BIRD DROPPINGS COMPETE WITH BAIT SPRAYS FOR RHAGOLETIS-POMONELLA (WALSH) FLIES (DIPTERA, TEPHRITIDAE)

Published studies have shown inconsistent effects of proteinaceous bai t sprays against apple maggot flies, Rhagoletis pomonella (Walsh). Exp lanations of inconsistency could involve the presence of natural food such as bird droppings competing with bait sprays for attraction of fl ies. Under field, semi-field, or laboratory conditions, we found that: (1) aqueous solutions of 10% proteinaceous bait (Nulure) were signifi cantly more attractive than water to protein-denied but not to protein -provided apple maggot flies; (2) addition of 2% toxicant (malathion 5 0 EC) did not affect attractiveness of Nulure droplets but did signifi cantly deter feeding by arriving protein-provided flies (though not pr otein-denied flies); (3) droppings collected from barn swallows, chick ens, and unidentified birds on apple trees were significantly more att ractive than solutions or droplets of Nulure to protein-denied flies: (4) droppings that were freshly deposited or fresh from cold storage w ere significantly less attractive than droppings held under ambient co nditions for 1 or 2 days; (5) droppings allowed to dry for 1 day at 25 -degrees-C, 60% RH were no less attractive than droppings that receive d water to simulate dew or rainfall; and (6) droppings treated with an tibiotics were significantly less attractive than droppings not treate d with antibiotics, indicating that bacteria may be involved in genera ting attractive volatiles. Together, these findings suggest that in si tuations where natural sources of protein such as bird droppings or in sect honeydew are abundant, apple maggot flies may be relatively unaff ected by addition of proteinaceous bait to insecticide sprays.