Fruit growers are haunted by the fear of finding worms in apples. Infected apples indeed must be withdrawn from the market, which justifies the use of numerous treatments with chemical insecticides or biological control methods. INRA researchers1 studied the impact of the various control methods in testing stations and in fruit farms They showed that the biodiversity in insect populations was greater, and the reproduction of an insectivorous bird, the great tit, improved in orchards using biological controls. The apple worm is a butterfly caterpillar, the codling moth. Chemical and biological control methods are used to fight against this parasite according to three major growing conditions.
- In organic orchards, only biological and biotechnical control methods are allowed. The main method used is sexual confusion: a synthetic sexual pheromone, similar to that produced by female butterflies to attract males, is emitted into the atmosphere with diffusers. As the environment is saturated with the substance, males become unable to find females. The butterfly reproduction is thus at a standstill. If necessary, the method can be completed with the use of a parasitic micro-organism of the worm, i.e. the carpovirusine.
- In orchards with integrated plant protection, male confusion is the method employed, completed if necessary by the use of chemical insecticides.
- In orchards with conventional protection, chemical control is preferred, with high frequency treatments all through the reproductive period of the insect. Concerning acarids, insects, or birds, three groups of results emerge from the comparison of the various control conditions:
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