The team

Picture of all the team members

🌻 Eloise 🌻

🎤 Hi! So, tell us about you! What's your name? Where are you from?

Hi! I'm Eloise, I'm 24 and I'm from France.

🎤 What do you do in France?

I'm an engineering student, I study mathematics, physic, mechanic and many other things! In France, I'm an apprentice at a company : I do both courses and work in that company. It's a lot of work but it's really cool to learn the different skills needed for various positions.

🎤 So, why did you choose to do your 4th year's internship in biology?  

Well, biology is a domain that always interest me. Before going in an engineering school, I did a year in a medicine school, but I finally stopped because there was no mutual aid and no teamwork... Doing my internship in biology was a good opportunity for me to learn more about it.

🎤 How's life in Canada?  

Really good! I met a lot of people here, all of them very nice! I was a little bit worried about people in Canada because I was told that they're not really kind with strangers and that I'll have to be careful with what I say, but so far, every person I have met has been really helpful and kind with me.

🎤 Do you like Canada?

I really like Canada, there are a lot of beautiful places to discover, so many different cultures and a lot of diversity. The only thing I regret is not having enough time to explore all.

🎤 Do you find your internship interesting?

Yeah, my internship is really interesting, I learned a lot about the city, the trees and the cankerworms since I arrived. My professor is really patient and kind, he really helps me to improve my English!

🎤 Thanks Eloïse for your time, we'll see you soon!

🍪 Jiaxin 🍪

🎤 Hi, everybody! Let me introduce myself to you first!

My name is Zhang Jiaxin. Zhang is my last name and Jiaxin is my first name. So you can call me Jiaxin. I am a 21-year-old Chinese girl. And I come here this summer for a three-months internship, taking part in the science project and being a member of Dr. Á vila'slab.

🎤 What do you do in China?

In China, I major in horticulture, the study of fruit trees, vegetables, flowers and tea. I still have one more year of studies at my university before I can graduate. After my graduation, I plan to further my studies on plants by joining a graduate program.

🎤 So what do you think about this internship?

I was very excited to get the chance to come here for the project. I am interested in studying how the animals affect the trees, and I think it's very cool to come to another country and meet new friends from all over the world.

🎤 How's life in Canada?  

Actually, I really love the weather here in summer. I have heard winter it's terrible here, but I really want to see the snow scene. People I meet here so far are really nice so I enjoy these days very much! Lastly, I hope our results do help improve the environment here!

 

The study

Our study focuses on tree defoliation due to the feeding of cankerworm.

In fact, the cankerworms appear in early spring, at the same time as the young tree shoots, and start feeding from then on. 

Cankerworms could have serious consequences for trees, but unlike certain species such as processionary caterpillars (Thaumetopoea pityocampa), they pose no threat to humans or animals.

🎯 The goals 🎯

The goals of our study are :

1. To determine the typical levels of leaf damage on two of the most common tree species due to the feeding action of cankerworms and other common caterpillars.
2. Compare these levels with historical Records.
3. Determine if the level of leaf damage is related to the availability of natural enemies of the caterpillars.

📋 The fieldwork 📋

The first part of the fieldwork is to locate the site. To do this, we use Google Maps and Google Earth to visualize the streets where the trees we are looking for are located: elms and ashes.

We are also preparing the blank data sheets we will use to write the data.

The second part of the work consists in going out into the field to take a few measurements on the trees and collect leaf samples. 

We take these measurements:

• Tree diameter
• Distance to the nearest-neighbor
• Crown condition 
• Number of potential predators in the area

Tree diameter

To measure the tree diameter we use a diameter tape. We place our arms and the tape so that we are at about 1m50 from the ground.

Distance to the nearest-neighbor

We then measure the distance between the tree we are studying and its nearest neighbor. When the nearest tree is the same species we only take this measurement and if it's another species, we take this measurement and the distance to the nearest tree of the same species.

To measure this distance, we use a 50 m tape. 

Crown condition

To assess the crown condition, we look at six different branches on the same tree and we estimate the condition with a scale that we have already created. 

Scale:

Predators

To observe potential predators we look at the surroundings of the tree and write down the individuals we can see. We also use binoculars to identify better the species. 

We proceed at a 10 min by 10 min observation to do the measurements. 

The main cankerworms predators are :

• Birds
• Wasps
• Bumblebees
• Hornets

Collecting samples

On the field, we also have to collect leaves samples. To do that, we use an 8 m-long pole pruner, this tool must be used carefully with two people when all extensions are added. One person holds the pole pruner while the other one pulls the rope to cut the branch. 

🔬 The lab work 🔬

The lab work consists on scanning the leaves. To do this, we use image analysis software (WinFolia) which provides us the data from the leaves (perimeter, area, length, width, etc.).

The trees

 🌿 Green Ash 🌿

Fraxinus pennsylvanica

General :

Deciduous trees to 12 m tall; trunk to 45 cm in diameter, lager on good site; bark greyish brown, becomes broken into firm, narrow, irregular, slightly raised ridges running into each other and giving somewhat.

Leaves: 

25-30 cm long; typically 7 leaflets (sometimes 5), oval, 7-12 cm wide, tapered to each end; green above, paler and sparely hairy below; edges toothed or smooth.

Flowers: 

Inconspicuous in compact, many-flowered clusters; appear at same time as leaves, with sexes on separate trees.

Fruit: 

Samaras (seeds with long, membranous, yellowish green wing), to 4.5 cm long, 6 mm wide; in hanging clusters.

🍃 Elm 🍃

Ulmus americana

General : 

Deciduous trees, typically 20-25 m tall, 90-120 cm in diameter, large on good sites; crown umbrella-like on mature trees; bark dark greyish brown with broad, deep, intersecting ridges, often scaly; buds sharp-pointed, pale reddish brown with slightly hairy scales, somewhat flattened and lying close to twig; sapwood nearly white.

Leaves: 

Oval, 10 cm long, 5-9 cm wide; dark green and slightly rough above, pale green below, with soft hairs; edges double-toothed; leaf-based not symmetrical; leaf veins prominent.

Flowers: 

In little bunches early in spring before leaves appear; both sexes in same flower.

Fruits: 

Flat, oval, 1-seeded samaras, about 1 cm wide; wing deeply notched at tip, hairless except fringe around edge.

 

 

🌱 Fun botany knowledge 🌱

1. Look at picture 1. This is one leaf without doubt.
2. Then look at picture 2. How many leaves can you see? Five? The answer is no. This is still one leaf that has five little leaves. Based on how the little leaves lined, this kind of leaf is named pinnate compound leaves.
3. Let’s learn more about pinnate compound leaves. Can you tell me the difference between picture 3 and picture 4?
4. So the leaves that have one little leaf on the top is called odd-pinnately compound leaves. And the leaves that have nothing on the top is called even-pinnately compound leaves.
5. I think you have known more about plant’s leaves now. Congratulations!  

Cankerworms

If you walk by trees in Winnipeg between the end of May and the middle of June, you will probably meet some little creatures that seem to levitate beneath the trees. These little guys are called cankerworms. 

There is multiples species of cankerworms, which belongs to the family of caterpillars. In our blog, we will focus on three different species : 

• Spring cankerworms (Paleacrita vernata)
• Fall cankerworms (Alsophila pometaria)
• Elm spanworms (Ennomos subsignaria)

🐛 The spring and fall cankerworms 🐛

Have you ever wondered where the name cankerworm comes from? 

Well, scientists gave them that name because of the way they move :  by forming a loop with the central part of their body and then extending the front to straighten out. They give the impression of measuring the ground they cover. The name "cankerworm" refers to medieval surveyors who used a surveyor's rope to measure distances on the ground. [1]

The spring and fall cankerworm can both have the same colours ranging from yellowish-green to greenish-brown to black.

The only way to distinguish them is to look at their back legs. The spring cankerworm have 2 pairs of back legs while the fall cankerworm have 3. 

Spring cankerworm with 2 pairs of back legs [2]

Fall cankerworm with 3 pairs of back legs (first pair is reduced) [2]

The cankerworms are phyllophages, i.e. they feed on the leaf tissue of plants. During the spring, they caused a lot of damage on certain species of trees. They really like hardwood trees like elm, ash, oak, maple, cherry, or linden.

They usually appear in the early spring and disappear in the middle of June.

Here is a short video explaining the life cycle of the cankerworm. 

 

🐛 The elm spanworms 🐛

Unlike cankerworms, which tend to be green or dull brown, elm spanworms can be identified by their orange heads, purplish-black bodies and grippy, pincer-like feet. [3]

Elm spanworm with its orange head [4]

As cankerworms, the spanworm's eggs overwinter on trees. Eggs hatch May begin in mid-to late May. Then, they feed on trees during approximately 6 weeks. The difference between cankerworms and spanworms is on the pupation stage : elm spanworms pupate by spinning coarse netlike cocoons of silken threads often on partially defoliated leaves. Finally, adults emerge in late June through July and put the eggs on the trees. [5]