| Western poplar clearwing moths [Paranthrene robiniae (Hy. Edwards)] are endemic in Pacific Northwest riparian habitats at low population densities. These moths have colonized commercial hybrid poplar plantings where larvae damage the poplar trees by boring into the trunks. In newly planted poplars a single P. robiniae larva can cause tree mortality. Prior to the introduction of agroforestry into eastern Washington and Oregon Paranthrene robiniae (Hy. Edwards) was not considered a pest of economic importance.; In 2002, there was an outbreak of P. robiniae, documented with pheromone baited trap catches increasing 190-fold from those of 2001. Chlorpyrifos applications failed to reduce P. robiniae populations. Investigatory research started in August 2002, to see if a pheromone control strategy would be feasible. In this preliminary study we found that we were able to shut down trap capture of P. robiniae in 0.4 ha plots by attaching pheromone lures to every other tree.; We began a pheromone control strategy in 2003, but because of difficulties in acquiring adequate pheromone, and late applications, we were unable to show a reduction in damage to first and second yr trees. We continued our pheromone control strategy in 2004 with adequate pheromone to cover entire farms and applied the pheromone before P. robiniae began their flight season. With that approach, we were able to show a reduction in damage to first and second yr trees. With sustained use of this pheromone control strategy we have continued to document reductions in damage.; With persistent pheromone saturation, trap capture of P. robiniae was shut down to the point where weekly counts of the monitoring traps did not provide an adequate way to monitor P. robiniae populations, and thus infield pheromone levels. Nemapogon variatella (Clemens), a fungus moth, is attracted to the same pheromone as P. robiniae. However, we have no evidence to show that N. variatella populations have been affected by our pheromone control strategy. By monitoring N. variatella in monitoring traps baited with P. robiniae pheromone, we can use N. variatella as a "canary" species and monitor ambient in field pheromone levels in the absence of P. robiniae. |
