Pheromones Project submitted for Refresher Course In Current

Pheromones 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

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.

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.

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

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

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

Insect pheromones n 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.

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…

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.

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

Pheromones in mammals n 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…

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

Pheromones in mammals n 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.

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

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.

Production and perception of pheromones n n 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.

Use of pheromones Synthetic pheromones (Parapheromones) are used in three basic ways 1. 2. 3. In sampling and detection. To attract and kill To disrupt mating

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

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

Conclusion n n 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.