Use of infra-doses of sugars to control Cydia pomonella L. (Lepidoptera:Tortricidae) on apple trees in Algeria

During three years (2017–2019), nine randomized block trials were conducted in apple orchards on two varieties (Golden Delicious and Royal gala). Five trials tested different doses of sorbitol (from 0.1 to 100 ppm), the other trials compared sorbitol with other sugars (fructose, sucrose) and investigated the possibility of combining sorbitol with a chemical treatment tested at the recommended and reduced dose. The results showed that the efficacy of the treatments (Abbott) was better with sorbitol at 100 ppm concentration on both varieties tested, and that the efficacy of sorbitol was higher than sucrose and close to fructose. The combination of 100 ppm sorbitol with insecticide offers a synergistic effect and greater efficacy gain than both insecticide alone and sorbitol alone, and that treatment with sorbitol combined with insecticide at the half dose is as effective as treatment with sorbitol combined with insecticide at the complete dose.