Editor’s note: The concept of "stability of termiticide in tank mixtures" is applicable to other termiticides. Here, PCT reports on the results of tests with imidacloprid. Other termiticides may have either similar or different results.
It’s Monday at 7 a.m. A technician from XYZ Pest Control has just mixed his tank and is heading out for a termite job. The phone rings. It’s his customer and she needs to reschedule the treatment. His next job isn’t until Wednesday. How long can the mixed termiticide solution stay in the tank without compromising its effectiveness?
This is a common question asked of Entomologist Dr. Shripat Kamble of the University of Nebraska, Lincoln. "While many people think technicians use the mix right away, that is not the true situation. When you consider factors like weather, a technician calling in sick or a customer calling to reschedule, a mixed termiticide solution may sit in a tank for more than a day," he explained as he began his presentation at October’s National Pest Management Association PestWorld conference.
Kamble and two graduate students, Neil Spomer and Timothy Husen, developed a research study to determine the stability of termiticides once mixed in the tank. They also wanted to find out how sun impacted the solution. Although what they found might surprise some pest control professionals, the results will likely encourage additional confidence in the stability of today’s termiticides.
the Materials. The research team studied the length of time various termiticides will remain stable in a tank-mixed water solution, both in sun and shade, at various concentrations. Kamble presented the data for imidacloprid (Premise termiticide) at PestWorld 2006. (Editor’s note: The research presented was performed with imadicloprid but the concept of "stability of termiticide in tank mixtures" is applicable to other termiticides.) The research team used three concentrations of imidacloprid: 0.10 percent, 0.075 percent and 0.05 percent active ingredient. Each concentration was replicated four times.
While 50- and 100-gallon fiberglass and heavy-duty polyethylene tanks are commonly used in the field by the industry, Kamble said it was not practical to use them for this research as 48 tanks were needed. After a thorough search of various tank materials, the researchers found 1-gallon polyethylene sprayers that would work well. Kamble contacted the manufacturer, which assured him the polyethylene sprayers would protect the chemical from sunlight.
"However, we were still not quite confident so we decided to do our own testing to look at if UV light was going to penetrate the polyethylene sprayers," Kamble said. "So we also tested using one 50-gallon fiberglass tank, and inside of that tank we used small glass containers that had the same Premise samples that we had in the other polyethylene sprayers."
Later the researchers would analyze these samples to ensure they were getting the same protection from sunlight in the polyethylene sprayers they chose for the study.
THE METHODS. Kamble, Spomer and Husen set up the spray tanks on a trailer in open sun. Once this was complete, they replicated the study with the trailer parked in a warehouse to determine if sun exposure had any impact on the degradation of the imidacloprid.
When collecting the samples, they agitated each polyethylene tank by hand for 60 seconds to ensure a uniform solution. They then transferred 3.4 ounces of the imidacloprid water dilution into 4-ounce amber glass containers to put in the 50-gallon fiberglass tank. "One of the reasons we wanted to use a 1-gallon sprayer is because it was very easy for us to lift it up and shake it very vigorously," Kamble said. "The reason we used amber containers was to make sure sunlight would not come into contact with the solution."
The team collected samples at the start and then again at 24 hours, 48 hours, 72 hours, seven days and 14 days. "We know no one will keep a tank sitting for seven days, but we were curious to see what really happens, so we went all the way to two weeks."
After drawing samples, they extracted the imidacloprid and analyzed it using high performance liquid chromatography. "We worked shoulder-to shoulder with chemists from Bayer using the proper procedures of how to analyze and extract the materials to validate our procedures," Kamble said.
REST EASY. For pest control professionals who have found themselves asking, "What do I do with this full tank?" given inclement weather or other unexpected event, they can rest easy about the stability of today’s termiticides. The data showed imidacloprid remained stable in a polyethylene tank-mixed water dilution for more than 72 hours.
"I’m happy to report, looking at 0.10 percent at 24, hours, 48 hours, 72 hours, at one week and even two weeks, there is really not much degradation," Kamble said. "At 48 and 72 hours, almost nothing is lost — about 98 percent of the material is still intact." The results were somewhat similar for the 0.075 and 0.05 concentrations.
In addition, polyethylene tanks protected imidacloprid from sunlight. "Whether the samples were taken from the sun or shade, there was really no significant difference," Kamble said. "Polyethylene filters the UV light from the sun so there was no effect on the chemical."
In an instance where a technician calls in sick or a customer needs to reschedule at the last moment, pest control professionals can have confidence that termiticides in a tank-mix solution will not degrade quickly or lose effectiveness.
"This is a success story where we can confidently say that anytime something does happen or you want to mix termiticides and keep it overnight — or even for 48 or 72 hours, you are going to be just fine," Kamble said. "I think this will be very useful information for the future."
The author has been writing about the pest management industry for 13 years. She can be reached at firstname.lastname@example.org.
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