2012 Annual Report
1a.Objectives (from AD-416):
1. Examine the impact of hygroscopic feeding stimulants on lethality of attracticidal spheres. 2. Assess the attractiveness of integrated visual and olfactory components of attracticidal spheres. 3. Determine the protective capacity of attracticidal spheres. 4. Assess performance of commercial deployment of attracticidal spheres.
1b.Approach (from AD-416):
We will use laboratory and field-based experiments to determine the most effective attracticidal spheres for apple maggot fly control. Experiments will encompass inclusion of feeding stimulants, feeding attractants, and host apple volatiles. Ultimate evaluations will be made in commercial apple orchards.
We evaluated combinations of toxicant rate (spinosad: 0.0, 0.1, and 0.5%) and feeding attractant (ammonium carbonate: 0.0, 5.0, and 10.0%) as dispersible constituents of attracticidal spheres. In the first year of this experiment, greatest lethality was observed when AMF were exposed to treatments containing highest rate of toxicant; higher rate of feeding attractant contributed significantly to both lethality of traps and longevity of effects. In subsequent trials of lethality of controlled residues, we evaluated effects of 80 treatments: combinations of toxicant rate (0.0, 0.1. 1.0, 10.0, and 100.0 ppm); hygroscopic feeding attractant (0, 10, 100, and 1000 ppm); and feeding stimulant (0.0, 0.1, 1.0, and 10.0%). It was revealed that with controlled 3-component residues, factors contributing to lethality were toxicant rate and feeding stimulant rate; presence of higher rates of feeding attractant had no impact on lethality of residues. Combined results demonstrate that as a trap constituent, ammonium carbonate enhances release of sucrose and toxicant under trap exposure to environmental moisture, and may preserve the lethality of naturally formed toxicant residue on trap surfaces. Inclusion of feeding attractant in sphere caps marginally increased capture of foraging AMF, but resulted in capture 2-3x more nontarget Diptera, which may interfere with alightment of targeted AMF. From the findings, we selected a formulation and deployment strategy for demonstration in commercial orchards in the Northeast in year 2 of this project. Trap formulation consisted of 10% ammonium carbonate and 0.5% (ai) spinosad; unfortunately, traps of this type failed to control the outbreak of AMF experienced in this growing season. The most likely mechanism of trap failure was premature release of feeding stimulant and toxicant under the exceptionally wet conditions in the Northeast during this growing season. Traps were reformulated with higher rate of toxicant (1.0%) and feeding attractant was removed to limit the rate of output of toxicant and feeding stimulant. In year 3 of this project, field control was regained: oviposition injury was maintained at a rate below that considered commercially acceptable (1.0%), and injury in trap-protected plots did not differ from grower managed control plots.