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Wasps Versus Drug Smugglers
According to Discover Magazine, the
antennae of common wasps are as sensitive to smell as the nose of
drug-sniffing dogs used by the United States Drug Enforcement Agency
(DEA). Scientists at the University of Georgia at Tifton have
invented a gadget that takes advantage of the wasps ability to sniff
out odors such as those emitted by corpses, drugs, bombs or toxins.
It's called The Wasp Hound: a canister the size of an ordinary soda
can, containing insects trained via classical conditioning to
associate a certain odor with food (a simple sugar syrup).
When the wasps in the Wasp Hound canister detect the chemical odor
they are trained for, they cluster around the source. A minicam
inside detects the wasps' movements and transmits the results to a
laptop computer.
The scientists point out the advantages of
insect sniffers over our canine pals: The wasps are small and
portable, and the training only takes 5 - 10 minutes. They don't eat
much, and nobody gets attached to the darned things. They die after
48 hours, but they just insert a new batch and the device is again
ready for action. They claim the wasps can be trained to recognize
most chemicals.
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Wasps that construct nests made of a papery material are
commonly called paper wasps. The nests consist of a single upside-down
layer of brood cells. There are 22 species of paper wasps in North
America and about 700 species world-wide. Most are resident in the
tropics of the western hemisphere. The two most common paper wasps in
the American midwest are Polistes dominulus, an introduced species, and
Polistes fuscatus, the native "golden paper wasp." It is my opinion,
after 5 years of careful field work and observance, that dominulus is
replacing fuscatus, at least in the environs of DuPage County, Illinois.
Most paper wasps measure about 2 cm (0.75 in) long and are black, brown,
or reddish in color with yellow markings. Paper wasps will defend their
nest if attacked. Adults forage for nectar, their source of energy, and
for caterpillars to feed the larvae (young). They are natural enemies of
many garden insect pests.
The nests of most species are suspended from a single, central stalk, or
pedicle, and have the shape of an upside-down umbrella. Some tropical
species make nests that hang in a vertical sheet of cells. Plant and
wood fibers are collected by the wasps, mixed with saliva, and chewed
into a paper-like material that is formed into the thin cells of the
nest. The nests are constructed in protected places, such as under the
eaves of buildings or in dense vegetation. The nest pictured here was
constructed under the iron railing of a bridge over the DuPage River
West Branch. Normally a colony of several to several dozen paper wasps
inhabit the nest.
The colony is founded in early spring, soon after the queens emerge from
hibernation. As the colony matures, males and the next year's queens are
produced. These queens mate with males and are the only members of the
colony to survive through winter. In late summer or fall, the founding
queen, workers (sterile females), and males all die. The newly mated
queens hibernate, in piles of wood, in vegetation, or in holes. The
following spring they emerge and begin the cycle anew. A similar life
cycle is found in bumble bees.
In most temperate species of paper wasps, colonies are founded by one
female who dominates the colony and lays most of the eggs. This female
constructs the nest, lays eggs, forages, and raises the first generation
of offspring. She then stops foraging, becomes the queen, and rules by
dominating her offspring of workers. This is a classic dominance
hierarchy with the queen maintaining control through aggressive
interactions. Each individual in line maintains dominance over all
others below her through confrontation and aggressive interactions. If
the queen dies or is otherwise lost, the most aggressive worker takes
over. This worker begins laying eggs and continues to dominate all below
her. Since the workers have not mated, they can only lay unfertilized
eggs, which develop into males, a typical trait in wasps.
Some queens that are unsuccessful at establishing their own nest may
join another queen, submitting to her dominance and becoming a worker.
Studies have shown that such individuals, called joiners, are most often
sisters of the queen. Since this individual mated the previous fall, her
eggs can develop into workers and she could become the next queen if the
founding queen is lost. Occasionally a joiner dominates the founding
queen and takes over the nest, a behavior known as usurpation. In such
rare cases, the usurper becomes the queen and the previous queen becomes
a worker. |
