaolin has been reported as effective against several arthropod pests, among them the olive fruit fly. Due to its low toxicity and low environmental impact, this product is considered an alternative to synthetic insecticides in organic agriculture. Kaolin is sprayed as a water suspension on crops, where it forms a particle barrier film that interferes during the host plant location and acceptance process by the insect. This leads to a reduction of both pest infestation and fruit damage. To be effective, the suspension must coat all parts of the plants.

Therefore, spray equipment parameters must be adjusted to achieve an efficient application. According to preliminary studies conducted in commercial olive orchards, the optimal coverage and drop size of 5% kaolin in olive trees is achieved with 0,8 mm diameter nozzles and at 20 bar spray pressure. By following this adjustment, the kaolin application can be used as an alternative pest management to synthetic insecticides and as a support control strategy to others alternative techniques like olive fruit fly mass-trapping.