Laboratory of  Experimental Entomology and BioControl Theory Russia, 199034, St.-Petersburg, Zoological Institute.  Phone: +7 (812) 714 0442; Fax: +7 (812) 714 0444; E-mail:  sreznik@zin.ru

Diapause in flies (Diptera) and its control

Project conducted by E.B. Vinogradova

The results of this project were summarized in the monograph:

E.B. Vinogradova. 1991. Diapause in flies and its control (Proceedings of ZIN RAS Vol. 214).  St. Petersburg, Nauka. 253 pp. (in Russian)

The main ideas on the diapause phenomenon and its photoperiodic and temperature control in flies (Calliphoridae, Sarcophagidae and Muscidae) are summarized in this monograph. They are based on the results of numerous experimental investigations, which were conducted mainly by three scientists: D.L. Denlinger, D.S. Saunders and the author. Morphological, physiological and behavioral traits of diapause are considered. The syndrome of the reproductive diapause includes the suppression of ovaries and accessory glands development, cessation of the mating (though the spermatogenesis takes place), hypertrophy of the fat body and the change in its biochemical composition, reduction of oxygen consumption, changes in the feeding and behavior (the suppression of locomotor activity and tendency to crowd). In sarcophagids the pupal diapause occurs normally in the phanerocephalic stage and in muscids in red-eye pharate imago (Haematobia irritans). The diapause is characterized by reduced respiratory rate and unique individual cycles of metabolic activity. The larval diapause envelops firstly the delay of the pupariation, lowered rate of respiration, change in the haemocytes state and high level of nonspecific hardiness to the damage influences. The expression of various elements of diapause syndrome can vary considerably in different species. The literature data on the hibernation and diapausing stages in 130 species are summarized in three tables. Normally sarcophagids diapause as pupae. Calliphorids have larval and reproductive diapauses; a few species have both diapauses. In muscids the larval hibernation prevails, the adults hibernate more rarely.

Photoperiodic and temperature reactions, which control the diapause; the experimental data for eight model species are presented: Calliphora vicina, Protophormia terraenovae, Phormia regina and Musca autumnalis with the reproductive diapause; Calliphora vicina and Lucilia caesar with larval diapause; Liopygia crassipalpis and L. argyrostoma with the pupal diapause. In flies are two most interesting features in the diapause control. In sarcophagids early appearance of photoperiodic sensitivity in late embryos, which are still in female body, is observed. In calliphorids the larval diapause is under maternal control: the maternally operating photoperiod determines not only the incidence of diapause in the progeny, but also the quality of diapause. In C. vicina the formation of maternal influence during the ontogenesis of maternal generation has been studied by means of various manipulations with photoperiodic and temperature regimes. Two models for the induction of pupal diapause in L. argyrostoma were offered by D.S. Saunders (1973) and D. Gibbs (1975); the model for the reproductive diapause in M. autumnalis was worked out by N.R. Read and R.D. Moon (1986). Common physiological basis for the induction of pupal diapause and for the circadian rhythm of flies eclosion has been shown (L. argyrostoma); the experimental data agree with a computer model for the insect clock-counter system (Saunders, Lewis, 1987).

Variability and the genetics of flies diapause. The successful selections of the stocks with increased (Neobellieria bullata, Liosarcophaga similis, Calliphora vicina), decreased (N. bullata, Poecilometopa spilogaster) incidence of diapause and without diapause (Agria housei) are based on the intrapopulation variation of diapause. The geographical variation is considered on two model species with large area of distribution. The variations of long and intensive reproductive diapause in Protophormia terraenovae and weak diapause in Calliphora vicina are expressed insufficiently. On the contrary, the variation of larval diapause in C. vicina is very high. The populations differ in maternal photoperiodic parameters, upper range of temperature favorable for induction of dipause, in the incidence of diapause and its intensity. Geographical differentiation of diapause behavior is related to the duration of frost period, which correlates positively with winter temperature and latitude. The results of crossing between seven diapausing and nondiapausing geographical forms testify to the polygenic inheritance of larval diapause in C. vicina. The similar results were obtained in Boettcherisca peregrina, Lucilia caesar and L. argyrostoma.

Endogenous component of diapause control in the laboratory strains cultivated long time under constant conditions is considered. In some generation (or generations) the diapause tendency alters spontaneously contrary to the rearing regime. In Calliphora vicina the endogenous irregular rises of the reproductive diapause incidence appear under the condition of strain rearing. On the contrary, the tendencies to the larval diapause (C. vicina) and to the pupal one (Boettcherisca septentrionalis) are concealed, they are revealed only under the rearing of immature stages at the more low temperatures.

Hormonal control of larval and pupal diapauses. The axis brain-ring gland occupies the key position in the control both larval and pupal diapauses. The main reason of the pupal diapause consists in the absence of critical titer of ecdysteroids. The blocking of the release of prothoracotropic hormone from brain and the development of the refractoriness in prothoracic glands with respect to this hormone induce the pupal diapause. Juvenile hormone takes part in the control of diapause too, its activity correlates with the unique infradian cycles of metabolic activity in the middle of diapause. The dynamic character of the pupal diapause is conformed by the changes in the sensitivity of diapausing pupae to the ecdysteroids, organic solvents and high temperature shock. In Calliphora vicina there is a twofold mechanism controlling the maternally determinated larval diapause: the influence of some maternal "diapause factor" on the developing ooytes and the realization of developmental programme by own neuroendocrine system of the larvae. The latter level resembles the fundamental pattern of diapause induction in sarcophagids. In addition, the lowering of the sensitivity of embryonic tissues in respect to the exogenous ecdysteroids occurs. In chapter 6 the use of the data concerning the seasonality of development and the diapause in the practice of the laboratory and industrial cultivation of the flies, in the forensic medicine and in the phenological prognosis and of the control of synanthropic and synbovine flies are considered. Some periods of preimaginal development and egg maturation in 28 species are presented.

Other references
Papers published in English are indicated by blue color:

Vinogradova E.B.& Reznik S.Ya. 2002. Effects of female age and stepwise photoperiodic change on the larval diapause in Calliphora vicina R.-D. (Diptera, Calliphoridae). Entomol. Obozr.  81(4): 785-794.

Vinogradova E.B. & Reznik S.Ya. 2000. Influence of female age on progeny larval diapause in the blowfly, Calliphora vicina R.-D. (Diptera, Calliphoridae). Entomol. Obozr. 81: 296-302.

Vinogradova E.B. & Reznik S.Ya. 2000. Endogenous change of the tendency to larval diapause in laboratory generation sequences of the blowfly , Calliphora vicina R.-D. (Diptera, Calliphoridae). Intern. J. Dipterological Res. 11: 3-8.

Vinogradova E.B. & Reznik S.Ya. 1999. Endogenous changes of the tendency to diapause in the blowfly, Calliphora vicina (Diptera, Calliphoridae). Proceedings of the Zoological Institute RAS 281: 151-155.