The sun generates patterns of polarized light, especially in the ultraviolet range, and these patterns indicate the location of the sun when it is not directly visible on a cloudy day, or just before sunrise or just after sunset. Unlike the human eye that has receptors for only brightness and color, bees also have special receptors for ultraviolet and polarized light.
Remember that a honey bee has five eyes, three simple eyes and two compound eyes. Each of the compound eyes has 4,500 light sensors, called ommatidia, and there are three types of ommatidia, containing different sets of light-sensitive cells, that are distributed over the retina in a pattern that is described by Motohiro Wakakuwa and colleagues as "rather random" and much more complicated than had been previously accepted.
Rudiger Wehner and Stephan Strasser demonstrated that there is a group of about 150 specialized ommatidia in the uppermost dorsal area of the eye that has polarized ultraviolet receptors configured in such a way that they can translate the information from polarized light into "modulations of perceived brightness." This provides cues from which they can derive directional information in lieu of being able to see the sun. The researchers actually painted out different parts of bees' eyes and recorded their behavior, and these observations established that this group of specialized ommatidia is, indeed, the polarized light (POL) area of the eye.
Unlike baiting a hook with a worm with the intention of trying to deceive a fish, mimicry is natural behavior of an animal trying to survive. Defensive mimicry may be more familiar, such as camouflage, where the subject tries to blend with the background, or Batesian mimicry, where a harmless species resembles a species that is toxic or harmful, duping predators into avoiding the safe prey because it appears to be harmful. In aggressive mimicry, a predator gives off signals that usually promise food or sex to their prey, and then they just sit back and wait for the prey to come to them. For example, the predator may look or smell enough like a female bee so that a male bee will be fooled into approaching.
In the Mojave Desert, a cluster of tiny, millimeter-long blister beetle larvae Meloe franciscanus give off a pheromone (a stimulating scent) that fools male solitary bees, Hapropoda pallid, into mistaking the larvae for a female bee ready to mate. When a male bee is attracted by their scent and attempts to mate with the ball of larvae, several hundred larvae attach themselves to the back of the unsuspecting bee as he struggles to get away. The larvae stay with the male, and when he actually mates with a real female bee, the larvae move onto the female; when she goes underground to lay an egg on her stockpile of nectar and pollen, they eat everything in sight, including the egg. Some spiders are aggressive mimics that can lure bees into their webs.
The golden orb weaver, also called the golden silk spider or banana spider, Nephila clavipes, attracts bees by spinning a golden-colored web in a brightly lit area; and while bees can associate other webs with danger, scientists speculate that the golden color of these webs mimics yellow nectar-bearing flowers and so attracts instead of warning the bees. Argiope agentata spiders attract bees by weaving patterns in the center of their webs that appear to mimic the nectar guides in the center of flowers. Small female crab-spiders mimic different flowers by adapting their entire body to the color of the flower and then making themselves inconspicuous on a petal until a bee comes to nectar, at which point they attack the bee.
In yet another variation of aggressive mimicry, some robber flies in the genus Mallophora closely resemble bumblebees, even down to hind legs that look like the pollen-carrying legs of the bees. When an unwitting bumblebee approaches the fly, it captures the bee and squeezes it tightly against its own body and then pierces a hole in the bee's body and feeds on its insides, leaving only the exoskeleton remaining. Aggressive mimicry takes many forms and is not unique to predators of bees; this mimicry subjects many insects, birds, and other animals to these types of seductive attacks.
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08152010
1. What is special about bees living in colonies
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