Managing Insecticide Resistance
I’m sure you have heard about resistance issues by now. Extension personnel preach about fungicide rotation on golf courses to avoid resistance. Greenhouses always rotate miticides. But what about insecticide resistance in a landscape setting? When do we need to focus on rotating mode of actions? Are some insects more prone to developing resistance? What products are available for rotation?
For the most part, our biggest concerns are immobile insects and insects with high reproduction rates or insects with multiple generations within a year. Let’s compare Japanese beetles and scale insects. Japanese beetles are strong fliers that have a single generation per year. Untreated Japanese beetles can easily fly in and join the treated population, which makes the likelihood of those Japanese beetles developing resistance low.
Most scale insects in Central Indiana and Ohio have a single generation per year. Japanese maple scale could have two. Always look at what life cycles are for your specific geography. Either way, all scale insects are relatively immobile. We aren’t introducing untreated insects, like with the Japanese beetles, so there is a greater chance of the scale insects developing resistance.
So what products are available for rotation?
Miticides: If you make multiple applications to control mites each year, you should rotate your chemistry and mode of action. We have several offerings at Advanced Turf. Tetrasan 5 WDG is excellent to use early. It controls eggs and nymphs and sterilizes adult females. I wouldn’t use it as a rescue treatment. My favorite miticide is Forbid 4F. It controls all stages and moves through the leaf to control mites on the underside of the leaf. I’d always use a true miticide versus something like bifenthrin.
Insecticides: Insecticide modes of actions and IRAC codes to prevent resistance are limited. For the most part, we are using neonicotinoids (imidacloprid, clothianidin, dinotefuran) and pyrethroids (bifenthrin, cyfluthrin, lambda-cyhalothrin, permethrin – all those “ins”). There is carbaryl, an old carbamate, but I don’t feel it’s being used much in the landscape. Other chemicals are out there with different chemical modes of actions, too, but, once again, they aren’t commonly used.
In the residential landscape, we use systemic neonicotinoids wherever we can. We can use them as a foliar application and as a soil application. Safari 20 SG can be used as a trunk spray. These products all have “the bee box” on the label, and there are a lot of restrictions. We have to “bee” cautious (pun intended) when using these chemicals. There is more and more EPA scrutiny with this class of chemistry. If we abuse them, they will disappear.
We use pyrethroids the most; they are the most common go-to product. They are also priced well for entry into the market. Pyrethroids are good contact insecticides with some residual, but we tend to forget that they can kill bees when misused, too.
Is there another rotational product we can use to protect against resistance? When it comes to our soft-bodied insects that are prone to developing resistance issues, yes. Distance IGR is an insect growth regulator that prevents insects from becoming adults. Adding Distance into your ornamental program could be crucial to developing an Integrated Pest Management program.
Due to bee safety issues, we have minimal options to choose from for use on flowering plants. However, Distance IGR would be a “bee-safe” product to use on your flowering annuals and perennials for aphid control.
Extension entomologists and the DNR also suggest Distance IGR for scale control. Scale populations are booming and can be challenging to manage. Distance IGR would be a great option to add to the tank when treating scale populations.
We are developing programs containing Distance IGR for use on ornamentals. Stay tuned!