Disclaimer: This is not an endorsement of Avaunt. The content of this post is meant to be educational. The informed opinion presented here is based off of two trials we completed in Santa Maria using a backpack sprayer and a standard tractor spray. Additional information is from the scientific literature.

In early September, Mark Bolda and I were presenting research from our respective programs to Naturipe growers. We both were asked about Sefina and we shared our experiences with the product. Many growers had jumped on the opportunity to use Sefina under the Section 18 Emergency Exemption this year, but there were questions about mode of action. Mark has written an excellent post about it on 9 Sep 2024 in his Strawberries and Caneberries blog. I suggest you read it!

Like Sefina, Avaunt Evo is another new insecticide that is actually coming on to the market next year. I anticipate there will be questions about its mode of action and best practices. I am writing this post to help answer some of those questions.

Figure 1. DALL-E generated images of a jug of insecticide and insects jousting in the style of a medieval English tapestry.

Here’s what we know right now.

Indoxacarb, the active ingredient in Avaunt Evo, is a group 22 insecticide, has been around since 2004 and was first registered as a bait for ants according to a search on PPLS. It was first demonstrated to be effective against Lygus in the early 2000s. It has expanded across many crops since then. And finally, after twenty years it will be labeled for use on California strawberries. A lot of PCAs will have experience using indoxacarb in their vegetables, so it isn’t a new chemistry to them.

Figure 2: Indoxacarb chemical structure. Image from Chemservice

Indoxacarb targets the voltage-gated sodium channels, similar to DDT and pyrethroids. However, what makes it different is that it binds at a different site on these sodium channels. Once ingested it causes “paralysis and an irreversible halt in feeding” according to Wing et al. 2000. There are four protein subunits to the channel and many ways an insect can develop resistance. At one point there were 50 different mutations in insects that conferred resistance to pyrethroids (Dong et al. 2014).

Tillman et al. 2001 conducted contact and plant feeding assays on Lygus lineolaris. Contact resulted in no effect, but only through feeding. The same study by Tillman et al. 2001 found no contact effect on Geocoris (Big eye bugs), however when those same beneficials were fed corn earworm eggs that had been sprayed with indoxacarb, they died. Luckily only less than 15% of the Big-eye bugs actually fed on the sprayed eggs. In cotton, Lygus lineolaris populations fell without affecting the beneficials.

In my own trial with Avaunt Evo, I have seen some good control of Lygus nymphs compared to other products, especially the organics. The only “downside” is that like Sefina, the Lygus must ingest indoxacarb before it can work. I would not expect a quick knockdown after 24 hours. It was difficult to see a negative effect on the beneficials in my trial therefore I can’t make a definitive comment on safety for beneficials. The literature suggests minimal effect.

Figure 3: Number of Lygus spp. nymphs collected by vacuum over three weeks since the first application on 27 Jun 2024. Sorted by number of insects from largest to smallest. ◊=organic. *Indicates rate per 100 gallons. The gray bar is the untreated control plot. The yellow bar is the grower standard at maximum labeled rate and frequency. Beleaf was sprayed twice, 1 week apart. Sefina was sprayed twice 2 weeks apart. Data was subject to ANOVA and Tukey means separation using Proc Glimmix with a Poisson distribution in SAS 9.4®. Error bars represent standard error of the mean. Means that do not share the same letter are significantly different (α= 0.05). This is a reanalysis using a Poisson distribution which allowed for greater separation between treatments.

Overall, I would not compare Avaunt and Sefina modes of action with that of neonicotinoids and pyrethroids. Avaunt and Sefina are new-ish modes of action that will help in your rotation. Avaunt isn’t a silver bullet, but a bullet, nonetheless. It will take the pressure off of Rimon (novaluron) and Beleaf (flonicamid) from doing most of the heavy lifting.

With La Nina forecasted for winter 2024, we might see higher pest pressure earlier because of the warm temperatures as pest populations will grow through the winter. Having additional modes of action comes just in time. Be vigilant and keep your eyes on the bug!