Ant Farmers Use Pesticide

Leaf-cutter ants- Wikipedia

Ants beat us to the discovery of pesticide use by millions of years.  A report in Livescience.com describes the association of leaf-cutter ants and the fungus crop they raise with the help of bacteria.
 
There are at least 230 species which farm fungus on leaves to eat as a primary food source.  Another fungus, called Escovopsis attacks and parasitizes the ant's fungal crop.  The ants have learned to "weed" the leaves by lapping up the spores of the invaders.

Previous studies have shown that the ants carry bacteria on their bodies.  These have been identified as Pseudonocardia, related to bacteria that have led to the discovery of antibiotic agents in the past.  What is new is a report in the Proceedings of the Royal Society which has shown that leaf cutter ants carried predominately two specific strains.

"The researchers also tested how effective different Pseudonocardia strains were in suppressing fungal growth, particularly that of the ants' nemesis Escovopsis. Here, they found that the parasite was more susceptible to the antibiotics produced by Pseudonocardia than were other fungi. They also noticed that strains of Pseudonocardia found dwelling on ants were more effective against the parasite than free-living strains." 

When ant queens take flight to set up a new colony, they carry the fungus with them, ready to start a new farming operation like we carry seeds of familiar crops.  Also like us, they may carry the parasitic fungus, an early form of an "invasive species".  

An instructive video from Science Nation demonstrates the ants at work.  Research may even lead to the discovery of new antibiotics or how leaves might be converted to biofuel.

Bobcat Melodies

Do you ever hear night time animal cries and wonder what made them?   Birds and mammals can make some scary sounds which are difficult to identify.

We were discussing sightings of bobcats while sitting around a fire at the Missouri Native Plant Society meeting last week.  Suddenly we heard distant haunting night sounds, a cross between a baby's cry and a screech owl.  Most of us guessed it was a bobcat cry.

According to Wikipedia, bobcats (Lynx rufus) are crepuscular, that is they are active in the hours around dawn and dusk.  This is a time that brings out certain species such as deer, rabbits, rodents, skunks, as well as many insects.

"The bobcat is crepuscular. It keeps on the move from three hours before sunset until about midnight, and then again from before dawn until three hours after sunrise. Each night it will move from 2 to 7 miles (3.2 to 11 km) along its habitual route.^[13] This behavior may vary seasonally, as bobcats become more diurnal (active during the day) during fall and winter. This is a response to the activity of their prey, which are more active during the day in colder months.^[12]

Was it a bobcat?  Who knows?  Cats have a wide variety of vocalizations (think Tabby's meow, hissing at the dog, and mating cats under your window at night.)  It turns out that bobcats are also versatile vocalizers.

There is some help on animal sounds available on the Web.  Many sites like junglewalk.com and thryomanes are geared to exotic animals from around the world.  An extensive library of audio and video can be found at macaulaylibrary.org.  I was not successful in finding a single source for North American mammal sounds.  Let me know if you can find a good source. I did find a variety of bobcat vocalizations at http://www.soundboard.com/category/Science-Nature.aspx.  From now on, I will probably think every nocturnal muffled scream is a bobcat until proven otherwise.

You can read this Missouri Conservationist  article on bobcats from the May issue.

Complex Mayflies

Mayfly- Click to enlarge

I have been under the impression that the presence of mayfly larvae in a stream is an indicator of high quality water with good oxygenation.  In some cases that is true, but the whole story is more complex.

There are 15 families of Mayflies found in Missouri,  all lumped in the order Ephemeroptera.  The name reflects their ephemeral existence because of the mouthless adults life span of a few hours to two days.
We tend to think of their presence in streams as an indicator of good oxygenation because some species with fixed gills require flowing water with adequate oxygen content.  It turns out that some other species have developed motile gills to tolerate lentic* (still) water in ponds and lakes as well as low oxygen conditions.

The larvae that we look for in macroinvertebrate sampling will molt from 12 to 45 times over two weeks to two years before reaching adulthood.  Even then they are not done, as the last molt before adulthood is quite different from a human teenager.  It comes out as a "dun", a dull colored, sexually immature winged creature which then molts into the adult capable of mating.  No other insect has this intermediate form.

Swarm hatch on truck

Although many mayflies deposit their eggs in masses by dipping their ovipositor in the water as they fly, others drop them singly or from the air over water.  When the eggs hit the water they begin to develop immediately.  A female may drop as many at 500-3000 or more.  If they drop them all at one time, there may be a swarm hatch all at once, sometimes dramatic in number.

Mayfly nymphs usually live on detritus or algae which they scrape off the stream bottom.  For this reason, well oxygenated streams with clean silt free bottoms are especially important as the nymphs fulfill a reluctant role near the bottom of the food chain. While some have evolved to withstand low oxygen and stagnant waters, the presence of lots of nymphs in lotic* (moving) water is usually an indicator of good quality water.  Trout fishermen (the top of the food chain?) also use Mayflies' presence to help them choose which fly to tie on.  You gotta love them.


The Missouri Stream Team newsletter has all this information and a lot more.  Just go to their
facts site  and download #14.

*Words for the day:
Lentic ecosystems are still waters such as marshes, ponds, and lakes. 
Lotic ecosystems have flowing water such as springs, creeks and rivers.
Now don't you feel better?

Ain't Nothing Shaking

National Institute of Biology, Slovenia

We think of insects communicating with clicks and chirps, but shaking?  A story in livescience.com* explains the mechanics of stinkbug communication, and it ain't stink.  It turns out that stinkbugs and burrower bug's leafy habitat isn't just for eating and shelter.

Researchers used lasers to detect the vibrations on leaves created by 21 different species of bugs they studied.  The vibrations are very low frequency but would be audible to us if they were louder.  The principal is similar to a tin can telephone, very rudimentary, but pretty sophisticated for a bug only one-half inch long.

"The insects displayed a wide array of vibration-producing methods, from fluttering their abdomens to shaking their entire bodies to tapping their front legs on the plant surface. Different species had different vibration patterns, limiting cross talk. Male and females of the same species also had distinct calls. For example, the researchers reported, female southern green stinkbugs call out with relatively long vibrations spaced far apart, while males call out with short bursts of vibration spaced closer together."

Different species produced a variety of frequencies, patterns and durations of calls.  Some shook their whole bodies, other just tapped their front legs on the leaf.  However they did it, it turned on another bug.  Just think, the old rock song "Ain't Nothing Shaking but the Leaves in the Trees," might have been a love song among stink bugs.

* Reported November 18, 2010 in Cancun, Mexico, at the second Pan-American/Iberian Meeting on Acoustics by researchers from the National Institute of Biology in Slovenia.

This from Bob Ranney

 On January 22, the MO League of Conservation Voters will hold an open conference on conservation related legislative issues to be faced in Missouri over the next year.  The meeting will be on the MU campus in Columbia.  Participants will have access to a wide range of presentations, but also must select a breakout session they want to attend.  The subjects include:

• Citizen Advocacy
• Climate Change
• Energy and Green Building
• The Green Economy/Jobs
• Public Land Use
• Solid Waste Reduction
• Sustainable Agriculture
• Transportation and Land Use
• Water/Floodplain development

This should be a very informative conference that will bring us up to date on issues of concern to all conservation oriented Missourians.  Because the emphasis here is on legislative action, we can’t go as representatives of our chapter, but it would be great if a group of us could go together.

For more information go to this web site.

To sign up for carpool, call Bob Ranney at 417-379-1757 or email rjranney@sbcglobal.net

American Burying Beetle

from Wikimedia

I just finished reading an article* by the Director of the Center for American Burying Beetle Conservation (CABBC).  In the words of Dave Barry, "I am not making this up."  Behind this long name lies a interesting story.

The American Burying Beetle (Nicophorus americanus) is an endangered species initially found in 35 states but now only occasionally is found in seven.  In addition to its colorful body, its colorful habits are worth exploring.

The beetles are drawn to the smell of decomposing flesh from as far away as two miles!  Once there, they mate (gets a little strange, doesn't it?) and then go about burying the carcass.  The may lay on their back together and use their 12 little legs to move the body to the right spot.  Once there, they strip off any fur and feathers, converting it into a little meatball which they cover with antibacterial secretions.

They live underground most of the time as their kids are growing up.  They can call their cute little white larva to supper with squeaking sounds they make with their wings.  They actually feed the little ones when they are young by regurgitating partially eaten rotten meat into their mouths.  Apparently their young don't like brocolli either.

Like other burying beetles, americanus carries mites on its body.  Somewhat disgusting to look at under magnification, they serve a purpose.  The mites eat fly maggots that are voracious competition for the dead meat so they are apparently welcomed passengers.  As my mother would say, "Each to his own taste said the woman as she kissed her cow."

The CABBC is located at the St. Louis Zoo.  There they raise the beetles in captivity and are considering reintroducing the beetle into the wild.  As you can see from the map, we are close to the known range for the americanus which is still found in Arkansas and Oklahoma.  Keep your eyes open and maybe you can put Missouri on the map.

* From Missouri Update, a publication of the Nature Conservancy.  To read the story, Go to http://www.nature.org/wherewework/northamerica/states/missouri/, then click on the bison photo that’s labeled "Read the 2010 Missouri Update" to download the pdf file.  The Nature's Undertaker article is on Page 14.  While you are at it, Page 1-5 has a good story on Bison.

Stream Nutrients

Determining the health of a stream is complex, especially when you factor in the factors of location, soil, and especially the impact of human activity on the watershed.  Any attempt to develop a standard scale is all the more difficult.
Take for example the nutrient levels of  total nitrogen (TN) and total phosphorus (TP).  In the words of the Missouri Department of Natural Resources on the DNR Website:

"Too much nutrient loading to a water body can cause rapid growth of algal blooms, organic enrichment and depletion of dissolved oxygen. Too little may result in insufficient enrichment of the aquatic food chain, which would be detrimental to a healthy aquatic biological community."

It is complicated further by the varying geology and human density around the state, making it difficult to set a standard for the state.  A heavily karst region like the Ozarks will have smaller nutrient levels that a muddy Northern Missouri stream.  The answer to which is better?  "It depends."
One thing we know is that our Stream Team monitoring is an important tool in the assessment of the stream health.

"An assessment of algal, macroinvertebrate, and fish communities in streams with low-level nutrients found that algal communities correlated well with increasing nutrient levels. Using algal community data to investigate nutrient conditions have been shown to be a successful method in many water-quality monitoring programs."

Unfortunately, there are tremendous scientific and political opinions on what Numeric Nutrient criteria should be.  I suspect that any criteria put out, like many other solid numeric criteria such as the econimic numbers we read daily, will be the "best guess" available at the time, interpreted by the organization with the "Final Word.'
This isn't meant as criticism, just an observation that with complex data, sometimes you just have to take a position to believe in and adjust it later.  In the words of a famous philosopher:

"Everybody should believe in something. I believe I'll have another drink."
                              — W.C. Fields

David Casaletto* wrote the story in the Ozarks Water Watch newsletter quoted above that has a lot of good information on the subject.  This is a great resource for other local water issues and is available by email simply by signing up at http://www.uwrb.org/

* David Casaletto is the President and executive director of Ozarks water Watch and Acting executive director of Table Rock Lake Water Quality.