Laboratory evaluation of microwaves for control of the western drywood termite
2000
Lewis, V.R. | Power, A.B. | Haverty, M.I.
Lethal effects of microwaves on the western drywood termite, Incisitermes minor (Hagen), were evaluated under laboratory conditions. Douglas-fir 2 by 4 boards were artificially infested with 75 drywood termite workers, 25 in each of three routed-out galleries. The boards containing termites were randomly assigned to microwave ovens rated at 500, and 1,000, and 2,000 watts (W). All ovens had the same wavelength frequency: 2.4 GHz. Seventy boards were treated: 25 each for the 500-W oven and the 1,000-W oven, and 20 for the 2,000-W oven. Boards were randomly chosen and oriented within ovens and were treated with one of five treatment times. The treatment times varied with the wattage of oven and ranged from 20 to 150 seconds. Untreated boards (controls) were also prepared to measure nontreatment sources of termite mortality. All boards were split open 1 day after treatment, and counts were made of live and dead termites. Termite mortality exceeded 84 percent for all treated irrespective of oven wattage. Higher wattage ovens had higher termite mortality levels. However, the difference was not significant. Variance in mortality for treated boards was considerable. Only for the last three treatment times did means for all treated boards reach 100 percent mortality. The results suggest drywood termites can escape the lethal effects of microwaves. Although the exact mechanism of escape is not known, additional laboratory studies measuring changes in temperature using optically heat sensitive devices and water vials unequal heat distribution with ovens. Results of this study support the variation in mortality during an earlier field study using commercial microwave devices for controlling drywood termite infestations in structures.
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