1. Lecture 25: The Perfumes of Sex & Life CHEMICAL COMMUNICATION

2. Key Points: Chemical communication What is the difference between semiochemicals and pheromones Describe two modes of action of pheromones How can sex pheromones improve our food quality Name three pheromones and how they work Define Intra specific and Interspecific How does an HIPV work

3. Semiochemicals KAIROMONESKAIROMONES –Inter-species specific –Advantage to the receiver ALLOMONESALLOMONES –Inter-species specific –Advantage to the sender PHEROMONESPHEROMONES –Intra-specific

4. Pheromones “ A chemical signal released to the outside of the body of the producer that effects the physiology or behavior of a receiving individual of the same species. ”“ A chemical signal released to the outside of the body of the producer that effects the physiology or behavior of a receiving individual of the same species. ” From the Greek pherein (to carry) + hormon (to excite)From the Greek pherein (to carry) + hormon (to excite)

5. Pheromones Produced from exocrine glandsProduced from exocrine glands –that ’ s EXO not ENDO –Produced in liquid, but can be released as –streams, droplets, thin films, aerosols Creation of the “ Active Space ”Creation of the “ Active Space ”

6. Pheromonal Active Space For some insects it can be quite largeFor some insects it can be quite large –Gypsy Moth –1,800 meters (that is more than one mile) by 100 meters by 100 meters by 50 meters by 50 meters And powerfulAnd powerful –one GM female possesses 0.01 μg which hypothetically could incite a response in one billion males.

7. Pheromones Two MODES OF ACTIONTwo MODES OF ACTION 1) RELEASERS immediate effect on the central nervous system & behavior of the receiving animal. 2) PRIMERS triggers a chain of physiological- developmental events that may take days, to weeks before an overt response is seen.

8. Pheromones Classes/TypesClasses/Types –Sex pheromones –Trail pheromones –Alarm pheromones –Aggregation pheromones –“ Social ” pheromones

9. Sex Pheromones The best known & best studied of all pheromone classes.The best known & best studied of all pheromone classes. –Function: Gender attraction –Most frequently females “ calling ” to males –Occasionally males “ calling ” to females –Rarely, sex attractants released by both genders of a species.

10. Sex Pheromones Chemistry of sex pheromones known for several hundred insect species.Chemistry of sex pheromones known for several hundred insect species. Uses:Uses: –monitoring –control trap outtrap out male confusionmale confusion

12. Vine mealybug a) native to the Mediterranean region b) spreading throughout CA vineyards

13. “Microencapsulated” sex pheromone and mating disruption Control Sex pheromone a 0 1 2 3 4 5 VMB / vine / 2 min search b

14. Anagyrus pseudococci

15. Trail Pheromones Commonly found in numerous social insect speciesCommonly found in numerous social insect species –ants, termites & some non-social aggregating caterpillars (tent caterpillars) –Used for orientation to & from the nest for the establishment of foraging trails (highways)

16. Trail Pheromones VolatileVolatile –frequently added to when forage is rewarding –quickly dissipates when forage is reduced SourcesSources –tarsal glands - abdominal glands - venom Potential for control??Potential for control?? –Has been tried experimentally with pest ants e.g., fire antse.g., fire ants

17. Alarm Pheromones Common in social insects & aggregate feedersCommon in social insects & aggregate feeders –wasps, termites, bees, & some aphids FunctionFunction –defense recruitment of nest-matesrecruitment of nest-mates –dispersal aphidsaphids VolatileVolatile

18. Aggregation Pheromones Function:Function: –Signal that recruits conspecifics to a food source. –Known in bark beetles & certain desert grasshoppers. –Can also function in an anti-aggregation mode when sufficient individuals are present.

19. Herbivore induced plant volatile (HIPV’s) Produced by plants when herbivores feed on them Pulls in natural enemies and increases biocontrol i.e. winter green (methyl salicylate)

20. “ Social Pheromones ” Best known in the social Hymenoptera, most especially the honey bee.Best known in the social Hymenoptera, most especially the honey bee. “ Queen Substance ” “ Queen Substance ” first elucidated in the 1950 tiesfirst elucidated in the 1950 ties chemically complex (long chain fatty acids)chemically complex (long chain fatty acids) from the mandibular glands of a gynefrom the mandibular glands of a gyne

21. “ Social Pheromones ” Gynes have a dilemmaGynes have a dilemma –Must maintain their reproductive status!! –Do this in two ways: suppress ovarian development by daughterssuppress ovarian development by daughters prevent daughters from replacing her.prevent daughters from replacing her. –Solution chemo-sterilizationchemo-sterilization

22. Key Points: Chemical communication What is the difference between semiochemicals and pheromones Describe two modes of action of pheromones How can sex pheromones improve our food quality Name three pheromones and how they work Define Intra specific and Interspecific How does an HIPV work