Antennae Detect a Variety of Signals

black and yellow bee in close up photo against black background

Biological Strategy

Western honeybee

Holly Kerstiens

Image: Harry Strauss / Pixabay / Free non-commercial use

Cooperate Within the Same Species

A species is a group of organisms capable of breeding to produce fertile offspring. When individuals within a species undertake activities that benefit one another, that cooperation benefits not just the individuals, but also local and wider populations of that species. Collaborating in activities such as finding food, controlling parasites, and protecting from predators enhances overall survival. To cooperate, there must be enough benefit to an individual, and especially to a population, to justify any risk taken by individuals. Through cooperation, risk is distributed among individuals and the benefits to the community are greater than the sum of the benefits to individuals. An example is birds that gather in flocks, a cooperative activity more beneficial than acting alone. While some birds forage, others watch for predators. When one finds food, others also feed on it. Despite potential short-term competition for an individual that finds food, over the long-term, that same individual benefits when others find different food sources.

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Sense Sound and Other Vibrations From the Environment

For living systems, sensing sound and other vibrations is important for communicating and detecting conditions within their environment. Living systems must locate a signal’s source so that they can move toward it (such as when it is food or a potential mate) or away from it (such as when it is a predator). To prompt an appropriate response, living systems must sense these signals, recognize their amplitude or volume (which is sometimes very low), and determine their direction. Living systems must be attuned to signals relevant to them and able to distinguish these from irrelevant sounds to avoid expending unnecessary energy. For example, owls’ ears are asymmetrically placed. This enables them to detect sounds more accurately, which helps them locate small prey at night and avoid wasting energy chasing down irrelevant sounds.

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Sense Chemicals (Odor, Taste, etc.) From the Environment

Chemicals are important for signaling and communication among living systems, either intentionally (such as when two living systems try to find one another) or unintentionally (such as when a plant emits a chemical signal that an herbivore can use to find a tasty bite). They are also important for other uses, such as navigating or finding sources for minerals. But chemical signals are often relatively weak and disperse when moving through water or gases. Therefore, detecting them requires specialized abilities, including a way to determine where they are coming from. A well known example of sensing chemicals can be seen in ants following a pheromone trail laid down by others in their colony to locate a quality and abundant food source.

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Insects

Class Insecta (“an insect”): Flies, ants, beetles, cockroaches, fleas, dragonflies

Insects are the most abundant arthropods—they make up 90% of the animals in the phylum. They’re found everywhere on earth except the deep ocean, and scientists estimate there are millions of insects not yet described. Most live on land, but many live in freshwater or saltwater marshes for part of their life cycles. Insects have three distinct body sections: a head, which has specialized mouthparts, a thorax, which has jointed legs, and an abdomen. They have well-developed nervous and sensory systems, and are the only invertebrate that can fly, thanks to their lightweight exoskeletons and small size.

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The antennae of a bee allows it to sense a variety of signals including chemicals, light, vibrations, and electric fields.

The antennae of bees serve the same purpose as a nose in humans; they’re filled with receptors for chemical odorants in the environment and help the bee smell the world.

The antennae of male bees are often much longer than their female counterparts. Male antennae have an extra segment and the segments themselves have more length. This is because male antennae are specialized to pick up the subtle scent of female pheromones. Some honeybee workers have been shown to smell their Queen from up to 60 meters away.

The receptors on the antennae are divided into 4 categories: plates, pegs, hairs and pits. Plates are receptors for chemicals and light, pegs and pits are for smelling and hairs for touch. The arrangement of the sensors is very specific, with a tuft of hairs for feeling texture at the tip of the antennae and the majority of the receptors related to smell (known as pore plates) found on the last eight sub-segments. A male bee can have up to 100x the number of sensors on his antennae that a female can.

Another receptor, the Johnston’s organ, is found inside the antennae near the head. It detects movement and vibration around the antennae and has a variety of applications from allowing the bee to judge its speed, as well to detect electric fields. Bumblebees, for instance, can use the mechanoreceptors on their antennae to sense electric field strengths as small as 15.3 Vm-1.

This information is also available from the University of Calgary Invertebrate collection, where it was curated as part of a study on design inspired by bees.

Image: Rob Alexander / CC BY NC - Creative Commons Attribution + Noncommercial

A male Melissodes rivalis bee with much longer antennae than the female.

Image: Rob Alexander / CC BY NC - Creative Commons Attribution + Noncommercial

A female Melissodes rivalis bee.

Image: Soraya Villalobos / CC BY NC - Creative Commons Attribution + Noncommercial

A female Melissodes confusus.

Image: Rob Alexander / CC BY NC - Creative Commons Attribution + Noncommercial

A male Melissodes confusus, with much longer antennae than the female.

Last Updated April 3, 2019

References

Book

The Bees of the World, Second Edition.

Hopkins Fulfillment Service | Michener CD.

“When a virgin queen enters the congregation area, drones (from a few hundred to thousands) begin pursuit, first attracted to chemical cues but also using vision at closer range… Compared with worker bees, drones have larger antennae and about seven times as many placoid sensilla (≈18,000 compared with ≈2,700).” Wanner, 2007:14383

Journal article

A honey bee odorant receptor for the queen substance 9-oxo-2-decenoic acid

PNAS | 04/09/2007 | Wanner KW, Nichols AS, Walden KKO, Brockmann A, Luetje CW, Robertson HM.

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Reference

Book

The Beekeeper's Handbook

Cornell University Press | Sammataro D, Morse RA.

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Reference

Journal article

Sensory allometry, foraging task specialization and resource exploitation in honeybees.

Behav Ecol Sociobiol | Riveros AJ, Gronenberg W.

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Reference

“Mechanosensory hairs are common across the Phylum Arthropoda (16). These sensors typically have mechanical resonances between 100 and 500 Hz and react to vibrations from the wingbeats of approaching predators (22) and air currents (23, 24). In contrast, bumblebee hairs have a resonant frequency of approximately 3.8 kHz, a result of low mass and high stiffness.” Sutton, 2016:7263

Journal article

Mechanosensory hairs in bumblebees (Bombus terrestris) detect weak electric fields.

PNAS | 26/04/2016 | Sutton GP, Clarke D, Morley EL, Robert D.

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