APPLE MAGGOT FLY RESPONSE TO RED SPHERE TRAPS IN RELATION TO FLY AGE AND EXPERIENCE

Responses of the apple maggot fly, Rhagoletis pomanella (Walsh), to 8 cm red sticky sphere traps, baited with the synthetic fruit odor butyl hexanoate, were investigated in field-caged apple trees containing gr een or red Gravenstein apples. Trap capture rate and the probability o f oviposition in apples before capture generally increased with female age and number of mature eggs in ovaries. Two days of pre-test exposu re of mature females to red hawthorns, green Red Delicious apples or g reen Gravenstein apples had no significant effect on the likelihood of a fly finding a red sphere. However, before capture on a sphere or de parting a tree, hawthorn-exposed females found significantly fewer app les and laid significantly fewer eggs than females exposed to Gravenst ein apples. Variation in duration of pre-test exposure (1-4 days) of f lies to Gravenstein apples had no detectable influence on female respo nse to apples or to a red sphere in a test tree. The relevance of thes e findings to effectiveness of sphere traps for R, pomonella control i n commercial orchards is discussed.