A Method to Screen Pome Fruit for Resistance to Skin-chewing Insects and to Analyze Feeding Trends

Abstract

Insect feeding traces on fruit are a major concern to orchardists. Breeding fruit for insect resistance is becoming more important as available pesticides are limited by more stringent regulations, problems of insect resistance, and residue limits. We present a method to analyze fruit skin damage via treatment of video images. This aspect has not been well studied to date, but would allow a more rapid assessment of fruit resistance to insects in breeding programs. The method uses equipment available on the world video and computer markets. Over 24 hours, larvae of lightbrown apple moth [Epiphyas postvittana Walker (Lepidoptera: Tortricidae)] were permitted to chew restricted areas of skin on the pear cultivars Sensation Red Bartlett, Packham's Triumph, Doyenne du Comice, Beurre d'Anjou, and Corella (Pyrus communis L.); Twentieth Century (Pyrus pyrifolia Burm. Nak.); Ya Li (Pyrus ×bretschneideri Rehd.); and F1 hybrids of `Packham's Triumph' × `Twentieth Century'. Optimum experimental conditions and statistical analyses are described and sensitivity of the various cultivars is discussed. The method allowed us to identify some highly resistant and sensitive pear hybrids. The ability to rapidly screen F1 hybrids for insect resistance may encourage breeders to incorporate such a factor in breeding programs, and should hasten the release of resistant cultivars. The application of this technique in the orchard is discussed. The method also allows the analysis of various aspects of larval feeding, such as number and size of wounds, which may be responses to various fruit skin defense systems.