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BIO COMMUNICATION IN INSECTS

Chairman:Dr. M. Senthilkumar, Dept of Entomology,Members: Dr. V. Sathyaseelan, Dept of Entomology, Dr. A. Srinivasaperumal. Dept of Agronomy.

A.VINITHRAM.Sc.,(Agri),

INTRODUCTION

COMMUNICATION: It is the exchange of information between individuals. Adapted for symbolic communication, but most of insect’s

"language" skills are acquired through learning.  For members of the insect species, it is an essential part of all

social interactions. Their brains are unique.

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COMMUNICATION IN INSECTS

The majority of insect species live a solitary life, with few contacts between conspecific individuals.

Social insects, however, are characterized by communities in which they live in permanent contact with their nestmates.

Bees and bumble bees, wasps, ants and termites since long have fascinated man because of their well organized and often impressive colonies.

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Why do insects communicate ? Recognition of kin or nest mates.

Locating or identifying a member of the opposite sex.

Facilitation of courtship and mating.

Giving directions for location of food.

Regulating spatial distribution of individuals, aggregation or dispersal; establishing and maintaining a territory.

Warning of danger; setting off an alarm.

Expressing threat or submission.

Mimicry

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TYPES OF BIO-COMMUNICATION

1. Visual communication2. Chemical communication3. Tactile communication4. Acoustic communication

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1. VISUAL COMMUNICATION Most visual communicate are effective during daylight, but

some insects can generate their own light and use visual signals that can be seen at night.

Also for partner location, prior to mating, the males’ big compound eyes can help in finding the females .

Male dragonflies recognizes female dragonflies

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The male Photinus comsumilis during a rising flight movement emit a series of 3.5 short flashes and a female respond after a double flash.

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FIREFLIES

LIGHT PRODUCING MECHANISM IN FIREFLIES

BIOLUMINESCENCE:

When oxygen combines with calcium, adenosine triphosphate (ATP) and the chemical luciferin in the presence of luciferase, a bioluminescent enzyme, light is produced. Unlike a light bulb, which produces a lot of heat in addition to light, a firefly's light is cold light, without a lot of energy being lost as heat. 8

1.In order for this reaction to occur, a chemical named “Luciferin”, which emits light, is required.

2.First, luciferin bind with an enzyme “luciferase”. This enzyme acts as a catalyst to speed up the reaction.

3.Then, oxygen is needed to oxidize the reaction.

4. As a result of this chemical reaction, energy is released in a form of light due to energy from the excitation of the electrons in the ions. The photons of visible light produced is about 50 kcal.

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In alfalfa butterflies, males have U.V. reflective scales and missing scales is a sign for male ageing.

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1.)Batesian mimicryDanaus chrysippus (The Plain tiger)

Hypolimna smisippus(Female DanaidEggfly)

Model-Non edible

Mimic-Edible

2.Mullerian mimicry Heliconius butterfly genus

TYPES OF MIMICRY

SURPRISE AND STARTLE EFFECTSurprise combined with rapid escape flight is often a sufficient defence.Startle is the combination of the elements of surprise and fright.

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Spinx mothHawk moth larva

Under winged moth

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CRYPSIS

Crypsis, or avoiding detection by blending into the background, is one of the most common and successful defenses.

Toad bug

Amazon caterpillarKatydid fly

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EXAMPLES FOR CAMOUFLAGE

Brimstone butterfly

Camo moth

Swallowtail butterfly

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BEHAVIOURAL APPROACH1) Aposematism

The opposite of crypsis or a warning signal to predators.

Patterened colour combinations of reds, yellows, oranges, whites, and blacks.

Warning colouration boldly signals that this insect is toxic, is bad tasting, or can sting or cause injury.

Cinnabar moth larva

Automeris metzli (Saturniidae)

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2)THANATOSIS

Things that eat other things tend to quickly lose interest in dead prey, so some insects that employ the strategy of playing dead (thanatosis) can often escape unharmed.

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CHEMICAL COMMUNICATION

A total of 731 insect species were involved in responses to the 323 chemical compounds.Insect behaviours that are modulated by chemical senses, or the complexity of structures responsible for chemical signalling and perception, the chemical communication channel is a predominant feature of insects (Greenfield, 2002).The small to minute body sizes of insects may be largely responsible for their general reliance on chemical senses.

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SEMIOCHEMICALSA broad term for chemicals involved in insect communication is semiochemical, from the Greek semeion sign (Law and Regnier, 1971).

Classification:1. Pheromone (Intraspecific signals)2. Allelochemicals (interspecific signals)

1.PHEROMONEPheromone - from Greek word pherein (to transfert) and

hormone (to excite) : semiochemical exchanged between individuals of the same species.

Induces specific reaction such as special behaviour or developmental process.

TYPES OF PHEROMONEBased on

Changes in insect: primer pheromone releaser pheromone

Functional group: type 1 type 2

No of compound: mono component multicomponent

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BASED ON CHANGES IN INSECT

•Pheromones were originally defined as 'substances secreted to the outside by an individual and received by a second individual of the same species in which they release a specific reaction,

•for instance a definite behaviour [releaser pheromone] or developmental process [primer pheromone]' (Karlson and Luscher, 1959).

2020 (Ekerholm and

Hallberg,2005)

Primer pheromone:

The most famous example of a primer pheromone is the honey bee queen mandibular pheromone (a mixture of two fatty acids: 9-ODA and 9-HDA) which suppresses ovary development in worker bees (Free, 1987).

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IN TERMITES: The king(s) and queen(s) inhibit, in concernt, the formation of

neotenics using a putative, non-volatile, inhibitory chemical substance. Which is spread among nestmates by trophallaxis

When this inhibitory signal is decreased neotenics form from the immature termites.

CHC’s may also be involved in fertility signaling or reproductive control.(Liebig et al. 2009; Weil et al. 2009).

BROOD CARE BEHAVIOUR: The eggs laid by the queen(s) are collected, handled, piled at

specific spots by workers (and in exceptional cases by soldiers; Hanus et al. 2005 ), and protected from pathogens and desiccation by worker saliva.

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Releaser pheromone: The most commonly known are sex pheromones, which are highly species specific and serve to attract mates for reproduction. The first sex pheromone was identified in 1959 from the silk moth Bombyx mori (Butenandt et al., 1959). Many further insect sex pheromones have been identified to date and a number are commercially used in pheromone traps for pest control (Bell, 2004)

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• Pine moth (Dendrolimus spectabilis) pheromone

• Flutter dance : male silkmoth (right) gets excited by the female (left). She is releasing bombykol from her gland.

• Tse-Tse fly (Glossina austeni) contact sex pheromone

• Gypsy moth (Lymantria dispar) - Gyplure, Dispalure.

Name of the insect Pheromone

Pink bollworm, Pectinophora gossypiella

Gabbage looper, Trichoplusia ni

Tobacco cutworm, Spodoptera litura

Gram pod borer, Helicoverpa armigera

Honey bee queen, Apis sp

Gossyplure

Looplure

Spodolure, litlure

Helilure

Queen’s substance

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• Releasing the sex attractant pheromone-calling.

• Pheromone gland exposed to outside by -depressing the tip of the abdomen -extension of the abdomen -gland is inverted by haemolymph pressure

• Exposure of the gland is accompanied by wing vibration which facilitate dispersal.

PHEROMONE DISPERSAL

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SEX PHEROMONE TRAP Most pheromones are “sex pheromones”, these are chemicals released by female moths to attract a male partner. As a consequence the traps will catch only male moths and usually of only one species. To catch other species, different pheromones will have to be used.

Types of sex pheromone trap1.) Funnel trap:It consists of funnel base with handle and attached to a support of the stick.Funnel trap is mainly used to collect larger moths with the help of lures or pheromones kept inside. Spodolure, Helilure, Gypsy moth lure.

2.) Delta trap: A type of trap often used with

pheromone baits is the “ delta trap “. It is a triangular trap made of plastic or weather proof card. Insects that fly into the trap are caught on a surface treated with a special type of non-dying glue. Recommended to capture smaller moths and fruit flies. Pine moth lure, European corn borer, Spodolure, TLM lure, Helilure, Gypsy moth lure, Grain weevil.

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3.) Wota trap:Mass trapping pests of field crops such as sugarcane borers, Wota-T is easy to assemble on a single pole.It consists of an adapter basin to hold water mixed with kerosene/ detergent and a lure holder with a canopy.Spodolure, Helilure, INB lure, TLM lure.

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4.) Fruit fly trap:

This hanging bucket is used to capture Melon fruit fly and Oriental fruit fly.This is also used for trapping Mediterranean fruit fly.This trap has yellow bowl with entry hole and also a translucent dome.Bacu lure for Bactrocera cucurbitae, fruit fly lure.

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Trail pheromones, employed by social insects for orientation and to recruit nest mates to a suitable food source.

They are produced by a variety of glands and can be composed of numerous different, mostly volatile compounds.

When navigating their territory, ants and termites deposit these pheromones on the ground thus developing an extensive net of chemical routes. (Holldobler and Wilson, 1990; Pasteels and Bordereau, 1998; Kaib, 1999).

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TRAIL PHEROMONE

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Lays trails and lead to feed.

Chemical nature of trail pheromones are hexanoic, heptanoic, decenoic acids ( in formicine ants).

Trail pheromones can be used to kill ants.

Trail pheromones mixed with baits can attract ants which when transported by ants to their nest it will kills all young ones.

ANTS

Some ant species use ‘propaganda’ pheromones to confuse the enemy ants and make them fight among themselves.

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Honeybee releases orientation pheromones, a mixture of geraniol, citral, farnesol and other minor compounds from their Nasonov gland into the air in a number of orienting situations.

(Free, 1987; Winston, 1987).

An insect may rely upon angling the flight path relative to the direction of the wind that brings the odor, resulting in a zig-zag upwind flight towards the source.

Each directional shift is produced where the odor diminishes at the edge of the plume.

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Alarm pheromones are chemical substances released by insects to warn members of the same species about the presence of or attack by an enemy (mostly a predator).

This warning elicits different behaviour in different insects as listed below:

1.) Dispersion or escape in aphids and bugs.

2.) Aggression in ants and soldier termites.

3.) Attraction in wasps and worker bees.

The chemical nature of alarm pheromones are terpenes (aphids), aldehydes (hemiptera) and formic acid (ants).

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Alarm phermone

In Aphids:Aphid alarm signaling was first characterized in the 1970s.

In response to predation and other disturbances, the cornicles’ of aphids emit an odor repellent to conspecifics (Kislow and Edwards, 1972).

This pheromone induces Myzus persicae to stop feeding and move away from the signaler or to drop from the host plant waving their antennae before and during these aversive behaviours.

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In ants:All Formicid species were subsequently found to produce and use an alarm pheromone (Holldobler and Wilson 1990).The response to “aggressive alarms” is characterized by rapid movements oriented toward the emitter and by aggressive attitudes ranging from mandible and gaster movements.Responses to “panic alarms” entail escape, dispersion, and flight behaviors.Workers’ displacement speed is increased, as well as the frequency of direction changes.

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Alarm pheromone in Honeybees:

A vital role honeybee colony defense is played by so-called guard bees, which patrol the nest entrance and represent the first line of colony defense.

These guards are also specialized for the production of alarm pheromone which they release to recruit nestmates from the interior of the colony in case of danger (Boch et al., 1962; Collins et al., 1982).

The perception of the pheromone increases workers movement and promotes aggression.

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The most famous example is the so-called killer bee, where the alarm pheromone from a single bee can within seconds alert the entire hive to attack and kill a potential predator (Winston, 1992).

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IN TERMITES:

1.) Specific alarm:

It involves the local excitement of one or few individuals.

2.) General alarm:

It takes place when a strong disturbance is perceived at all once by a group of termites.

The defense glands found in the heads of soldiers release the semiochemicals involved both.

It is elicited by the vibratory movements of soldiers liberating frontal gland secretion.

Elicited by physical contact between alerted and recruited termites. 40

Pheromones which induce aggregation or congregation of insects for protection, reproduction and feeding or combinations are called aggregation pheromones.

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Aggregation pheromone:

Eg: Bark beetles start to bore into the bark and release a long-range aggregation pheromone,

A mixture of terpenoids some of which are synthesized , others produced by symbiotic bacteria in the beetle gut or sequestered from host tree compounds (Greenfield, 2002; Wyatt, 2003).

Males of phloem beetle Ips confusus incorporate their pheromone in faecal matter which attract both male and female to the infested tree.

Some common names of aggregation pheromones are:

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Pheromone InsectFrontlain Dendroctonus frontalis

Ipsenol Ips confusus

Periplanone Periplanata americana

Dimethyl decanol Tribolium confusum

LESSER GRAIN BORER (Rhyzopertha

dominica)

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Upon locating food sources, male R.dominica release two aggregation.

Pheromones, Dominicalure-1 (DL-1) and Dominicalure-2 (DL-2), which augment recruitment of conspecifics to located food resources.

Eg: Californian western pine beetle, Dendroctonus brevicomis (Scolytinae), which attacks ponderosa pine (Pinus ponderosa).

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bucket trap

The lures are kept inside the bucket trap.

Bucket traps are used to collect rhinoceros beetle, red palm weevil

The communication between two different species of organisms or insects.

It classified into allomones, kairomones, synamones, apneumones.

Allomones : From Greek word (allos+hormon=excite others) allomone is a chemical or mixture of chemicals released by one organism that induces a response in another organism which is advantageous to the releaser.Example: The defensive secretions of insects and plants that are poisonous to attacking predators.

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Allelochemicals

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The alde-hydic secretions flows from the

two glands on the stink bug’s thorax providing a repellent odour barrier when touched by a predator.

Bombardier beetles (Brachinus spp.) and vinegaroons (Mastigoproctus spp.) spray corrosive quinones/ hydroquinones and concentrated acetic acid solutions, at approaching predators thereby creating a defence.

Ants release a defensive allomone called citral from its mandibular glands.

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Allomones in other insects include:

o Sting gland in beeso Formic acid in ants

Allomones also serve plants as defence mechanism

against herbivores and reduce competition with other plants.

The neotrophical social wasp Mischocyttarus drewseni applies a secretion to the stem of its nest that repels foraging ants.

Some trophical flowers which are pollinated by bats emit odours which attract bat to the flowers.

KAIROMONE (GREEK KAIROS- OPPORTUNISTIC OREXPLOITATIVE)

Kairomone is a chemical or mixture of chemicals released by one organism that induces a response in another organism.

Helpful to recipient.

Eg.Heptanoic acid released by larva of potato tuber moth Phthorimaea operculella increases searching by its parasitoid

- farnesene secreted by codling moth larva attracts its parasitoid

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Synamone

Chemical released by one organism that induce a response in another species.

Helpful to emitter and receiver. It encourages mutualistic relation

between organisms. Eg. Termites and protozoans .

Eg: Flower fragrance:Orchids (Ophrys) attract males of solitary bees by a mixture of compounds resembling the sex pheromone of con-specific females, but males are not awarded with nectar(pollination by deceit).

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APNEUMONES

Chemical substances emitted by a non- living material that evoke a behavioural or physiological reaction adoptively favourable to a receiving organism, but detrimental to another species, which may be found in or on the non- living material.

Eg: An ichunuemonid parasite of Venturia canescens is attracted by the smell of the oatmeal, which is the food of its host.

Here it is advantageous to the recipient which is the parasitoid but detrimental to host insect living on the oat meal (non- living material)

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TACTILE COMMUNICATION

"Keep in touch!"  For you, it's probably just a metaphor, but for some insects it's really a channel of communication

  Since many insects have poor vision and sound perception, physical contact provides an important avenue of communication.

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 In blister beetles (family Meloidae), courtship begins with a series of antennal taps by the male on each side of the female's body. 

She signals her receptivity by lifting her wing covers (elytra) and allowing him to climb on her back.

But to complete his quest, the male must continue tapping, alternating from side to side at just the right frequency until the female is stimulated to extend her genitalia and begin mating.

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Antennal tapping is also an essential component of communication in both ants and termites.

It's not clear exactly what information may be exchanged, but it certainly involves nestmate recognition and leads to exchange of food through trophallaxis. 

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• Antennal tapping on the hind legs is used during tandem running in both ants and termites.

 • This is a "follow-the-leader"

behavior in which the tapping informs the leader that she has not lost her disciple. 

• If tapping stops, the leader instinctively turns around and searches in ever-widening circles until she re-establishes contact with the follower.

IN TERMITES:

Drumming behaviour occurs in both soldiers and workers,

But its alarm pheromone capacity is low. A chain vibrating soldiers can spread an alarm across a

distance of more than a meter in less than a second (Rohrig et al. 1999).

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DANCE LANGUAGE OF HONEY BEES

Karl von Frisch, 1886-1982Austrian, began work in 1919Trained European honey bees, Apis mellifera, to feedersFirst believed bees used flower scents or other odors to find food sourcesBegan to pay close attention to dances performed by returning foragersDances very precise, with varying tempo and direction

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1. “Round dance”

• When food source is < 50 m from hive• After distributing some of her new- found nectar to waiting bees the scout will begin running in a small circle, switching direction.• After the dance ends food is again distributed at this or some other place on the comb and the dance may be repeated three or (rarely) more times.• The round dance does not give directional information.

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2. “Waggle dance”

• When food source is > 50 meters away

Waggle run- Abdomen wagging and wing fluttering-Angle repeated with respect to vertical, or gravity (here 20° right)

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By moving feeder to different angles and locations -• Number of waggles per run correlates with distance to food source (more= farther)• Dance “tempo” (slower= farther) • The duration of the dance (longer= better food)

Other bees follow the dancer (“audience”)

SCOUT: finds new food sources & dances

RECRUITS: follow dances & then forage

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Direction of the food source isindicated by the direction the dancer faces during theStraight portion of the dancewhen the bee is waggling. Ifshe waggles while facingstraight upward, than the foodsource may be found in thedirection of the sun.

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If she waggles at an angle 60 degrees to the left of upward the food source may be found 60 degrees to the left of the sun.

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If the dancer waggles 120degrees to the right ofupward, the food sourcemay be found 120 degreesto the right of the sun.The dancer emits soundsduring the waggle run thathelp the recruitsdetermine direction in thedarkness of the hive.

COMMUNICATION IN TREEHOPPERS

Certain treehoppers (order Hemiptera: family Membracidae) produce vibrations in the tissue of their host plant that can be felt by all other treehoppers on the same plant.The signals apparently work as an alarm system, and in some species, they may be used by nymphs to elicit protective maternal behaviour.Substrate vibrations can be a particularly effective communication system for small insects who cannot generate an acoustic signal loud enough to be heard more than few inches away.

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ACOUSTIC COMMUNICATION

Acoustic communication can be made to vary in frequency , amplitude and periodicity Together, these three variables can create an extremely wide and complex range of signals from an insect's mating call to human speech and vocal music.Since sound waves move rapidly through air (about 331 m/sec), acoustic signals can be quickly started, stopped, or modified to send a time-sensitive message

.

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ACOUSTIC SOUND PRODUCTION IN MOTH:

“Whispering” moths exemplify another antidetection strategy (Nakano et al., 2008).

Ostrinia furnicalis, male Asian corn borer moths, use specialized very low intensity courtship songs produced by sex-specific scales on the forewings and mesothorax.

In order to protect the pair from conspecific competitors and predators, this male moth produces the sounds in the female’s ear, which provide a private communication channel between them. (Conner, 2014).

Toxic tiger moths (Arctiidae) send loud return sounds to approaching insectivorous bats.These sounds warn the bat that the moth is unpalatable and potentially harmful, and may also interfere with the echolocation capabilities of bats.

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APOSEMATIC SOUND Aposematic sounds often converge structurally, having broad frequency ranges, low pattern complexity.Such signals are readily detected by a wide range of predators.

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CATEGORIES OF SOUND PRODUCING MECHANISMS (Claridge, 2005)

A. Vibration (including Tremulation) The oscillatory movement of the wings of an insect sets

up regions of compression and rarefaction and a vibrational sound is produced.

EXAMPLES : The flight sound, made by the wings, in swarming mosquitoes

is considered to be used for species-specific recognition (e.g. Gibson, Warren, & Russell, 2010; Roth, 1948).

Wing vibration is also used in the courtship dances of Drosophila species (Von Schilcher, 1976).

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B. Percussion – Striking one part of the body against another as a communication system for pair formation.

EXAMPLE:1)The Australian moth (Lepidoptera); males produce ultrasonic acoustical long distance signals to attract sexually receptive females and to establish territorial residency in competition with other males (Alcock & Bailey, 1995).

2) Species of the suborder Arctoperlaria (Plecoptera) produce drumming signals on the substrate as a mating system. The male emits a species-specific call searching for the female. (Stewart & Sandberg, 2005).

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C. Stridulation –

Stridulation consists of sounds produced by frictional mechanisms, involving the movements of two specialized body parts against each other in a systematic patterned manner (Claridge, 2005).

In orthopteran insects response stridulation from the receptive female orientation towards and locomotion to the male.

“Rivalry song”

The female arrived near the male, stridulating in response to mate song; the male, once noticing the female, sings the courtship song, engages the genitalia and copulation occurs .(Haskell, 1958).

STRIDULATION IN CRICKET:

Busnel (1953) said that the male cricket, Oecanthus pellucens moves around the territory, patrolling, singing its normal song, if it encounters another interfering male, it sings a type of song called the “warning song”.

This interesting behaviour appears analogous to the territory marking of certain song-birds, which is established by the male by singing at the territorial boundaries prior to the commencement of the mating season (Haskell, 1961).

The male field cricket Teleogryllus oceanicus stridulates by scissoring the wings; females are attracted to the males’ songs. (Hedwig & Robert, 2014; Zuk, Rotenberry, & Tinghitella, 2006).

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IN TERMITES:

It produced drumming. It has also been hypothesized that the synchronized

drumming of Macrotermitinae, Which evokes a rhythmical hissing may act as an

aposematic signal to warn away predators. (Howse 1984; Connetable et al. 1999).

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• D. Click mechanisms • These sounds depend on the deformation of a modified

area of cuticle, generally by contraction and relaxation specialized musculature within the insect body.

• This acoustic signal constitutes the first step in pair formation, attracting females at long distances, and is involved in male-male interactions (Sueur & Aubin, 2003).

For example, the males of Tibicina (Hemiptera) cicada species produce a sustained and monotonous calling song by tymbal activity.

Tymbals – muscular vibration of drum-like membranesThe loudest calls in the insect

world come from male cicadas.

The females are silent.

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E. Air expulsion:This sound is described as an exhalatory sound, frequently expelled via the tracheal spiracles, however little is known about its function (Ewing, 1989).

EXAMPLE: The Madagascar hissing cockroach Gromphadorhina

portentosa, is able to produce audible hisses from a pair of modified spiracles.

Adult males hiss in three social contexts: during courtship, during copulation, and during aggressive encounter.

Adults and nymphs of both sexes also hiss when disturbed (Nelson & Fraser, 1980).

conclusion

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