Category: entomology

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Let’s go back to 1914

I am the editor of a small, regional journal called the Journal of the Entomological Society of British Columbia. Although it is a small journal – publishing a few papers and other items in a single issue each year – both the journal and the society that manages it have a deep history. The ESBC was founded in 1902, and the JESBC  has been around in one form or another since 1906 when it was called the Bulletin of the British Columbia Entomological Society.

That deep history combined with the fact that we currently publish excellent peer-reviewed reports that are of particular interest to entomologists working in the Pacific Northwest are what induce me to expend considerable time and effort on its yearly production. Our journal has been, and currently is, run mainly on volunteer efforts. It has always truly been a labor of love.

The JESBC has recently shifted to being completely open access. We are indexed on a number of major abstracting services. And our web editor has been spearheading an incredible effort to get all of our archives online and all of our citations over the years cross-referenced. In other words, our journal has always continued to evolve with the times, and we are working to ensure that trend continues.

As old issues have come online, I have enjoyed dipping into them to read some of the reports from the past. So, in what I intend to be a regular occurrence on this blog, I’d like to highlight a few of the items that I’ve read and that I hope may interest some of you as well.

Recently I was sampling volume 7 (1915), back when the journal was called the Proceedings of the Entomological Society of British Columbia (yes, we’ve had a number of name changes over the years). In it there are a number of articles that discuss a major “locust” infestation in the southern interior of British Columbia. From the reports, the insects involved were seemingly the migratory grasshopper, Melanoplus sanguinipes (called Melanoplus affinis in these reports) and the red-legged grasshopper, Melanoplus femurrubrum. Some very cursory research on my part found no other mentions of the infestation on the internet, so these reports may be the only easily accessible documentation of that event.

Here are some of my thoughts on several relevant articles from that issue:

Ruhman, M. 1915. Insect-notes from the Okanagan 1914. Proc. Entomol. Soc. British Columbia 7:7-11. LINK

This article is a survey of all of the recorded insect pest outbreaks in the Okanagan (southern interior) of BC. Besides being a comprehensive list with some very interesting and sometimes rather extensive notes on a variety of insects, the author mentions the grasshopper infestation briefly as follows:

…(the grasshoppers) are certainly plentiful enough to be taken notice of. Mr. Ben Hoy reports on the 14th that he visited a small orchard surrounded with range land practically defoliated by grasshoppers (species not identified) in Kelowna.

 

Wilson, T. 1915. The outbreak of locusts of 1914. Proc. Entomol. Soc. British Columbia 7:41-42. LINK

This paper outlines the geographical extent of the infestation and begins by particularly condemning the practice of “clean cultivation” – that is, removal of all weeds and alternate crop plants from near orchards and between the rows of trees – as a major driver of damage to orchards. In other words, maintenance of an orchard monoculture and the removal of alternate host plants for the grasshoppers meant that the grasshoppers turned to the fruit trees for food. This is, of course, an agricultural lesson that needs to be taken to heart even today.

Wilson also spent some time explaining the natural history of these insects and then lists what he feels are major reasons for the infestation:

The first reason I advance was the abnormally hot and dry season we have experienced, even for the Dry Belt. This condition was most conducive to the spread of these sun-loving dry-country insects. Second, the influx of settlers and the consequent diminution of the natural food of the locusts. Thirdly too heavy grazing on the range, or perhaps, more correctly stated, injudicious grazing on the range, has done away with the food-plants and forced the locusts to places where they would obtain the requisite amount of nutrition.

This is an interesting analysis, and one that provides a great picture of what was going on in the region at the time in terms of climate, culture, and biology.

 

Taylor, L.E. 1915. Notes on birds likely to be of service in the destruction of grasshoppers in the Nicola Valley. Proc. Entomol. Soc. British Columbia 7:43-45. LINK

Taylor provides an extensive list of birds that were likely to be present in the region at the time and gives estimates for how important they might have been as predators on grasshoppers. Besides being a potentially useful checklist of birds in the Nicola Valley in 1914, Taylor also vaguely mentions resources that he used to develop his estimates. It would be interesting to be able to dig up these reports and compare them to what, if anything, is known today about diets of various bird species.

 

Gibson, A. 1915. The Kansas remedy for the control of locusts. Proc. Entomol. Soc. British Columbia 7:45. LINK

This report is, frankly, frightening. But it is also a good glimpse into pest management back in the early-1900s. In this article, Gibson proposes experimenting with the “Kansas remedy” for control of grasshoppers. The Kansas remedy was comprised of:

Bran, 20 lb.; Paris green, 1 lb.; molasses, 2 quarts; lemons, 3 fruits; water, 3.5 gallons.

Most of the ingredients are identifiable. But what is that Paris green stuff? Well, it’s copper(II) acetoarsenite. As you might imagine, copper and arsenic make for a very toxic brew. And, being heavy metals, a persistent, toxic brew to be precise. I’m personally not a big fan of pesticides unless absolutely necessary, but I can say that I’m glad that what we do use today is safer than this.

I’m also curious to know if this concoction was ever tried in parts of British Columbia. According to the short article it was used in parts of eastern Canada. A bit of digging shows that it was also at least tested, if not used, elsewhere. If the areas that in which was used could be identified today, it would be interesting to survey longterm effects on biodiversity of heavy metals used in agricultural settings.

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Besides being an interesting glimpse into the past, these articles demonstrate the value of a longstanding, regional journal to the practice of science. I think that it is fair to say that without this journal (and others like it) reports like these would either never have been recorded in the first place or would have been buried in files somewhere and lost to contemporary analysis.

From these articles we learn that there was a substantial and damaging grasshopper infestation in the BC’s southern interior around 1914. We read some statements on the climatic conditions and the agricultural practices at the time that were thought to be partially responsible for driving this infestation. We are given a number of interesting natural history observations. We receive what amounts to a checklist of some birds in the region at that time (attention ornithologists!). And we are told about cultural and (sort of scary) chemical methods that were being proposed as pest management methods.

The JESBC, and other journals like it, are full of this type of information. Contemporary archiving, indexing, optical character recognition, cross referencing, and other means of resurrecting this literature are adding value to these fantastic resources. I imagine the value will continue to increase as imaginative people find new ways to sort through this kind of data.

In the meantime, we all now have the opportunity to use our own grey matter-based “technology” to learn from the past. I hope that as I pull out a few of these reports to highlight on this blog over the coming months you’ll also take some time to find some items that interest you.

If bump into anything interesting, feel free to share your finds here in the comments or on Twitter.

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Update (12 November 2013): Chris MacQuarrie pointed this out on Twitter:

Indeed, that is the case. Here is some more information on Norman Criddle and his mixture. Also of interest in that link is the mention of the Rocky Mountain locust, a once prominent species that ended up on the same tragic trajectory followed by the passenger pigeon and (very nearly) the plains bison.

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It’s cold out there!

Most of us would find it pretty hard to live outside all winter anywhere in Canada, let alone in places where temperatures routinely dip below -30ºC. But this is exactly what the mountain pine beetle (and many other insects) does. The question is, of course, how does it pull this off? What is it about mountain pine beetle larval physiology that allows the insects to make it through long months of deep cold?

A paper by Tiffany Bonnett and others, that recently came out of our lab, probes this process in pine beetles in a way that has not been done before. The publication is entitled “Global and comparative proteomic profiling of overwintering and developing mountain pine beetle, Dendroctonus ponderosae (Coleoptera: Curculionidae), larvae” and is available as an open access publication. We have also published the raw genomics data online at figshare. You can find those data here, here, and here.

 

What did we do?

Larval mountain pine beetles were collected from trees near to Valemount, BC during the early autumn and late autumn, and then again during the early spring and late spring. The larval beetles were prepared in the lab so that we could use a process called iTRAQ to assess all of the proteins present in the larvae at each of the different collection time points. Essentially we took four snapshots – two in the autumn and two in the spring – an then compared them to each other see what was changing. This gave us a huge amount of data to work with and we used statistics to tell us which proteins increased or decreased in prevalence across either the autumn or the spring.

 

What did we find?

Among other things:

  • Larvae expend a fair amount of energy on detoxification of host resin compounds, both in preparation for the winter, and then during feeding after winter is over.
  • Stress physiology plays a large role in this entire process, particularly in the autumn as the larvae are dealing with host tree resin toxins and readying themselves for the upcoming onset of winter.
  • We saw evidence for the involvement of several compounds that may play an antifreeze role.
  • There is an evident shift between emphasizing overwintering preparations (in the autumn) and emphasizing completing development (in the spring), consistent with expected shifting priorities at different points in the life cycle.

 

Why is this novel?

The overwintering larvae of the mountain pine beetle remain nestled under the protective bark of their host tree. This makes them quite difficult to work with, and until now not very much information had been generated on this life stage, particularly in the context of winter survival. This work, which has harnessed the power of some very useful genomics databases, has cracked the door (or the bark?) open to allow us to see in broad sweeping terms what is going on in this insect during this vital time in its life cycle. We have seen aspects of larval mountain pine beetle physiology that have never been seen before, and that provides the power to ask new questions and to investigate key genes and pathways in a much more directed manner.

 

Why is this important?

Up until now, the main known winter survival mechanism for larval mountain pine beetles was the accumulation of glycerol in the autumn. Glycerol acts as a natural antifreeze and is part of the overwintering survival tool kit of many insects. But in most known cases, glycerol is not the only part of the equation, and we didn’t think that it was the sole story in mountain pine beetle either. And it turns out that we were correct with that guess – there are a lot of other things going on as well.

In a larger sense, this means that we now have targets to focus on as we work to understand how deep winter cold can impact populations. Overwintering mortality is one of the major factors contributing to control of bark beetle populations. Now that the mountain pine beetle is moving from the cold interior of British Columbia into even-colder central Alberta, a major research question relates to the climate in its expanding geographical range and how that is going to affect the insect’s potential spread to other regions. Overlay that question with the impacts of climate change, and it should be apparent that understanding mountain pine beetle overwintering physiology is becoming more and more vital.

 

Where do we go from here?

We now have numerous potential gene targets to look at, any of which is a project unto itself. Because we have shown in other work that larval mountain pine beetles in the late summer are feeding on potentially very toxic food, we are interested in finding out how larval ability to detoxify and digest their food in the autumn can make or break their chances for winter survival. We suspect that certain larvae are better adapted than others at dealing with the nutritional challenges that they face, and thus better able to produce antifreeze compounds and the other components that allow overwintering success.

In other words, we suspect that there is variation in the mountain pine beetle population that results in some larvae surviving the winter while others don’t. We, along with collaborators, hope to determine which genes are important in this process and how selection pressure in their historical and expanding ranges are changing mountain pine beetle populations.

Some of our key questions are:

  • How do specific proteins function in protecting larvae from the cold?
  • What happens if we “knock out” some of those proteins?
  • What characteristics of tree defense and nutrition make some host trees more or less likely to allow the resident larvae to survive a winter?
  • Do adult beetle parents choose trees based in any way on how their young may fare?
  • Where in the genome should we expect to see natural selection as the insects move into colder and more inhospitable regions? How will these evolutionary shifts be observed in changes in behavior and physiology?
  • What are the larger implications of climate change on these processes?

As you can see – and as is the case with science in general – this paper not only provides some answers, but also provides fertile ground for more questions. This work, and other related work in our larger mountain pine beetle system genomics project, has given us the means to chase down some of the answers. We are looking forward to the interesting work ahead. Since this publication and its associated data are all open access, we also look forward to seeing what other people might find to do with our data.

ResearchBlogging.org
Tiffany R. Bonnett, Jeanne A. Robert, Caitlin Pitt, Jordie D. Fraser, Christopher I. Keeling, Jörg Bohlmann, Dezene P.W. Huber (2012). Global and comparative proteomic profiling of overwintering and developing mountain pine beetle, Dendroctonus ponderosae (Coleoptera: Curculionidae), larvae Insect Biochemistry and Molecular Biology DOI: 10.1016/j.ibmb.2012.08.003

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Canada (finally) notices neonicotinoids

Many of you have probably heard that neonicotinoid pesticides seem to be responsible for negative effects on various pollinators, including bumblebees and honey bees.

With limited time today (and for this entire week), I won’t add much more than that right now, other than to say that others have written a ton about it already. So check out some of the links that I’ve provided for some background information.

But, I do have a reason for this brief blog post. It turns out that the Canadian government, via the Health Canada Pest Management Regulatory Agency (PMRA) are starting to take some notice and have issued a notice of intent to begin consultations on this subject. The notice of intent gives 90 days for interested parties to comment.

Some quotes from the notice of intent:

…in spring 2013 with more typical weather patterns, we continued to receive a significant number of pollinator mortality reports from both corn and soybean growing regions of Ontario and Quebec, as well as Manitoba. Consequently, we have concluded that current agricultural practices related to the use of neonicotinoid treated corn and soybean seed are not sustainable.

Bee health is a complex issue that goes beyond the incidents in 2012 and 2013 and may involve a number of additional factors, including parasites, disease and climate. Health Canada’s PMRA is currently conducting a re-evaluation of all uses of neonicotinoid insecticides in cooperation with the United States Environmental Protection Agency (US EPA) as part of the work being done with international partners. We are expediting this re-evaluation, which will help us better understand and manage potential risks these pesticides may pose to long-term bee health.

A few things to keep in mind:

  • Although the notice of intent seems to mainly target dust-related problems – and pesticide-laced dust is definitely an issue – it’s not the only issue.
  • Neonicotinoids are systemic pesticides. That means that they end up in the plant’s tissues. This is why they are very effective against herbivores (and why they were touted as such a great thing) because they are mainly targeted at things that are eating plant tissues. But the pesticide also ends up in the pollen and nectar, and that is what bees and other pollinators forage on.
  • On that topic, it’s not just honey bees that are affected. Bumblebees, as noted above, are also known to be vulnerable. In addition there are many other native pollinators – bees and otherwise – that are likely to be affected (and honey bees are not native pollinators in North America).
  • Many other organisms and ecosystems may be harmed by this class of pesticides, including fish, birds, non-pollinating insects, and soil microorganisms. This article is a decent synopsis.

It’s good to see something resembling traction on this issue emerging here in Canada.

If anyone feels so inclined, the notice of intent contains instructions for making a statement on the continued use of neonicotinoids in Canada.

 

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To spray or not to spray?

Earlier this afternoon I was interviewed by the local television station news program on the occasion of today being Canada’s National Day of the Honey Bee.

As I noted in my previous post, our city is currently being inundated with forest tent caterpillars. They are everywhere, and it’s hard to take a walk in one of our city’s wonderful green spaces without literally bumping into them at every turn as they rappel out of the trees above. Yesterday evening I spent a bit of time in my yard and then spent most of the rest of the evening removing strands of caterpillar silk that had festooned me.

What does this have to do with Honey Bee Day? Well, as the planned news story is bound to point out, the temptation for caterpillar-plagued homeowners is going to be to spray the heck out of the little leaf-munching critters with whatever pesticide they can get their hands on. That urge, I would argue, is a mistake for a number of reasons:

  • At this point in the tent caterpillar infestation, they have done almost as much damage as they can do. I have been observing that they are growing quite well (unfortunately for us!) and are going to be entering their pupal (cocoon) stage shortly. In other words, spraying now won’t do much to reduce any remaining damage that they may still do. The damage is mainly done.
  • In any case, in the face of such a massive infestation, spraying a can of pesticide at a few of the caterpillars is analogous to facing up against the JTF2 with a BB gun. You may inflict some minor damage for a moment, but you’re going to be overrun anyhow.
  • For smaller trees and shrubs (many of which these caterpillars only eat reluctantly at best anyhow), physical removal is as effective as spraying, and definitely much better for the environment.
  • And, spraying WILL impact other arthropods that are beneficial, including enemies of the forest tent caterpillar… and pollinators such as honeybees and various native pollinators (bumblebees and others).

That final point, I believe, is going to be one of the messages of the news item later today. Specifically, don’t lose sight of the forest for the trees.

Or, in other words, don’t lose sight of…

  • the honeybees
  • the native pollinators
  • the spiders that eat garden pests
  • the parasitoid flies that dine on tent caterpillars
  • the ladybugs that eat your aphids
  • the seed-dispersing ants
  • the dragonflies that eat mosquitoes
  • that beautiful swallowtail butterfly that brightens your day
  • …you fill in the blank…

…for the caterpillars.

I realize that even after reading this, some folks are still going to want to buy a can or two of pesticide and use it in their yards. If that is you, then:

  • be sure to carefully follow the directions on the label because they are there for a reason.
  • remember that these are powerful chemicals and that more is not necessarily better.
  • do your best to limit your application to the area in which you deem that it’s needed.
  • protect yourself, your kids, and your pets during and after spraying.

I’ll close with a personal story. The other day I was in a garden store buying a few bedding plants and some soil for our gardens and containers. Near the checkout there was a display of pesticide that is labeled for use against forest tent caterpillar. A customer and a store employee were talking about how best to use the stuff. Being a nosy entomologist I joined the conversation and made my case. Following more discussion between the three of us the customer finally said, “well, I know that this won’t really help with the problem in my yard, but I’m just so grossed out by them that I want to do something.”

I’m not sure if she ended up buying the product or not. But I suspect that a lot of spraying goes on for that very reason – i.e. a general dislike of insects – particularly in vast quantities – combined with a desire to do something… anything.

So, one last plea – please carefully consider your need use a pesticide in this situation. This plague will be over for the year soon enough. If we are lucky, natural enemies and disease will knock the population down this year and we won’t be seeing these creatures in any substantial quantities for quite a few years to come. In the meantime pesticides will not alleviate the problem, but they might end up hurting some friends that you may not even know that you have.

If you would like more information on pollinator conservation, please see this page hosted by the Xerces Society.

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(And a small side note: I’ve been seeing a few “friendly flies” around lately. So hopefully their population levels will pick up and they’ll help to wipe out this infestation. Fingers crossed! Keep in mind that these creatures are called “friendly” for a reason. Specifically, they like to land on various surfaces, including people. But they are harmless to everything except for forest tent caterpillar cocoons. If they are going to be a factor in knocking down the tent caterpillar infestation, there are going to be a lot of them around very soon. Here is a picture of one so that you know what to look for. Click on the photograph to enlarge. Notice the stripes on the thorax, the pattern on the abdomen, and the nice, big reddish/burgundy eyes.)

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What’s with all these caterpillars?

Prince George, British Columbia, where I live, is in the midst of a forest tent caterpillar outbreak. The number of these little caterpillars has been increasing each year for the past three or so years. And that means that people are noticing them and asking questions. This morning I received a phone call from an affiliated pair of local radio stations and gave them an interview. That has not been my first inquiry on the topic and so, because Twitter is not the best long-term repository for such answers, I’m hoping that this blog post will answer many of the questions that folks might have. I’ll update this post as I receive new questions. So fire away.

What are some of the basic facts about this insect? The forest tent caterpillar is a native species with a range that extends across much of Canada and the USA. They generally present wherever its host trees reside, and they numerous hosts depending upon the geographical locale. Here in western Canada they often feed on aspens and other poplars. They also eat the leaves on some other leafy-tree (angiosperm) species, although there are also some that they avoid. But they do not attack conifers.

Despite their name, forest tent caterpillars do not construct tents. They get their name because they are related to other species – notably eastern tent caterpillars – that do. Forest tent caterpillars do spin silk and often leave large patches of silk in areas where they congregate. Although they do not have tents, they do aggregate in groups and they also move around in little parades following each other from branch to branch and from tree to tree. In some major outbreaks the number of aggregating and parading caterpillars can be so high as to make roadways slippery and dangerous to drive on.

What is the life cycle like? How long will these caterpillars be around? Forest tent caterpillars spend the winter in the egg stage. They hatch out around the same time as bud burst, which means that they have leaves to eat as soon as they leave their eggs. The new caterpillars are quite small, but grow rapidly as they defoliate trees. They move in groups from one tree to the next when food is depleted. The caterpillar stage lasts for a few weeks – usually from about mid-May until the end of June or early-July depending on the local climate. At that point, once they have grown to a good size, they pupate in little cocoons in sheltered locations. The pupal stage lasts a few weeks and then adult moths emerge in July and early-August. The adult moths only live a few days, during which time they mate and the female lays a band of a few hundred eggs around the branch of a host tree. Then the next generation is ready to take on the winter and to emerge the following spring. If you see a lot of adult moths one year (as we did last year here in Prince George), there is a good chance that you’ll have more caterpillars the next year. So keep an eye on the number of adult moths in your area this summer.

Why are there so many of them this year? Forest tent caterpillar populations are cyclical. On occasion – perhaps every ten years or so in any particular location – there can be a population explosion for a few years. The explosions are always self-limiting, as are most biological phenomena. A variety of factors are likely involved in ending an outbreak: disease, predators and parasitoids, starvation, or even untimely inclement weather. Sometimes one of these is all that’s needed to knock the populations down to sub-outbreak levels; often several of these factors work in concert to have that effect.

Are they going to kill my trees? Probably not. Most healthy trees can survive a few years of defoliation. In fact, many trees put out a second set of leaves after losing their first set. Add to that the fact that even in a large infestation, caterpillar populations in any given area may focus on one stand of trees one year, and another the next. So not every tree is necessarily going to be fully defoliated in every year. Defoliation takes away the tree’s food source, because trees, like other plants, make their food by catching sunlight and carbon dioxide with their leaves. So forest tent caterpillars reduce yearly growth in trees. In fact, researchers can study tree rings, which are indicators of growth, to track past outbreaks of defoliators.

A few trees will undoubtedly die if they are already stressed or if an infestation continues on for a number of years before the caterpillar population collapses. But if you see any large tree in an area that harbors forest tent caterpillars, you can bet that it’s already survived a number of previous outbreaks.

What can I do about it? Not much. Once populations get to this level, pesticide spraying is mainly futile, particularly in small areas such as a few trees in your backyard. At most you will spend money and time on a treatment that really won’t have much of an effect. Killing a few caterpillars may make it seem like you’re doing something, but there are plenty more where they came from. At worst, you will kill beneficial organisms (including some that would otherwise be happily killing forest tent caterpillars); you will have deleterious effects on your local ecosystem; and you could be exposing your family and pets to pesticides.

As pointed out by another entomologist on Twitter, there are some cases where larger scale use of Btk, which is not toxic to most creatures other than tent caterpillars, is advisable:

But those are usually special, large-scale situations, often involving aerial applications.

In most cases you can take a non-pesticide approach in your yard. You may want to do this if you have young trees in your yard that may not be as resilient as older, larger trees. You can remove caterpillars by hand or with your garden nozzle. And you can use sticky bands on the trunk so that nomadic parades of caterpillars can’t get to the leaves by climbing up the tree (although they may descend from above on little silk lines). Besides that, though, it’s best to just let nature take its course. The population will collapse soon enough, and in the meantime it is an interesting biological phenomenon to observe.

Have you done any research on forest tent caterpillars? Yes. About a decade ago I was involved in work on tree responses to having their leaves fed on by this insect. In one study we surveyed all of the genes that were turned on and off in leaves while the tree was being fed on. In another study, we found that while the caterpillar was feeding on some leaves, undamaged leaves in other parts of the tree began to release chemical signals into the air. We think that those signals are used to attract in enemies of the caterpillars. In other words, it seems that the tree is calling for help when it detects that it is being fed upon. There is still more work to do on that, however.  For instance, we are not sure which of the chemicals that the attacked tree is releasing – if any – serve to attract enemies of the caterpillar.

Can you make these things into wine? Yes.

Where can I find more information? Along with some of the links above, you can look here, here, and here.