Les abelles són conegudes per l'habilitat que tenen de comunicar-se a partir d'un llenguatge que utilitza la dansa com instrument. El ball de les abelles serveix per indicar la ubicació dels recursos naturals imprescindibles per a la supervivència de l'arna. Un estudi ha revelat que la gravetat juga un paper molt important en la precisió d'aquesta dansa. L'abella recol·lectora mostrarà el seu botí a les seves germanes, i amb el seu ball indicarà la direcció, sentit i distància on es troben els diferents recursos naturals. Margaret Couvillon, una investigadora de la Universitat de Sussex en el Regne Unit ha estudiat aquest petits insectes, fascinada pel mecanisme d'aquesta dansa.
Quan l'abella camina per les bresques diposades verticalment, balla i fa vibrar el seu cos i les ales. La recol·lectora repeteix aquest procediment moltes vegades, disposant el seu cos en un angle equivalent a la direcció on es troben les fonts de nèctar. Aquest angle es correspon amb l'angle dibuixat pel Sol, l'arna i la localització exacte de les reserves alimentàries. La investigadora Margaret Couvillon va observar que en algunes ocasions les abelles cometen petits errors en les seves danses, amb un dibuix angular que no es prou exacte.
L'estudi volia aclarir si aquest error era intencionat i pretenia indicar alguna cosa en especial o simplement era un defecte del propi ball. Després de curosos estudis i observats aproximadament uns 200 balls, la conclusió va determinar que l'error era degut a la pròpia gravetat, que dificultava l'execució del ball, sobretot en aquells balls, on la posició horitzontal de l'abella era la més compromesa. Tot i això, i el més sorprenen, la resta d'abelles eren capaces de minimitzar l'error, corretgint l'error en el vol posterior.
Curiositats de la natura!
L'estudi es detalla en el 18 d'abril emissió de la revista Biology Letters.
The waggle dancing bee walks along the vertical honeycombs quickly vibrating her body and wings. The bee repeats this walk many times with her body angled in the same direction, indicating and re-indicating the same angle. [ Photos: Honeybee Scouts Find Food ]
The dance signals the
direction of the food patch in relation to the sun, which is always
interpreted by the other bees as straight up (regardless of where it is in the
sky). If the dancing bee positions its body straight up, that indicates to the
other bees to fly straight toward where the sun is on the horizon. If the
dancer angles her body with face pointing down toward the ground, which means
the food patch is located directly opposite the sun's position on the horizon.
The researchers realized that
sometimes, the bees' dances are more variable. If the bee is trying to signal
to others to head 20 degrees from the sun, they will sometimes signal 18, then
22, then 19 and maybe 23, but the average will be 20.
"If you watch, each one of
these successive waggle runs is a bit different from the last," Couvillon
said. "The angles are a little noisy — there's a bit of error."
The researchers wondered if this
variation was meant to signal something specific (such as a dispersed patch),
or if it was a mistake.
Defying gravity
They carefully measured the dances of the honeybee foragers in a hive in their lab with clear walls, so the researchers could watch the bees come and go when foraging in the countryside. The team watched 198 waggle dances, and specifically compared the amount of variation — how often the bees strayed from their intended angle — with the angle they were trying to signal.
They carefully measured the dances of the honeybee foragers in a hive in their lab with clear walls, so the researchers could watch the bees come and go when foraging in the countryside. The team watched 198 waggle dances, and specifically compared the amount of variation — how often the bees strayed from their intended angle — with the angle they were trying to signal.
When bees signaled angles close
to the horizon, like 90 or 270 degrees, they seemed to have much more trouble
staying on point than when walking directly up or down. The researchers think
that horizontal angles are more difficult because the bees need to work against
gravity to stay in a straight line.
Preliminary data from one of
Couvillon's colleagues shows that when a bee has more trouble repeating an
angle clearly, her nest mates may ignore her.
The study is detailed in the
April 18 issue of the journal Biology Letters.
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