If you’re involved in selecting public health mosquito control products to control nuisance populations and disease vectors, how do you begin to assess and choose what products get put into your program? Because of the wide variety of products on the market today, having a clear decision process can facilitate a smooth and effective selection exercise.

Where to start?

Begin by considering the fundamental goals of your control program. Are you focused on proactive population suppression? Or do you tend to operate (or does your budget dictate) a more responsive approach to population spikes? An integrated approach supports doing both – using larvicides for preemptive suppression and adulticides for emerging populations.

Reviewing the program goals and seasonality windows can often lead you towards the first important choice in public health mosquito control – larviciding or adulticiding measures.

Larvicides or Adulticides

Larviciding involves treating the water where mosquitoes lay eggs with insecticides to prevent larvae from becoming adults. Think of it as stealth mosquito control – it works proactively behind the scenes, with great benefit to your overall program. At first glance, the upfront cost of larvicide products can appear to be prohibitive. But larviciding, when done correctly, will actually reduce the amount of adulticide treatments needed to deliver and maintain nuisance and disease control in your district or county.

Early in the season, population suppression using larvicides is typically most effective. Breeding habitats – and their ease of access for treatment – are often important factors in product selection for larvicides. But by mid-to-late season, combating disease vectors and population spikes with adulticides may become more impactful.

Adulticides are delivered in an Ultra-Low-Volume (ULV) spray mist that typically puts out less than 1 oz of product per land acre. In addition to being economical, adulticides allow you to act fast and deliver immediate relief against nuisance or disease vectors. When your constituents demand quick action, an adulticide treatment is a very visible and politically “immediate” way to show you’re taking public health seriously. On the flip side, adulticide treatments may face public pushback from residents, on a wide range of issues from the impact of a treatment on the environment, to human risks associated with pesticide exposure, and everything in between. So, know your constituents and be prepared to address application safety.

Susceptibility Concerns

When it comes to using any control product in your program, what do you know about how susceptible your local mosquito populations are to that product?  This applies more specifically to adulticide products. Why?

Although there are many adulticide formulations available for public health mosquito control, they only fall into one of two approved classes of chemistry – organophosphates or pyrethroids. So its best practice to rotate between these two chemistry classes to prevent developing susceptibility issues and extend the life of all available products. But the reality is that many parts of the country (and world) are already experiencing very real susceptibility challenges with pyrethroid-based products, which are also widely used in agricultural and pest control applications, as well as mosquito control.

While there is a race to find a new class of chemistry for public health mosquito control products, we have to steward the two classes of chemistry we have wisely! Having field trial data or indicator results from bottle bioassay tests that show the susceptibility levels inside your district or county can go a long way in making wise product selections for mosquito control.