Field Evaluation of Lepidopteran Pest Population Densities in Selected Cranberry Varieties

Host plant resistance, an important strategy of Integrated Pest Management, was examined in the American Cranberry, Vaccinium macrocarpon Ait. (Ericaceae). This study assessed field population densities of the three most economically important pest species in Wisconsin: blackheaded fireworm, Rhopobota naevana (Hübner) (Lepidoptera: Tortricidae), sparganothis fruitworm, Sparganothis sulfureana (Clemens) (Lepidoptera: Tortricidae), and cranberry fruitworm, Acrobasis vaccinii (Riley) (Lepidoptera: Pyralidae) in five different cranberry varieties, i.e. Stevens, Ben Lear, GH-1, Mullica Queen, and HyRed. Traps containing female sex pheromone lures for each of the three insect species were placed in five different cranberry varieties in commercial marshes in central Wisconsin. Male moths of all three species were trapped in the summers of 2013 and 2014 and trap counts were compared to determine whether moth populations differed among varieties. Larvae in damaged cranberries were also collected both seasons to assess larval population densities in the same varieties. A significant difference was found in adult sparganothis fruitworm populations among different varieties. Ben Lear and Mullica Queen had lower population densities than Stevens and GH-1 and HyRed had lower population densities than Stevens. No significant difference in adult population densities among varieties was found for blackheaded fireworm or cranberry fruitworm and there were no significant differences in larval population densities. If this and other ongoing research demonstrate higher resistance in a particular variety, that variety could be incorporated into future plantings and breeding programs, ultimately reducing the need for chemical control.