Field
Trials

Location and Preparation

We evaluated Interval33™ in field tests in eastern Colorado Our experimental sites were cattle ranches bordered with old wooden fenceposts, many of which are infested with termites (R. tibialis). To determine if a post was infested with termites, we used wood frame traps consisting of a square wood frame (15.2 cm by 15.2 cm, fir), containing several pieces of double-corrugated cardboard cut to fit the center of the frame and held in place by a 0.64 cm wire mesh. These traps were completely buried in a hole (30 cm deep) dug at the base of a wooden fencepost. The traps were checked after two weeks and, if termites were found in the traps, the traps were removed and the post was then used as a point source for the field test.

 Fenceline at rangeland test site with old fenceposts.

Checking frame trap for presence of termites.

Set Up

Bait stations were 8-ounce polyethylene jars (with screwcap lids) with 36 holes (3 mm) drilled around the circumference and filled to within 3 cm of the top with soil containing 15% moisture.  Treatment (3 grams Interval33™ termite attractant) was mixed into the soil prior to filling the jars.  The jars were placed as pairs with one control (unbaited) and one Interval33™-baited jar buried (in holes 30 cm deep) 1 meter away from an infested fence post and 1 meter apart with both stations on the same side of the fence line (Figure 1A).  For controls, two stations (both unbaited) were placed in the same manner (Figure 1B).  In preliminary experiments unbaited stations in proximity (within 1.5 meters) to a CO₂-baited (Interval33™) station were occupied by termites as frequently as the station containing the bait. We found that the point source of Interval33™ not only attracted termites to the baited station, but that it directed them to forage in the larger area of CO₂-enriched soil surrounding the station.  We concluded that a single station containing Interval33™ was sufficient to create a gradient of CO₂ in the soil, extending from the station in all directions for up to 2 meters.  For this reason, we concluded that any station within that soil CO₂ gradient should be considered baited.  In the current test two stations (one baited and one unbaited) were placed near each fence post and both stations were considered baited because the surrounding soil had elevated CO₂ levels.  The appropriate controls for this experiment were sets of 2 stations (neither of which contained Interval33™) placed in an identical manner near the fence posts.

Statistical Analysis: Logistic regression analysis was conducted using SAS (SAS Institute Inc.,Cary, NC) to determine significant differences (alpha = 0.05) between activity in jars at Interval33™-treated fenceposts and at control fenceposts.

Jar trap station filled with soil containing Interval33™

Placing jar stations in ground around fenceposts

Results

Significantly more stations baited with Interval33™ were positive throughout the season than unbaited stations (Figure 2).  Eighty five percent of stations treated with Interval33™ were found and utilized by foraging termites by the end of the trial.  Termites were found in only 1 (6.25%) untreated (control) station and the insects did not locate this station until week 5 of the study.  These results demonstrate that Interval33™ is an effective termite attractant. As a commercial attractant, it may significantly reduce the amount of time required for termites to locate monitoring stations

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