The potential for pheromone-based monitoring to predict larval populations of diamondback moth, Plutella xylostella (L.), in canola (Brassica napus L.)

摘要

Numbers of adult diamondback moth, Plutella xylostella (L.), captured in pheromone-baited traps may predict the density of damaging larval stages in canola, Brassica napus L. Two years of season-long experiments in Alberta, Canada compared captures of male moths in traps baited with commercial pheromone to larval densities. Significant relationships between moth catch and larval density were infrequent and generally curvilinear indicating that moth numbers were not directly related to larval density. Stronger relationships occurred late season and may indicate that population establishment is necessary before moth capture can predict larval populations. Relationships between moth capture and immature stages sampled at the same time were similar to those sampled two weeks later. A statistically similar number of moths was captured throughout the season in traps baited with lures changed at 6-versus 3-week intervals. During years of moderate and low populations of diamondback moth in canola, moth counts from one pheromone-baited trap per field are sensitive enough to detect densities of immature stages and are more accurate than sweep net sampling. Experiments have contributed to the development of a monitoring system to forecast P. xylostella densities in canola, but research of additional variables may help to develop a consistent relationship between moth catch and larval and pupal densities