Pheromonal trapping methods for the lesser grain borer, Rhyzopertha dominica (Fab.), in warehouses

Typescript (photocopy).Tests were performed in warehouses to develop optimal trapping methods for the lesser grain borer, Rhyzopertha dominica (Fab.), using dominicalure as the attractant and to study their efficiency for estimating infestation magnitude. Food packets were also useful in assessing the relative abundance of R. dominica in warehouses, but problems were found in their use. In studying the adult insect infestation of bagged grain, probe traps were effective for detecting R. dominica and the catch was directly and highly related to the insect population density inside the bags. The sampling spear was less efficient than the probe trap. Probe traps with 50 (mu)l of dominicalure 1 in a rubber band were superior to control traps, which capture insect numbers equal to traps baited with dominicalure 2. For aerial trapping, dominicalure was a powerful attractant both inside a warehouse and outdoors. No differences in attractiveness was found among dominicalure 1, dominicalure 2, and mixtures tested. Color of traps had no attraction by itself nor as a complement to the attractiveness of dominicalure-baited traps. The Lindgren funnel trap was the best design of the eight traps tested. The most effective pheromone dispenser type of the four tested was a 0.4 ml polyethylene test tube. Traps with 50 (mu)l of dominicalure 1 in a test tube were attractive for 30 days under summer conditions. The lowest pheromone dose tested, 50 (mu)l of dominicalure 1 in one test tube, was as effective as doses of 100, 150, and 200 (mu)l of substance in 2, 3, and 4 test tubes, respectively. More R. dominica adults were caught when the pheromone-baited traps were placed along walls and close to the ground than at the middle of the room or at greater heights, respectively. R. dominica behaved as a crepuscular insect during the summer and fall, with peaks of flight activity around sunrise and sunset. The peak at sunset was notably large. At night, flight was normally minimum, but it increased when warehouse lights were on. This species required relatively high temperatures to fly. Temperatures for 0, 50, and 100% of probability of flight occurrence were 19.6, 24.5 and 29.4(DEGREES)C, respectively. Dominicalure-baited Lindgren funnel traps estimated accurately the aerial density of the lesser grain borer determined by the periodicity in flight