CLASSIFICATION OF PHEROMONES,INSECT PHEROMNES,MAMMALIAN PRIMER PHEROMONES,SCENT MARKING

1. PHEROMONES &
CHEMICAL
COMMUNICATION
Submitted by
SIMNA SIDDIQUE
II MSc Zoology
GCW, Vazhuthacaud ,TVM

2. • The term “pheromone” is based on the Greek words Pheran – to transfer –
and Horman – to excite
• They are chemical molecules released in humans, insects, and animals to
trigger a response to or to elicit specific behavioural expressions or
hormonal changes from the opposite sex, the same sex or both sexes of the
same species.
• These signaling molecules are contained in body fluids such as urine, sweat,
specialized exocrine glands, and genital mucous secretions
• Response to pheromone is instinct
• Act on recipient- olfaction, absorption, ingestion

3. CLASSIFICATION OF PHEROMONES
• Signalling pheromones: These trigger immediate reaction in the recipient,
mediated through CNS. short term effect .Sex attractants, alarm pheromones,
trail pheromones etc comes under this,
• Primer pheromones: Slow reaction, brings their effect through neurohumoral
and hormonal changes, long lasting effect
• Imprinting pheromones ;Acts on CNS of a neonate ,results in permanent
modification of the behavior during adult stage.

4. INSECT PHEROMONES
• Alarm pheromones: signalling pheromones produced when an individual encounters
some sort of threat. Eg: When an ant is disturbed,it releases pheromones that can be
detected by other ants several cm away. 4 alkylpyrazines, known to be ant alarm
pheromones.
• Trail pheromones : signalling pheromone ,Certain ants ,as they return to the nest with
food, lay down a trail pheromone. This trail attracts & guides other ants to the food. It is
continuously renewed as long as the food is present.
• Queen Mandibular pheromones: primer pheromones secreted by mandibular glands of
honeybee queen to attract worker bees. It coordinates activities of worker bees & also
control the non development of the ovaries of the workers. It is a mixture of unsaturated
fattyacids

5. Sex attractants
• Signalling pheromones used by many insects and mammals to attract opposite sex
• Usually produced by females
• Bombykol – produced by female silk moth, Gyplure- produced by female gypsy moth, honey
bee queen substance
1. The sex attractant produced by many insects can attract opposite sex from long distance.
Eg: Female emperor moth Endia pavonica can attract males from a distance of 13 km .
2. In meal worm beetle, first male mate with female and cover her with another pheromone
which prevents other males from mating with her.
3. Some tiny parasitic wasps- recognise and follow sex attractants produced by the host (scale
insect) they parasitize. These wasps gets attracted by the pheromones secreted by the scale
insects & lay their eggs in the bodies of the scale insects.

6. 4. Some male cockroaches and crickets produce a pheromones called seducin
from their bodies, on which the females nibble during copulation
5. Bolas spiders release pheromones that mimics the sex attractant pheromones
of females of certain night flying moths it preys upon. Male moths gets
attracted by this pheromone will fall into the trap of spider.
6. In cotton leaf worm moths ,first male to arrive at the female then releases
another chemical which acts as a jamming device to confuse other males.
7. In some species both sexes secrete pheromones, eg in Salt marsh moth. This
results in group meeting and the female can make her choice.

7. Mammalian pheromones
• Purpose: species and racial identity, group recognition, individual identity, identify sex,
attracting opposite sex for mating, territorial marking, identification of mood,
maintanence of dominance, strengthening of mother infant bond, giving alarm signals.
• Source : cutaneous glands/scent glands.40 different types of scent glands are present
in mammals, highly developed in nocturnals.
• The pheromones are either disseminated directly to the environment, or passed out via
urine, faeces, vaginal secretion or saliva.
• These pheromones have a releaser effect or primer effect on the recipient
• Eg: Civetone and Muskone are the sex attractant produced by civet and muskdeer.
These pheromones are highly volatile and diffusible.
• Civetone is also used for defence and territory marking

8. Scent marking
• Specialised acts of behaviour which facilitates the transfer of the odour to
specific sites
• Two ways of scent marking:- Passive marking, Active marking
• Passive marking : non specific liberation of pheromone & its application to the
substratum as the animal travels. Eg; pedal glands markings in ruminants
• Active marking : The animal deliberately deposits the pheromone on selected
locations. Eg: Male lion marks his territory by urine marking, Orytolagus cuniculus
produce special fecal pellets coated with pheromone to scent mark the boundary of
their territory.

9. Mammalian Primer Pheromones
• Slow acting pheromones
• Primer pheromones affecting oestrous cycle, implantation and sexual maturation has been well studied
in mouse
• Group of females- without contact with male- oestrous cycle stops- one of the female produce
primer pheromones –cause mutual disruption of oestrous cycle in other females also.
• Male induction of oestrous ( Whitten effect)- group of females-exposed to male for a short term-
oestrous cycles resumes. This oestrous induction and synchronisation is called whitten effect
• Male induced implantation failure (Bruce effect)- failure of implantation in newely inseminated female
following exposure to an alien male. Pregnancy blocked due to implantation failure. Females ability to
discriminate btw the odour of the stud male and the alien male.
• Vanderbergh effect: maturation of young male mice – accelerated- housing them in cages with
females for a period of five weeks after weaning. The testicular growth enhances, puberty preponed.

10. REFERENCE:
• Ecology, ethology ,evolution, zoogeography textbook, Academica publication
• M.K. McClintockHuman pheromones: primers, releasers, signallers or modulators?
K. Wallen, E. Schneider (Eds.), Reproduction in context, MIT Press, Cambridge, MA (2000),
pp. 335-420
• Pheromones in sex and reproduction: Do they have a role in humans? TaymourMostafa,
Journal of advanced research, volume 3, January 2012, Pages 1-9

11. THANK YOU