Resistance to Development of Larvae of the Apple Maggot in Crab Apples12

Abstract

Six varieties of crab apples, ‘Almey’, Malus sikkimensis, Bailey, Malus toringoides Hughes, ‘DuPont Flowering’, ‘Henrietta Crosby’, and ‘Morden 455’, were found resistant to development of larvae of Rhagoletis pomonella (Walsh). Resistance was correlated with total phenol content but bioassays with an artificial diet suggested qualitative differences between susceptible and resistant varieties also occurred. Gallic, tannic and o-coumaric acids, quercetin, naringenin, and d-catechin, added to the diet at 1000 ppm, prevented larval development.