1. Pheromones Dr.ANJU JAIN Project submitted for Refresher Course In
“Current Trends in Physiology”
Conducted by
Department of Zoology, University of Delhi
Sponsored by
CPDHE
Submitted by
Dr.ANJU JAIN
Lecturer in Zoology
University of Delhi
January 2003

2. Definition
A pheromone is a chemical or mixture of chemicals that is released into the environment by an organism and that causes a specific behavioral or physiological reaction in a receiving organism of the same species.

3. Chemicals in Communication
Semiochemicals are the substances that carry information between organisms.
Allelochemics are the semiochemicals used for interspecies communication.
Pheromones are the semiochemicals used for intraspecies communication.

4. Types of pheromones
Signalling (releaser) pheromones:
They induce a rapid behavioural response in the recipient usually mediated through the Central Nervous System
contd…

5. Types of pheromones
Imprinting pheromones cause permanent alterations in adult behaviour by organizing the central nervous system of the preweaning offspring at a critical period.
contd…

6. Types of pheromones
Primer pheromones: They bring about a delayed response to prolonged stimulation in the recipient mediated through neuroendocrine pathway

7. Insect pheromones
1. Sex pheromones: They are produced by females to attract males or may be produced by males to attract females. The release of sex pheromone is often associated with sexual maturity and environmental stimuli such as light intensity and photoperiod. Female sex pheromones are usually received by sensory sensillae on male antennae.

8. Insect pheromones
2 Alarm pheromones: They elicit attack or retreat behaviour and are common in social insects such as ants and bees.
3. Aggregation pheromones: These pheromones cause insects to aggregate or congregate at food sites, reproductive habitats and hibernation sites. They are well known in bark beetles and Dendroctonus.
contd…

9. Insect pheromones
4. Trail marking pheromones: These pheromones are produced by foraging termites and ants to indicate sources of requisites to other members of the colony.
5.  Spacing pheromones: They are also called as epideictic pheromones and they elicit dispersal away from potentially crowded food sources, thereby reducing the numbers. They are the pheromones that serve to repel, rather than attract.

10. Pheromones in Fishes Pheromones are involved in alarm reaction
schooling behaviour
migration
individual and species identification
reproduction

11. Pheromones in mammals
The odour of a strange male mouse blocked the pregnancy of a newly conceived female mouse. The odour of the original male left pregnancy undisturbed. Odour of the strange male suppressed the secretion of the hormone prolactin so that normal estrous was restored; this is referred as Helen-Bruce effect. However, after 6 days of first copulation Bruce effect does not occur.
contd…

12. Pheromones in mammals
· Rats living in groups show a similar estrous synchronizing phenomenon with chemosensory cues providing the stimuli allowing synchronization of estrous cycle (McClintock, 1979).
· Tiger produce pheromones to mark their respective territories. Phenylehylamine was the main constituent.

13. Pheromones in mammals
Dogs use urine to mark their territories, the pheromones present in urine indicates minute details like individual identity, male or female, dominant or sub-dominant etc.

14. Human Pheromones
In 1971 McClintock observed Lee Boot effect i.e.; synchronization in onset of their menstrual dates, the reason assigned was body smell.
George Dodd reported pheromone called X-androstenol from male sweat, and its principal function is in attracting the females, during sexual interaction.
contd…

15. Human Pheromones
A recent study established the existence of 2 human pheromones in women, one produced prior to ovulation during the follicular phase which shortens the ovarian cycle in recipients and a second one produced around the time of ovulation which lengthens the ovarian cycle in recipients.

16. Production and perception of pheromones
Pheromones are produced by definite glands. The location and structure of these glands on the body varies in different organisms. Mandibular glands, scent glands, labial glands, abdominal glands and anal glands are some of the examples.
Structures perceiving pheromone consists of receptor cells and nerves and the messages are sent to central nervous system.

17. Use of pheromones
Synthetic pheromones (Parapheromones) are used in three basic ways 
In sampling and detection.
To attract and kill
To disrupt mating

18. Advantages of Pheromones vs
Advantages of Pheromones vs. Insecticides for the Control of Insect Pests
extremely specific
low effective dose
non-toxic
non-persistent in the environment
compatible with other IPM practices

19. technical aspects of application
Disadvantages of Pheromones vs. Insecticides for the Control of Insect Pests
technical aspects of application
each pest species has a unique pheromone
high synthesis costs

20. Conclusion
Pheromonal communication still remains largely unexplored, we have very little information on the chemistry synthesis, neural, endocrine mechanisms, and biological functions of the pheromones in human beings.
 Further research will help to explore the possibilities to use pheromone based methods in combination with other methods for direct insect control.