Effect of the Ex ect of the Exogenous F ogenous Foliar Spr oliar Sprays of Micr ys of Micro-Doses of F o-Doses of Fructose and Glucose, on Egg-Laying of Cydia Pomonella L. and its Oviposition Site Selection in Apple Orchard

Abstract

A better understanding of the new concept of ‘sweet immunity’, represented by the use of sugars to reduce the susceptibility of plants to pests, would help implication of this knowledge within a new apple orchard protection strategy against Cydia pomonella. Behavioral and effect of two sugars, fructose (100 ppm), glucose (100 ppm), and chemical insecticide (deltamethrin) on egg-laying of C. pomonella were evaluated on two varieties (Golden delicious and Royal gala). The spraying of the two sugars, besides the insecticide, during the first, the third flight on the Golden delicious variety and the fourth flight on the Royal gala variety reduced significantly the number of eggs laid on leaves and fruits compared with control. Preferred oviposition sites for moths of all flights were leaves than fruits, whereas no eggs were found on branches. Between six studied sites, more eggs were laid on upper surface of the corymb leaves (51.67 %) in all flights of two varieties than fruit with 8.2 %, and none on the branches. Our results indicate that the responses of the codling moth egg-laying to foliar sprays of sugars are probably due to gustatory cues that reduce C. pomonella egg-laying, and they may have their importance in the signaling pathways of plant resistance to Lepidoptera.

Keywords

• cydia pomonella
• glucose
• fructose
• golden delicious
• royal gala.