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

Check it out at The Radula.

Labels: biodiversity, carnivals, ecology, environment, humans

The 22nd edition of the Circus of the Spineless is now online at Burning Silo. Check it out for some beautiful photos and accounts of our invertebrate friends.

Labels: biodiversity, carnivals, 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

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

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 against our own foolhardy exploitation of resources. The honeybee "crisis" everyone is clamoring about now is a perfect example of this. Bring an alien species to a large region to replace hundreds of native species that could do the job, albeit less efficiently from a human perspective, and one disease, one environmental problem, and you are in trouble.

Another cost is to our own human sense of place. When distinctive plants and animals disappear from places - a good example here is of pacific islands, whose endemic plants and animals have been decimated, and replaced with a few ubiquitous species now found on nearly all the islands - we lose some of the wonder we have for the natural world. In fact, each successive generation has less appreciation its own corner of the planet, because fewer species remain to distinguish it from anywhere else on earth.

Perhaps these issues are just too abstract for an organization that wants to promote one simple idea, that "trees are good" - not even always true, in an ecosystem that was historically treeless, another distinction NADF fails to make in its black-and-white view of ecology. Perhaps there's no point in anything but pooh-poohing those of us who wish for a different ethic - many of these have been cultivated for generations, and some are human-created hybrids, so really what difference does it make where we plant them? I argue only that these are minor points in the greater struggle to convince humanity, especially that small portion of humanity that has the time and money to support any sort of environmental ethic that it chooses, that ecology and biodiversity are not actually words that can describe numbers of species over an entire planet. They much more aptly describe the mosaic of species assemblages that found a way to evolve in every possible environment that is found on earth. If we lose that idea, then biodiversity itself is a meaningless concept.

Labels: biodiversity, ecology, invasive species, nature

Almost as a reiteration to my earlier post, here is another article close on the heels of the last, about drying conditions in the West. Climate change is not a vague, unproven myth that wacko lefties perpetuate in order to undermine Big Business. It's here, folks, and because it is being combined with other fast-acting anthropogenic effects (that I previously discussed), ways of life and species assemblages in the West will be radically changing in the next couple of decades.

And, having done ecological research (my dissertation) in high altitude zones of the "sky islands" myself, on species that may cease to exist in the southern half of Arizona within my lifetime, it is not exactly with glee that I draw your attention.

Labels: biodiversity, ecology, environment, evolution, invasive species

I thought about doing a post on all the wasp mimics out there, but within the flies (Diptera) there are plenty, and it clearly evolved multiple times - in most cases, not all the species within the following family are mimics. Obviously it would be some benefit for any insect to be thought a wasp by a vertebrate predator. Flies cannot sting for defense, so some of them just look a lot like wasps so predators will think they can sting. The ways in which they mimic wasps are fascinating.

The following families include wasp mimics: Micropezidae, Conopidae, Mydidae and Syrphidae. I'm surely missing some - don't be shy about pointing it out, all you Dipterists out there.

There is a whole family of bee mimics as well, the Bombylidae (the bumblebee genus is Bombus). They are big fuzzy things (below right), but if you look closely, you will see only two wings, which gives away their lineage - all bees and wasps (and all orders of insects except for the flies) have four wings.

But I'm more interested in the wasp mimics here. I'll start with my favorite, a Micropezid I caught in Costa Rica, at the La Selva research station. These are fantastic mimics, and a still photo just doesn't do them justice because their behavior is an important part of the package. You can see the fly has a pointy abdomen, which helps, and when grabbed, it pokes its abdomen into the grabber's skin repeatedly as if to sting. (Kinda cute, since it's completely harmless.) The other important combination of morphology and behavior has to do with the long forelegs, which end in white tips (which you should be able to see in the photo, along the edge of my thumbnail). In the tropics especially, the long antennae of stinging wasps have white or yellow tips. Flies, as a group, have very small antennae, but this family of flies has long legs. It was a quicker evolutionary step for the mimic species to use its forelegs to mimic antennae, than to develop long antennae itself. So you will see this fly walking rapidly along leaves in the manner of wasps, tapping its forelegs in front of it just as wasps use their antennae. It's really amazing to watch. (Although this fly family is more ubiquitous in the tropics, there are North American species and I have seen them in central Virginia.)

Conopids have a generally different look, mimicking thread-waisted wasps (Sphecidae) rather specifically. A common wasp-mimic morphology is to have a somewhat constricted abdomen, because a distinguishing character of the Hymenoptera (ants, bees, wasps) is a distinct constriction in the first few abdomenal segments, which means that hymenopterans are more or less restricted to liquefied foods, but also allows flexible reach for the abdomen when stinging prey or for defense. The conopids combine this with the elongated abdomen characteristic of sphecid (digger) wasps. I'm not aware of any specific behaviors that help promote their ruse.

Some Mydidae (mydas flies) apparently go for the pompilid (spider wasp) look. According to the source for this photo of Mydas clavatus, Tom Murray, it is mimicking spider wasps in a particular genus, Anoplius. Pompilids have a quite characteristic look of a black body and darkly pigmented wings. The photo on the right is Anoplius.

The syrphids (hoverflies) are not so precise in their mimicry. Here are two, with one clearly mimicking a bumble bee, and the other just looking generally wasp-like with its black and yellow markings. Their behavior does not necessarily contribute to the show; as their common name suggests, syrphids spend a lot of time hovering, which is generally unwasplike.








Thus mimicry takes many forms. It is interesting that some mimics seem to be modeling specific insects while others just seem to have the general look of wasps or bees. Does the selection pressure differ for these mimics, and why? Perhaps the generalist mimics live where there are a big enough variety of stinging Hymenoptera that they don't need to get specific. Why do some converge on specific families? Is there a dominant model present in those habitats? I'll admit up front that I have not done a literature search, so I don't know what is known specifically about the evolution of mimicry in these groups. I just like them because they are so cool.

The only picture of mine above is the worst one by far, of the micropezid. The syrphids and Anoplius come from Forestry Images, a wonderful image database, and the rest are by Tom Murray, and used with his permission. See many wonderful fly images of his here.

Labels: bees, biodiversity, cool bugs, ecology, evolution, flies, insects, wasps

The western U.S. has been under "drought" conditions on and off for the last ten years or so. Why is "drought" in quotes? Because drought is a relative condition, referring to less rain than normal - a level of rain considered drought in the Alaka`i Swamp would cause major flooding in Tucson.

So what is really going on in the West? The quick answer is that we probably don't have enough data really to know. Ten years of dry conditions is a blink in the long term. The ultimate question is if the current drier trend is something that will continue in the long term, or is really just a blip, and the truth is that no one can know for sure.

But what we can know about is the long term climate of the past. A panel of scientists analyzing conditions in the southwest noted the following (from a NY Times article [sub. req'd]):

...the water allocation agreement for the basin, the Colorado River Compact, was negotiated in 1922 based on river flow records dating to the 1890s, when gauging stations were established. The agreement assumed that the annual river flow was 16.4 million acre feet -- enough to cover 16.4 million acres to a depth of one foot.

But for some time, the panel said, researchers have known that the early 20th century was unusually wet and that 15 million acre feet was a more accurate estimate of the flow. Recent studies based on tree rings put the figure lower still -- as low as 13 million acre feet -- and suggest that "drought episodes are a recurrent and integral feature of the region's climate."

The harsh reality is apparently that over the last couple of centuries at least, the typical amount of water in the west jibes pretty closely with conditions we are seeing more recently, and the period when the west became heavily settled coincides with an unusual wet spell, combined with technology (dams, etc.) that allowed people to use more of the water that is there.

The long term implications for this trend are far-reaching. Biologically, the landscape of the west has been irreparably altered by the introduction of dams and cattle. Both of these in turn have facilitated establishment by lots of invasive weeds that are massively altering the landscape further. Two examples: Salt cedar and Russian olive have taken over many riparian areas in the southwest, and are spreading north (probably helped by human-enhanced climate change). Salt cedar not only crowds out native plants and lowers the water table, but its excretion of salt changes the chemistry of the soil, making restoration of these areas especially difficult. Native riparian trees such as willows can compete with salt cedar under the natural cycle of floods, but thousands of dams (built to provide water and power to an increasingly unsustainable western human population) have disrupted this cycle, under which conditions salt cedar easily takes over, disrupting the entire ecology of the system, because so many animals, vertebrate and invertebrate, depend on the native willows.

Cheatgrass is an invasive grass that produces intense fires that occur much more often than the normal fire cycle to which the animals and plants of the Great Basin are adapted. Neither are cows, so in addition to drought itself, cheatgrass has gotten a lot of attention because it impacts "traditional" ranching in the area.

But the effects of the West suddenly finding itself quite overpopulated given the amount of water we can expect in the near future reach into the sociological as well. As one example of many, our local Women's Resource Center, which provides support primarily to victims of domestic violence, has to gear itself up every summer for a big run on its services; the drier the summer, the more domestic abuse, presumably because of family stress about financial problems.

The bottom line is that at the very least, the level and methods of ranching and agriculture that people have become accustomed to over the last few generations in areas defined as desert, based on their low rainfall, is no longer sustainable. There are different ways of ranching cattle that can significantly reduce problems associated with overgrazing, but people are slow to change. If we are not actually experiencing a "drought," but rather emerging from a wet period, dark times are ahead for rural western economies, because the cities will be grabbing the resources to sustain millions of people living in the desert. Forget about the cows...which if you are an ecologist such as myself, would be a silver lining in all of this, if the native ecosystems that are left weren't going to disappear along with them.

Labels: biodiversity, ecology, environment, invasive species

What do you think this sound is? Continue reading for the answer...

Since it's been two weeks since my last "cool bug" post, I thought I had better change the name of the series... we'll see where it goes from here.

Today's subject is a fruit fly, Rhagoletis juglandis. This is not related to the fruit fly of genetics fame, Drosophila melanogaster, which is in a different family. Nearly all drosophilids only eat fruit once it is rotting; flies in the family Tephritidae, including the genus Rhagoletis, feed on ripe fruit and thus are known to entomologists as the "true" fruit flies.



I will admit up front that these flies are mainly of interest to me as larvae (at the left), because they serve as hosts for one of my favorite parasitic wasps, Diachasmimorpha juglandis, below. R. juglandis larvae feed on and live in the fruit of the Arizona walnut (Julglans major) (i.e., the husk surrounding the actual nut), and D. juglandis females parasitize them through the walnut fruit skin.


The fly larvae live in groups in the walnut husk, sometimes by the dozens. All the larvae in a fruit may or may not have the same parents, if there have been multiple ovipositions in the fruit.




In the picture to the right is a mating pair of R. juglandis adults on a plastic walnut model. Males and females mate multiply, with several individuals if given the opportunity.





There are territorial contests by the males on the ripe walnuts while they are still hanging in the tree. This behavior is known as "boxing." The males stand on their hind legs and bat their forelegs and wings together. (In the picture to the left, the wings are only a blur.) The idea is that the winners of these contests have access to more females, who will come to the walnut to mate and lay eggs. Some poor females are forced to mate as they extrude their ovipositors to dig a hole in the husk in which to lay eggs; the males will grab them from behind and mate with them before they have a chance to oviposit. Sometimes, though, males are so intent on fighting with each other that they don't seem to notice a third male that is mating with the female on the fruit while they are going after each other.


While males are duking it out, mated females also get the opportunity to finally oviposit without harassment (left). A female drills a hole in the husk with the tip of her ovipositor (which eventually shows signs of wear) and deposits several eggs in a cavity just beneath the surface of the husk. These grow and feed inside the husk until they are ready to pupate, when they exit the fruit and burrow into the soil. Sometimes there are so many larvae within the husk of a walnut that their feeding is audible. Click here to listen to the sounds of feeding fly larvae in a walnut.

Unfortunately for the larvae, the racket they make chowing down on the walnut is their undoing... as will be revealed in the next Cool Bug of the Fortnight!

Here are references for more information on Rhagoletis juglandis:

Papaj, D.R., 1994. OVIPOSITION SITE GUARDING BY MALE WALNUT FLIES AND ITS POSSIBLE CONSEQUENCES FOR MATING SUCCESS. BEHAVIORAL ECOLOGY AND SOCIOBIOLOGY 34 (3): 187-195.

Henneman, M.L. and Papaj, D.R., 1999. Role of host fruit color in the behavior of Rhagoletis juglandis (Diptera: Tephritidae). Entomologia Experimentalis et Applicata 93:247-256.

Nufio CR, Papaj DR, Alonso-Pimentel H, 2000. Host utilization by the walnut fly, Rhagoletis juglandis (Diptera : Tephritidae). ENVIRONMENTAL ENTOMOLOGY 29 (5): 994-1001.

Labels: biodiversity, cool bugs, ecology, evolution, flies, insects

I decided a good weekly column would be a post about one of the cool insects I have known during my career.

My first featured bug will be a species of honeypot ant from the southwestern deserts, Myrmecocystus mexicanus.

This is a fun species to mess with because they are the most nocturnal ants I've ever seen. Some other species are nocturnal, but you sometimes see them during the day; others you find at night but they can be easily observed with a flashlight. M. mexicanus, however, is completely anti-phototaxic - the second a light is shone on workers, they run away from it. This provides a cool effect when you go out at night an locate a nest, which is very distinctive. When you shine a flashlight on the nest, you see a lot of ants hanging around on the surface that immediately go down the hole, as if they were being slowly sucked. Turn off the light a minute, then turn it back on, and you can repeat the process. Kinda mean to do over and over, I guess, but this is serious minutes of entertainment.

I got to know these ants while working as a field assistant on a grad student's project. The grad and I mused that it would be great fun to design different types of ant furniture, including an M. mexicanus lamp. The colony could be contained in a hollow lamp, which they could crawl around on but not off (there are handy materials for keeping ants contained). When you turned on the light at night, they would all quietly slip back into the lamp, which would then be ant-free in a couple seconds. Hmm, maybe not a huge money-maker, but it could definitely be marketed to entomologists...

The cool thing about honeypot ants in general (i.e., several species in the genus Myrmecocystus) is that they use some workers, called replete workers, as storage vessels. This is a great way to get through the dry season in a desert. They in turn become famine food for larger animals, including humans - the abdomens are quite sweet and tasty. Some people with captive colonies feed the ants specific foods to get a good flavor in the replete workers. Molasses is supposed to be a good one.

There are several more pictures of the M. mexicanus here.

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

A post at the invasive species weblog sums up a lot of the important issues surrounding invasives. One of my favorites for class discussion in my invasive species course is number 8: What is the definition of natural? Seems easy to define on the surface, but murky waters lie beneath. And the answer to this question is so incredibly important to how we regulate, control, and even think about species assemblages.

Difficult questions: Is everything humans do unnatural? Are only some things humans do unnatural? Why? There are some purists who fiercely contend that because humans evolved on this earth as every other species did, whatever we do is an extension of natural processes. The problem is that the logical conclusion of this particular natural process is the extinction of the majority of species on this planet. Of course for us ecologists, this is a painful idea, because we have built careers on our fascination with the diversity and complexity of life. Perhaps for most laypeople that appreciation just isn't there, and so I'm simply biased. One analogy I like to imagine is that of the linguists out there witnessing the extinction of hundreds (thousands?) of the world's languages as different cultures are wiped out or assimilated. Like species, they cannot be brought back. But for me the idea of lost languages is not emotionally charged as is the idea of lost species.

So I have to justify my belief that the movement of species around the globe by humans is an unnatural process, because it results in the loss of biodiversity. But I continue to struggle with the philosophical question of whether biodiversity has inherent value, or only a value imposed by humans (in the sense that gold and diamonds have value). Because I am human, I cannot answer this question completely. Biodiversity does have value to me, because life itself is awe-inspiring. Habitat diversity, an extension of biodiversity, is similarly important - i.e., India looks different from South Africa which looks different from Antarctica. This is partly what gives us our "sense of place" as so eloquently presented by Jeff Lockwood at the University of Wyoming. Many of us are disheartened by the strips of chain stores that characterize so many American cities now. (I literally have trouble remembering what state I'm in sometimes when cruising down such a strip.) The rapid, constant movement of species around the globe is resulting in the same phenomenon on the level of habitat. Look at the plants on most tropical islands these days, and they pretty much look the same, unless you find a really remote spot.

Such is the value of biodiversity to me. That's pretty much why I fervently believe that nearly all post- (and some pre-) industrial movements of species are unnatural and destructive. Even in the best-case scenario, when native species are not destroyed, when alien species quietly integrate themselves into a habitat with no overt ecological impacts, the habitat still suffers slow death by a thousand cuts.

Unfortunately, as far as policy-makers are concerned, short-term economics trumps all. Which means we pay a lot more down the road for control of invasives than we would now for prevention of species movements. And we only bother paying for the control of those which have a current economic impact. In this country, protection of biodiversity is hardly on the radar. Even in Australia and New Zealand, which have much stricter controls than the U.S., the political force of "free trade" (I'll leave the loaded definition of that term to the economists) is becoming overwhelming, with continual pressure to roll back what regulations there are. Which brings me full circle to a previous post.

Labels: biodiversity, invasive species

It has surprised me that I have not heard about environmentalists complaining about the planned 700-mile fence along the U.S. - Mexico border. As an ecologist, my first reaction was to guess that it would be a disaster for the many endangered species in the Sonoran Desert, and it turns out this assessment is shared by The Center for Biological Diversity, in Tucson.

Many large mammals in the Sonoran Desert need access to large ranges in order to survive. The fragmentation of populations is a detriment to endangered species recovery. In addition, the construction and maintenance of such a wall will obviously result in a lot of habitat destruction in the area.

Labels: biodiversity, environment, nature