Last week, I posted an updated IPM plan for Mandevilla that balances Thrips parvispinus (“Parvi”) control while taking into consideration other pests, as well as costs. The last post covered propagation in detail, including biocontrols and chemicals.

This week I’ll be going over the best way to balance control of Thrips parvispinus (“Parvi”) and two-spotted spider mite (TSSM) in production. I’ll provide a working Parvi spray program that gives you high-quality plants by sale, but also makes sure spider mites don’t walk away with your crop (or your wallet!).

New IPM Program Incorporating TSSM Control

If you missed it in the last post, the PDF below contains the proposed new IPM program for Mandevilla. Although growers have previously been able to do a weekly spray rotation for Parvispinus, in 2025, many growers got surprised when their battle turned from Parvispinus to TSSM due to resistance. Resistance development isn’t surprising, given that many of the best chemicals for Parvi also overlap with TSSM. Unfortunately, TSSM caused crop losses for some farms.

This new program takes into account TSSM resistance management. The name of the game here is essentially reduced sprays for Parvispinus that can promote resistance in both pests, along with incorporating microbials and some well-timed natural enemies for TSSM.

Note that there are certainly other ways to achieve the same goals out there! This is the plan I’ve come up with that makes the most sense to me and the growers I work closely with. But it’s certainly not the be-all and end-all plan. Make sure to work with your consultant or biocontrol/pesticide rep to tweak this plan as needed, so it works for you, both logistically and economically.

TSSM in Early Production: The Perfect Time for Biocontrol

In the previous post, we talked about using cutting dips to reduced Parvispinus coming in on imported plant material by around 70%. Using Suffoil-X as the cutting dip will also provide some reduction of spider mite eggs. We also talked about using Kontos at the end of propagation to hit 3 pests at once: Parvispinus, oleander aphid and TSSM. But what else can we do early to get on top of TSSM before it becomes a big issue?

Once all rooted cuttings are potted up, but while pots are still pot tight, it makes sense to do some TSSM biocontrol here. The thrips pressure should be low (and stay low for a while) due to treatments in propagation that focused on this pest. And, applications of S. carpocapse nematodes will help continue to suppress Parvi at this crop stage.

This leaves us an important 1-3 month window where biocontrol can be used instead of pesticides for TSSM, to avoid or delay resistance. This is not dissimilar to using biocontrol for Bemisia whitefly in poinsettia to ensure pesticides will work later, when you need them most.

But which spider mite natural enemy should you choose?

After chatting with Sarah Stuive from Global Horticultural, we settled on loose Amblyseius fallacis (at a rate of 1-2/square meter).

Why did we pick this particular mite?

The primary reason is that A. fallacis is more compatible with pesticides than other TSSM natural enemies, especially Pythoseiulus persimilis (which is affected by Kontos for up to 6 weeks). And, as a loose product, it’s relatively cheap compared to other products. It also doesn’t necessarily need TSSM to be present to survive if supplemental food is provided (Artemia cysts, pollen or Ephesita eggs), meaning it could be used preventively.

If sprays are needed for Parvispinus control during the window between potting and fall cleanup, more compatible pesticides should be chosen, as to not disrupt TSSM biocontrol.

For example, Rimon (novaluron; Pedestal in the U.S.) can be used to knock back Parvispinus larvae (the most likely life stage present early in production), and is considered safe for predatory mites. Rycar (pyrifluquinazon) can be added for some efficacy against adult Parvispinus, if needed. Ference (cyantraniliprole; Mainspring in the U.S.) is another chemical option against Parvispinus adults and larvae that’s worked for some growers, and is considered safe for predatory mites.

TSSM and Parvi Control After Spacing: Microbials to the Rescue?

Reducing pesticide applications for Parvispinus to decrease resistance issues means tolerating SOME parvispinus in the crop (and damage) between potting and late October or early November. On farm trials with grower cooperators over a 4 year period demonstrated that the plants will grow out of this damage, as long as Parvispinus pressure is significantly knocked back in mid Fall.

The most effective option for Fall cleanup of Parvispinus is currently 2 applications of Pylon at 1ml/L (chlorfenapyr; Piston in the U.S.), done 5-7 days apart. If the flowers are taken off between the 2 sprays, this increases efficacy even more, as adult thrips have no place to hide.

Unfortunately, Pylon is going to kill off your A. fallacis at this point. Further, the low temperatures mandevilla are grown at in Ontario from November to late February (anywhere from 14 to 20 °C) are not very conducive to arthropod natural enemies. So how do you bridge the months between fall cleanup and early March, when biocontrols can be used again?

During this time, a product like Lalguard M52 is going to be your only non-chemical option for TSSM control. Combining both an entomopathogenic fungus that attacks TSSM with an oil, means the product provides a 1-2 punch. (Other products like Bioceres EC have the same properties, I just haven’t tested them in a commercial operation myself).

Note that these microbial products work best at growing conditions of 20 °C and above. Below this temperature, the efficacy of all entomopathogenic fungi tends to drop off dramatically.

We used weekly sprays of M52 at an operation having a population of TSSM that showed resistance to all chemical classes of miticides in December, 2025. The grower used a rate of 3ml/L of M52 per week, and made sure they got good contact on both the upper and lower leaf surfaces.

Using this technique, they were able to effectively knock back their TSSM without sacrificing their Parvipsinus control, as M52 worked to effectively suppress both pests. They did not need other chemicals for TSSM until temperatures warmed up this week (Feb 22, 2026). Given that it has been 3 months since they last used a chemical miticide, this gives them a better chance of working.

Spring Nights Bring More Mites: And Biocontrol Again?

Ok, well, actually it’s sunny spring days that speed up TSSM development time, but I couldn’t make that rhyme (so sue me).

At this point, increasing levels of TSSM may make you want to reach for your sprayer once again. However, if you’re like the grower above, and you’ve hit a period of resistance in TSSM within the current crop cycle, it would be a good idea to rotate all miticides with applications of Lalguard M52 from now until sale, to help prevent resistance from developing again.

As for WHICH miticides you want to alternate with M52, that depends on your spray history for both TSSM and Parvi. You can see which pesticides have efficacy on TSSM on the Ontario Crop Protection Hub. I’ve listed Magister in the PDF of the new IPM program for Mandevilla, as I’ve been impressed with this chemical (even at the lowest label rates), but other options may be better for you.

As always, make sure to rotate chemical groups with each NEW generation of TSSM. For example, given the generation time of TSSM is 16 d at 20 °C, then you could do 2 applications of Tetrasan within 16 days (IRAC Group 10), before moving on to Magister and/or another IRAC Group 21 chemical from days 16-32.

However, another option would be to use sachets of Neosieulus californicus for TSSM control. Sachets make more sense now that the crop is spaced, and being in a sachet also affords the predatory mites some protection from the direct effects of sprays, like M52 applications.

If Californicus sachets are too expensive farm-wide, then consider applying them to highly susceptible varieties only.

Crop Clean Up for TSSM: The Big Guns

When the Mandevilla crop is fully trellised and beings to flower in earnest, cleanups for both Parvi and TSSM are going to be necessary close to sale.

In my experience working with Parvi over the last 5 years, the best option for spring clean up is another application of Pylon (2x, 5-7 days apart). If you’ve already done 2 of your 3 allotted applications of Pylon per crop, Avid, Ference, and Rimon can also be added into the rotation. Pylon and Avid will both have efficacy against TSSM, and any hot spots can be treated with weekly applications of M52 for both TSSM and Parvi.

Note that Pylon can cause some streaking in dark red flowers, so you may want to time your applications for when the plants have lots of unopened buds on them.

Although it would be great if Success (spinosad) could be an option at this time of year, on-farm tests have shown that VERY high rates of Success are needed for Parvispinus control (10x the label rate, and no less than 3 applications 5-7 days apart), which violates the legal label.

Take Home Messages From Part 2

• Remember, this is just one plan I’ve come up with working with certain growers. Reps from other biocontrol / pesticide companies may have other effective plans as well. Feel free to take this scaffolding and adjust it to fit YOUR operation and your needs. Just make sure you are balancing costs with efficacy across all 3 major pests (Parvi, TSSM and Oleander aphid).
• Pesticide resistance in TSSM has been seen in several large farms across the province. This was more common in operations doing weekly spray applications for Parvispinus. The only way out of this predicament is WEEKLY applications of Lalguard M52 or similar microbial that has the ability to suppress BOTH TSSM and Parvi. This will buy you time until you can clean up with a miticide again (usually a minimum of 3 generations once resistance has been seen).
• To avoid resistance, consider using predatory mites for TSSM in 2 specific windows: right after potting (before Fall cleanup), and when temperatures rise in the spring, until Spring cleanup.
• Make sure to always rotate miticide classes when treating TSSM. It’s a good idea to include M52 between chemical miticide applications to help mitigate resistance.

And remember to stay tuned for PART THREE, where I go more in-depth into Parvispinus control from potting until sale.