An index for assigning distances between odor‐baited spheres on perimeter trees of orchards for control of apple maggot flies

Abstract

AbstractPreviously, the distances between odor‐baited spheres deployed on perimeter trees of apple orchards for behavioral control of apple maggot flies, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae), have been assigned largely arbitrarily. Here, we report a new approach for assigning distances that employs an index incorporating the state of four environmental variables: the size of orchard trees, quality of pruning, cultivar composition, and nature of bordering habitat. The deployment of odor‐baited spheres on the perimeters of 12 plots of apple trees (each ∼0.4 ha) in commercial orchards in 2003 resulted in an apple maggot control which was no different from that achieved by insecticide sprays in adjacent plots in 2003, and no different from that achieved by an arbitrary assignment of distances between odor‐baited spheres on perimeter trees in these same plots in 2001 and 2002. However, only 61–67% of spheres were used under the new index approach compared with the previous arbitrary approach, thereby substantially reducing the cost of behavioral control. Our findings are discussed in relation to use of the index for blocks of trees which are large in size and pruned poorly vs. small in size and pruned well, and in relation to the cost‐competitiveness of odor‐baited perimeter spheres vs. insecticidal sprays for the control of apple maggots.