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May 2007

The Rapture of the Bees?

In yesterday's Science Times, the Tuesday Science section of the New York Times, I found an article (Bees Vanish; Scientists Race for Reasons, bu Alexie Barrionnuevo) on the mystery of our disappearing bees. It's a progress report on the study of bees, trying to figure out why 25% of U.S bees have disappeared, as in, never returned to their hives.

My favorite line is the one which say that among the rather fanciful theories held by members of the public is that it is due to "the rapture of the bees, in which God recalled them to heaven." (Persons allergic to bees, take note, they may be there too!)

In any case, the scientists studying the problem are focusing on the three prospects they think are most likely: a virus, a fungus, or a pesticide. They have been collecting dead bees and carrying out autopsies and genetic analysis.

Here are some of their findings, as reported in the article:

--bees in declining hives have many abnormal microorganisms, as if they had weakened immune systems

--they don't seem to have any more of known hive enemies, such as the varroa mite.

--known symptoms of poisoning from feeding on Bt corn (a genetically modified crop), such as blood poisoning, haven't shown up.

--gamma ray irradiation of empty bee boxes seemed to be safe for new bee colonies (implying maybe a pathogen that the radiation killed?)

The research that continues includes more bee autopsies, to search for known pathogens; study of genes, to see if there are active genes reacting to a toxin or pathogen (they had already sequenced the genes of bees, just finishing last year); and screening for 117 chemicals.

Among chemicals, a prime suspect is one called imidacloprid, sold as Gaucho, which is a neonicotinoid. I assume this means it is a synthetic compound based on nicotine, which is one of the most poisonous of natural plant extracts. Imidacloprid was banned in France in 1999, accused of harming their bees. However, French bees haven't recovered as fully as expected, so perhaps this wasn't the cause, or at least not the only cause.

So we wait and see. I spent the afternoon watching bumblebees work a patch of phacelia, contemplating our dependence on honey bees for so much of what we eat.

Moth Pheromone Lures

I just read the comment seeking information on moth pheromone lures to control light brown apple moths in home orchards (see previous post, with comment). I haven't checked to see if the right lures are available in California, though Peaceful Valley would be a good place to look. However, it has been my understanding that these lures work best in a larger planting. In just a few trees, the lures will confuse a few male moths, leaving nearby females unfertilized, but females ready to lay eggs are likely to just fly in from the next yard. In larger orchards, they even recommend putting the lures not only throughout the orchard, but also outside the margins of the orchard all around, so that nearby moths won't be fertilized.

The CDFA is using traps to monitor for the moths, I think that have some pheromone in them and catch the moths on a sticky surface. This is a good idea of you want to know if they are around, and IF you can identify what you have caught. In Australia, grape growers use a homemade trap to catch insects and see what they have. They use (cheap) port wine, in a 10% solution, in a container that is about 6 inches wide and 8 inches deep. They put a wire mesh with half-inch holes in it over the container to keep the birds out. Then they inspect it at least twice a week, so that freshly caught moths may still be floating, so easier to count and identify. Again, both of these kinds of traps are for monitoring, rather than control, but we are in the monitoring phase right now, for the most part. And both traps depend on your being able to recognize the insect--or take it to a County Agricultural Commissioner who can.

What you are more likely to see than adults is the yellow green caterpillar with a brown head, and some webbing around young leaves, and maybe involving the young fruits. They say the caterpillars are more common low on the tree, which is good, since that is where you are most likely to be looking. If think you see one, you can bag or bottle it up, with some of the plant, and consult your local ag commissioner.

As I say, very few of these moths are being spotted so far, so noticing them is probably more important than combating them. You are far likelier to have damage from ordinary pests, such as codling moth, than this still quite rare moth.

If you want to do something to decrease the likelihood of damage to backyard trees, thin your fruit properly, since the critter is more damaging when it is able to web several fruits together, and pick up fallen fruit.

Moth Invaders?

I've spent the past few days researching the light brown apple moth, an insect that has recently appeared in the Bay Area. It is native to Southeast Australia, and has escaped to New Zealand, Great Britain, Ireland, and Hawaii. Now a number of them have been found here in California. There is a map on the California Department of Food and Agriculture site showing where they have been found. It's at:

The Chronicle had an article about the pest in the Business Section on Thursday, April 5th, and will be running more stories in the Home Section. I have written an article for the Chronicle about the biology of the pest; Ron Sullivan and Joel Eaton will be reporting on the steps being taken to contain it. Look for at least one of these stories on Saturday, April 14th--and part of the matter might be carried forward to Wednesday, April 18th.

It is a tiny moth, with a small caterpillar that is mostly a leafroller. That is, it rolls itself up in the leaf to feed. One important fact to know abot it is that it eats over 200 kinds of plants, so once we had it, it would be almost impossible to get rid of.  Another is that it damages grapes, including the fruits, when it gets them tied up in its webbing early in the season. Another is that some of California's trading partners would demand special treatment of crops for export, and others might refuse to trade with California. You can see why the California Department of Food and Agriculture wants to keep it out of the state's agricultural areas, or, preferably send it packing out of the state.

Watch for quarantine information. It is important not to carry the pest accidentally into uninfested areas. It can live on a number of garden flowers and vegetables, so expect some upcoming crimps in your usual gardener's generosity. You know, the "Here, take a bouquet home with you. And would you like some Swiss chard."

Stay tuned to learn more about this invading pest.