Attracticidal spheres for controlling apple maggot flies: commercial-orchard trials

Wooden pesticide-treated red spheres and biodegradable sugar/flour pesticid e-treated red spheres were compared with wooden sticky-coated red spheres a nd insecticide sprays for controlling apple maggot flies, Rhagoletis pomone lla (Walsh) (Diptera: Tephritidae), in small blocks of apple trees in Massa chusetts commercial orchards in 1997, 1998 and 1999. Pesticide-treated sphe res received a coating of 70% latex paint, 20% feeding stimulant (sucrose), and 10% formulated insecticide (containing 20% imidacloprid). To replenish sucrose lost during rainfall, wooden spheres were capped with a disc compr ised of hardened sucrose that seeped onto the sphere surface, whereas the s urface of sugar/flour spheres received sucrose that seeped from the interio r. Each year, each of the 24 perimeter trees of each non-sprayed block rece ived a sphere baited with butyl hexanoate (an attractive component of host fruit odor), with the intent of intercepting immigrating flies. Based on ca ptures of flies on unbaited sticky-coated red spheres placed near the cente r of each block and on periodic samples of fruit for injury, there was a co nsistent pattern of treatment performance. Each year, sticky-coated spheres were only slightly less effective than two or three sprays of organophosph ate insecticide, sugar/flour pesticide-treated spheres were only slightly l ess effective than sticky spheres, and wooden pesticide-treated spheres wer e least effective. Versions of pesticide-treated spheres used in 1999 were more durable than those used in previous years, but further improvement is needed before either wooden or sugar/flour pesticide-treated spheres can be recommended for grower use.