Field observations of pesticide resistance

I was asked to treat a suite that had been unsuccessfully chemically treated for two and a half years – that would be 30 unsuccessful treatments. The landlord hired Bug-n-Scrub to spend an entire day vacuuming, steaming, and doing laundry and the next day I spent 1.75 hours thoroughly chemically treating the suite with Tempo 25673 at the maximum concentration allowed by law. In Canada I can only apply Dragnet/Prelude, Tempo, or Demand CS as a residual. Dragnet has a much lower residual than Tempo and Demand CS has highly restrictive label directions making it less useful. Tempo is really my best option.

I noted, while in conversation with the tenant, that there was a large amount of bed bug spotting on her shoes. I asked that they be removed so I could inspect but I saw no live activity. I then noted a deck of playing cards on the kitchen table – the face side of the cards were covered in bug excrement while the other side had a much smaller amount of excrement. I deduced the bugs were attacking the tenant at the kitchen table with bugs feeding on her ankles while others ran about the table defecating on the playing cards while the tenant played solitaire. I have seen some crazy stuff but this one topped them all.

At 18 days I inspected a location in the kitchen in which I had treated bugs directly. I thought the bugs would be dead but when I poked them with a credit card 3 bugs ran away!! Those bugs were treated directly, sat on Tempo residual for 18 days, and still survived.

The modified glueboards I installed started collecting 400 bugs a day and over the course of 2 months that has been whittled down to 47 per day. To date I have collected 12,100 bugs on traps. Clearly 30 chemical treatments provided earlier and my later course of Tempo were ineffective.

I collected a few samples of these bugs and tested them for chemical resistance. I painted the bottom of a small teflon pan to give the bugs better traction and treated it with Tempo as per my normal methods. As soon as the spray was dry I placed 12 bugs on the surface and left them there for 24 hours. It appeared that 2 bugs were incapacitated, one was feeling ill, and 9 were perfectly healthy. They would attempt to climb the side of the teflon pan and vigorously right themselves when they fell upside down. In a normal suite a bed bug might spend, lets be generous, perhaps 10 minutes on treated surfaces. How is that supposed to work?

Given the size and age of the infestation and the tendency toward day feeding (bugs in the shoes and cards) these bugs have been dispersing throughout the apartment building and throughout Winnipeg for at least a year. And social service folks I speak with tell me these situations are common. It should come as no surprise that Winnipeg exterminators are finding bed bugs harder to treat.

Two weeks ago I treated a severe infestation in another home with Tempo 25673. The tenant did not have a proper bed so I could not provide modified glue board traps. When I returned for retreatment I noted, perhaps, 50 bugs harbouring on treated surfaces. Perhaps this batch of bugs is related to the last batch. It appears my predictions of chemical treatments being worthless in 5 years was optimistic – perhaps it will be sooner than that.

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