Evaluation of six techniques for control of the western drywood termite (Isoptera: Kalotermitidae) in structures.
Chemical and nonchemical methods for control of the drywood termite Incisitermes minor were evaluated under conditions that simulated infestations in structures. The efficacy of excessive heat or cold, electrocution, microwaves and 2 fumigants (sulfuryl fluoride and methyl bromide) was evaluated. Termite mortality in artificially-infested boards was 100% at 3 days after treatment for both fumigant gases. Heating the whole structure or spot-applications using microwaves resulted in 96 and 90% mortality, resp., 3 days after treatment. Mortality levels 4 weeks after treatment increased to 98% for heat and 92% for microwaves. Spot-applications of liquid nitrogen at 381.8 kg/m3 achieved 100% mortality 3 days after treatment. However, for 122.7 and 57.3 kg/m3, mortality levels 4 weeks after treatment were 99 and 87%, resp. Mortality by spot-applications of electricity was 44% 3 days after treatment in the 1st test. Four weeks after treatment, mortality increased to 81%. In a 2nd electrocution test, using spot-application techniques infrequently used in structures, mortality levels increased to 93% at 3 days and 99% at 4 weeks after treatment. The distribution of termite survivors within the test building and test boards varied for some treatment techniques. For naturally-infested boards, both fumigants exceeded 99% mortality. Use of heat and microwaves resulted in 100 and 99% mortality levels, resp., 4 weeks after treatment. Applications of liquid nitrogen resulted in mortality ≥99.8% at 381.8 and 122.7 kg/m3; however, mortality for 57.3 kg/m3 was significantly lower (74%). Mortality levels from electrocution were 89 and 95% 4 weeks after treatment, resp., in the 2 tests. Damage to test boards and the test building did occur. Six test boards were scorched during microwave treatment, 80% of test boards were damaged during electrocution and visible signs of damage to the test building were noted for whole-structure heating. This study provided information for the evaluation of the relative efficacy of fumigation and nonchemical alternatives for the control of drywood termite infestations in structures.