Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 27, 2003
Publication Date: February 1, 2004
Citation: Leskey, T.C., Wright, S.E. 2004. Monitoring plum curculio, conotrachelus nenuphar (herbst) (coleoptera: curculionidae) populations in apple and peach orchards in the mid-atlantic. Journal of Economic Entomology. 97:79-88. Interpretive Summary: The importance of effective monitoring systems to detect key insect pests in orchard ecosystems grows as greater restrictions are placed on use of conventional insecticides. The plum curculio is a pest of both stone and pome fruit and recent studies in the northeastern and midwestern United States have focused on development of baited traps as monitoring tools for this pest. We evaluated responses of plum curculio to black pyramid and clear Plexiglas panel traps deployed outside the border row of commercial and unsprayed apple and peach orchards, and also branch-mimicking cylinder and trunk-mounted screen traps attached to trees in the border row. We evaluated four bait treatments in conjunction with each trap type: the synthetic fruit volatile, benzaldehyde, the male plum curculio-produced aggregation pheromone, grandisoic acid, benzaldehyde in combination with the pheromone; and an unbaited control treatment. Although different trap types and bait combinations had significant effects on the number of captured plum curculios, none of the traps provided a reliable indication of the damaging potential of the plum curculio population indicating that more competitive baits and traps are needed to effectively monitor this important fruit pest.
Technical Abstract: We evaluated responses of plum curculio, Conotrachelus nenuphar (Herbst), to four trap types in commercial and unsprayed apple and peach orchards. Trap types included black pyramid and clear Plexiglas panel traps deployed outside the orchard 2 m from the border row, and branch-mimicking cylinder and trunk-mounted screen traps attached to trees in the border row. We evaluated four bait treatments in conjunction with each trap type: the synthetic fruit volatile benzaldehyde, the aggregation pheromone, grandisoic acid (GA), benzaldehyde in combination with GA; and an unbaited control treatment. In commercial apple orchards, significantly more plum curculios were captured in traps baited with benzaldehyde + GA compared with traps baited with benzaldehyde or GA alone, or with unbaited traps. Furthermore, significantly more plum curculios were captured by screen traps baited with benzaldehyde + GA compared to unbaited control traps. Significantly more plum curculios were captured by screen traps compared to any other trap type in an unsprayed apple orchard and numerically more plum curculios were captured by cylinder and screen traps compared to pyramid and panel traps in an unsprayed peach orchard. Very few captures were recorded in commercial peach orchards. Dissections of trapped female plum curculios indicate that bivoltine populations are present in the mid-Atlantic. In general, the correlations between timing and amount of trap captures and timing and amount of fruit injury inflicted concurrently or one week following trap captures were very weak for all trap types and bait combinations. Our results agree with previous studies in the northeastern United States in which trap captures can be increased by presence of semiochemical baits but fail to reflect amount or timing of oviposition injury observed in fruit trees. Thus far, baited traps fail to serve as reliable tools to determine need for and timing of insecticide application against plum curculio.