2010 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.
The overall aim of this project is to enhance the performance and commercial value of attracticidal spheres for behavioral control of apple maggot fly (AMF). The impact of inclusion of hygroscopic feeding attractants on lethality of attracticidal spheres has been evaluated. Specifically, under a laboratory trial which assessed residual lethality of varying concentrations of the toxicant spinosad (Entrust) combined with the feeding stimulant sucrose and the feeding attractant ammonium carbonate against AMF was completed. These results were used to generate the formulation used in subsequent experiments. Results have revealed that residue containing 10-1000 ppm ammonium carbonate (feeding attractant), 1-10% sucrose (feeding stimulant) and 10-100 ppm spinosad (toxicant) will reliably result in 80-100% mortality within 48h, respectively. Based on rainfall trials to date, caps exposed to 45+ cm of rainfall still maintain lethality of 85% or more, as long as the caps contain a high rate of hygroscopic feeding attractant. If the rate of this additive (ammonium carbonate) is reduced or eliminated, traps only maintain this level of lethality through ~25 cm of accumulated rainfall. Given a target of >85% lethality through 40 cm of rainfall, these bioassay results translated into field deployment of traps bearing 10% ammonium carbonate, 70% sucrose, and 0.5% (AI) spinosad. AMF are visual specialists, although results revealed that spheres deviating from full round form by 1%, 2%, and 4%, and compared with a full round stimulus resulted in overall captures that were not significantly different among treatments. Overall captures were reduced 12.4, 10.1, and 24.6%, for shape deviations of 1%, 2%, and 4%, respectively, indicating that release caps should be manufactured to provide a visual stimulus which is as close to full round as mechanically possible. Inclusion of feeding attractants increases the attractiveness of spheres to non-target Diptera 2-3x compared with spheres lacking feeding attractants and may interfere with the ability of foraging AMF to alight on traps. However, the inclusion of the 5-component apple volatile lure appears to increase overall captures of AMF across treatments regardless of inclusion of close-range feeding attractants indicating that this fruit volatile lure reliably attracts AMF to tree canopies bearing this host-based stimulus. The protective capacity of sphere traps correlates with the lethality rates found in the laboratory. Traps bearing hygroscopic feeding attractants provided the greatest level of fruit protection; the presence of fruit-volatile baits adjacent to traps had little impact on the close-range spatial protective capacity of the visual traps. Extension programs describing progress made in the development of attracticidal spheres for AMF based on this have been delivered in NH in July 2008 and 2009, and in VA in May 2009. The ADODR has monitored activities through emails, meetings, and calls.