page_title: Pheromone
section_title: Sex
hierarchical_section_title: Pheromone / Types / Sex
caption_attribution_description: English: Danaus chrysippus, known as the Plain Tiger or African Monarch, is a common butterfly which is widespread in Asia and Africa. It belongs to the Danainae ("Milkweed butterflies") subfamily of the brush-footed butterfly family, Nymphalidae. The Plain Tiger can be considered the archetypical danaine of India. Accordingly, this species has been studied in greater detail than other members of its subfamily occurring in India. The male Plain Tiger is smaller than the female, but more brightly colored. In addition, males have a number of secondary sexual characteristics. The male has a pouch on the hindwing. This spot is white with a thick black border and bulges slightly. It is a cluster of specialised scent scales used to attract females. The males possess two brush-like organs which can be pushed out of the tip of the abdomen. Taken at Kudayathoor, Kerala, India. മലയാളം: എരിക്കുതപ്പി ചിത്രശലഭം. എറണാകുളം ജില്ലയിലെ കടവൂര് നിന്നുമെടുത്ത ചിത്രം.
context_page_description: A pheromone is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to impact the behavior of the receiving individuals. There are alarm pheromones, food trail pheromones, sex pheromones, and many others that affect behavior or physiology. Pheromones are used from basic unicellular prokaryotes to complex multicellular eukaryotes. Their use among insects has been particularly well documented. In addition, some vertebrates, plants and ciliates communicate by using pheromones.
context_section_description: In animals, sex pheromones indicate the availability of the female for breeding. Male animals may also emit pheromones that convey information about their species and genotype.
  At the microscopic level, a number of bacterial species (e.g. Bacillus subtilis, Streptococcus pneumoniae, Bacillus cereus) release specific chemicals into the surrounding media to induce the "competent" state in neighboring bacteria. Competence is a physiological state that allows bacterial cells to take up DNA from other cells and incorporate this DNA into their own genome, a sexual process called transformation.
  Among eukaryotic microorganisms, pheromones promote sexual interaction in numerous species. These species include the yeast Saccharomyces cerevisiae, the filamentous fungi Neurospora crassa and Mucor mucedo, the water mold Achlya ambisexualis, the aquatic fungus Allomyces macrogynus, the slime mold Dictyostelium discoideum, the ciliate protozoan Blepharisma japonicum and the multicellular green algae Volvox carteri. In addition, male copepods can follow a three-dimensional pheromone trail left by a swimming female, and male gametes of many animals use a pheromone to help find a female gamete for fertilization.
  Many well-studied insect species, such as the ant Leptothorax acervorum, the moths Helicoverpa zea and Agrotis ipsilon, the bee Xylocopa sonorina and the butterfly Edith's checkerspot release sex pheromones to attract a mate, and some lepidopterans (moths and butterflies) can detect a potential mate from as far away as 10 km (6.2 mi). Some insects, such as ghost moths, use pheromones during lek mating. Traps containing pheromones are used by farmers to detect and monitor insect populations in orchards. In addition, Colias eurytheme butterflies release pheromones, an olfactory cue important for mate selection.
  The effect of Hz-2V virus infection on the reproductive physiology and behavior of female Helicoverpa zea moths is that in the absence of males they exhibited calling behavior and called as often but for shorter periods on average than control females. Even after these contacts virus-infected females made many frequent contacts with males and continued to call; they were found to produce five to seven times more pheromone and attracted twice as many males as did control females in flight tunnel experiments.
  Pheromones are also utilized by bee and wasp species. Some pheromones can be used to suppress the sexual behavior of other individuals allowing for a reproductive monopoly – the wasp R. marginata uses this. With regard to the Bombus hyperboreus species, males, otherwise known as drones, patrol circuits of scent marks (pheromones) to find queens. In particular, pheromones for the Bombus hyperboreus, include octadecenol, 2,3-dihydro-6-transfarnesol, citronellol, and geranylcitronellol.
  Pheromones are also used in the detection of oestrus in sows. Boar pheromones are sprayed into the sty, and those sows that exhibit sexual arousal are known to be currently available for breeding. Sea urchins release pheromones into the surrounding water, sending a chemical message that triggers other urchins in the colony to eject their sex cells simultaneously.
caption: Male Danaus chrysippus showing the pheromone pouch and brush-like organ in Kerala, India
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