Captures of two leafroller moth species (Lepidoptera: Tortricidae) in traps baited with varying dosages of pheromone lures or commercial mating-disruption dispensers in untreated and pheromone-treated orchard plots

Abstract

AbstractA 2-year study conducted in 0.6-ha apple (Malus domestica Borkh.) blocks examined the effects of treatment with pheromone rope dispensers on captures of the obliquebanded leafroller, Choristoneura rosaceana (Harris, 1841), and the redbanded leafroller, Argyrotaenia velutinana (Walker, 1863), in traps baited with varying dosages of pheromone lures or Isomate®-OBLR/PLR Plus pheromone rope dispensers. In untreated blocks, captures of male A. velutinana were high and did not differ among (i) traps baited with a standard lure loading used to monitor this pest, (ii) lure loadings 10 and 100 times the standard loading, and (iii) traps baited with an Isomate-OBLR/PLR Plus pheromone rope dispenser. In pheromone-treated blocks, captures of A. velutinana in traps were reduced 94%–99% for all loadings tested (up to 1000 times the standard loading). The results for C. rosaceana were different. In untreated blocks in 2002, traps baited with 10 or 30 standard lures captured significantly more C. rosaceana than traps baited with a single standard lure; however, in 2003, traps baited with the standard lure loading captured significantly more moths than traps baited with 100 and 1000 times the standard loading. Also, traps baited with Isomate-OBLR/PLR Plus pheromone rope dispensers captured significantly fewer C. rosaceana than traps with standard lures in untreated blocks. In pheromone-treated blocks, traps baited with standard monitoring lures and lures with higher loadings (10 and 1000 times the standard) captured equivalent numbers of C. rosaceana; the capture of moths was reduced by only 50%–71%. We conclude that Isomate-OBLR/PLR Plus pheromone rope dispensers deployed in Michigan, United States of America, are effective in disrupting orientation of A. velutinana; however, they are not very effective for C. rosaceana. In addition, increasing lure loading above that of 1× monitoring lures (rubber septa or membrane type) does not appear to reliably increase the effectiveness of monitoring of males of either leafroller species in orchards where pheromone ropes are deployed at recommended densities.