Cover Story

New Insecticides for Turfgrass Insect Pest Management

By Ben McGraw, Ph.D.

Three new insecticides were registered for control of turfgrass insect pests in Pennsylvania in 2022. These new products represent active ingredients from different insecticide classes, including an anthranilic diamide (tetraniliprole Tetrino®, Bayer), a combination product (Alucion®, BASF) and an insect growth regulator (Suprado™, QualiPro). Given that these actives are diverse in their chemical structures and modes of action, they differ in the pest activity and how/ when they should be applied. Our laboratory has spent the last three to five years testing these products on various pests including ants, caterpillars, white grubs, weevils, and leatherjackets. In this article I will highlight the strengths of each and where I can see these products being useful as rotational partners in integrated pest management programs.

Alucion (BASF):

Active ingredients: Alpha-cypermethrin (Insecticide Resistance Action Committee (IRAC) class = 3A) + dinotefuran (IRAC class = 4A)

Labelled pests: Annual bluegrass weevil (ABW), Ants, Caterpillars, Billbugs, Chinch bugs, Leatherjackets, Mole crickets

CHARACTERISTICS:

Alucion is marketed as being the only non-restricted use pyrethroid labeled for golf courses, though it may be used in athletic fields, residential and commercial lawns, parks, and athletic fields. This product is a combination of a pyrethroid and neonicotinoid, two of the more commonly used insecticides worldwide. However, this is where the similarity in classes ends. Pyrethroids are relatively broad-spectrum and have little mobility (bind tightly with organic matter) and have short residual activity. These attributes limit pyrethroids to being used primarily as contact insecticide for surfaceactive insects. Conversely, neonicotinoids are small molecular weight compounds that are highly soluble, have low binding potential, and lengthy residual activity. These attributes allow for systemic uptake and expression within the plant. Combining these classes allows for matching strengths of each class and thus expanding the spectrum of pests controlled. In theory, quick action of the pyrethroid combined with the residual activity of the neonicotinoid make combination products a good fit for pests that have susceptible and tolerant stages (e.g. eggs, pupae) present at the same time (e.g. ABW, billbugs, chinch bugs, turfgrass ants) and thus require curative control and prevention of future stages at the same time.

STRENGTHS:

Alucion has performed well in our field trials against insects that would either be sensitive to or targeted with pyrethroids including caterpillars (e.g. black cutworm, fall armyworm), leatherjackets, and ABW. With ABW, I would have suspected that Alucion would work best as an adulticide, given that we generally do not see much ABW activity with neonicotinoids. The label states that Alucion provides suppression, which is appropriate for most ABW products, though doesn’t diminish the value of the insecticide. Multiple trials against susceptible and moderately pyrethroid-resistant ABW have shown that our greatest levels of control were when Alucion was applied when larvae were between 1st and 3rd instars……a time when they are located in the plant and largely protected from most chemistries. It is unlikely that alpha-cypermethrin persists long enough to control larvae when they emerge in the soil, and thus it is likely that dinotefuran is providing some relief through translaminar activity. The timing of this application (1st generation early-instars) is likely to provide some control of turfgrass ants at the same time. Turfgrass ant trials conducted in 2022 would suggest that Alucion is similar to a pyrethroid alone when the application is delayed until mounding is well underway (early June). Combination products are the current recommendation for turfgrass ant control, and they usually work best when applied at sight of first mounding (~ late April – early May in PA). Future trials need to address earlier timings to reduce mounding.

Suprado (QualiPro):

Active ingredient: Novaluron (IRAC class = 15)

Labelled pests: ABW, billbugs, caterpillars, white grubs, chinch bugs

CHARACTERISTICS:

Novaluron is a benzyl urea insect growth regulator (IGR). Unlike traditional chemistries, IGRs disrupt the insect’s endocrine system rather than targeting the nervous system. Because of this, IGRs are generally regarded as having less potential for issues with mammals (e.g. non-target wildlife and applicators). Suprado is the first IGR to be registered for use in turfgrass since Mach II (halofenozide) was released in the late 1990s. Much like the two active ingredients in Alucion, halofezonide and novaluron could not be more different. Halofenozide mimics an insect hormone (ecdysone) and causes premature molting and eventual death of immature insects. Novaluron disrupts chitin synthesis when the new exoskeleton is being formed, leading to death shortly after the insect molts. We can therefore deduce that Suprado should 1) be used to control immature stages (larvae, nymphs) and 2) it will take some time after application for the insect to die since the insect must advance to their next instar to have its exoskeleton weakened. White grubs are listed on the Suprado label, though based on binding characteristics (i.e. soil adsorption values) it is unlikely that the active ingredient will be able to reach the rootzone. Additionally, the half-life of novaluron would suggest minimal residual activity in the soil, making it primarily a contact insecticide that needs to be delivered to where the pest resides.

STRENGTHS:

Our lab has only evaluated Suprado for ABW control. Data from multiple trials conducted between 2019 and 2021 suggest that the product will be an important rotational partner in management programs. We hypothesized that Suprado would work best when applied to larvae exiting the plant (3rd-4th instars) when they would be more likely to be exposed to the IGR. High levels of control (>90%) were seen when single applications of labeled rates (1 gal/ac) were applied at this time, but surprising much earlier as well (e.g. adult and early-instar peaks). Slightly lower control was observed when lower rates were applied when mature larvae (5th instar) were the dominant stage.

Laboratory studies were conducted to explain how a larvicide with minimal persistence could provide such high levels of control when applied when only adults were present. No adult mortality was observed when treated topically. However, we observed > 90% reduction in eggs, indicating a negative impact on egg development. Furthermore, when adults were allowed to oviposit on turf, removed, and then the turf was treated, upwards of 85% reductions in larvae were observed, suggesting that the product has ovicidal effects as well. These effects have been seen with novaluron and other benzyl urea IGRs in agricultural systems.

Taken together, Suprado application timing appears quite flexible, though I would caution against making applications too early (i.e. during adult migration) or too late (i.e. when mature larvae and pupae are present). Given the activity against multiple ABW stages, Suprado is a nice choice for a summer generation application when stages are asynchronous. Also, pyrethroid resistance status has not been shown to impact control, making it an important tool in resistance management programs.

Tetrino (Envu):

Active ingredients: (IRAC class = 28),

Labelled pests: ABW, billbugs, caterpillars, white grubs, chinch bugs

CHARACTERISTICS:

Tetraniliprole is the third active ingredient from the anthranilic diamide class to be registered in turfgrass. In general, the diamides have many positive attributes such as systemic uptake, lengthy residual activity, low impact on beneficial insects, and are virtually non-toxic to mammals. Solubility and binding of tetraniliprole appear to be like that of the other diamides (chlorantraniliprole (Acelepryn), cyantraniliprole (Ference)), though residual activity (half-life in soil) is less than Acelepryn and more similar to Ference. The product should persist long enough to provide preventive control of insects like white grubs and caterpillars.

STRENGTHS:

Multiple trials conducted since 2016 have shown a broad range of activity against many of our pests in the northeast. White grub control has been shown to be best when Tetrino is applied closer to egg hatch or during similar timeframes as neonicotinoids (e.g. late Juneearly July) rather than in spring as with Acelepryn applications (e.g. late AprilJune). Tetrino is also an effective rotational partner in ABW programs, with best results being achieved when applications are made either slightly before larvae exit the stem or when larvae are beginning to emerge in the soil (i.e. rhododendron full bloom). Chinch bug trials conducted in 2022 show that Tetrino is similar to other diamides and that only minimal (<20%) control can be expected.

Probably some of our most surprising trial results have been observed when we apply Tetrino as a curative or rescue treatment. The strengths of neonicotinoids and diamides are in their residual activity, which allows for flexible application timing and preventive control. Very little curative activity is seen with these actives. We have observed that Tetrino is unique to the diamides in that it provides moderate curative control of ABW and white grubs as well. Control of late-instar ABW with Tetrino exceeded that of trichlorfon (Dylox) and other diamides. Curative control of white grubs has also exceeded that of industry standards, though best results have been observed when grubs are still small (prior to September/late 2nd instar).

CONCLUSION:

It is no small miracle to see three new insecticides registered for turfgrass in one calendar year. Each of these new products are likely to have major impacts on pest management programs. It is important to recognize that none are a one-size-fits-all solution for every pest need. It is important to read and follow directions and safety precautions on labels…and consult an extension agent if you have questions regarding the proper use of these products.