Anthropology News, Science News

  Strange things are happening in the lowland tropical forests of
Panama and Costa Rica. A tiny parasitic fly is affecting the social
behavior of a nocturnal bee, helping to determine which individuals
become queens and which become workers.

The finding by
researchers from the University of Washington and the Smithsonian
Tropical Research Institute is the first documented example of a
parasite having a positive affect on the social behavior of its host.
This is accomplished by cleptoparasitism – in this case fly larvae
stealing food from the developing immature bees. The researchers found
that smaller bees that emerge in a nest are dominated by their mothers.
These small bees are more likely to stay and act as helping workers,
while larger bees tend to depart and start new nests as egg-laying
queens. Bees that emerge from cells, or brood chambers, that also house
flies are smaller than their nest mates from fly-free cells. The flies
may encourage worker behavior in some bees.

"We often think of
parasitism in terms of it affecting an animal’s fitness, its survival
or its ability to reproduce," said Sean O’Donnell, a UW associate
professor of psychology and co-author of the paper appearing in the
current issue of the Journal of Insect Behavior.  "Here the parasite is not living inside another animal, but is still stealing resources from the host.

"We
think these fly parasites are not affecting the lifespan of the bees,
and the bees’ mothers benefit by having a helper, or worker, stay
around to protect the nest, increasing survivability."

O’Donnell
and his colleagues studied two closely related tropical social bees,
Megalopta genalis and Megalopta ecuadoria, and a family of very small
parasitic flies called Chloropidae.

The bees are important pollinators of night-blooming plants and the
female bees can nest alone or live in small colonies. A colony is
typically made up of two to four individuals – a queen and her
offspring.

Behavioral observations showed that
non-reproductive foragers and guards are significantly smaller than the
queen bee in a nest, although the relative size of individual bees
varied from nest to nest. Here’s where the flies apparently fit in and
are affecting the bees’ behavior. The bees nest in hollowed twigs and
sticks hanging in the tropical understory and the flies flick their
eggs into the entrance to the bee nests. Some of these eggs randomly
fall into cells, or chambers, prepared by the bees, each to hold a
larva and pollen that the larva eats. The cells are then sealed, so if
a cell does contain fly eggs the young flies are competing with the bee
larva for a limited amount of food.

"There is a natural size
variation in bees and this is based in part on the amount of food
available in the cell," said O’Donnell. "A fly or flies in a cell
reducing the amount of food could be a potentially important factor. It
seems that the more flies in a cell the smaller the bee is. The key
here is relative body size compared to nest mates. The larger
individuals become queens because they are not dominated."

The
researchers were able to culture the bees and flies from individual
cells and counted as many as 15 of the tiny flies in a single cell.
Some cells did not contain flies.

"This study is a
counterintuitive take on parasitic infection. It encourages us to look
for complicated ecological relationships between different species.
Parasitism may encourage sociality in some situations. Here it is
promoting social behavior," O’Donnell said.

Source – University of Washington

The adage that your enemies know your weaknesses best is especially true
in the case of plants and predators that have co-evolved: As the
predators evolve new strategies for attack, plants counter with their
own unique defenses.

Milkweed is the latest example of this response, according to
Cornell research suggesting that plant may be shifting away from
elaborate defenses against specialized caterpillars toward a more
energy-efficient approach. Genetic analysis reveals an evolutionary
trend for milkweed plants away from resisting predators to putting more
effort into repairing themselves faster than caterpillars –
particularly the monarch butterfly caterpillar — can eat them.

"An important question with co-evolution is where does it end?" said
Anurag Agrawal, Cornell associate professor of ecology and evolutionary
biology and lead author of a paper in the current issue of the
Proceedings of the National Academy of Sciences. "One answer is when it
becomes too costly. Some plants seem to have shifted away from
resisting herbivory [plant eating] and have taken that same energy and
used it to repair themselves."

The paper is important because it sheds light on key theories of
co-evolution, claiming that pressure by foraging insects makes plants
diversify as they evolve new defensive strategies and that such
diversification follows trends in one direction or another, said
Agrawal.

Milkweed species have evolved elaborate resistance strategies to
fight off caterpillars that eat their leaves. These include hairs on
their leaves, heart poisons called cardenolides in their tissues and
milky-white toxic latex that pours from the plants’ tubes. A
caterpillar’s bite into a milkweed leaf leads to a flood of latex that
is "like getting a gallon of sticky paint thrown into your face," said
Agrawal.

Some caterpillars, in turn, have adapted by shaving the leaf,
cutting a leaf’s veins in a circle and then eating in the middle where
the latex doesn’t flow. Also, the monarch caterpillar has become immune
to the cardenolides.

Using DNA sequence data to look at relationships between 38 species
of milkweed, Agrawal and colleague Mark Fishbein, a Portland State
University biologist, found evolutionary declines in milkweed’s three
most important resistance traits (hairs, cardenolides and latex) and an
escalation in the plant’s ability to regrow.

Agrawal was surprised, he said, to find that the plant became more
tolerant rather than more diverse in its defenses. The reason, he
speculated, could be because as its predators have become so
specialized, the plant was better off choosing a new defensive tactic
"to tolerate the herbivory damage instead of resisting it." It is
unknown whether such strategies have also evolved in animals trying to
evade parasites.

The findings address questions about plant evolution, biodiversity
and keystone species and may give plant scientists clues about
profitable pest control strategies.

The study was funded by the National Science Foundation.

A CARNIVOROUS slug that sucks worms in “like
spaghetti” and which has never been seen before in Western Europe, has
been discovered in Welsh gardens, biologists revealed yesterday.

The slug, which boasts blade-like teeth, has turned up in a garden in Caerphilly to the amazement of experts.A  similar type of creature – which is completely white and without eyes – is normally found in Turkey and Georgia. The bizarre subterranean beast has since become the first creature to boast a scientific name based on a Welsh word.

A
spokeswoman for the National Museum in Cardiff said the origin of this
particular slug, named Selenochlamys ysbryda by museum experts, is a
mystery as to how it got to Britain.

The slugs came to the attention of the museum after being found by a gardener, who wishes to remain anonymous. The spokeswoman believed the creatures could be more widespread in South Wales. She
added: “Unlike most slugs, the ghost slug is carnivorous and kills
earthworms at night with powerful, blade-like teeth, sucking them in
like spaghetti. “It has no eyes, is completely white, and lives underground, squeezing its flexible body into cracks to get at the worms.”

Ben
Rowson, a biologist at the National Museum in Cardiff, said: “The ghost
slug belongs to an obscure and almost unpronounceable group of slugs –
the Trigonochlamydidae.

“We had to thumb through lots of old
publications in Russian and German to find anything like them – but
then discovered they were something entirely new.”

He added: “They may well eat other slugs too.”

Unlike
others from the group of creatures which are larger, have no eyes and a
different internal anatomy, the scientists realised it was an
undescribed species that had no scientific name. They decided
to name the creature Selenochlamys ysbryda, partly from the Welsh word
ysbryd meaning ghost, a name which appears with the species’
description in June’s edition of the Journal of Conchology. Mr
Rowson added: “Selenochlamys ysbryda seemed appropriate for this
spooky, nocturnal hunter and indicates where it was first found.

“We think this is the first time a Welsh word has been used in an animal’s scientific name.”

Bill
Symondson, an ecologist at Cardiff University, added: “The lack of eyes
and body colour could indicate the species evolved in a cave system. “It
was probably introduced to Britain in plant pots, making it an ‘alien’
species, although we can’t be certain. We’re concerned that it might
become a pest, but we need to find out more about it first.”

John
Humphries, Western Mail gardening columnist, urged garden centres and
gardeners to inspect plants for such creatures, before they escape and
breed in the wider environment. “I’ve never heard of the ghost
slug but I assume it is one of these pests that come into the UK on
container plants and get introduced accidentally.

“There are more and more such pests coming in.

“And
no matter how much we may hate our indigenous slugs and snails that eat
our produce – and there have been an awful lot of them this year – it
is better the devil you know.

“Without earthworms our soil would be rock hard and they do a lot of good for the garden.

“Once here, the pests can cause a lot of damage which can be difficult to stop and they could upset the balance of things.”

To
monitor the ghost slug’s trail, the museum has produced a simple
identification guide available from their website
www.museumwales.ac.uk/

Although the methods used are somewhat questionable the end result speaks for itself.

Recently scientists trained tobacco hornworm caterpillars to
avoid a nail polish-like odor delivered in association with a mild
shock in the lab. After the caterpillar entered the pupal stage and changed into a moth they still avoided the nail-polish odor, this showing that they retained the memory of their youth.

"We concluded that indeed the association does persist and is
accessible to the adults in this artificial scenario," said study
senior author Martha Weiss, a biologist at Georgetown University in
Washington, D.C.
The finding also supports the idea that a piece of the caterpillar brain persists through metamorphosis, she added.

Scientists have long wondered whether memory could survive the dramatic
reorganization of the moth brain during metamorphosis, Weiss noted. "The transition from a caterpillar to a moth or butterfly is really very dramatic," she said.
For example, caterpillars and moths move, eat, and sense the world differently—not to mention appear nothing alike. (see previous post: Bird Poop Bugs)

Caterpillars younger than three weeks old learned to avoid the nail-polish odor but could not recall the information as adults. However caterpillars trained to avoid the nail-polish odor in the final stages before puation retained the lessons.

Larvae trained during the mid stage of caterpillars growth showed that in the final stages before pupation,
they would avoid the odor. However this was not the case when they grew to moth adults.

The research may help explain how adult female moths that can eat a
variety of food choose to lay their eggs on the same type of plant they
fed on as larvae. If the moths retain some memories from their larval stage, as this
research shows, then they could remember what they ate as "kids."

Study author Weiss describes it as an "if it was good enough for me, it’s good enough for my kids" type of selection. 

The eye spots on the wings of butterflies and moths are intended to be conspicuous to predators, not to resemble the eyes of larger animals, a new study found.

With 150 years of believing that Butterflies and Moths have eye spots to intimidate their predators, Martin Stevens, a behavioral ecologist, has found no proof to backup this age old theory. Now Martin is leading a study into what these eye spots truly do. ]

Martin and his team created artificial paper "Moths" with varying eye spot markings and nailed them to woodland trees. With an additional incentive of meal worm being attached to each moth the woodland birds should have a happy hour at the local watering hole, well, tree. Ideally the local blackbirds, house sparrows and other woodland birds would approach and either be discouraged to eat the worm or happily go ahead and pick it right off the moth.

If eye spots worked by mimicking eyes, the paper insects with circular spots would present a threat and be preyed on last. This was not the case, Martin said " Making the spots appear more eye like by moving the center "pupil" of the eye inward didn’t give the
paper moths any advantage."

Large bars and squares placed on the waterproof paper wings of the paper moths provided as much protection as circles and the larger the
marking, the less it was preyed upon. Likewise, the more the Insect
spots were on the wing, the less birds attacked them.

Martin and his co workers concluded that the ‘visual loudness’ of the markings would startle or frighten the predator into avoiding the paper moths.

The well renowned evolutionary ecologist,
Tom Sherratt said that;

"It does seem very likely, based on [the new] work, that it’s the
conspicuousness of the signal that is more of a deterrent than
anything to do with it resembling an eye,"

For more information try the following sources:
National Geographic

Behavioral Ecology (March Issue)

The Swallowtail butterfly’s larva has a clever disguise, looking like crap can have its advantages!

This Asian butterfly mimics the appearance of bird droppings during the larval stage to prevent predators from feasting on its juicy goodness. Although during the last phase of larvae it turns green to disguise itself with the leaves that it finds home.

In a new study, Japanese entomologists have found that a single hormone is responsible for turning the color of the caterpillars. hormone levels fall when the caterpillar changes from one guise to the next. This hormone can also change the texture and color pigment pattern making the disguise all the better from one bug to the next.

The study, conducted by Ryo Futahashi and Haruhiko Fujiwara, was released today in the journal Science.