Adenotrophic

viviparity Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the m ...

means "gland fed, live birth". This is the reproductive mode of insects such as

tsetse flies Tsetse ( , or ) (sometimes spelled tzetze; also known as tik-tik flies), are large, biting flies that inhabit much of tropical Africa. Tsetse flies include all the species in the genus ''Glossina'', which are placed in their own family, Glo ...

(

Glossinidae Tsetse ( , or ) (sometimes spelled tzetze; also known as tik-tik flies), are large, biting flies that inhabit much of tropical Africa. Tsetse flies include all the species in the genus ''Glossina'', which are placed in their own family, Glos ...

), keds (

Hippoboscidae __NOTOC__ Hippoboscidae, the louse flies or keds, are obligate parasites of mammals and birds. In this family, the winged species can fly at least reasonably well, though others with vestigial or no wings are flightless and highly apomorphic. As ...

) and bat flies (

Streblidae The Streblidae are a family of flies in the superfamily Hippoboscoidea, and together with their relatives the Nycteribiidae, are known as bat flies. They are winged or wingless ectoparasites of bats, and often have long legs. They appear to be ho ...

and

Nycteribiidae Nycteribiidae is a family of the true fly superfamily Hippoboscoidea are known as "bat flies", together with their close relatives the Streblidae. As the latter do not seem to be a monophyletic group, it is conceivable that bat flies cannot be u ...

), as adenotrophic viviparity is a characteristic feature of the superfamily

Hippoboscoidea Hippoboscoidea is a superfamily of the Calyptratae. The flies in this superfamily are blood-feeding obligate parasites of their hosts. Four families are often placed here: * Glossinidae - Tsetse flies *Hippoboscidae - Ked flies *Nycteribiidae - B ...

. It has also been observed in members of the subfamily Mesembrinellinae. In adenotrophic viviparity, the eggs (usually one at a time) are retained within the female's body, hatch, and are nourished through "milk glands" until the developed larvae are ready to

pupate 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 their ...

. The larvae are then 'larviposited' and immediately pupate. This is one way insects avoid predation during their most vulnerable life stage. Following the birth of the juvenile, lactation ceases and a period of

involution Involution may refer to: * Involute, a construction in the differential geometry of curves * '' Agricultural Involution: The Processes of Ecological Change in Indonesia'', a 1963 study of intensification of production through increased labour inpu ...

of the milk gland secretory cells begins where they return to their original size. During this period,

embryogenesis An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm ...

begins in the next egg. The glands producing the milk secretions differ between the Hippoboscoidea and Mesembrinellinae observances; in the latter, lactation occurs via

accessory glands Male accessory glands (MAG) in humans are the seminal vesicles, prostate gland, and the bulbourethral glands (also called Cowper's glands). In insects, male accessory glands produce products that mix with the sperm to protect and preserve them, in ...

and

spermatheca The spermatheca (pronounced plural: spermathecae ), also called receptaculum seminis (plural: receptacula seminis), is an organ of the female reproductive tract in insects, e.g. ants, bees, some molluscs, oligochaeta worms and certain other ...

e as opposed to specific milk glands. In either case, the milk secretions are closely analogous to mammalian milk, including proteins such as

lipocalin The lipocalins are a family of proteins which transport small hydrophobic molecules such as steroids, bilins, retinoids, and lipids and most lipocalins are also able to bind to complexed iron (via siderophores or flavonoids) as well as heme. T ...

s and MGP2–10 proteins (the latter of which are analogous to

casein Casein ( , from Latin ''caseus'' "cheese") is a family of related phosphoproteins (CSN1S1, αS1, aS2, CSN2, β, K-casein, κ) that are commonly found in mammalian milk, comprising about 80% of the proteins in cow's milk and between 20% and 60% of ...

s in mammals) and bacterial

endosymbiont An ''endosymbiont'' or ''endobiont'' is any organism that lives within the body or cells of another organism most often, though not always, in a mutualistic relationship. (The term endosymbiosis is from the Greek: ἔνδον ''endon'' "within" ...

s (such as ''

Wigglesworthia glossinidia ''Wigglesworthia glossinidia'' is a species of gram-negative bacteria which was isolated from the gut of the tsetse fly. ''W. glossinidia'' is a bacterial endosymbiont of the tsetse fly. Because of this relationship, ''Wigglesworthia'' has lost a ...

'' in the tsetse fly). Adenotrophic viviparity differs from

ovoviviparity Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop insi ...

, in which one or more eggs hatch internally in the female, but they are not nourished after hatching and are immediately 'larviposited' and continue their development outside the female.

References

Insect physiology {{insect-stub