Barnstable County, MA Tickology Project - 2018, 20 Sep 2018

Previous Meeting

Next Meeting

⏯

youtube image

►

From YouTube: Tickology: Deer Tick - The Disease Ecosystem

Description

Part 10 of the Tickology video project.

A

Hi I'm larry dapsis,, I'm the entomologist with cape cod, cooperative extension and.

A

In this segment, we're going to be talking about the functioning of the.

A

Tick borne disease ecosystem and it's a very interesting set of processes that.

A

Are going on before our eyes, and we may not even realize it.

A

Ecology happens to be my favorite discipline in science and one of the.

A

Reasons for this is that we find out that everything is interconnected. You.

A

Can't have an impact on one thing over here and not have an impact on something.

A

Else over there that you didn't even know about or even anticipate and so.

A

We're gonna start telling our story of mice and men and women ticks and acorns.

A

One of the questions I get all the time from people particularly baby boomers.

A

Larry forty or fifty years ago, we just didn't- have to worry about these.

A

Things at all what it what is different today what's.

A

Changed they don't realize, what's happened over time and a lot of things.

A

Have changed over time, so it's a very good question to ask, though so, where are.

A

We, if we look at lyme disease in since bi-state all six new england states.

A

Occupy the top six positions in the country, so we truly are living at ground.

A

Zero, so it's a fair question: ask: how did we get into this pickle? Well, a lot of.

A

People for many years, including today, want to blame the deer. Okay. It's all.

A

About the deer, and certainly deer can feed a lot of ticks. You see here on that.

A

Deers ear, there's there's lots of fully engorged female deer ticks and each one.

A

Of those ticks can lay a thousand to 3,000 eggs. So why aren't we just overrun.

A

With ticks, we're certainly have a lot of ticks out there, but not certainly on to.

A

The extent that these numbers would suggest there's other things going on so.

A

Is it all about the deer well rick ross felt at carey institute of ecosystem.

A

Studies in new york study this for a number of years. They looked at deer.

A

Density in the fall when larval stage would be actively feeding and then they.

A

Looked at the density of nymph stage takes two years later, so there's a time.

A

Lag in there and we'll explain that in a few minutes. And so if the density of.

A

Deer truly were correlated with the density of ticks. We would see these data.

A

Points line up in a straight line from the lower left to the upper right, but we.

A

Do not it looks like a random assortment of data points, and so, if you calculate.

A

The relatedness of these things that statistic r-squared, that's the.

A

Correlation coefficient, the correlation coefficient, is essentially zero. There is.

A

No correlation between the density of deer and the number of ticks you're.

A

Gonna see two years later in our own research. Here we did surveillance on.

A

Cape cod at nantucket for six years and we look at the deer density on cape cod.

A

Relatives knee and tuck it here on cape cod. We have about 10 deer per square.

A

Mile not a whole lot, I don't on an tucket yeah they've got 50 per square mile. Those things are everywhere. Does nyan.

A

Tuck, it have five times more ticks than we here on cape cod. Well, we sample tick.

A

Populations, so we can compare apples to apples and what we do is we drag a piece.

A

Of white flannel through vegetation, so we'll do a drag for 30 seconds count. The.

A

Number of ticks: do it again for 30 seconds count the number of ticks and.

A

You come up with this metric of deer tick nymphs per hour, so you can measure.

A

Relative density, and so if you look at cape cod versus nantucket, we have about.

A

The same number of ticks, so it's not about the deer. There are other things.

A

Involved here, so what we know is that if you look from the bottom up so to speak,.

A

Acorns mice and ticks are all linked, and I can see you scratching your heads now.

A

Larry explain this one to me so so here we go.

A

Understand that acorns, that is, the fuel that drives this whole ecosystem. Okay, it.

A

All starts really with the acorn and the way this works is in the fall. If you.

A

Have a large number of acorns that fallen on that next year, you're gonna.

A

See an increase in mice, population and yeah. The mice are very happy when those.

A

Situations happen and the next year, you're gonna see an increase in the tick.

A

Population and again that's good news for the ticks. But let's say we have a.

A

Year, where there's low no way, corn production.

A

Okay, so let's say when the fall we have, you know a lack of acorns and during.

A

That late summer, there were plenty of mice to support those larval ticks and.

A

Those larval ticks that fed on the mice they're going to become nymph stage.

A

Ticks and hunker down for the winter. So then we have this crash of no acorns in.

A

The fall and what that does is it leads to a crash of the mouse population, so.

A

Yeah sad news all around so in the spring.

A

Those nymph stage tics emerge, and so now people and pets you can have a higher.

A

Exposure risk, so here's the best way to think about this is it ticks like little.

A

Landmines, you bump into one something bad might just happen and think about.

A

The mice, their little minesweepers, so, if they're out doing their daily mouse.

A

Thing they're picking up ticks in each tick that attaches to a mouse is one.

A

Less tick that you might be exposed to so without the minesweepers yeah, it.

A

Rhesus our exposure risk so when I was digging into this area of the ecosystem.

A

I came across records that in 2004 in massachusetts we had a statewide acorn.

A

Crop failure- and this is pretty interesting, so this allows us to test.

A

This idea about the minesweepers, and so when I looked at the data for lyme.

A

Disease, the following year, there was a 51% increase, the incidence rate of lyme.

A

Disease in massachusetts, so this minesweeper idea has a lot of merit. What.

A

Else has been going on well. Over the years we've been cutting down a lot of.

A

Trees here on cape cod- and it's not just the acreage of trees- that if we we have.

A

Cut down is that we've cut these forests into patches or islands a process. What.

A

We call forest fragmentation and fragment fragmented force, has a lot of.

A

Consequences so we look at this land-use pattern. Change, yeah, listen area of.

A

Falmouth back in 1950 and sure there was lots of woods, there's a number of farms.

A

Here and number of homes around this pond and if we look at this place,.

A

Almost 60 years later, yeah, that is a suburban neighborhood. So we've you know.

A

These collections of homes and we've got these small patches of woods all around.

A

The residents- and that has consequences, and one of the consequences is that you.

A

Reduce biological diversity and it's not just reducing the the numbers of types.

A

Of creatures, but the kinds of creatures, and so with things like red, fox, yeah,.

A

It's certain point: you don't have enough woods to allow them to have a territory.

A

And a significance of fox is that they are the most efficient predator on these.

A

Things like what footed mice that are excellent reservoir hosts for this lyme.

A

Disease bacteria, so it leaves my south there to live longer periods of time and.

A

Allows them to infect more and more ticks, not just the mice, but also the.

A

Eastern chipmunk, which is a second runner up to the reservoir situation, so.

A

Without the fox we've, given the landscape to the rodents and let them.

A

Roam freely, the other thing that the poor fox are dealing with is that, as.

A

Coyotes move into an area, they will outright, kill foxes or drive them out. So.

A

Without the fox, we've got an appendage situation here, and things like possums.

A

So you're, looking at this saying why the heck would I care about a possum well.

A

Here's why we should care about our poor possums disappearing, because they are.

A

The equivalent in the tick world of rambo.

A

Yeah, they kill a lot of ticks and so animals will allow a certain number of.

A

Ticks to attach to them before they they start doing something about it. So even.

A

Mice and birds, and things like that and possums happen to be very intolerant.

A

They do not really permit any ticks to feed on them, so they're excellent.

A

Groomers and they don't just dislodge the ticks, they actually eat the ticks.

A

And so, if you look at the data that the kerry institute has been working on when.

A

They look at possums. An individual opossum is responsible for over 5,000.

A

Tick deaths per week, so if there was anything we can do in our landscape to.

A

Encourage the reintroduction or or increase the opossum population, we.

A

Really ought to consider doing that and we have to look at climate. So one of the.

A

Things we know is that when we have sunny dry, warm springs ticks, it might be.

A

Up on top of vegetation questing' waiting for dinner, somehow stroll by.

A

So they can attach when you get situations where you get. You know.

A

Drought and you know so dry leaf litter. Those questing' ticks quickly move down.

A

Deeper into the leaf litter ticks can't drink water. They have to get into an.

A

Environment where they can absorb water vapor from the air, and so basically that.

A

Means that during very dry weather during the spring, there's they're out.

A

For fewer periods of time out for less time, so it reduces our exposure risk.

A

Whereas we have, you know, wet springs that allows ticks to be up on top of.

A

This vegetation, questing and looking for meals, so it increases our exposure risk.

A

So weather, certainly coupled with the acorn story, makes a big difference here.

A

So here's my contact information always open for business. Look forward to your.

A

Phone calls and exchanging emails and we'd like to thank cape cod, healthcare.

A

For their generous support of this program,.