Can Biflex Mikron be passed on Between Treated and Untreated Ants?

Lab tests indicate that Biflex Mikron insecticide from FMC can be transferred between ants within the nest.

Biflex Mikron is a dual-active insecticide that combines a pyrethroid (bifenthrin) and a neonicotinoid (acetamiprid). Over the past two years, FMC has been conducting a series of trials to answer pest managers’ questions regarding its mode of action. These trials have examined its repellent qualities against German cockroaches and more recently against black ants, as well as the rate of insecticide transfer between treated and untreated German cockroaches. But what about ants? Can Biflex Mikron be transferred from a single treated individual to untreated nestmates?

Scott Kleinschmidt from Australian Timber & Pest Research (ATP Research) was called upon to devise a scientific trial that would provide the answers. In the trial, Mr Kleinschmidt placed freshly collected black ants into 32 test arenas. Five ants were added to half of the arenas, and ten ants were added to the remaining arenas (Figure 1).


Test arenas for science experiment
Figure 1: Test arenas with a single treated black ant (donor) per five or 10 untreated nestmates (recipients)


Four chemicals were used in the trial; three market-leading chemical products and water (as a control):

  1. Termidor (fipronil)
  2. Seclira (dinotefuran)
  3. Biflex Mikron (bifenthrin + acetamiprid)
  4. Water

Separate populations of black ants were lightly misted with one of the products at recommended label rates (one treatment per population). A single treated ant (donor) was placed into a test arena containing either five or ten untreated ants (recipients). Overall, the trial consisted of four treatments at two different donor/recipient ratios (1:5 and 1:10). Four replicates were carried out for each treatment.

The ants were free to roam within each test arena and to interact with the treated ant as they wished. The trial was monitored for four hours after treatment for the 1:5 ratio and six hours after treatment for the 1:10 ratio, with the number of dead or moribund ants recorded at 30-minute intervals.

The 1:5 ratio produced similar results across the three chemical products with all of them successfully transferring the active ingredient from the treated ant to the untreated nestmates. All the chemical products recorded 100% mortality during the four-hour trial period, as compared to zero mortality in the water-treated population (Figure 2).

Black ant mortality chart
Figure 2: Black ant mortality after adding one treated ant to five untreated nestmates (average of four replicates)


In the 1:10 ratio, Termidor (100%) and Biflex Mikron (97.5%) recorded similar mortality, with Seclira slightly less at 87.5% mortality during the six-hour trial period, as compared to zero mortality in the water-treated population (Figure 3).

Black ant mortality chart
Figure 3: Black ant mortality after adding one treated ant to ten untreated nestmates (average of four replicates)


It was observed during the trial period that untreated ants (recipients) would regularly stop and interact with the treated ant (donor) even after the donor had died. The interaction was often via rubbing or tapping its antennae across the donor’s body. This is normal ant behaviour; ants use their antennae to pick up scents in the air, to tap the ground and other ants, and to investigate potential food sources.

They often have to clean their antennae to allow these sensitive body parts to operate optimally. They do this via a special cleaning structure on their front legs that is used to groom their antennae. Once the antenna is clean, the ant must then clean the cleaning mechanism, which it does with its mouth, thus allowing any chemical it has picked up with its antennae to enter the ant’s body. This behaviour is one of the key routes for the transfer of chemicals from the donor ant to the recipient ant.

The results from this trial and the previous repellency trial on black ants in the Winter issue of Professional Pest Manager demonstrate that Biflex Mikron treated surfaces are not repellent to foraging ants; ants will display normal behaviour and will interact with treated ants and can transfer chemical from treated ants to untreated nestmates.

This trial further challenges the general perception that pyrethroid chemicals are repellent to pests. The term ‘repellency’ has reduced relevance for ant management as compared to termite management, as ants have much thicker and tougher cuticles compared to termites and have less contact with a treated surface as compared to termites, which can be surrounded by treated soil.

This trial looking at nestmate interaction was undertaken as part of FMC’s commitment to increasing its knowledge base regarding what FMC products can and cannot do. These trials are for the benefit of pest managers to help them use Biflex Mikron to its full potential and serve as an add-on to the trial data submitted to the APVMA that proves the efficacy of the product.

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