Western flower thrips adult on an open Mandevilla flower. Photo credit: Caitlin MacDonald, USEL student.
Now that the warm weather is finally upon us, it’s time to start worrying about thrips control.
What we’ve learned over the years is that pesticides just don’t cut it – the only reliable chemical for western flower thrips in Ontario is DDVP, which requires constant application. This means biological control is your best bet. Here’s a summary of the most effective tools, tricks, and timing, to ensure your biocontrol dollars are well spent.
Today I want to share with you one of my favourite things of all time – the Bug Dorm. Basically a mini, insect-proof tent, Bug Dorms are an amazingly useful tool for conducting quick-and-dirty experiments in your greenhouse. By containing (or excluding) insects, they can help growers answer SPECIFIC pest questions in their SPECIFIC crop or operation, without needing to wait for researchers to find the answers.
Effective biocontrol programs for western flower thrips often usemultiple natural enemies. These includepredatory mites like N. cucumeris or A. swirskii, but also generalist predators like Atheta and Orius, which can feed on mite eggs and nymphs.
Check out this flyer for details on my “Intro to IPM” workshop on Feb 25th. The workshop will cover identification of common pests (insects AND diseases!), review of IPM basics, and optimizing IPM strategies in greenhouse floriculture crops.
This is a great workshop for new greenhouse employees, first year scouts, or as a refresher.
A more advanced workshop will be offered in the summer on integration of biocontrol and IPM for key pests (date and exact topic TBD, so check back!).
It’s an exciting time for Floriculture IPM! I am VERY pleased to announce the launch of the all newGreenhouseIPM website! GreenhouseIPM.org presents a compilation of up-to-date information on Integrated Pest Management (IPM) and biological control in greenhouses.
And, as part of the website launch, we are holding a FREE THRIPS WORKSHOP (with a free lunch!). The workshop will cover all the components of thrips IPM and how they fit into a greenhouse production system.
Dates are Nov 23rd (8:30-1pm) OR Nov 30th (8:30-1pm) at Rittenhouse Hall. Please RSVP Rose Buitenhuis: (email@example.com or 905-562-0320 x749). SPACE IS LIMITED SO RESERVE YOUR SPOT NOW!
The most current information on thrips and whitefly IPM is now at your fingertips at greenhouseipm.org.
GreenhouseIPM.org provides detailed descriptions of pests, biocontrol agents and detailed instructions on how best to use biocontrols within an IPM program.
Its initial format it focuses on two key pests – whiteflies and thrips – and their control. The site will evolve to encompass all common insect and mite pests, as well as diseases, in greenhouse crops.
What’s the first thing you do with your shipments of predatory mites, parasitoids and predators when you receive them? You probably check to see if these natural enemiesare alive before you put them out in the crop.
Now Albert Grimm (Jeffries Greenhouses) and I have come up with a way to check if many of your microbial products are still viable, too.
We’re still in the process of testing these methods for all microbial products, so please consider this preliminary. Right now, we know this works for Beauveria and Metarhizium-based products only (e.g. BotaniGard, BioCeres and Met52). I’m hoping to put the methods up for more products in December.
Figure 1. Various fungi growing on a 3M Yeast and Mold Petrifilm
Distilled (sterile) water. Unopened bottled water will do in a pinch. Do NOT use tap water.
Figure 2. 0.2mL sterile, disposable pipettes that can be obtained from Amazon.ca.
Step 1: Disinfect the water cup and the measuring spoon with rubbing alcohol. Wipe dry with paper towels. Step 2: In one plastic cup, add a small amount of sterile water (a few mL is fine). Keep for Step 4 to act as a control. Step 3. Take a second cup to mix up your product in. Add 200 mL of sterile water. Then add approx. 1/16th of a teaspoon (0.3ml) of product (Beauveria or Metarhizium). To measure, fill the smallest baking measuring spoon (1/8th of a teaspoon) about half way. Stir well. This will give an approximate concentration of 1 g/L, which is similar to recommended rates of these products. Step 4: Take a disposable pipette and fill with sterile water. (Make sure to re-seal your bag of pipettes so they stay clean and sterile). Grab a single Petrifilm and peel back the thin, clear cover on top. Carefully squeeze the pipette to form a line of water across the surface of the Petri film. Step 5. Repeat Step 4 on the same Petrifilm using your product in solution. You can use the same disposable pipette (since it only had sterile water in it previously).
Figure 3. Photo courtesy of Albert Grimm. A 3M Petrifilm used to test the viability of Met52 and BotaniGard. The blank water control indicates that all fungi came from the products, not from the water source (here, distilled water).
Step 6. Gently drop the plastic cover back over the Petrifilm. Write directly on the plastic cover with a sharpie to indicate the position of your “control” water line and your “product” water line (see Fig 3). Store the film between 20-25 °C in a dark location.
Step 7: After a minimum of 16 h (the time it takes for Beauveria spores to germinate), check your Petrifilm. The sterile water line should be blank. The Beauveria and Metarhizium lines should be light blue -the film has a dye in it that reacts to fungi (Fig. 3). Note that this dye reacts to ANY fungi or yeast. Thus, you CANNOT use it to diagnose what fungus is growing. This is why the sterile water control is so important – you want to be sure the reaction is from your microbial product, and not from random fungal spores in your water.
With the growers still tentative in their use of microbial-based products, this viability test may give growers some piece of mind. It will be particularly useful for product that’s been shipped in hot summer months, or in the dead of winter, as some products are sensitive to extreme temperatures. It can also be used to testproduct that has beensitting in storage for long periods.
Note that this is a simple live/dead test. These methods do not quantify how much of the product is still viable. That’s something Dr. Anissa Poleatewich (Vineland) and I are working on, as we think it would be useful to know if your product is decreasing in efficacy over time. So, stay tuned for more information as we perfect our methods.
A Blog for Ontario Greenhouse Floriculture Growers
Welcome to the very first posting for the new ONfloriculture blog! With regular contriubtions from OMAFRA Floriculture Specialists, the goal of this blog is to provide Ontario greenhouse floriculture growers with timely, technical information to grow the best crops they can.
I encourage you to sign up using the “Follow” feature to your right: this way, new posts magically appear in your inbox. Alternatively, you can check back regularly for new information and helpful resources. The blog will cover such topics as new strides in floriculture IPM of both pests and diseases, new pesticide registrations, flower production, emerging pests, and industry events.
Looking for a Particular Topic?
See the Topic Word Cloud on the right side of the screen. Topics build themselves as we post blogs. By clicking on a particular topic (e.g. “Thrips”), you’ll be taken to all related posts. The most posted-about topics will be in larger font.
Short on time?
Feel like you don’t have time to really read a whole blog post? Hey, I know the feeling. So, for all posts, I’ll be doing my best to bold the most important parts, in case you only have time to skim.
Well, now that I’ve gotten your attention, let’s be clear that I’m talking about bugs, here, people. Specifically, Western flower thrips and predatory mites such as N. cucumerisandA. swirskii.
Second instar (L2) western flower thrips next to a predatory mite egg (left) and 2 adult mites (right). Photo credit: Sarah Jandricic.
We all know that predatory mites only kill and eat the small, first larval stage of thrips (referred to as L1’s). Larger life stages (i.e. L2’s and adult thrips) are simply too large for the mites to kill.
But, that doesn’t mean they don’t help control them.
Predatory mites will repeatedly attempt to kill L2 thrips – attacking them up to 40 times an hour (1). The L2 thrips are able to fend off these attacks by either running away, or “slapping” mites in the face with their abdomens. You can watch the hilarity that ensues when mites attempt to attack too-large thrips larvae here.
But this “harassment” by mites takes it’s toll on thrips. Because thrips spend more time fending off mites, they spend 30% less time feeding (2). Over time, this translates to 40% less damage on plants with predatory mites, compared to no mites (2). And, the presence of mites can reduce survival of L2 thrips by up to 78% (1), probably because eating less means the thrips lack the nutritional reserves to complete development.
And all of this is accomplished just through “intimidation” of thrips by mites – not through consumption. Scientists term these “non-consumptive” effects, and we are just starting to learn the importance of these effects in biological control. Research is now suggesting that non-consumptive effects like “harassment” may actually account for 50% of the pest control we see in greenhouses (3).
This makes sense with our thrips example. Not only do mites reduce the feeding and survival of larval thrips, but ongoing research from Cornell University shows that the presence of mites reduces the number of eggs laid by adult thrips, and shortens adult thrips lifespan (4). Even the presence of predatory mite eggs on a plant has been shown to “scare” L1 thrips into eating less, according to research from Austria (5).
And, it would make sense that the more mites you have, the higher the number of “scary” encounters thrips will have with them, improving control.
So, lets give a hand to the hard working, harassing, predatory mite, who’s doing more than we ever thought in floriculture IPM. Stay creepy, little guys. Stay creepy.
References: (1) Jandricic, S.E., Schmidt, D., Bryant, G., and Frank, S.P, NC State University. Unpublished data. (2) Jandricic, S.E. and Frank, S.P. 2014. Too scared to eat: non-consumptive effects of predatory mites. IOBC/wprs Bulletin 102: 111-115; (3) Preisser, E. L, Bolnick, D. I., & Benard, M. F. 2005: Scared to death? The effects of intimidation and consumption in predator-prey interactions. Ecology 86: 501-509. (4) Loughner, R., and Nyrop, J. Cornell University. Unpublished data. (5) Walzer, A., & Schausberger, P. 2009: Non-consumptive effects of predator mites on thrips and its host plant. Oikos 118: 934-940.