Evaluation of small impasse termite barrier plots around utility penetrations and vertical walls against two subterranean termites, Heterotermes aureus and Gnathamitermes perplexus (Isoptera) in Southern Arizona

Novel laminate polymer membranes (IMPASSE) containing lambda-cyhalothrin within an interior layer surrounded by polymer layers were established at the Santa Rita Experimental Range, south of Tucson, Arizona. Fourteen concrete slabs were constructed to overlie the IMPASSE Termite Barrier (ITB) for a period of 6 years. Seven slabs consisted of ITB fabric seamed around utility penetrations with a single utility penetration (SUP), while another seven slabs with double utility penetrations(DUP) consisted of ITB seamed on vertical surfaces and with a "T"-fold. Evaluation portals were established within each slab to assess foraging termite activity underneath and into the slabs. Thirty (30) termite-monitoring stations were placed adjacent to the 14 slabs to monitor termite foraging activity in the area. Monitoring stations showed evidence of occupancy by termites upon 37 % of the inspec- tions. G. perplexus was identified as the most abundant termite, occurring in 68% of the inspections where termite activity was detected. Evidence of foraging by H. aureus termites into a monitoring station was detected in 9% of occupied stations upon inspection. During the 23 sampling dates, the number of monitoring stations with evidence of termite occupancy ranged from a maximum of 14 to a low of four. SUP treatment slabs scored positive for termite foraging activity in adjacent monitoring stations on an average of 41 ± 3.4 m during the inspection period (59-m). The mean number of months that there was evidence of termite occupancy in the monitoring stations adjacent to the DUP slabs was 37.2 ± 6.3 m. Although the termite foraging activity around slabs differed, there was no significant difference in the mean number of months that termites occupied stations adjacent to SUP and DUP slabs. There were no hits (entry by termites into a portal anytime during the study) to any of the ITB observation portals (N=28). Six hits to the control portals (N= 14) were observed. Subterranean termite forag-ing activity was significantly more likely to occur into control portals than observation portals covered with the ITB. The ITB sealed around utility penetrations, and the ITB sealed around vertical surfaces provided a high degree of protection against subterranean termites attack while located in areas of persistent subterranean termite foraging activity.