pheromones and their importance is discussed.

1. Pheromones
Namrita Singh Tomar
M.sc Final (Zoology)

2. Introduction
Pheromones (chemical communication) is a
chemical that is produced & released into the
environment by one organism and affect the
behavior of another organism of the same species.
Karlson & Luscher (1959) coined the term
‘pheromones’.
They are used as chemo signals in intraspecific
communication .
Pheromones are also called ectohormone & release
in minute quantity.
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3. Discovery
◎ In the 18th century, the discovery of pheromones took
place by chance. A French biologist, Bonnet, discovered
the long trail of ants. Bonnet placed a colony of ants at
one end of a table and a small heap of sugar at the other
end.
◎ He observed that the ants coming out of the colony
moved across the table to the pile, picking up sugar and
moving back to the colony with it. The ants moved to and
fro along a definite track, with none diverting from it
Bonnet wanted to know why the ants followed such a definite
trail and so he broke the continuity of this path by rubbing his
finger across the line of the ants. The ants stopped and
searched about at the rubbed area.
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4. Bruce had recognized 3 types of Pheromones
1) Releaser pheromones
These are also know as signalling pheromones. It
stimulate the CNS of recepient an immediate change
in its behaviour. Releaser pheromones in mammals
are present in the urine and footpads. Urine of male
mice, deer, dog, horses etc. contains releaser
pheromones for attracting females.
Types of Pheromones
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5. 2)The Primer Pheromones
They evoke a prolonged or long term
endocrine or physiological responses in
receivers mediated by the direct effects
on the target organs.
For example In ants, termites and honey
bees, members of the same colony share a
common pheromone which differs from that
of the other colonies of the same
species.
3)Imprinting pheromones
They act at critical period of
developmental age and cause permanent
change in the adult behaviour.
For example mice and rats.
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6. * These are derivatives from protein & fatty acide.
* These are volatile in nature.
* These are species specific their effect depend on cone
and distance between the orgnism.
* These are secreted by endocrine gland.
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Character of Pheromones
Difference Between Hormones & Pheromones
i. These are released by endocrine gland and transmitted
externally.
ii. These are species specific and produce specific
developmental response in the bodies of other
members of the same species.

7. Mode of
Action
◎ By Olfaction Insect-Insect &
mammals both example sex
attacked.
◎ By Physical contact –Adult male
locust release .Pheromones
that comes in contact which
means that induces growth &
metamorphosis in it nymph. 7

8. Pheromones in Animals:
1. Pheromones in Invertebrates:
The males of Lepidoptera (butterflies
and moths) produce scent from glands
known as androconial which are located
in wings associated with scales.
Androconial have a somewhat elongated
structure and terminates in a row of fine
processes called fimbriae.
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Production and Perceptions
Glands producing pheromones
Pheromones are produced by definite glands. The
location & structure of these glands on the body
varies in different animals. The insects have been
most extensively studied for their pheromones and
structures related to their production and
perception.
Honey bee have 2 main gland which produce pheromones
1) Mandibular glands are located in the head region.
2) Nassanoff’s gland or Wax gland in the abdomen .
These glands are well developed in the queen and
worker’s , but generally reduced in the drones.

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◎ Silk moth produced Bombykol
◎ Bee produced Honey bee queen substance
◎ Gypsy moth produce Gyplure
◎ Musk deer produced Muscone
◎ Civet produced civetone

11. ◎ 2. Pheromones in Vertebrates:
Many vertebrate produce colour scent or pheromones to carry
out many important function . House shrew, striped hyena and
black tailed deer produced scent under stress.
The scent is released in many ways along with urine, faeces
and saliva, they are also produced through special glands.
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Markings with urine and faeces:
A. Many mammals communicate through
pheromones present in urine and/or faeces.
B. These are used to scent mark a core area, home
range or territory.
C. Some animals also use urine and faeces to mark
pathways, resting grounds, feeding grounds and
sleeping sites. It is also used to mark rivals,
opponents, defeated animals etc.

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Functions of Pheromones:
A. Sex attractants:
Female insects usually releases pheromones by exposing the
glands by movement of abdomen. Generally they are released
at particular time of the day, depending upon the diurnal or
nocturnal nature of the animal. The scent thus released excite
the approaching male and serves as a guide for reaching the
female.
A. Pheromones of males:
these are present in very few instances such as male protruding
sex attractant . This is tree of the make beetle Harpobitiacus.
B. Communication in social insects:
In case of fire ants, pheromones play a role in communication.
The worker, after discovering a food source, returns back to the
nest by laying a trail.
C. Maintenance of social structure:
The queen bee produces pheromones which help in controlling
the social structure of her colony.

13. ◎ Adverse Effects of
Pheromones:
◎ Pheromones sometimes have
certain adverse effect on the
user:
◎ 1. The pheromones produced
by Anagasta larva induce the
parasite, Venturia, to make
probing movement with its
ovipositor. This increases the
larva getting parasitized.
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◎ 2. Pheromones sometimes advertise the
presence of an insect predator and
potential parasite. The clerid beetle
(Thanasimus dubius) is a predator of
Dendroctonus (beetle). It thus is able to
locate its host by responding to the
pheromones frontalin secreted by the
host.

15. Thanks!
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