Degree Type


Date of Award


Degree Name

Doctor of Philosophy




The temporal efficiency of the Pherocon('(REGTM)) AM trap in capturing western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, adults was studied over a ten-day period in two fields of continuous corn with different infestation levels. Traps were either replaced every two days or left out for the entire period and were either baited with a Conrel('(REGTM)) fiber or unbaited. Unbaited traps replaced every two days captured more beetles than traps left in the field for ten days. When the traps were baited the opposite was true;Trap catches of unbaited traps were compared with catches from traps baited with either one or five Conrel fibers per trap. All three treatments were significantly different from each other. Traps with five fibers caught only 1.6 times as many WCR adults as traps with one fiber;Captures of WCR adults in Pherocon AM traps baited with one of eleven pheromone sources were compared with each other and with an unbaited trap over a 42-day period. The sources consisted of three concentrations in two sizes of Hercon('(REGTM)) Luretape('TM) dispensers, four concentrations in rubber septa, and one Conrel fiber. The 6.45 cm('2) Hercon sheet loaded with the highest concentration of pheromone outcaptured the other sources and was used in subsequent research;Virgin WCR males were marked and released at different distances in opposite directions from a row of Pherocon AM traps baited with Hercon dispensers. The tests were conducted over a two-year period in two fields with row directions perpendicular to each other. Isoprobability recapture lines were determined to be circular and to occur at about 60 m for 1%, 40 m for 1.5%, 25 m for 2%, 15 m for 3%, 10 m for 6%, and 7.5 m for 11%. The pheromone is dispersed primarily by eddying within the planting;Unbaited traps and traps baited with caged virgin WCR females were placed in the centers of pairs of adjacent 5 x 5 grids of Hercon dispensers to test male response disruption. Over a two-year period, distances of 7.5, 15, 22.5, 30, 37.5, 45, and 52.5 meters between pheromone sources were examined. Sources spaced 30 meters apart or less caused a significant reduction in the number and percentage of responding males. Ninety and one-hundred percent response disruption was obtained with the 15 and 7.5 meter spacings, respectively.



Digital Repository @ Iowa State University,

Copyright Owner

Mark N. Wisniewski



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113 pages

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Entomology Commons