COMMUNICATION IN INSECTS CONTENTS Introduction Types of insect

COMMUNICATION IN INSECTS

CONTENTS -Introduction -Types of insect communication -Chemical communication -Visual communication -Audio communication -Tactile communication

INTRODUCTION COMMUNICATION • It is the exchange of information between individuals. • The one that transmits the message (emitter) and the other that receives and processes that message (receiver). • Insects communicate by touch, smell, sound, and sight. • The most important communication they have is with members of the same species; They use different signals to find mates, give warnings about danger, tell about food sources and to ward off predators or attract prey.

Types of insect communication Chemical communication Visual communication Audio communication Tactile communication

CHEMICAL COMMUNICATION • Insects communicate with two different types of chemical message, called Pheromones and Allelochemicals. • These are smells that insects give off and are sometimes called ‘insect perfumes’. • Pheromones are the chemical messages that insects use to communicate with other members of the same species. • Types of pheromones are trail pheromones, alarm pheromones, sex pheromones, aggregation pheromones.

PHEROMONE S TRAIL PHEROMONES • are used by ants, caterpillars and other insects. • These signals are like maps that help insects to find food. • The first insect to find the food leaves a trail of scent back to the insect colony. The other insects can then follow this trail to find more food. Eg-Ants

• Termites also mark their trail by pheromone produced by special gland located on abdomen and used to add workers which help in food gathering. • Fire ants deposit trail pheromones by discharging the contents of the Dufour’s gland through the extruded sting on the ground surface.

ALARM PHEROMONES • Are signals that are put out by insects if they are disturbed or threatened. • This type of signal makes ants run out of their tunnels and all over ground if their nest is disturbed. • Isoamyl acetate releases by the sting apparatus of honey bees. • Aphids give alarm pheromones that urge neighboring aphids to flee from nearby predators.

SEX PHEROMONES • Used to attract insects of the same species. • Eg- Bombykol released by the female silkworm to attract the partner. • Similarly, disparlure release by female gypsy moth. • Mandibular gland of queen honey bee produces pheromone to attract drones. • Nasanov pheromone is released by worker bees to orient returning forager bees back to the colony.

• To broadcast this scent bees raise their abdomens, which contain the Nasanov’s glands, and fan their wings vigorously. • In the fig. fanning honey bee exposes Nasanov’s gland releasing pheromone to entice swarm into an empty hive.

AGGREGATION PHEROMONES • Used to send out messages to many insects within one species. • Eg- a pheromone called Exo-brevicomin , is released through faecal matter of beetles act as aggregator, attracting more and more beetles to invade the trees.

ALLELOCHEMICALS • Chemical signals that travel between individual of different species. • These includes kairomones and allomones. • Used for defensive signals such as repellents, compounds used to locate suitable host plant, and other signals to regulate interspecific behaviors.

VISUAL COMMUNICATION • Visual communication in insects takes place by two main system: body color patterns and light signals. • There are species that emit light signals to attract other organisms. Eg- fireflies • Butterflies, flies and other insects use colors in visual communication. • Some male flies have bright spots on their wings that they flap around and show off to females during the mating season.

• Caligo memnon, with its spots that resembles two big owl eyes allow them to drive away predators. § Males of Photinus pyralis emit a signal J shape flash during a rising flight movement and the female responds with a single flash after a two second intervals. § The male Photinus comsumilis emit a series of 3 -5 short flashes and a a female respond after a double flash.

o. The click beetle (Pyrophorus noctilucus) has two small bioluminescent organs located behind its head. o. The light of these organs get more intense when being menaced. q Larvae or larviform adult females from the beetle genus Phrixothrix emit two types of light: green and red. q. They emit red light by two organs located in their heads only when they feel menaced in order to alert other larvae about the presence of predators.

AUDIO COMMUNICATION • • • Insects make sound to attract others of their own species or to send out signals to other species. Leaf hoppers produce and transmit sound through plants. Similarly some orthopterans used plants as transmission channel and produce vibrational songs. When insects produce sound by rubbing parts of their body together it is called stridulation.

o In grasshoppers, a row of peg like structure found on the inner surface of hind femora which are collectively called as file and are rubbed back & forth over the edge of the forewing. • In case of crickets, the pegs are located on one of the forewing (tegmina), the other forewing has a flat surface known as file. • The song is produced by the pegs being dragged across the file as the wings rub together.

• In cicadas, the tymbal is a sound producing organ found in the abdomen. • The song is produced by using muscle to deform this structure producing a click. • The muscle tension is then released produced another click. §In Acherontia, sound is produced by expelling air from the pharynx. §Sound is also produced by the vibration of wings. Eg- mosquitoes, honey bees.

TACTILE COMMUNICATION • Information transmitted in the form of physical contact (touch signal) is called tactile communication. • Insects communicate through touch with their antennae and their mouths. • This form of communication is very useful when insects that are living in dark places need to recognise other insects that they live with. • Eg- Termites –blind workers totally depend on this phenomenon.

• Antennal tapping is an essential component of tactile communication in both ants and termites. • Worker ants in tactile communication. §The male Drosophila attracted to female visually but the recognition of the species is done by tactile method i. e. by tapping the female with his forelegs.

Language of Honey bee • The worker bees communicate about food mainly by a dance language. • Bees mainly perform two types of dances. 1. Round dance 2. Waggle dance. ROUND DANCE: a bee informs other bees in her hive of a rich source of nectar found near it by means of round dance.

• The bees turn in circle, once to the left then once to the right, repeating the dance in one place for about one-half minute. • It gives no direction, but the bees know the food is to be found close to the hive. WAGGLE DANCE: if the food is farther away than about 160 feet, the round dance is replaced by tail-wagging dance, making the figure of eight. • This dance convey information about both the distance and direction in which food source is available in relation to the sun.

REFERENCES • Matthews Robert and Matthews Janice, Insect Behavior (1972), A Wiley-Interscience Publication, New York • Prasad S. Animal Behavior (2004), CBS Publishers and Distributers, New Delhi • Singh H. R. and Kumar Neeraj, Ecology and Environmental Science (2013 -14), Vishal Publishing Co. , Delhi • www. skwirk. com • https: //allyouneedisbiology. wordpress. com • https: //www. slideshare. net

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