EUROPEAN CORN-BORER (LEPIDOPTERA, PYRALIDAE) MOTH CAPTURES IN AERIAL WATER PAN TRAPS INFLUENCED BY REPLACEMENT OF PHEROMONE AT DIFFERENT INTERVALS

Aerial water pan pheromone traps were used to monitor flights of the European corn borer, Ostrinia nubilalis (Hubner), in two locations in South Dakota during 1987 and at three sites in Illinois in 1988. Our objective was to evaluate the effect of different pheromone septa replacement intervals on European corn borer moth captures in aerial water pan pheromone traps. At each location, four treatments were arranged in a randomized complete-block design. The treatments consisted of differing the length of time pheromone septa were allowed to remain in the water pan traps and were as follows: (1) septa replaced weekly, (2) septa replaced biweekly (once every 2 wk), (3) septa replaced every 3 wk or monthly, and (4) traps used without septa. Results indicate that even when pheromone septa are changed very infrequently (3 wk to monthly), distinct flights of male European corn borer moths can be detected. Moth captures were generally greater in water pan traps in which septa were changed weekly; however, in many instances, no significant differences in trap catches occurred among the three pheromone replacement treatments. When European corn borer populations are very low, the length of time between pheromone septa replacement may not significantly affect the capture of male moths. Replacement of pheromone septa on a biweekly basis should work satisfactorily for a large-scale monitoring program where expense is a concern.