1. Pheromones and Insect Communication
By Jennie Englehart

2. What are Pheromones?
Pheromones are molecules used for communication between organisms. Chemicals involved in communication are known as semiochemical.
Pheromones are a subclass of semiochemicals used for intraspecific communication of species.

3. What are Pheromones?
Primer Pheromones have longer term physiological effects on the receiver.
Examples of primer pheromones include:
Termite Caste determination
Locust development rates
Any pheromone that has effects on the development of the organism receiving the signal is considered a primer pheromone.

4. What are Pheromones?
Releaser Pheromones illicit an immediate behavioural response in the receiver.
Most pheromones are releaser pheromones and are divided into groups based upon function such as:
Sexual
Aggregation
Alarm
Recruitment
Territorial

5. What are Pheromones?
Chemicals involved in interactions with members of a different species are called allelochemicals and are divided based on the benefits or costs of the signaller or receiver:
Effect
Allomones
Benefit the sender
Kairomones
Benefit the receiver
Synomones
Benefit both

6. Advantages/Disadvantages of Chemical Communication
Effective over far distances
Effective in environments with reduced visual stimuli
Longer lasting than visual or auditory signals
Metabolically "inexpensive" because only small quantities are needed   

7. Advantages/Disadvantages of Chemical Communication
Low information content (presence/absence)
Difficult to locate sender
Long fade time

8. Specificity
In biological signalling systems, selection pressures such as interspecific sexual selection and speciation result in specificity of the signal.
Alarm signals may not be species specific.
Predator-prey signalling resulting in cross-species evolution of the signal
Prey species with shared predators will respond to the same signal
Means of gaining specificity:
Evolution of large peptide molecules
Stereoisomers of phereomone molecule
Enantiomers
The mosquito, Culex quinquefasciatus, has an oviposition pheromone known as 1-Bombykol
Chiral cpd

9. Coding by olfactory receptors
Pheromone molecules strike antennal sensilli and enter a pore system that has tubules leading to the dendritic terminal where transduction of the polarized dendrite occurs.
Odour molecules bind to receptor sites on the membrane of the dendrite which give rise to nerve impulses

10. Coding by olfactory receptors
The code of information is passed to the antennal lobe.
Terminate in branches on antennal glomeruli.
Neurons with cell bodies in antennal lobe synapse with incoming receptor axons and project to lateral lobes of the protocerebrum, sending branches to the mushroom body calyces.
Descending neurons with cell bodies in protocerebrum lead from lateral lobes to motor centres in the ventral nerve cord of the insect.

11. Pheromone Secretary Organs in Insects
Exocrine Glands are divided into two types based on their structural organization of secretory cells:
Type I
Glands with secretory cells of Type I are directly derived from the tegumental epidermis. Secretory cells form a monolayered epithelium either as part of the external body tegument through which they directly discharge their secretory products.
Type III
More complex
The gland is formed by a variable number of bicellular units, each comprising a secretory cell and duct cell.
Type I unicellular glands on the antennae of Aleochara bilineata

12. Primer Pheromones Termite Caste Determination
Several primer pheromones affect juvenile hormone levels and other endocrine glands or receivers.
Pheromones inhibit differentiation of pseudogates

13. Primer Pheromones Locust Development
Adults and nymphs have separate aggregation pheromone systems
Aggregation pheromone produced by gregarious is mediated by primer pheromones, so it acts as a primer that speeds of maturation of females.
Nymphal aggregation pheromones have the primer effect of slowing down the development of adults of either sex.
Lead to synchronised development of locust.

14. Sex Pheromones
Chemical signalling through pheromones may be an effective means for females to attract males for copulation.

15. Aggregation and Host-marking pheromones
Aggregation pheromones lead to the formation of groups near the pheromone source
This may be through attracting organisms or stopping passing conspecifics.

16. Aggregation and Host-marking pheromones
Parasitic insects often mark their hosts using host-marking pheromones
Host marking species lay their eggs in hosts of limited size, which can successfully support developping parasitoid larvae

17. Alarm Pheromones
Alarm pheromones are fight or flight responses to stressful environments.
Bees release an alarm pheromone soon after stinging a predator.

18. Alarm Pheromones
Slave making ants take advantage of alarm pheromones as well.

19. Recruitment Pheromones
Among social insects, trail following (or recruitment) pheromones are clearly defined.
These pheromones are useful in foraging and recruitment to food

20. Territorial/Home Range Pheromones
Pheromones in the form of scent marks have an important role in territorial behaviour in insects.
A benefit of scent mark comes from the unique separation of signaller and signal
Territorial pheromones have a low energy investment

21. Queen Recognition Pheromones
Pheromones produced by social insect queens perform both primer and releaser functions in controlling colony behaviour.
Primer pheromones function by physiologically altering the reproductive systems.
The queen also emits a releaser pheromone to attract workers to their queen

22. Queen Recognition Pheromones
Worker produced pheromones
Workers do not produce queen pheromone; their main mandibular gland is used in royal jelly.
Other worker produced pheromones are often used in alarm and defensive behaviour.

23. Pheromones and Predator-Prey Interactions
Some predators conceal their own ‘odour’ in order to gain acceptance into social insect colonies.
This is achieved through the use of cuticular hydrocarbons.

24. Mutualism
Many mutualistic interactions between conspecifics require chemical cues.
Interspecific interaction between insects and other species in which both benefit is mutualistic.
An excellent example may be the interaction between Ants and lycaenid butterfly caterpillars

25. Mutualism
pMg

26. Evesdropping
Pheromonal excretions of insects may be exploited by conspecifics, predators, or parasites through ‘evesdropping’

27. Pheromone Communication in Social Insects
Recognition of kin
Recognition of members of the same family in insects may be mediated by chemical cues such as pheromones.

28. Pheromone Communication in Social Insects
Nestmate recognition
Nestmate recognition is another common facet of pheromone communication.
Recognition of members of the same nest site is vastly important in protection of the nest site.

29. Application of Pheromones in Pest Management
Synthesis of insect pheromones may be exploited industrially by means of synthesizing pheromones of insect pests.
These pheromones may be proven useful in protecting crops and residents

30. Application of Pheromones in Pest Management
Pest management may be mediated through:
Mass trapping
Lure and kill
Mating disruption

31. Conclusion

32. References
P. Howse, I. Stevens, O. Jones,1998 , Insect Pheromones and their Use in Pest Management
T. Wyatt, 2003, Pheromones and Animal Behaviour
R. Vander Meer, M. Breed, K. Espelie, M. Winston, 1998, Pheromone Communication in Social Insects
Happ et al, 1968, Bioassay, Preliminary Purification , and Effect of Age , Crowding, and Mating on the Release of Sex Pheromone by Female Tenebrio molitor
Tillman et al, 1999, Insect pheromones—an overview of biosynthesis and endocrine regulation
Holldobler et al, 2001, Recruitment pheromone in the harvester ant genus Pogonomyrmex
Maclean et al, 2003, Calorimetric investigations on the action of alarm pheromones in the hornet Vespa crabro
Wang et al, 2008, Processing of sting pheromone and its components in the antennal lobe of the worker honeybee
Branco et al, 2006, Modelling response of insect trap captures to pheromone dose
Tschinkel et al, 1967, Sex Pheromone of the Mealworm Beetle
Bryning et al, 2005, IDENTIFICATION OF A SEX PHEROMONE FROM MALE
YELLOW MEALWORM BEETLES, Tenebrio molitor
Tanaka et al, 1985, A Sex Attractant of the Yellow MealWorm , Tenebrio molitor and its Role in mating behaviour

33. Questions.....