Pheromones
(exohormones, ectohormones)
Bi1100en Hormones – Cellular and Molecular Mechanisms
Substances ensuring chemical communication among individuals of the
same species.
▪ excreted by the exocrine glands into the environment (excretion or secretion)
▪ invertebrates (insects, echinoderms), some vertebrates, plants, but also
unicellular organisms (fungi)
▪ neural and hormonal regulation
▪ mostly volatile, but also liquid in nature
▪ usually active in minute amounts and low concentrations (several molecules)
▪ act over long distances
▪ affected by atmospheric conditions
▪ effect on behavior, development processes
Pheromones
According to the chemical structure of the pheromone.
By type of behavior that is affected:
▪ sex - Partner localisation, pre-mating behavior, but also pheromones
regulating reproduction (e.g. marking a place for the egg laying)
▪ warning / alarm - defensive behavior and escape reactions (e.g. aphids) or
aggression (e.g. ants or bees)
▪ aggregation / antiaggregation (dispersing) - act independently of sex for
the purpose of defending, reproducing or designating a food source (e.g.
Coleoptera, Diptera, Hemiptera, or Orthoptera)
▪ territorial (e.g. in the urine of dogs and cats)
▪ tracking (e.g. marking of food routes by ants)
▪ migratory (e.g. synchronised migration of caterpillars)
▪ triggering (releaser) - act for a short time, but elicits a strong response (e.g.
pheromones produced by a female rabbit during lactation trigger and
strengthen nursing behavior)
Types of pheromones
▪ neuronal and hormonal control of
pheromone production (e.g.
pheromone biosynthesisactivating
neuropoptides, PBAN)
▪ synthetic pathway according to
the chemical structure of the
pheromone
Pheromones – mode of action
https://doi.org/10.3389/fendo.2011.00046
Helicoverpa armigera
▪ affect recipients through the activation of nerve pathways, including the
autonomic nervous system
▪ crossing the body surface > providing protection against degrading enzymes
and binding to receptors in the olfactory organs (tentacles, sensills) >
depolarization of neuronal receptor > brain > response of target organism
▪ physiological changes, affecting the immune system (inflammatory response)
or behavior
Pheromones – mode of action
Bombyx mori
▪ E10,Z12-hexadecadien-1-ol
▪ pheromone produced by female silkworms (Bombyx mori) attracting males
▪ binding to the pheromone-binding protein (BmorPBP), which transfers the
pheromone to its own receptor
▪ used in pheromone traps to confuse males who do not subsequently find
females
Bombykol – the first described pheromone
(Adolf Butenandt, 1959)
Pheromones of invertebrates
▪ e.g. neamtode ascarosides (wormbook.org)
▪ simple molecules > rearrangement produces pheromones with different effects
▪ ascaroside 3 attracts males but repels hermaphrodites
▪ modified ascaroside 3 is the strong attractant even for hermaphrodites
Honey bee pheromones
„Primer“ pheromones - trigger physiological changes without immediate effect
on behavior (control of caste development and reproduction)
"Releaser“ pheromones - cause immediate changes in behavior (aggregation,
foraging, caring for offspring, etc.)
Queen's pheromones
▪ effect on activity of workers, suppresses
the production of new workers and queen
Pheromones of workers
▪ ethyloleate inhibits onset of foraging
Pheromones of drones
▪ mandibular gland - engagement flights
Pheromones of brood
▪ together with queen‘s pheromone
regulate ovarian development
▪ a chemically very diverse group of substances
isopentyl acetate
terpenoid citral
2-heptanone
9-oxo-2-trans-decenoic acid
Honey bee pheromones
Honey bee pheromones
Mandibular gland
▪ queen signal (17 major chemical components; e.g. 9-oxo-2-trans-decenoic
acid or 4-hydroxy-3-methoxyphenyl ethanol)
Koschevnikov gland
▪ produces alarm hormone in workers (released after using a sting)
Dufour's gland
▪ fertility signal important for egg laying and worker defense
Tarsal glands
▪ oily product – foraging workers, suppresses the development of new mother
Nasonov gland
Honey bee pheromones
Nasonov pheromone
▪ released only by workers (Nasonov gland on the dorsal side of abdomen)
▪ a mixture of several substances (citral, ditral, nerol, geraniol, nerolicacid,
geranicacid, farnesol); produced artificially (attracting swarms, pollination)
▪ guiding other individuals to the hive or to a source of food and water that
does not have its own characteristic odor trace
Vertebrate pheromones
▪ captured generally by olfactory cells (small volatile molecules), by cells in
vomeronasal organ (VNO, Jacobson‘s organ) or both
▪ VNO in amphibians, reptiles and mammals (except of most of the primates),
it is not present in birds
▪ the role of VNO in humans is still a quaestion (present in the fetus, then
apparently atrophies)
▪ a number of G protein-coupled VNO receptors identified (V1Rs, V2Rs and
V3Rs families); they can be used to detect pheromones
Vertebrate pheromones - gene for ancestral V1 receptor
Mol. Biol. Evol. 2018 35(12):2928–2939 doi: 10.1093/molbev/msy186
Vertebrate pheromones
▪ receptor in VNO > primary neural processing in accassory olfactory bulbs
(AOB) > progression to deeper areas of the brain (amygdala, hypothalamus)
> influencing behavior and physiological processes (e.g. endocrine activity)
How Animals Communicate Via Pheromones
Vertebrate pheromones
▪ hypothalamic-pituitary-adrenal / gonadal axis stimulation
▪ male pigs secrete steroid hormones in their saliva (3α-androstenol and 5αandrostenone),
to which the sows respond with a mating behavior
▪ mice differentiate close relatives based on olfactory signals, thus minimizing
the risk of inbreeding in mating (Science. 1994 Oct 14;266(5183):271-3)
▪ anxiety in rats can be caused by the pheromone from perianal glands
(PNAS. 2014 Dec 30;111(52):18751-6. doi: 10.1073/pnas). Two substances
> binding to V1Rs and MOS receptors (main olfactory system) > activation of
olfactory systems > behavior change.
Mammalian pheromones
▪ research of human pheromones problematic (presence in mixtures x purity)
▪ the main sense is sight, but olfactory system is present > pheromones
▪ genes encoding VNO receptors dysfunctional, no evidence of VNO association
with CNS x pheromone receptors have been identified in the olfactory mucosa
▪ potentially, steroids are used as pheromones (androstenol, androstenone,
androsterone and others released in the armpit)
Synchronisation of the menstrual cycle?
Androstenone as an attractant for women?
Underarm pheromones provide information about the immune system (the role of
MHC in partner selection)?