Controlling Parvispinus, Oleander Aphid and Spider Mites in Mandevilla: Part 2 – Spider Mite Resistance Management.

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!).

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How To Manage Parvispinus, Oleander Aphid and Spider Mites Effectively in Mandevilla: Part 1 – Propagation.

When Thrips parvispinus first came on the scene in Ontario, our one goal was to knock back this pest any way we could. Four years later, we are suffering the effects of an all-chemical program. This includes high costs, along with insecticide resistance developing in two-spotted spider mite, which used to be managed biologically before Parvipsinus came along.

Based on OMAFA’s work with commercial farms, along with input from technical reps from biocontrol companies, we’ve come up with a more refined IPM program for Mandevilla that balances Parvispinus control while taking into consideration other pests, as well as costs.

I’ll be going over this program in detail over a 3 part series, so buckle up!

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In Case You Missed It: Two-Spot Cotton Leafhopper – a New Pest of Hibiscus.

*Fig. 1.* *Two-spot cotton leafhopper. Photo by A. Revynthi, University of Florida.*

Just when we think we have Thrips parvispinus under control, a new pest is threatening tropical ornamentals. The two-spot cotton leafhopper (Amrasca biguttula) is mainly a pest of – you guessed it, COTTON – but also attacks hibiscus. Growers in Ontario should be aware of this pest if importing hibiscus cuttings from the Southern U.S., where this pest has currently invaded.

There’s been lots of good information shared on this pest recently. Read on for a summary relevant to ornamental growers, including what to look for, effective pesticides and what actions you should take NOW.

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In Case you Missed it: UofF Webinar on Latest Thrips parvispinus Research

On March 12th, 2025, Dr. Alexandra Revynthi’s lab (University of Florida) gave an amazing update on what they’ve been working on with regards to Thrips parvispinus. A lot of this was important basic knowledge about their biology, such as development time and survival at high temperatures. There were also quite a few lab and small greenhouse trials looking at potential biocontrol agents.

Some of this will be information we build on to create effective IPM programs for Parvi in the future. But some of these findings, you could put into use right now.

You can go watch the full webinar using the link in the full blog post, or read my summary notes and see what I thought were the important take-aways.

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High Quality Photos for Thrips Identification: Rating Phone Attachments.

This is a guest post by Avery Johnson (former OMAFA summer student and current M.Sc. student studying Thrips parvispinus) and S. Jandricic.

Having difficulty identifying thrips on sticky cards and need clear photos to send to your consultant or extension agent? Don’t want to invest in a microscope? Well, you’re in luck, because we’ve done the legwork to find some good alternatives to get high quality photos.

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Pesticide Rotation Guide for Thrips parvispinus in Canadian Greenhouses

By Sarah Jandricic (OMAFA) and Judy Colley (Plant Products)

*A female (left) and male (right) Thrips parvispinus on a mandevilla flower.*

With the arrival of mandevilla, dipladenia and hibiscus cuttings, now is the time to start planning your management program for Thrips parvispinus. Unfortunately, it looks like this pest is here to stay in North America, and in the tropical plant industry at large.

In this post, we’ll focus on pesticide rotations to manage pesticide resistance, as well as a few tips and tricks to make sure your pesticides stay working.

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“How-to” Video of the Week: Plant Washes and Other Tools to Make Detecting Parvispinus Easier

*OMAFA Summer Student Avery Johnson demonstrating plant washes on-farm.*

In this week’s “how-to” video, we’ll explore using plant washes on-farm.

Plant washes are a simple but effective method to detect low levels of critical pests, such as Thrips parvispinus.

Once you’ve washed out your pests, we’ve also developed a quick “decision tree” to help you easily determine if you’re dealing with Thrips parvispinus or another thrips pest.

Keep reading to find the link to the video and additional resources.

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Potted Chrysanthemums 2024: Dips, Thrips and Threats

Every year at this time, growers start to think about strategies to minimizing western flower thrips on their chrysanthemum crops. This year, Thrips parvispinus is causing extra concern, given that chrysanthemum is one of its reported hosts.

Although there have been no reports yet of Parvispinus damaging chrysanthemums in North America, it’s still good to exercise a bit of caution. However, jumping the gun and spraying chemicals will likely just disrupt your biocontrol program for western flower thrips, leaving you with a bigger mess on your hands.

This post contains information on things you can do to put your mind at ease about all sorts of thrips this chrysanthemum season.

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In Case you Missed it: “A Pain in the Parvi” GrowON Webinar Recording (Plus, Another Thrips parvipsinus Webinar with GrowPro!)

In case you missed the GrowON webinar by myself and Judy Colley from Plant Products on Jan 29th, we’ve now uploaded to Youtube!

You can find it the ONFloriculture Youtube page, along with lots of other useful videos and webinars.

Are recorded webinars not your thing? Well, then you have two additional options!

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Trap Plants as a Tool Against Thrips parvispinus in Tropicals

*Sweet alyssum (Lobularia) as a trap plant for T. parvispinus.*

Thrips parvispinus has become a serious pest of tropical ornamental crops in North American since 2020. Due to the severity of the damage, IPM strategies are needed to complement chemical control until an effective and economical biocontrol program can be developed for this pest.

Mass trapping through traps, lures, or trap plants can be an effective strategy for thrips. We’ve already seen that mass trapping cards REALLY help with this pest (more on that, later). And, it seems that trap plants may also be an effective strategy when used properly in vegetative crops.

Read on for what we did and how to implement it on YOUR farm.

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