Voltinism is a term used in biology to indicate the number of broods or generations of an organism in a year. The term is most often applied to insects, and is particularly in use in

sericulture Sericulture, or silk farming, is the cultivation of silkworms to produce silk. Although there are several commercial species of silkworms, ''Bombyx mori'' (the caterpillar of the domestic silkmoth) is the most widely used and intensively studie ...

, where

silkworm The domestic silk moth (''Bombyx mori''), is an insect from the moth family Bombycidae. It is the closest relative of ''Bombyx mandarina'', the wild silk moth. The silkworm is the larva or caterpillar of a silk moth. It is an economically imp ...

varieties vary in their voltinism. * Univoltine (monovoltine) – (adjective) referring to organisms having one brood or generation per year * Bivoltine (divoltine) – (adjective) referring to organisms having two broods or generations per year *Trivoltine – (adjective) referring to organisms having three broods or generations per year * Multivoltine (polyvoltine) – (adjective) referring to organisms having more than two broods or generations per year * Semivoltine – There are two meanings: :* (''biology'') Less than univoltine; having a brood or generation less often than once per year :* or (adjective) referring to organisms whose

generation time In population biology and demography, generation time is the average time between two consecutive generations in the lineages of a population. In human populations, generation time typically ranges from 22 to 33 years. Historians sometimes use this ...

is more than one year.

Examples

The

speckled wood butterfly The speckled wood (''Pararge aegeria'') is a butterfly found in and on the borders of woodland areas throughout much of the Palearctic realm. The species is subdivided into multiple subspecies, including ''Pararge aegeria aegeria'', ''Pararge ae ...

is univoltine in the northern part of its range, e.g. northern Scandinavia. Adults emerge in late spring, mate, and die shortly after laying eggs; their offspring will grow until

pupation A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in thei ...

, enter

diapause In animal dormancy, diapause is the delay in development in response to regular and recurring periods of adverse environmental conditions.Tauber, M.J., Tauber, C.A., Masaki, S. (1986) ''Seasonal Adaptations of Insects''. Oxford University Press It ...

in anticipation of the winter, and emerge as adults the following year – thus resulting in a single generation of butterflies per year. In southern Scandinavia, the same species is bivoltine – here, the offspring of spring-emerging adults will develop directly into adults during the summer, mate, and die. Their offspring in turn constitute a second generation, which is the generation that will enter winter diapause and emerge as adults (and mate) in the spring of the following year. This results in a pattern of one short-lived generation (c. 2–3 months) that breeds during the summer, and one long-lived generation (c. 9–10 months) that diapauses through the winter and breeds in the spring. The Rocky Mountain parnassian and the

High brown fritillary ''Fabriciana adippe'', the high brown fritillary, is a large and brightly colored butterfly of the family Nymphalidae, native to Europe and across the Palearctic to Japan. It is known for being Great Britain's most threatened butterfly and is li ...

are more examples of univoltine butterfly species.Aalberg Haugen IM, Berger D, and Gotthard K. 2012. The evolution of alternative developmental pathways: footprints of selection on life-history traits in a butterfly. 12pp. Journal of Evolutionary Biology, 25:7, Available online

/ref> The bee species ''

Macrotera portalis ''Macrotera portalis'' is a species of communal, ground nesting, partially bivoltine bees found in arid grasslands and desert regions of North America. An oligolectic bee, ''M. portalis'' gathers pollen only from plants in the genus ''Sphaeralcea ...

'' is bivoltine, and is estimated to have about 2 or 3 broods annually. During winter, individuals remain in diapause, in their pharate or prepupal stage. This diapause stage continues until metamorphosis in the next spring or summer, whereupon the bees emerge as adults.Buchmann, Stephen L
"Bees"
''

Bees Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyletic lineage within the superfamil ...

'', Retrieved on 15 October 2015. Another example of a bivoltine species is ''

Cyclosa turbinata ''Cyclosa turbinata'' is a species of orb weaver belonging to the family of spiders known as Araneidae. It is found in a range from the United States to Panama, West Indies, Galapagos Islands, and has been introduced into Hawaii. Geographic Loc ...

'' which is known to reproduce once in the late spring and once again in the fall. The Dawson's burrowing bee is an example of a univoltine insect of the order

Hymenoptera Hymenoptera is a large order (biology), order of insects, comprising the sawfly, sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are Par ...

. The brood of one winter will remain dormant underground until the following winter, and then will surface from their burrows to mate once, and establish new nests.

Partial voltinism

The term partial voltinism is used to refer to two different (but not necessarily exclusive) situations: * An organism wherein generations overlap in time, and so are not completely reproductively isolated. For example, in bees of the subfamily

Halictinae Within the insect order Hymenoptera, the Halictinae are the largest, most diverse, and most recently diverged of the four halictid subfamilies. They comprise over 2400 bee species belonging to the five taxonomic tribes Augochlorini, Thrinchos ...

, one generation is produced in the early summer and one in the late summer, but males produced in the early summer may also

mate Mate may refer to: Science * Mate, one of a pair of animals involved in: ** Mate choice, intersexual selection ** Mating * Multi-antimicrobial extrusion protein, or MATE, an efflux transporter family of proteins Person or title * Friendship ...

in the late summer.Seger J. 1983. Partial bivoltinism may cause alternating sex-ratio biases that favor eusociality. 4pp. Nature, 301:59-62, Available online

/ref> * (More commonly) a population where the voltinism is mixed, because of genetic variation (e.g., in the

hybrid zone A hybrid zone exists where the ranges of two interbreeding species or diverged intraspecific lineages meet and cross-fertilize. Hybrid zones can form ''in situ'' due to the evolution of a new lineage but generally they result from secondary contact ...

between a univoltine and a bivoltine area) and/or because environmental stimuli do not induce bivoltinism in all individuals (or across all years). For example, far-northern populations of the

green-veined white The green-veined white (''Pieris napi'') is a butterfly of the family Pieridae. Appearance and distribution A circumboreal species widespread across Europe and Asia, including the Indian subcontinent, Japan, the Maghreb and North America. It is ...

butterfly ''Pieris napi'' are mostly univoltine, but some individuals may avert

and produce an additional generation under warm conditions.Kivelä SM, Svensson B, Tiwe A, and Gotthard K. 2015. Thermal plasticity of growth and development varies adaptively among alternative developmental pathways. 13pp. Evolution, 69:9, Available online

/ref>

Evolution

The number of breeding cycles in a year is under genetic control in many species and they are evolved in response to the environment. Many

phytophagous A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpar ...

species that are dependent on seasonal plant resources are univoltine. Some such species have the ability to

for a large part of the year, typically during a cold winter.Hunter, M.D. and J.N. McNeil. 1997 Host-plant quality influences diapause and voltinism in a polyphagous insect herbivore. Ecology 78: 977-986

/ref> Others that bore in wood or other low-grade, but plentiful, food material may spend nearly the entire year feeding, with only brief pupal, adult and egg stages to complete a univoltine life cycle. Yet other species that live in tropical regions with little seasonality may be highly multivoltine, with several generations feeding on constantly growing vegetation (such as some species of

Saturniidae Saturniidae, commonly known as saturniids, is a family of Lepidoptera with an estimated 2,300 described species. The family contains some of the largest species of moths in the world. Notable members include the emperor moths, royal moths, and gi ...

), or continually renewed detritus, such as ''

Drosophila ''Drosophila'' () is a genus of flies, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or (less frequently) pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species ...

'' and many other genera of flies with a life cycle of just a week or two.

References

{{reflist Reproduction

Examples

Partial voltinism

Evolution

See also

References