Thrips parvispinus Webinar 3: Attacking Parvi from All Sides

*IPM Staff at a local greenhouse inspecting mandevilla flowers for Parvi.*

This post was written by Jessie deHaan (Research Technician, Vineland Research and Innovation Centre) and Dr. Sarah Jandricic (Greenhouse Floriculture Specialist, OMAFA).

Part 1 of the three-part webinar series on Thrips parvispinus focused on controlling incoming thrips on cuttings, while Part 2 shared the interesting behaviour and ecology that we’ve learned about Thrips parvispinus (Parvi) that could help us better manage this pest.

The final webinar is all about exploring Parvi IPM in greenhouse trials. Combining biologicals, chemical applications and other IPM interventions throughout plant production may help give you the best footing against Parvi – and other concurrent pests – while avoiding pesticide resistance.

Read on for the link to the webinar and for our written summary.

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IPM in Mandevilla: Part 3 – Reducing Costs in Early Production.

Over the past few months, I’ve posted a series on IPM in Mandevilla – now one of our more challenging crops, thanks to Thrips parvispinus!

This week I’ll be going over strategies we’ve used at a few farms to decrease costs of IPM in Mandevilla NOW, in early production, which can creep up under weekly spray programs. I’ll also be incorporating some case studies from growers, to better illustrate what’s working in the real world.

I’ve included an updated chart for IPM of Mandevilla pests in this post that is a bit cleaner. Lastly, stay tuned for Part 4, which will cover how to save money in late production.

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Thrips parvispinus: Know Thy Enemy‘s Behaviour

This post written by Jessie deHaan (M.Sc.), Research Technician in the Biocontrol Lab at the Vineland Research and Innovation Centre.

Recent collaborative research from Ontario Ministry of Agriculture, Food and Agri-Business (OMAFA), Agriculture & Agri Food Canada (AAFC), and Vineland Research and Innovation Centre (Vineland) has helped reveal some key components of Thrips parvispinus ecology and behaviour.

This has helped us to develop monitoring approaches for this pest in greenhouse floriculture, and is helping to point us towards optimized control strategies.

This research was covered in a recent webinar hosted by Flowers Canada Growers (linked to in the post below). But if you’d rather read than watch, this post summarizes our findings!

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Dip, cool or steam? Clean Start treatments for Thrips parvispinus

Mandevilla cuttings in propagation with different treatment tags in them.

This post written by Ashley Summerfield (M.Sc.), Senior Research Technician in the Biocontrol Lab at the Vineland Research and Innovation Centre.

They say that “an ounce of prevention is worth a pound of the cure” and nowhere is this truer than in IPM. Reducing the incoming number of invading pests will inevitably improve the success of any pest management strategy.

This post covers recent research advances made by Vineland Research on treatments of propagative plant material to help control Thrips parvisipinus. This includes effects of treatments on all thrips life stages, including eggs, as well as potential phytotoxicity of treatments on tropical plants.

This post also includes a link to the recent webinar on starting clean for Parvi recorded by Flowers Canada Growers, if you prefer that format!

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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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