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

Abstract

AbstractPublished studies have shown inconsistent effects of proteinaceous bait sprays against apple maggot flies, Rhagoletis pomonella (Walsh). Explanations of inconsistency could involve the presence of natural food such as bird droppings competing with bait sprays for attraction of flies. Under field, semi-field, or laboratory conditions, we found that: (1) aqueous solutions of 10% proteinaceous bait (Nulure) were significantly more attractive than water to protein-denied but not to protein-provided apple maggot flies; (2) addition of 2% toxicant (malathion 50 EC) did not affect attractiveness of Nulure droplets but did significantly deter feeding by arriving protein-provided flies (though not protein-denied flies); (3) droppings collected from barn swallows, chickens, and unidentified birds on apple trees were significantly more attractive than solutions or droplets of Nulure to protein-denied flies; (4) droppings that were freshly deposited or fresh from cold storage were significantly less attractive than droppings held under ambient conditions for 1 or 2 days; (5) droppings allowed to dry for 1 day at 25 °C, 60% RH were no less attractive than droppings that received water to simulate dew or rainfall; and (6) droppings treated with antibiotics were significantly less attractive than droppings not treated with antibiotics, indicating that bacteria may be involved in generating attractive volatiles. Together, these findings suggest that in situations where natural sources of protein such as bird droppings or insect honeydew are abundant, apple maggot flies may be relatively unaffected by addition of proteinaceous bait to insecticide sprays.