Time to start getting your omega-3's from plants. We are long past the golden age of fish production and quickly approaching a complete crash of most fisheries, in case you had not noticed. Probably it was inevitable, but over a decade ago, a couple of biologists figured it was worth a shot to point out that policy changes actually taking the future into account, rather than simply pretending to, needed to be made. (Roughgarden J, Smith F, 1996. Why fisheries collapse and what to do about it. Proceedings of the National Academy of Science U S A. 93(10):5078-83 [open access].)

Apparently no one making the regulations even tried to implement their idea, which admittedly would probably not go over well in the real world, because it involved taxing, rather than subsidizing, fishermen.

To make their point, the authors first list some of the various rationalizations for the collapse of the Newfoundland cod industry:

Many causes have been cited for this collapse, including a lack of political will to impose adequate quotas, overoptimistic stock assessments by fishery scientists, poaching from foreign fleets, exceptional mortality from natural predators, climate change, subsidies to fishers, and overcapitalization...

Do any of these sound familiar to those reading a recent NY Times article about chinook salmon?

Of course this problem with the salmon fishery is not an isolated crisis in which we cannot possibly imagine the causes, despite such mind bogglingly out-of-touch utterances as this: "It's unprecedented that this fishery is in this kind of shape," said Donald McIsaac, executive director of the [Pacific Fisheries Management] council, which is organized under the auspices of the Commerce Department.

Perhaps it is unprecedented for that particular fishery, but why would anyone expect an outcome different from nearly every other heavily exploited fish species? For example, consider the crashed Newfoundland cod - historically it was one of the most abundant fisheries. No one could imagine the possibility of depleting it. There are now also warnings about tuna, another historically abundant species.

Ultiimately the issues cropping up are probably the tip of an iceberg that has repercussions not just for mere fisheries, but for the health of the entire planet, which remember is mostly ocean. This leads some to pin the blame on climate change for crashing fisheries. But they are missing the point. The problem specific to fisheries remains one of overexploitation - it just has not been correctly defined.

We now must face up to admitting that fishing limits, even those that have been faithfully adhered to, have been based at best on significant lack of ecological information, and at worst, on mostly short-term economic criteria.

As Roughgarden and Smith point out:

May et al. (May, R. M., J. R. Beddington, J. W. Horwood, and J. G. Shepherd. 1978. Exploiting natural populations in an uncertain world. Mathematical Biosciences 42:219-252) concluded that "What seems really needed is not further mathematical refinement, but rather robustly self-correcting strategies that can operate with only fuzzy knowledge about stock levels and recruitment curves."

For thirty years at least, it has been clear that fishery management has needed to focus on how to incorporate ecological complexity (compounded by complexity introduced by detrimental environmental impacts by all sorts of human activity), rather than crunch numbers based on the last available year of data for catch. Is there truly anyone in this business who can possibly be surprised that any fishery is collapsing now?

Of course, Roughgarden and Smith's analysis is naive in its economic assumptions such as this, when they state that after a crash "...the industry must contract anyway, and by managing for ecological stability the prospects of subsequent collapses are minimized." Unfortunately, for most natural resources, long-term gain is completely overshadowed by short-term profit, to an irrational degree, which will not emerge out of traditional economic models.

Still, the authors have a proposal that makes a little more sense for helping fisheries last a little longer:

(i) Establish a target stock at 3/4 of the average unharvested abundance [i.e., harvest much less than what appears to be ecologically sustainable].
(ii) Tax the revenues from any fish caught when the stock is below target.

As they discuss it, condition (1) essentially builds in insurance for fisheries, which only makes sense given our deep and continuing lack of understanding of the complex interactions of habitat loss and climate change, combined with only vague estimates for rates of increase, habitat carrying capacity, amount of predation, etc. And yet current practice ignores the environmental factors, and pretends that our numbers for the rest are accurate.

Condition (2) makes sense too, but seems unlikely to be successfully implemented. The point of it is to make it more costly, rather than more profitable, to fish when stocks are depleted below a sustainable level. Unfortunately, the current situation is that the harder it becomes to catch a certain species of fish, i.e. as it becomes depleted, the more rare it becomes, and thus more expensive. A tax would have to be severe indeed to cut into the profits of fishers catching the rarest fish, and thus politically probably impossible. If implemented it would surely increase poaching and the black market even beyond what it already is.

The damage is done. Fishing limits have been set historically (when they were set at all, usually belatedly) based on faulty ecological assumptions influenced by strong economic pressures, while ignoring the continuing fluctuations (many with unknown cause, such as in the case of the chinook salmon) that change the sustainable catch - and thus can crash a seemingly healthy fishery quickly after a series of below-normal population years. The mistake is similar to that made by authorities making Western water allocations during an unusually wet period there, and steadfastedly sticking by them even when a fraction of that water is now available. Perhaps moratoriums on fishing some populations such as the Newfoundland cod will give us a second chance to make saner policy. But it would be a foolish bet to make.

Labels: ecology, economics

The announcement of two Science papers (Fargione et al., 2008; Searchinger et al., 2008) calculating higher carbon dioxide emissions through changes in land use is making a lot of noise. But will the public get this travesty enough to force a change in federal policy on ethanol?

It didn't take these studies to wake up scientists and more progressive policy makers to the dangers of overemphasis on ethanol.

Yet a quick check on Technorati of responses to this news shows a lot of people still don't get it. Some bloggers gleefully have blamed environmentalists for going to town on ethanol use, but scientists (the great majority of whom are environmentalists, but not vice versa) have known better for a long time - some smart ones just got a couple of easy Science papers out of the hot political potato that biofuels production is becoming. The papers are highly complementary, and both expose the faulty math that has been done to promote ethanol production as "renewable" energy - which is not so renewable after all when rain forests and grasslands are destroyed to produce it.

Fargione et al. calculated actual carbon release due to land clearing in order to create more land for biofuel production, and Searchinger et al. produced a model which uses estimates of these numbers. Both methods produce the same conclusion: the worldwide ethanol frenzy, ostensibly about reducing greenhouse gas (GHG) emissions, will actually accelerate the production of atmospheric carbon dioxide through the destruction of ecosystems which have much higher carbon storage than the biofuels plants themselves do. This is not a problem of the future, but is currently happening, both directly and indirectly: either new land is cleared for biofuel production, or the conversion of current crop land (or animal-feed land) for biofuel forces creation of new crop land. The fallacy of this is most extreme in Indonesian peatlands, which Fargione et al. point out are huge carbon sinks, and thus liberating this carbon to grow palms for oil leaves us with a carbon debt that may not be repaid for over 800 years.

Searchinger et al.'s model, as all models do, must make numerous assumptions about the numbers that cannot necessarily be confirmed at this time. However, they take great pains to be conservative in their estimates of carbon released due to changing land use, and the logic in their introduction cannot be denied. They point out what is known from previous studies: the carbon cost of growing biofuel feedstocks, refining them into fuel, and then burning them, is no different from the carbon cost of oil. What supposedly swings the balance in favor of biofuels is that while they are growing they take up carbon from the atmosphere, while the burning of fossil fuels liberates previously sequestered carbon. Given that we know that land conversion means a lot less carbon sequestered in plants grown on the same acreage, the model is practically gratuitous.

So why the big push for "renewable" ethanol? It didn't come from environmentalists. It came from agribusiness, the huge corporations such as Archer Daniels Midland, who have the most to gain from this legislation. By declaring the production of ethanol "renewable," (not to mention running their ads on PBS), they have framed themselves as a company who cares about people and the environment. But the consequences of the ethanol rush would have been obvious to anyone formulating the policy. Simply, like most legislation we've seen over the last decade plus, this is all about money - specifically, taxpayer giveaways to huge corporations whose buddies happen to be running the government.

Given that once again we seem to have failed to find our magic energy bullet, then what is the solution? Are scientists who criticize various alternative energy sources on environmental grounds hopelessly naive? Not at all. They simply acknowledge that our range of solutions is quite a bit wider than that proposed by corporate giants who want all the taxpayers eggs in their industry's personal basket.


References

Fargione, J.,Hill, J., Tilman, D., Polasky, S., Hawthorne, P., 2008. Land clearing and the biofuel carbon debt. Science (in press).

Searchinger, T, Heimlich, R., Houghton, R. A. , Dong, F., Elobeid, A., Fabiosa, J., Tokgoz, S., Hayes, D., Yu, T. 2008. Use of U.S. croplands for biofuels increases greenhouse gases through emissions from land use change. Science (in press).

Labels: biodiversity, ecology, environment, forests, politics

The mountain pine beetle (Dendroctonus ponderosae, Coleoptera: Scolytidae) is native to western North America. A finer resolution of its range, however, reveals that it is historically native to some parts of the West, but not others. Specifically, it has generally had a limited presence in Canada, primarily due to very low winter temperatures. Although the pine beetle's cold tolerance is incredibly high because they have the anti-freeze compound glycerol in their bodies, generally sustained (5 or more days) temperatures below -30F kill most of them off. This has reduced the likelihood of mountain pine beetle outbreaks in Alberta, and thus susceptible trees there have historically been protected, but are now exposed and being attacked (Rice et al., 2007).

In the last 5-10 years, however, conditions in the West, including Alberta, have changed. Rising temperatures have meant that for several winters in a row, the northern Rockies have not reached low enough temperatures to kill off the mountain pine beetles infesting the trees there. Even in the U.S., the historical trend was that every few years most of the beetles are killed due to cold, and thus the outbreaks were knocked back. So the pine beetles, which are a native species, have begun behaving like an invasive one: they are multiplying rapidly without a natural check, and expanding their range, attacking populations of trees that are not adapted to them.

Compounding this problem is the recent history of fire suppression in the West. One of mountain pine beetle's favorite hosts, lodgepole pine (Pinus contorta) is a fire-adapted species; it is common for lodgepole stands left undisturbed to burn once or twice a century, and be replaced by seeds from serotinous cones (cones in which the seeds are sealed unless they reach the high temperatures of a fire). Lodgepole stands are striking in that usually all the trees are the same age and size due to the burn regimen. Mountain pine beetles prefer older, larger trees. The larger the tree, the more food available for the developing beetle larvae, and the larger the increase in population the next year, if there is not a sustained hard freeze. By suppressing natural fires in lodgepole habitat, we may have enhanced the long term outbreak we are seeing now.

But here's the flip side: mountain pine beetle outbreaks make lodgepole pine stands more susceptible to fire down the road (Page and Jenkins, 2007). For instance, the 1988 Yellowstone National Park fires were highly correlated spatially with trees affected by a mountain pine beetle outbreak about fifteen years before (Lynch et al., 2006). What we may be experiencing now is a mega-outbreak, due to warming and fire suppression, which will eventually contribute to massive forest fires throughout the West in the future (also increasing of course from drier weather), which may have the benefit of being a different kind of check on mountain pine beetle populations. But instead of the historical ecology, in which mountain pine beetle outbreaks occurred for maybe 3-4 years, decades apart, a whole new, different ecology driven by constant high beetle populations decimating the forest, which as a result may burn more often, will remake the landscape in ways that we cannot yet imagine.

Of course there are those who believe that we can replicate the ecological benefits of fire, while keeping the timber available for human use. However, thinning trees mechanically is a blunt instrument that does not mimic the effects of fire at all in the case of lodgepole (Sibold et al., 2007). In fact, there is the danger of unintentionally increasing the density of trees (and necessitating, further, constant thinning effort) if enough of the canopy is opened to encourage new seeds to germinate and grow. There are those who believe humans are all powerful and can easily control insect outbreaks and fires through management if only the wicked, meddling environmentalists would let them (never mind that somehow the forests managed themselves just fine for millennia). In fact, many species are adapted to respond to biotic (e.g. herbivory pressure) and abiotic (e.g. weather) influences in ways we don't even understand. Global climate change is now accepted by anyone rational to be at least partly enhanced by the massive release of carbon dioxide into the atmosphere by industrial humans that would not have occurred otherwise. Fire suppression is an active (and expensive) choice that trades short-term convenience for long-term ecological disruption, whose consequences we are barely beginning to understand. Those who blame "environmentalists" for the hundreds of acres of brown pines they see spreading like a cancer in the West, would find that ecologists (pretty much environmentalists by default) only wish they had such god-like power to affect the ecology of our forests, so they could save them from 150 years of disastrous "management."


References

Lynch, H.J., Renkin, R.A., Crabtree, R.L. & Moorcroft, P.R. (2006) The influence of previous mountain pine beetle (Dendroctonus ponderosae) activity on the 1988 Yellowstone fires. Ecosystems, 9:1318-1327.

Ono, H. (2003) Mountain Pine Beetle Symposium: Challenges and Solutions. Kelowna, British Columbia. T.L. Shore, J.E. Brooks, and J.E. Stone (editors). Natural Resources Canada, Canadian Forest Service, Pacific Forestry Centre, Information Report BC-X-399, Victoria, BC. 298 p.

Page, W.G. & Jenkins, M.J. (2007) Mountain pine beetle-induced changes to selected lodgepole pine fuel complexes within the intermountain region. Forest Science, 53:507-518.

Rice, A.V., Thormann, M.N. & Langor, D.W. (2007) Mountain pine beetle associated blue-stain fungi cause lesions on jack pine, lodgepole pine, and lodgepole x jack pine hybrids in Alberta. Canadian Journal of Botany-Revue Canadienne de Botanique, 85:307-315.

Sibold, J.S., Veblen, T.T., Chipko, K., Lawson, L., Mathis, E. & Scott, J. (2007) Influences of secondary disturbances on lodgepole pine stand development in rocky mountain national park. Ecological Applications, 17:1638-1655.


Thanks to T. Etienne for initial information on mountain pine beetle

Labels: ecology, environment, forests, insects, invasive species

Check it out at The Radula.

Labels: biodiversity, carnivals, ecology, environment, humans

Our local wilderness controversy has made national news. The article is suggestive of the growing recognition that land use is a complex problem because of the large diversity of stakeholders, but only scratches the surface of the problem.

The current backlash in Beaverhead County, Montana, is against a consortium of environmental groups (including the National Wildlife Federation, Trout Unlimited, and Montana Wilderness Association) and logging companies (including RY Timber and Sun Mountain Lumber) who recognize the need for some sort of compromise among those with widely divergent interests in public land. The group is presenting to the Forest Service a plan that exchanges more guaranteed logging in certain forest areas in southwest Montana for more acreage in the forest being designated as wilderness. The plan has the advantages of providing for stable timber harvests that are minimally invasive but will allow logging companies to keep operating, while it recognizes the value of preserving land in wilderness areas to maintain the watershed and prevent overexploitation of resources.

Unfortunately, in this county, "wilderness" and "environment" are the dirtiest words you can say. To put it in perspective, voters in Beaverhead County overwhelmingly supported a 2004 initiative (put on the ballot by an out-of-state mining company) to repeal a ban on cyanide leach mining, which has damaged many an ecosystem and watershed in several states. While the rest of the state was smart enough to understand that no number of local mining jobs is enough to offset the cost of a destroyed fishery, Beaverhead County, whose nearly entire economy is dependent on tourism on its blue-ribbon trout streams and ranching (which also requires clean river water), supported the initiative, apparently seeing the issue only as a vote against the evil environmentalists.

A deluge of letters to the editor is now condemning the proposed logging-environmental draft forest plan simply because it creates a few more thousand acres of wilderness, a small percentage within a sea of exploited forest. The letter writers take the common view that the creation of wilderness somehow takes land away from their use, because they prefer to use ATVs rather than their own two feet (or horses) for their recreation on public land. What has been lacking in every letter by an ATV user so far has been any acknowledgement that some ATVers themselves fuel anti-vehicle backlash when they ride off road illegally, trashing out areas that are no longer available for the enjoyment of others. They also do not acknowledge that hiking and skiing, being quite, no-emissions activities, do not impinge on anyone else's enjoyment of the forest, while the use of ATVs and snowmobiles very much degrades the forest experience of non-users. It is ironic that they claim that the use of the forest is being stolen from them by the addition of a few more acres where they are not allowed, when they have already stolen peace and fresh air from the rest of us in the great majority of the national forest.

They call for "management" of the forest because it is a "waste" to let nature take its course in the form of fires and insect outbreaks - and apparently they are ignorant that the potential new law as drafted allows for management of fire and insects in wilderness areas when deemed necessary, and the grandfathering of grazing rights. In the mythical world of the wilderness opponent, nature can be completely controlled and managed, and any failure to do so by the forest service is blamed on "environmentalists" (who apparently have god-like powers possessed by no one else).

The logging-environmental consortium came together to reach a compromise because all the organizations realize that current management policies are unsustainable. They have drafted a perfectly reasonable proposal that keeps logging alive in Montana, but supports both economic and ecological sustainability, unaddressed in past policies which subsidized logging companies to clear cut huge swaths of land, without remediation. The Forest Service is under no obligation to support the new plan, but would be well advised to do so. Those of us lucky to live in a county that consists mainly of public land would do well to remember that the land is not a personal playground to exploit here and now, but belongs to every single U.S. taxpayer, living and unborn, from sea to shining sea.

Labels: ecology, environment, forests

Acacia ants, in the genus Pseudomyrmex, and their acacia tree hosts, are a terrific example of coevolution between plants and insects. While yellow flowers and many species demonstrate a loose form of the coevolution between generalized pollinators and a large range of plants, the coevolution in this case is very specific, although there are other examples of Acacias with ants that have a looser association.

The species depicted here are likely Acacia cornigera and Pseudomyrmex ferruginea, native to Mexico and Central America. These photos were taken at Palo Verde National Park in Costa Rica.

While some instances of coevolution may be hard to demonstrate for certain, this case is definitive. First, a common name of this acacia species, bullhorn acacia, refers to the extremely large, swollen thorns shown here. The horns also happen to be hollow, and provide perfect chambers for nesting ants. (An ant on the left thorn can be seen entering a hole in it.)

Next, the tree provides food for the ants in two forms. The first is nectar, but this is not the generalized nectar production of flowers attracting pollinators. The acacia nectar is provided from extrafloral nectaries, found actually on the leaf petioles, as shown here (slightly out of focus). Because of the location and size of these nectaries, it is clear that the trees are obtaining a benefit apart from pollination.

Second, the tree also produces a unique protein source for the ants called Beltian bodies (after the naturalist Thomas Belt). These extraordinary structures are produced as part of new developing leaves. When the new leaves unfold and expand, there is a Beltian body on the tip of each leaflet. These are harvested by the acacia ants and provide most of their protein. Between the nectar and the Beltian bodies, and the housing provided by the thorns, the tree provides all an ant colony's needs.

What does the tree get in return? It gets extremely aggressive defense from herbivores, both large and small. Pseudomyrmex have one of the nastier stings in the world of Hymenoptera (the order comprising ants, bees and wasps). Any insect that alights on the tree is instantly driven away or killed, and the ants are quite effective against potential vertebrate herbivores as well -- to which I can attest first hand when I made the mistake of brushing against a branch while taking these pictures.

The ants are so aggressive that they also take care of potential plant competitors, by cutting down any seedlings that sprout in the vicinity of the tree. In this photo it should be clear that the acacia in the center is sitting in a circle of bare dirt, courtesy of its ant colony.

The relationship between the acacia tree and Pseudomyrmex ants is thus a true mutualism, in which both species have a large benefit from the association.

Labels: cool bugs, ecology, evolution, insects

Biological control of pest species has come under a lot of criticism in recent years. Employed by governments and private businesses since the late 1800's, the practice was largely unregulated until the 1980's, and regulation remains varied and complicated among different countries, and different states within the U.S.

Classical biological control specifically refers to the importation of an alien species to control pests that are usually aliens themselves. Traditionally, it has been employed in agricultural systems, in which the alien pest arrived in its new location accidentally. More recently, classical biocontrol has been undertaken to control pests in natural systems, which in the case of plants, were usually intentionally introduced through horticulture trade of botanical gardens. It is currently viewed by many ecologists as a critical tool in the battle against invasive alien species, which are growing into an ever larger economic and ecological problem.

The recent criticism of biocontrol has focused on the likelihood of "non-target" attacks, which occur when the introduced agent feeds on unintended prey or plant species, including natives. This is an especially important problem in areas with many endemic species - in the U.S., the states most affected are Hawai`i, California, and Florida because of their high native species diversity. The concern about non-target attacks is excessive, in the opinion of most biocontrol practitioners, including Messing and Wright (2006), who describe a scenario in which the peril to Hawai`i's agriculture and ecosystems is being increased by a bureaucracy that will not allow alien biocontrol agents to be imported, even to combat serious economic and ecological pests in Hawai`i that are contributing to the destruction of native ecosystems.

Certainly their concern for the native species of Hawaii is not misplaced. Invasive alien plants such as thorny blackberry crowd out natives and are less likely to be eaten by foraging alien herbivores such as pigs and goats. Generalist insects such as the two-spotted leafhopper consume hundreds of native plant species which have no natural defenses against the aliens feeding on them. So it does seem unreasonable that Hawai`i is so stingy with its species importation permits, when researchers do their best to show that their biological control agents will not feed on any native species. (I know both of the authors personally, and can verify that they are stringent in their criteria for potential non-target interactions.)

The problem with Messing and Wright's paper is the same problem with most discussions debating the use of biological control in the scientific literature, at conferences, and in online discussions. While we are focusing much energy and attention on predicting non-target interactions, which in many biocontrol programs has thus been adequately addressed, there is almost no discussion about doing a better job of predicting whether or not the introduced agent will actually be effective once introduced.

Messing and Wright themselves toss out that only 16% of effective biological control programs have been effective at controlling the target, and yet later in the paper complain about their inability to introduce agents, which is based on the assumption that the introduced agents will actually work. The high probability that (based on current practices) they will not work is never addressed in their paper. Twice the number of effective biocontrol agents, or around 33% actually establish -- probably an underestimate, since follow-up generally does not extend for years, and those that are not actively controlling the target could be missed early in monitoring -- and rarely has any follow-up been done to understand their role in the native ecosystems. If they are not attacking non-targets, and they are not controlling the pest, how are they interacting with native species?

It is true, as Messing and Wright point out, that in the current modern age of regulation, non-target effects have greatly decreased. But it is also true that even in the case where a known specialist was introduced, there can be indirect food web effects discovered when people have taken the trouble to look, which they rarely do. In one case (Willis and Memmott 2005), a native parasitoid attacking an specialist insect herbivore introduced to control an alien weed increased greatly in numbers and thus made native herbivores much more susceptible to attack, upsetting the food web in the system.

Effective biological control programs are indeed cost-effective, but a lot of money is spent for many years on the assessment of a single agent, and are we getting our money's worth if only 1 in 6 actually work? A whole new science may need to be developed to further our ability to predict the effectiveness of biological control agents. Those who are generally against biocontrol find the balance of effective agents vs. the risk of non-target effects, which while getting lower, will never be zero, to be unacceptable. What if biological programs could predict effectiveness 50% of the time? That would alter the equation, and make these programs more palatable to many ecologists such as myself.

How can something as notoriously unpredictable as species interactions be better assessed before release? One method which would give researchers much better data about the role of species in both native and alien habitats is the construction of quantitative food webs. Normally when biocontrol workers go the country of the target pest's origin, they observe only the two-species interactions between the target species an its natural predators or herbivores. This provides no predictive value because plants and animals do not interact in 2- or 3-species bubbles, they interact complexly both directly and indirectly with many species. Why don't we construct food webs of biocontrol agents in their native habitat and figure out why they seem to be effective there? We can also do retrospective studies on established biocontrol agents that are ineffective and use food webs in both the new and native habitats to try and understand why.

Of course, ecological research is conducted at the whim of funding agencies, largely NSF in the U.S. Politics and inertia often determine what is funded more than science does. Perhaps someday, however, people will realize that for both economic and political reasons, research into the prediction of the effectiveness of biocontrol agents makes clear economic, ecological, and political sense. We do need biocontrol as an option for saving some ecosystems. But we particularly need biocontrol that works.


References

Messing, R.H. and Wright, M.G., 2006. Biological control of invasive species: solution or pollution? Frontiers in Ecology and Evolution 4:132-140.

Willis, A.J. and Memmott, J. 2005. The potential for indirect effects between a weed, one of its biocontrol agents and native herbivores: A food web approach. Biological Control 35:299-306.

Labels: ecology, Hawaii, invasive species, USDA

Eupithecia is a large, worldwide genus of inchworms (moths in the family Geometridae). The Eupithecia in Hawaii are unique because of the particular ecological niche they fill - they are predators, while nearly all other known caterpillars are plant feeders only.

Here is the abstract of the original paper describing carnivorous Eupithecia (Montgomery, S. L., 1983. Carnivorous caterpillars: the behavior, biogeography and conservation of Eupithecia (Lepidoptera: Geometridae) in the Hawaiian Islands. GeoJournal 7:549-556.):

A completely new feeding pattern has been found among caterpillars native to Hawaii: certain geometrid larvae (commonly called inchworms) consume no leaves or other plant matter. Instead, they perch inconspicuously along leaf edges and stems to seize insects that touch their posterior body section. By bending the front of their body backwards in a very rapid strike, the caterpillars opportunistically capture their prey with elongated, spiny legs and 900 larvae and eggs of these moths have been collected from native forests of all the main islands and reared in the laboratory. All are species of Eupithecia, a worldwide group of over 1000 members that had been reported to feed only on plant matter such as flowers, leaves or seeds. At least 6 of Hawaii's described Eupithecia species are raptorially carnivorous, only 2 are known to feed predominantly on plant material, especially Metrosideros flowers. A diet including protein-rich flower pollen and a defensive behavior of snapping may have preadapted Hawaii's ancestral Eupithecia for a shift to predation. Severe barriers to dispersal of mantids and other continental insect predators into Hawaii resulted in an environment favoring behavioral and consequent morphological adaptations that produced these singular insects, which can be commonly called the grappling inchworms.

When insects colonized the remote Hawaiian Islands over millions of years, the results were remarkable because the chances of them getting there were so slim. This meant that a species that managed to be blown out over vast distances of ocean and land on one of the islands faced little competition or predation pressure. They then diversified into ecological niches that would not have been possible for their mainland relatives. Because there were fewer predators in the islands than the mainland from which the colonizing Eupithecia originated, there was wide-open opportunity in predation and Eupithecia had the right biological tools to grab it, despite its evolutionary history as an eater of plant parts. Interestingly, people collected these caterpillars for years without recognizing them as predators, because it was assumed that all caterpillars must be plant feeders. The story is that they always died in the lab until a fly inadvertantly got into a rearing cage, and the caterpillar was observed eating it. In the clarity of hindsight, it is interesting that it did not occur to people that these were predators, because they have quite distinct morphology and behavior. They have raptorial claws adapted for grabbing struggling prey, and long thin appendages on the tip of their abdomens which probably work somewhat like the trigger hairs in venus fly-traps. They are sit-and-wait predators, disguising their long bodies along the edge of a leaf -- behavior that makes no sense for an herbivore caterpillar which must move around a lot to feed on the plant. When an insect touches the Eupithecia while crawling up a leaf edge, it whips its head around and captures it.

Nearly all the 22 known Hawaiian species of Eupithecia behave as described in the paper. Interestingly, some are host plant specific, even though they do not eat the plant, because they look so much like that particular plant and it gives them a great advantage in disguise. Some are even specific to the part of the plant on which they rest. One Eupithecia is specific to the green, living fronds of the native Hawaiian fern known as uluhe, and it is the perfect green to match their color. Another dark brown species is always found on the mats of dead fronds underlying the green, living part of the plant.

One exception to the sit-and-wait behavior of most Hawaiian Eupithecia is the species E. monticolans (above), which appears to behave much more like a plant-feeding inchworm. It does not have the raptorial claws or the trigger hairs on the abdomen, and does not sit along leaf edges as its congeners do. When I first collected it, its food was not known, but assumed to be flowers on the `ohi`a tree (as mentioned in the above abstract). I suspected this was not necessarily the case because I collected many from trees that were not in flower. I was not successful in rearing E. monticolans caterpillars for over a year, until I inadvertantly provided one with leaves that were loaded with galls made by small insects related to aphids, in the family Psyllidae. Within a day the leaves looked like swiss cheese, with all the galls eaten out of the leaves. From then on, I always provided this species with leaves covered with galls and I never again had problems rearing them to adulthood. So while E. monticolans was thought to be a "missing link" from pollen-eating to predatory behavior, they are in fact predators, but without the morphology to make a quick strike, they must rely on eating sessile insects that cannot escape or defend themselves from a slow-moving caterpillar.

Almost no parasitoids have been reared from Eupithecia caterpillars. It certainly seems likely that Eupithecia may be rarely parasitized because it is difficult for a parasitic wasp to sneak up on it and lay an egg without being caught. Here is a brief video showing lightning-fast E. orichloris capturing a parasitic wasp (and releasing it - apparently they are not very tasty).



Listen to the jazz tune "Inchworm" here...

Labels: cool bugs, ecology, Hawaii, insects

The pipevine swallowtail is Battus philenor. In the U.S., it occurs roughly in the southern half of the country, east to west.
The caterpillars of B. philenor (below) feed exclusively on plants in the genus Aristolochia (pipevine). These plants are loaded with toxic compounds called aristolochic acids, which would kill, and thus deter, most herbivores. The pipevine swallowtail, however, is not harmed by aristolochic acids, and instead it sequesters them in its own body to use as a defense against predators. These butterflies are a classic example of aposematism, which means they advertise the fact that they taste bad to predators.
If an insect is black, red, yellow, orange, or any combination of those colors, it is likely to be distasteful. If an insect is green or brown and seems to blend into foliage, it likely tastes good to potential predators, and because of that it is hiding. Aposematic insects do not want to hide, they want to make it clear to the predators out there that they are no good to eat. This is because they are relying on learning by those predators (in the case of butterflies, often birds) learning to associate those colors with bad food. Another better known distasteful butterfly is the monarch, which feeds on milkweed, another plant with nasty chemicals.

Some butterflies which have aposematic coloring do not sequester nasty chemicals. Instead, they use a strategy of mimicry, and rely on the likelihood that predators will mistake them for bad food and avoid them as well. This of course only works if most of the aposematic butterflies do actually taste bad, because if a bird eats a black butterfly and it tastes good, it will not learn to avoid black butterflies, but to eat them. So generally in a population there is a stable balance of truly distasteful butterflies and mimics.
The caterpillars of B. philenor can either be black or red, and this is entirely due to the temperature at which they develop (Nice and Fordyce, 2006). When the temperature is over 30°C, A black caterpillar will overheat, so they become red instead, which keeps them cooler (black absorbs sunlight, and thus heat, much more readily than red). Interestingly, aposematism in B. philenor caterpillars seems to serve a dual function: in addition to deterring predators, the contrasting black or red color also deters a B. philenor adult female from laying more eggs on the same plant already occupied by larvae of the same species (Papaj and Newsom, 2005). This ensures that her offspring will have adequate food left for development.

Adult females lay their eggs preferentially on young foliage. This is probably because younger leaves are more tender and easy to eat by early stage caterpillars. Females determine the suitability of the foliage via chemical receptors (taste buds) on their feet. I established this in an unpublished study in which I stimulated oviposition by females on filter paper using organic extracts of young vs. old Aristolochia foliage (above); they much preferred to oviposit on extracts from young foliage. High pressure liquid chromatographic analysis revealed higher levels of several sugar alcohols in the younger foliage, so the butterflies may use that information to choose oviposition sites. At the time, however, we were unable to measure levels of aristolochic acids in young vs. old foliage, so that may also be a cue instead of or in addition to sugar alcohol levels.

These butterflies can be reared in the laboratory, but not easily. Getting butterflies to mate in a lab is challenging, but B. philenor was often quite accommodating. One could manipulate the genitalia of a male and female into contact, and sometimes get them to hold on and complete the mating (and thus get fertilized eggs in the female). Interestingly, what mattered in lab mating success often was the individual male - certain males could not be induced to mate, while with others we had success with several females.

These insects have been of interest to scientists not only because of their chemical relationship with their host plant, but because of their behavior as well. Many people assume that insects behave only according to instinct, but in fact many species have shown quite good learning ability. Parasitic wasps are often studied for their odor and sometimes visual learning skills, and butterflies as well are good learners. Mainly visual cues, e.g. color and shape, have been shown to be learned by B. philenor. For example, in parts of their range there are multiple species of Aristolochia upon which they feed, and females learn the leaf shape of the dominant species (Papaj 1986). This saves time for females searching for host plants, because ovipositing (egg laying) females can visually scan for potential host plants, and then test leaves of the correct shape for the compounds in Aristolochia, after which they confirm or reject it as a host plant.

A female B. philenor can also simultaneously learn one color associated with egg laying, and another color associated with nectar sources for food (Weiss and Papaj 2003). Similar ability has been found in some parasitic wasps. It actually should not be surprising that insects are good at learning. If your brain is tiny, you have fewer neurons to hardwire different behaviors, so it pays to be flexible anyway.


References

Nice, C.C. & Fordyce, J.A. (2006) How caterpillars avoid overheating: behavioral and phenotypic plasticity of pipevine swallowtail larvae. Oecologia, 146, 541-548.

Papaj, D.R. (1986) Conditioning of leaf-shape discrimination by chemical cues in the butterfly, Battus philenor. Animal Behaviour, 34, 1281-1288.

Papaj, D.R. & Newsom, G.M. (2005) A within-species warning function for an aposematic signal. Proceedings of the Royal Society B-Biological Sciences, 272, 2519-2523.

Weiss, M.R. & Papaj, D.R. (2003) Colour learning in two behavioural contexts: how much can a butterfly keep in mind? Animal Behaviour, 65, 425-434.

Labels: biodiversity, cool bugs, ecology, insects

Go to Geek Counterpoint for the latest Tangled Bank installment, addressing topics from genetics to exoplanets to the continuing discussion about Wikepedia's accuracy.

Labels: carnivals, ecology, environment, genetics

The blog carnival Oekologie #5 is now up at The Voltage Gate. With the wide variety of posts up about plants, animals, and their environment, there is something for everyone.

Labels: carnivals, ecology

Trap-jaw ants are the venus fly traps of ants, in the tropical/subtropical genus Odontomachus. They are some of the most incredible animals on earth, because of the speed at which they can snap their jaws together to snatch their prey. The species at left, O. clarus, is one I encountered in Arizona. Like many desert animals, these ants like to hunt at night, and it was common to see them milling about on the University of Arizona campus in the glow of the street lights. The workers are striking to see because they walk about with their huge jaws in the open position. In the picture you can barely see tiny trigger hairs, which are similar to trigger hairs in venus fly traps. Because this is an animal, though, there are large jaw muscles which contract like coiled springs to hold the jaws open. When there is pressure on a trigger hair, the effect is like unhooking a latch (think of a mousetrap), and the jaws explosively close on their prey, at a nearly unimaginable speed:

"Biologists clocked the speed at which the trap-jaw ant, Odontomachus bauri [at right], closes its mandibles at 35 to 64 meters per second, or 78 to 145 miles per hour - an action they say is the fastest self-powered predatory strike in the animal kingdom. The average duration of a strike was a mere 0.13 milliseconds, or 2,300 times faster than the blink of an eye."

To record the entire motion requires filming the ants at 50,000 frames per second, rather than the usual 24.

In their paper published last August (Patek, S.N., J.E. Baio, B.L. Fisher, and A.V. Suarez, 2006. Multifunctionality and mechanical origins: Ballistic jaw propulsion in trap-jaw ants. Proceedings of the National Academy of Sciences 103: 12787-12792), researchers added to this incredible story by discovering an additional purpose of the trap jaws. They first calculated the force of the mandibles: "...a single mandible could potentially generate a force that is 371-504 times the ant's body weight." Then they documented a previously unknown use for this force in O. bauri: self-propulsion.

You must watch these videos to fully appreciate this behavior. But, to summarize, by snapping their jaws against a hard surface, O. bauri achieves "heights up to 8.3 centimeters and horizontal distances up to 39.6 centimeters. That roughly translates, for a 5-foot-6-inch tall human, into a height of 44 feet and a horizontal distance of 132 feet." Of course, whenever comparisons are made between insects and humans, the former come out looking like Schwarzeneggers to the hundredth power. This is because such comparisons do not take into account the effects of scaling. The insect world, with the same gravity and atmosphere as we have, but with exoskeletons and light weight, is a very different place (which is a topic for a later time). Everyone knows you can drop an insect from great height and it will emerge unscathed. This is very useful if your escape route is flying eight times your body length straight up into the air.

To see some amazing biodiversity in action, watch the videos.


More incredible ant pictures are posted at myrmecos.net!

Labels: ants, behavior, biodiversity, cool bugs, ecology, insects

We have seen some recent outbreaks of Escherichia coli O157:H7, the common pathogenic strain of the common gut bacterium, in the human food supply, most notably in spinach last fall.

Since then, it has been common to see assertions in the mainstream media (e.g. by the quite knowledgeable food industry writer Michael Pollan) that E. coli O157 is purely a product of the mega-feedlot industry, because the pathogen is not found in the guts of grass-fed cattle. It is a very attractive assertion to those of us who support a trend away from factory farms, which are demonstrably less healthy both to humans and the environment in many ways. So, I thought it would be worthwhile to investigate this further.

Buried within a forest of "green" sites promoting this idea was a link by a commenter to a brief Kansas State news release claiming that this assertion was false. Dr. David Renter, assistant professor of veterinary epidemiology at KSU, has done research himself on this important human health topic and has studied the prevalence of E. coli O157 not only in feedlot vs. range-fed cattle, but in wildlife as well.

In Renter et al., 2003, he and his colleagues found E. coli O157 in 2.48% of fecal samples from rangeland cattle in Kansas and Nebraska, similar to a rate found in previous studies of "confined" (=feedlot) cattle. They also tested several hundred samples from wildlife, including coyotes, whitetailed deer, raccoons, and possums. In wildlife, the pathogen was only found in one possum sample.

An earlier study (Renter et al., 2001) confirmed the presence of E. coli O157 in fecal samples from wild deer in Nebraska, albeit at the very low rate of 0.25% (a rate of 25 out of 10,000).

Surpirsingly, Kudva et al. (1997) found, in sheep, the opposite trend I expected to see based on media reports on cows. Animals were innoculated with E. coli O157, then fed one of two diets: grass hay, or corn and alfalfa. In this case, grass-fed sheep were shedding bacteria twice as long as corn/alfalfa-fed sheep.

So where did the grain vs. grass theory come from? It turns out it was from a Science paper in 1998 by Diez-Gonzalez et al., which did not specifically address pathogenic E. coli. As explained by Gannon et al. (2002):

A grass diet would certainly be expected to cause a change in the intestinal microflora as well as parameters such as volatile fatty acid species and concentrations and the pH of the digesta. A recent study has shown that grain feeding selects for acidresistant E. coli strains and that feeding Timothy hay rapidly reduces the numbers of these organisms shed in the faeces... While this appears to be the case, the authors of this somewhat controversial study failed to demonstrate that E. coli O157: H7 was one of the acid-resistant E. coli strains selected for by grain feeding and reduced by hay feeding. Recent studies by Hovde and colleagues ... showed that hay feeding increases rather than decreases faecal shedding of E. coli O157: H7 by beef cattle which were orally inoculated with the organism.
... In addition, naturally occurring antimicrobial substances in certain plants may play a role in faecal shedding of the organism by cattle e.g. Duncan and colleagues have shown that certain coumarins derived from plants inhibit growth of E. coli O157: H7.

So, once again, complex nuances in a biological system fail to penetrate the aura of the either-or dichotomy so loved by the media.

There is no doubt that the relationship between E. coli, domesticated animals, and husbandry methods is not simple. As Renter et al. (2003) state:

The observed number of E. coli O157 XbaIPFGE subtypes, the frequency and persistence of specific subtypes, and the presence of indistinguishable subtypes in cattle, water, and wildlife indicate that the molecular epidemiology of E. coli O157 in range cattle production environments is complex. A clear description of the complex molecular epidemiology requires explicit definition of factors related to the molecular biology and micro- and macroecology of the organism.

The "subtypes" to which they refer number, in this study alone, 70 of just the O157 strain that they were studying. Many more exist. There are lots of possible ways to address the likely growing E. coli problem. Antibiotics are one, but there are of course problems with resistance there (Flucky et al., 2007). Hopefully, environmentally friendly rearing practices will be part of the solution, but it is clear they would not be a complete solution. E. coli O157, wherever and whenever it came from, will be with us for the duration. The question is, can we use prevention to keep it to a level that was shown in the wild deer (0.25%), or are we going to try to medicate it out of the system?

It would be wonderful if mass food supply problems had simple management answers - not that conversions of half our cattle back to pasture from feedlots would be easy. There are serious problems with our food supply, and we need aggressive journalists to be informing the public about agribusiness practices that should be changed in order to avoid major public health consequences - the recent melamine pet food scandal is a prime example of where both regulation and enforcement are severely lacking.

We need Michael Pollan and others like him to be watching out for us. But they must make absolutely sure that their credibility remains intact, because we need to know that they are more trustworthy sources than government and corporate spokesmen with obvious agendas. We need someone to be telling us the truth. So either the journalists must improve their scientific literacy enough to do the appropriate research for their story, or they must hire someone who has it already.

(Mr. Pollan, if you are hiring, I am available for freelance work.)


References:

Diez-Gonzalez F, Callaway TR, Kizoulis MG, Russell JB. (1998) Grain feeding and the dissemination of acidresistant Escherichia coli from cattle. Science, 281, 1666–8.

Fluckey, W.M., Loneragan, G.H., Warner, R. & Brashears, M.M. (2007) Antimicrobial drug resistance of Salmonella and Escherichia coli isolates from cattle feces, hides, and carcasses. Journal of Food Protection, 70, 551-556.

Gannon, V.P.J., Graham, T.A., King, R., Michele, P., Read, S., Ziebell, K. & Johnson, R.P. (2002) Escherichia coli O157: H7 infection in cows and calves in a beef cattle herd in Alberta, Canada. Epidemiology and Infection, 129, 163-172.

Kudva, I.T., Hunt, C.W., Williams, C.J., Nance, U.M. & Hovde, C.J. (1997) Evaluation of dietary influences on Escherichia coli O157:H7 shedding by sheep. Applied and Environmental Microbiology, 63, 3878-3886.

Renter, D.G., Sargeant, J.M. & Hungerford, L.L. (2004) Distribution of Escherichia coli O157: H7 within and among cattle operations in pasture-based agricultural areas. American Journal of Veterinary Research, 65, 1367-1376.

Renter, D.G., Sargeant, J.M., Oberst, R.D. & Samadpour, M. (2003) Diversity, frequency, and persistence of Escherichia coli O157 strains from range cattle environments. Applied and Environmental Microbiology, 69, 542-547.

Labels: ecology, environmental toxins, health

Arbor Day, April 27, is nearly upon us. Many of us are receiving solicitations in the mail about ordering trees through the National Arbor Day Foundation. But you should think carefully about what trees to order.

The Arbor Day Foundation remains behind the times when promoting tree-planting, because they barely mention problems with invasive trees on their site, and in none of the junk mail literature I have received. Although an entire page is devoted to invasive species that harm trees, the only reference to invasive trees is buried its FAQ:

10. Are the trees offered by the Foundation invasive?
The Foundation follows the guidelines of the National Invasive Species Information Center. Plants found to be invasive or problematic by this agency are removed from the lists of trees and shrubs offered by the Foundation. In addition, we take into consideration recommendations found in the publication entitled, Invasive Plants, Changing the Landscape of America, by the Federal Interagency Committee for the Management of Noxious and Exotic Weeds.

Naturally I'm not complaining about their policy, it shows they are at least paying some attention to the problem of invasives. What I object to is that the NADF, throughout the web site, promotes and sells trees purely by horticultural zone, as does every gardening catalog. The gardening catalogs, though, are about business, and up to this point, businesses spreading species around have not been held accountable for invasive outbreaks, so in their case this policy is understandable.

However, the NADF promotes itself as an organization that cares about ecology and the environment. Aside from fortunately not selling nasty invasive trees such as Russian olive and saltcedar, they do absolutely nothing to promote the idea that we should be cultivating local species, which is by now a standard ecological concept. Even if your exurbian front yard is hardly definable as a natural habitat, NADF should be attempting to instill in you the idea that what makes ecology important, and sustainability possible, is the recognition that certain species of trees belong in certain areas because they are used to interacting with the other species found in that area. Such a visible organization could be making great strides in promoting local habitat ecology, but they are making absolutely no effort to do so.

What difference does it make, if none of the trees they sell will become invasive? First of all, every time we move a species, or even an individual, around to where it doesn't belong, we are conducting an biological experiment. Maybe there are no problems 9,999 times out of 10,000; but the more often we do this, the more often number 10,000 comes up.

In addition, the homogenization of the planet comes with several costs. One cost is giving up the buffer that having millions of species across hundreds of ecosystem provides