Pepper Weevil & Cyclamen Mites

In this episode, Kristy sits down with co-host Cassie Russell, former acting Vegetable Crop Specialist and current acting Tree Fruit Specialist to talk about monitoring for the problematic invasive insect, the pepper weevil. For more information on how to properly identify pepper weevil, check out Which Weevil Warrants Worry? on the Ontario Greenhouse Vegetable blog. Suspect you have pepper weevil? Contact Cassie Russell (cassandra.russell2@ontario.ca), Amanda Tracey - Vegetable Crop Specialist (amanda.tracey@ontario.ca) or Cara McCreary - Greenhouse Vegetable IPM Specialist (cara.mccreary@ontario.ca). 

As well, Erica Pate, Fruit Crop Specialist sits in the 'Horticulture Hotseat' to shine some light on the tiny but destructive pest of strawberries, the cyclamen mite. 

For more updates on Ontario horticulture visit:

• www.onvegtables.com
• www.onfruit.ca
• https://onspecialtycrops.wordpress.com/

Have a question or a topic you'd like us to cover? Email us at ONhortcrops@gmail.com 

Music: Aspire by Scott Holmes

Transcript

0.00
Kristy: This is What’s Growing ON? A show where we dig up the latest dirt on Ontario horticulture production, helping producers navigate best management practices and taste the sweet success of a quality crop. My name is Kristy Grigg-McGuffin.

Cassie: And I’m Cassie Russell. Join us as we talk to specialists in the field of fruit, vegetables and specialty crops to find out what’s really growing on.

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0.42
 Kristy: Welcome to Episode 9 of the What’s Growing ON podcast. Today, we’re focusing on the importance of pest monitoring, especially when it comes to some of our smallest insect pests. 

To start, our very own What’s Growing ON co-host, Cassie Russell takes her turn wearing two hats to talk about a small but very destructive invasive insect, the pepper weevil. 

After that we hear from Erica Pate, fruit crop specialist on a pest the size of a grain of salt that can cause stunting and poor fruit quality in strawberries, the cyclamen mite.

 Cassie: For up to date information on fruit and vegetable crops grown in Ontario, check out our weekly crop updates at onvegetables.com and onfruit.ca.

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1.42
SEGMENT 1: Pepper Weevil

Kristy: For today’s vegetable segment, yes you heard that right, I’m taking the reins and I’m chatting with our very own co-host and one of our new OMAFRA team members, Cassie Russell on a little pest that’s been a large part of her life for the past few years. So, welcome Cassie!

Cassie: Thanks Kristy! Yeah, I’m really excited to be on this side of the interview today week. 

Kristy: So, before we get into things today, since you are a new face or a new voice to OMAFRA, wondering if you could give a bit of background on who you are? 

Cassie: For sure. Well, many of you might know, over the last several months I have been covering as acting vegetable specialist for OMAFRA covering tomatoes, peppers, eggplants and beets. Before that I had dipped my toes into a few other things, but my main background is entomology and I’m actually just finishing up a masters in science at the University of Guelph and the past three years I’ve been doing research on pepper weevil monitoring here in Ontario with Dr. Rebecca Hallett. 

Kristy: So, besides the peppers I grow in my backyard, I don’t work much with peppers, but even I have heard of this pepper weevil with some media coverage its recieved and so I get the sense it’s a pretty devestating pest? 

Cassie: Yeah, yeah it is. The damage it can cause can be quite devastating and that coupled with the fact that it’s still a relatively new pest to Ontario. It’s only been around for the past few years and not everyone can confidently identify it. Basically, this pest has been around in Southern North America since the 30’s. It’s originally from Mexico and has established in a lot of southern US states where it causes severe damage to peppers. And these pests cause direct damage to the fruit and make them unmarketable. So, with some insect pests, a lot can be foliar feeders or just cause secondary damage where you can have some thresholds as long as they don’t exceed certain numbers to defoliate a crop. Well, sadly not the case for pepper weevil, as soon as you get one – you’re in trouble.

Kristy: Just one eh? So,why are they so damaging? 

Cassie: Like a lot of insects, they have pretty high fecundity and a single female can lay hundreds of eggs. And the problem is, that when she has access to a whole field of peppers or other suitable fruits in the solanaceous family – they preferentially will lay a single egg in each fruit. The females use their snout to pierce a whole in the skin of developing fruits and lay an egg and seal it up. Over the next couple weeks that fruit will still continue to grow on the plant but the egg inside hatches into a larvae that starts tunneling inside and feeding on the internal tissues. So once that female lays her hundreds of eggs, that means hundreds of unmarketable peppers, and the problem starts there and just keeps on going. 

Kristy: You mean it gets worse?

Cassie: Haha, yes!  So, a lot of the times, especially early on when the larvae inside the growing peppers are still small, the peppers on the plant looks totally fine – and really the only “damage” you can see is this tiny little dimple where the female laid her egg and it’s super easy to overlook. As the larvae continue to grow inside these seemingly untouched peppers, sometimes the plants will abort those fruits, especially the smaller ones, so then all of sudden you have these scattered dropped peppers under your crop and if those aren’t removed asap – it just takes a couple days if the temperature is warm enough for those larvae to pupate inside the pepper, and then once an adult is formed, they chew a whole out of the pepper and start to look for a mate and continue the cycle of destruction from there, allowing the populations to get exponentially larger. 

Kristy: Well, you mentioned they actually pupate in the pepper, so does that mean that they require a host fruit to complete their lifecycle? 

Cassie: Yes, exactly. So that’s maybe their only limiting factor; they need a host fruit. Of course, they are aptly named pepper weevil as they have a strong preference to peppers as their hosts, but they also have the ability to reproduce in a number of other solanaceous crops. So actually a PhD student, Catalina Fernandez, did some work out of AAFC Harrow with Dr. Rose Labbe about host preference and assessing in a lab what host fruits they can complete their life cycle on, and it’s also published in the literature that they can survive on wild solanaceous hosts like nightshade which is super common throughout Ontario. But generally, the presence of pest is based on the availability of cultivated peppers year-round and is what determines if this pest is able to survive and limits the distribution to more tropical environments such as Mexico and the Southern US. 

Kristy: So, I know this summer was hot and humid, but Ontario is not tropical. So how is the pepper weevil causing problems here in Ontario peppers?

Cassie: Ya, so that’s a really great question, and probably the most common question I’ve gotten when I’ve gone down the states to present research on pepper weevil. They can’t believe we have it here in Canada. Firstly, it’s helpful to understand our production systems here in Ontario to understand why pepper weevil is a problem. So, peppers are grown both in greenhouse in field. Now, of course field peppers are seasonal; but what many might not know is greenhouse peppers sort of have a season too. They are definitely available for a longer stretch of the year, but there is a little window where the greenhouses get cleaned out and new transplants are planted and so we don’t get a lot of Ontario produced peppers. That and then also just general supply demand means we do import peppers. And, when we are importing form the Southern US and Mexico where as I mentioned these pests are widespread. So really, our general hypothesis here is that when imports come in, it’s really easy for pepper weevil to come in with the peppers and go undetected since they are living inside these seemingly undamaged fruits.  And the peppers are often packed in facilities that are usually close to our close to our growing systems and then it’s just a short flight away for these weevils to seek out a crop and start going town. 

So that’s why is really important that we have a monitoring program or network for these non-native pests, such as pepper weevil as it gives us a better chance to understand how they are coming in and what we can do to mitigate the spread and potential damage to crops here in Ontario.
 
Kristy: So, if there is potential of them coming in from the boarder, is there not the possibility that they could be intercepted or stopped at the boarder each year to prevent to cause damage during our season? Has any of that work been done? 

Cassie: Yeah, so that’s a great point. I know the CFIA did do an evaluation a number of years ago to see if pepper weevil should be considered a quarantine pest. Without getting into the details of it, they did publish their findings and they decided it didn’t really fit the criterial of a quarantine pest because of its tropical nature and didn’t pose a risk establishing here in Ontario. Which is fair, as we said they do require a host fruit to complete their lifecycle and we don’t necessarily have peppers growing year-round. But, personally I don’t think it was necessarily taken into enough consideration the high acreages of greenhouses we have here and those greenhouses do have a higher risk because they have host material available a lot longer through the year for those pest to survive on.

Kristy: Ok, so you’re writing your master’s thesis right now, specifically on monitoring for pepper weevil. So, could you elaborate more on what the monitoring program for pepper weevil is? 

Cassie: Yeah, I’d be happy to. So currently, there are a couple pepper weevil monitoring traps available that can be purchased. The most commonly used here in Ontario is from Trece and they are called Pherocon pepper weevil monitoring kits. These kits come with a few double-sided sticky cards and some pepper weevil lures. So, the lures are aggregation pheromones and I won’t go into detail on the whole chemical ecology background here, but basically this kind of pheromone is one that attracts both males and female adult pepper weevil. So, the idea is you fix these pheromone lures to your sticky card and deploy them on perimeters of your field or greenhouse to detect and intercept any incoming adults before they start laying eggs in the fruits. So, for using the traps, you should be checking them regularly – I recommend once or twice a week or as often as manageable and then replacing the lures and sticky cards every 2 weeks or more often if needed. So, sometimes I see these traps put on stakes in the ground for field peppers or in greenhouse systems hang it from a top wire; whatever works so that the trap is around or just above the plants fruit load. In greenhouse systems, those plants can be up to 15 feet high, so having that trap move up with the plant and keep it where the younger more immature fruits are, that’s really helpful because that’s where the weevils like to go, they like to young fruits. 

Kristy: And why do they go for the young fruits? 

Cassie: That goes back a bit to the chemical ecology of the pest. Basically, plants release these volatile organic compounds into the air and those are picked up by the adult weevils and drives their host selection. So, the adults are likely seeking out these younger fruits because they are the most suitable size to allow the larvae to develop with the fruit and give it the greatest chance of survival before the plant aborts the pepper. So, a few researchers in the states have been working with olfactometry to determine what specific chemical compounds are released from the plant at certain stages as well as at certain stages of feeding – because we actually know these weevils really like the volatiles released from the plants when they are being actively fed on. So, what a portion of my research was aiming at was to try and use this knowledge to see if we could add some compounds to the current pheromone lure to make it more attractive to the weevils and have greater success of capturing them on our monitoring traps. 

Kristy: Right, that makes sense. So, is the pheromone lure quite successful at capturing pepper weevil in the field?

Cassie: Unfortunately, not really. There is definitely room for improvement, especially using that information I just mentioned of integrating these host volatiles – or what we sometimes call kairomones – so using these and adding to the lures to make them more attractive. So that’s something that has been done for a lot of other pest monitoring programs in lots of different crops. So not a new concept, but still more work to be done for pepper weevil. Ultimately, they aren’t super attractive because these pheromone lures are being outcompeted by the natural volatiles in the environment.
So, as a little aside here, I’ve had people come to me saying they don’t want to use pheromone lures because they think they are going to attract weevils to their crop and cause these problems. But what I tell them, is in all honestly, the plants your planting are doing the long range attracting of the weevils, not the pheromone lures themselves. 

But anyways, getting back to your main question, yes, there’s room for improvement, and since they aren’t always the most attractive, it means that these monitoring traps have really low action thresholds for pepper weevil currently – specially when you find one PW on a trap, that is your call for action. So, really that’s why it’s so critical to couple your pheromone monitoring with actual crop scouting as well an looking for other signs of pepper weevil presence in your field or greenhouse.
 
 Kristy: Well, you were mentioning though how the damage was pretty difficult to see at first, so how do you actually scout for pepper weevil?

Cassie: And that’s a great question too. In the interest of time, I won’t go too much into detail, I could talk for hours on scouting for pepper weevil. Basically, you should be looking for those small oviposition scars, they are the size of a pin so really hard to see but that’s what you should be doing. Walking your crop, checking out peppers, seeing if you can see oviposition scars and also looking for dropped fruits. Ideally you want to try and catch them before the fruits have aborted and are on the ground, because that means it’s really close to that timeframe where the weevils are going to emerge and then you have to deal with that next generation. But looking for dropped fruits is an easy thing to scout for. Making sure that you’re examining the dropped fruits, removing and disposing of them appropriately so that those emerged weevils can’t come back into your field or greenhouse and making sure you are coupling the pheromone traps with regular crop scouting. If you are looking for more specific scouting guidelines or pictures of what to look for, you can send me an email or you can also contact either Amanda Tracey or Cara McCreary – both OMAFRA specialists who have been very involved in pepper weevil monitoring and management here in Ontario. We collectively have a lot of resources so always feel free to send any one of us an email. 

Kristy: Great, we will put contact info in the show notes. And can you touch briefly on management program for pepper weevil? What options growers have?

Cassie: There is not a lot of chemical management tools that we have available that work really well. As I was saying earlier when talking about the biology of the pest – those adults lay their egg into the pepper, so those immature stages that we normally target with chemical controls; they are pretty much protected by the fruits. So, any chemical controls we do have need to be targeted at the adults. Some new things that are on the horizons when looking at alternative management strategies. There is this sterile insect technique that has worked for some other insect pests and has the potential to be used in both field and greenhouse peppers. Dr. Rose Labbe and Dr. Cynthia Scott-Dupree are doing some preliminary research as a proof of concept for this sterile insect release technique for pepper weevil. On the chemical ecology side of things which I’m a bit more knowledgeable on. There is some interesting pathways that could be examined further just using those chemical cues to trick the weevils or put together a mass trapping strategy using these really attractive volatiles and have them all aggregate into one mass trapping strategy. There are some other cultural practices we can try and integrate but nothing really ready yet, but stay tuned.

Kristy: Ok, so you’ve covered the biology and why this can be such a difficult pest to deal with, what would you say is the take home message for pepper growers here in Ontario? 

Cassie: First, I’d say invest in monitoring, and don’t assume pepper weevil isn’t going to be your problem. I know that’s a common misconception here in Ontario – that pepper weevil is only a greenhouse problem, but really, it’s not. Scouting should be your first line of defense. And I know those traps are expensive and annoying to use, but really, it’s the best options we have right now and worth the investment. 

Another point I would say is don’t spray unnecessarily. You know, last week we talked a lot about resistance management and that kind of has a fit here. But also, we just don’t have a lot of products to work with. We are very limited and as I mentioned we can only target the adults. Really, if you are spraying you need to be spraying based on knowing the adults are present, so you have to have those monitoring efforts in place.

And the last would be communicating with the networks we have. Just in my three years working with growers and stakeholders on this pest, I feel like there can be this stigma associate with pepper weevil and a lot of finger pointing about where it comes from. Well, at the end of the day that’s not going to help anyone. Working together is going to keep a vibrant successful pepper sector here in Ontario so we need to work together to control and manage this pest. Since it’s a community pest, it has the potential to get very unmanageable quickly I we don’t work together. So, if we all collaborate and have these monitoring networks it helps us understand where and when these pests are coming in, how they are dispersing, identifying areas to increase scouting before the pest actually arrives and serve as a warning signal to our Ontario growers. 

And on that note, if you are monitoring, which you should be, please confirm your ID of pepper weevil with one of our specialist. You can reach out to myself or one of the other specialists I mentioned just to make sure that the weevil you’re finding on your traps is pepper weevil. These pheromone traps aren’t only going to attract that one target weevil and they can attract a number of other look a-like weevil species. And there is actually a great resource available online – Which weevil warrants worry. It’s a helpful article that Cara McCreary put together with some other colleagues just to help show some physical differences between pepper weevil and some other weevils pepper weevil is commonly mistaken for. So, I would strongly suggest looking at that before jumping to the assumption that you have pepper weevil in your field.  

Kristy: I think it’s really important that note you touched on the importance of a community program since it’s a regional issue and it doesn’t stop at the borders of farms so that communication with each other and willingness to share information is really important so we can be proactive with these issues. 

Cassie: Yes, exactly.  

Kristy: Great, well thanks so much Cassie. I know you’re busy finishing up your thesis so I hope it goes well and we really look forward to seeing some of those innovations for pepper weevil monitoring in the future and hoping that management gets a little easier. Thanks so much. 

Cassie: Yeah, for sure. Thanks so much Kristy, this was really fun!  

Music fades in

Kristy: I was just speaking with Cassie Russell, former Vegetable Crop Specialist now currently acting Tree Fruit Specialist with the Ontario Ministry of Agriculture, Food & Rural Affairs.

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SEGEMENT 2: Cyclamen mites

Kristy: In today’s fruit segment, we continue the conversation on some of our smaller pest and the big problems they cause. Erica Pate, OMAFRA fruit crop specialist steps into the spotlight to cover the who, what, where and when of cyclamen mites in strawberries in another round of Horticulture Hotseat.

Erica: Cyclamen mites are a challenging pest for Ontario strawberry growers. These tiny mites can stunt the growth of strawberry plants and can lead to reduced fruit production. 

So what are we talking about? Cyclamen mites are very small mites- only 0.1-0.3 mm in length- and you’ll need a 10-40X magnifying lens to see the mites. The mites are oval, amber to white. The eggs are clear and smooth, and groups of these eggs in crevices on the leaves look like piles of salt with the naked eye. Female mites can lay up to 90 eggs in their lifetime, and newly hatched mites can reach full maturity in 2 weeks- therefore populations can grow very quickly after a field becomes infested. 

Cyclamen mites are active in the spring on new growth- they really like humid conditions and are often found on the midrib of folded leaves or other protected part of the plant. They can go quiet at renovation but can rebound again in the fall with more new growth. You can identify mites in your field first by finding the damage. Infestations can lead to distorted, crinkled leaves that look tough and crispy, and they will stunt the plant growth. So if you are standing in your field and you look across a few rows and there are patches where the plants are shorter and looks more compact around the crown compared to healthy plants, or slow growing plants- I would suspect cyclamen mites. If the mites feed on blossoms the flowers will wither and die. Fruit will be small, bronzed and seedy. In serious infestations cyclamen mites can reduce fruit production. We usually expect to find mites in older plantings as the mites have had a couple years to build up, but still look for them in your 1 year old fields. 

Once damage is found and cyclamen mites are suspected, you can confirm it is cyclamen mites by looking at the youngest leaves close to the crown. These leaves should still be folded, or curled- once a leaf opens up the changes in temperature and humidity cause the mites to move down to younger leaves and protected areas. So pinch out the leaf, open it, and look at the midrib and base of the leaf close to the petiole for the mites- use a hand lens. You may be able to see the piles of salt I mentioned without a hand lens, by a hand lens will help as these are very small mites!!

Strawberry growers and nurseries have been dealing with cyclamen mites for years, but management has become more challenging in the last few years as there are fewer options available to growers. In 2018 we found cyclamen mite infestations in many June bearing fields. After one of the options for control lost registration in 2016- endosulfan- we are now left with just Agri-mek and Vegol Crop Oil that are registered for cyclamen mite control. So that doesn’t leave growers with many options for resistance management. And these mites are challenging to control to begin with- because they are so protected in the crown and young leaves, it can be hard to reach them with a miticide. That’s why spraying with a high volume is so important, and lowering your speed, so that you reach the mites with your product. Spraying in the spring and after renovation can be effective timing as it is easier to reach the mites before the canopy fills in. 

There are a few other tips to keep in mind if cyclamen mites are on your farm- avoid spraying pyrethroids as they are toxic to beneficials and can lead to mite flare ups. And avoid introducing cyclamen mites into new fields- they can be carried easily from one field to the next by people or equipment, so work in new fields first so you aren’t moving from a potentially infested field to a new, clean field. 

Walk your fields now and look for signs of damage- as I mentioned populations can peak again in late August and early September. If necessary, growers can spray in the late summer/ or plant to spray in the spring. In the spring begin monitoring when new leaves begin to emerge. If you do find mites or damage, spray the entire block. Plan now to integrate different practices to manage the mites. Avoid spreading cyclamen mites, reduce flare-ups, encourage beneficial activity, and spray effectively.

Kristy: That was Erica Pate, Fruit Crop Specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs. 

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30.02
Kristy: Thanks for tuning into our episode today.  This has been Kristy Grigg-McGuffin -

Cassie: - and Cassie Russell, for the What’s Growing ON podcast. For more information on horticulture grown in Ontario, check out the links to our fruit, vegetable and specialty crop blogs in the show notes.

Kristy: A big thanks again to our guests this week, Cassie Russell and Erica Pate.  And another big shout out to Michael Pupulin for the editing of our episodes. Music from this episode is the track Aspire from Scott Holmes.

Cassie:  We will be back soon with an all new episode of What’s Growing ON. In the meantime, if you have questions, comments or suggestions for a topic you would like us to cover, please send us an email us at ONhortcrops@gmail.com. We would love to hear from you.