Termination Of Pupal Diapause Research Articles

Ontogenetic patterns of cold-hardiness and glycerol production in Sarcophaga crassipalpis

Developmental patterns of low-temperature tolerance and glycerol production were determined for larval, pupal and adult stages of the flesh fly Sarcophaga crassipalpis Macquart (Diptera: Sarcophagidae). Both diapause and non-diapause-destined flies were reared at relatively high temperatures, 20° or 25°C, prior to testing. Cold tolerance was greatest for diapause pupae aged 12–35 days after pupariation. Among non-diapause-destined flies, pupae exhibited a greater level of low temperature tolerance than larvae or adults. Although diapause pupae were more tolerant than non-diapause pupae maximal cold tolerance was not attained in either group until 10 days after pupariation. Non-diapause-destined feeding and wandering larvae had higher glycerol levels than larvae destined for diapause. During the first 6 weeks after pupariation glycerol titres increased steadily in diapause pupae. Rapid loss of glycerol is associated with the termination of pupal diapause.

Two mechanisms in the biological clock ofPieris brassicae L.: an oscillator for diapause induction; an hour-glass for diapause termination

Resonance experiments for photoperiodic termination of pupal diapause demonstrated thatPieris brassicae uses a night-measuring hour-glass mechanism. In previous work the same resonance technique for diapause induction revealed that photoperiodic time-measurement is a function of the circadian system. For the first time in a living organism it has been shown that the biological clock operates by means of an oscillator for photoperiodic onset of a phenomenon and according to an hour-glass system for photoperiodic termination.

Brain and ring gland cyclic AMP and cyclic GMP levels during initiation and termination of pupal diapause in flesh flies

1. 1. Brain and ring gland concentrations of cyclic AMP were much higher shortly after pupariation in long day (non-diapause destined) flesh flies than in short day (destined for pupal diapause) flies. 2. 2. This difference was most striking in the ring gland (6 times higher in long day flies). 3. 3. Cholera toxin elevated brain-ring gland cAMP four-fold, thus accounting for its efficacy in averting diapause. 4. 4. No differences in cyclic GMP levels were detected between long and short day flies at pupariation. 5. 5. At diapause termination cAMP and cGMP concentrations in the brain and ring gland and cAMP in whole body homogenates changed only slightly, but whole body concentrations of cGMP rose markedly.

PREVENTING AND TERMINATING PUPAL DIAPAUSE INATHRYCIA CINEREA(DIPTERA: TACHINIDAE)

AbstractPupal diapause inAthrycia cinerea(Coq.), a larval parasite of bertha armyworm,Mamestra configurataWalk., was usually prevented if the parasite larvae were reared at 25°C, but not if they were reared at 20°C. Mature larvae of the parasite were more sensitive than younger larvae to this temperature effect. Diapause incidence inA.cinereaat 20°C was not reduced by using only young parent females for oviposition; by rearing the parent females at a high temperature (25°C) and long day (16 h) prior to and during oviposition; by using host larvae that had been light-programmed for non-diapause; or by increasing the photoperiod, to which the parasite larvae were exposed, from 12 to 16 h. Termination of pupal diapause was accelerated by low temperature; at least 24 weeks at 2 °C were required to synchronize adult emergence.

Action of ecdysoids, juvenoids, and non-hormonal agents on termination of pupal diapause in the flesh fly

Pupal diapause in Sarcophaga crassipalpis can be immediately terminated with high doses of ecdysterone or 5,β-hydroxyecdysterone. Within a range of lower doses diapause is not immediately terminated, but the duration of diapause is shortened. Injection of small doses at 3-day intervals is more effective than a single application of the same total amount. 5,β-hydroxy-ecdysterone is more effective than ecdysterone. The juvenoid isopropyl (2E,4E)-11-methoxy-3,7,11-trimethyl-2,4-dodecadienoate does not cause immediate termination of diapause but diapause is shortened. Simultaneous application of ecdysterone and the juvenoid synergistically produce a shorter duration of diapause than either hormone applied separately. Topical application of acetone and several other organic compounds can cause an immediate break of diapause. Neckligated pupae, however, do not respond to acetone treatment. Temperature shocks caused by brief exposure to high or low temperatures are ineffective. Although high doses of ecdysoids cause immediate termination of diapause, subsequent adult morphogenesis is protracted in direct proportion to the dose of ecdysoid. With the highest doses many flies fail to complete adult morphogenesis. Flies receiving high doses of ecdysoid are characterized by developmental abnormalities such as underdeveloped antennae, compound eyes, and mouthparts. By contrast, adultoids produced with juvenoids are characterized by abdominal abnormalities.

Termination of pupal diapause in Cuterebra tenebrosa (Diptera: Cuterebridae) with injections of ecdysterone.

Pupal diapause in Cuterebra tenebrosa Coquillett was terminated by injections of 0.1 to 0.6 μg of ecdysterone per pupa. Treated pupae resumed development 2–3 days after injection and emerged as adults in 44 days independent of prior time in diapause. Controls remained in diapause. Reproductive capability of the resulting flies was normal. This technique is practical and useful in shortening the long pupal diapause and Serves to coordinate development of pupae of different ages so adults emerge within a limited time range.

Termination of Pupal Diapause in the Bollworm12

Diapausing pupae of Heliothis zea (Boddie) were subjected to different photoperiods and temperatures in bioclimatic cabinets, and the number of days required for the termination of diapause was recorded. Termination of diapause in the bollworm was greatly influenced by temperature but not photoperiod, and the number of days for diapause termination was inversely relative to the temperature. Bollworms were reared in an insectary under natural daylengths and prevailing temperatures. All pupae that diapaused were held in the insectary over winter and the time of diapause termination in the spring was related to the occurrence of relatively consistent temperature above 10°C.

Influence of temperature and photoperiod on termination of pupal diapause in the Tasar silkworm, Antheraea mylitta

The pupal diapause of the Indian Tasar silkworm is sustained when pupae are stored in continuous darkness or exposed each day for up to 12 hr of illumination at 26°C. Diapause is terminated when pupae, one or more weeks after pupation, are exposed to continuous light or to 18 hr of daily illumination. The long-day treatment, if begun during the first week after spinning, loses nearly all of its effectiveness in provoking the termination of pupal diapause. By contrast, the response to long-day regimens is only slightly affected by brief exposure to high temperatures (10 min at 40 or 50°C) or by preliminary chilling at 2 or 5°C for 1 to 6 weeks.

Experiments on the diapause dynamics of Papilio polyxenes

The influence of the environmental parameters of photophase and temperature on the induction and termination of pupal diapause was investigated in Papilio polyxenes. Some data for other species and hybrids are added for comparison. Diapause can be induced by rearing larvae under a short daily photophase régime. Diapause termination in the apparent absence of environmental stimuli occurs after a highly variable length of time. Long daily photophase has a significant terminating effect. Exposure of pupae to a cold stimulus caused diapause termination, and the length of the development time after removal from cold is inversely related to the duration of cold exposure. The adaptive significance is discussed of these effects in natural populations.

Changes in the free amino acids of the haemolymph of Antheraea pernyi during induction and termination of diapause

Changes in the levels of haemolymph free amino acids were studied during the metamorphosis of a non-diapausing form and during the induction, maintenance, and termination of pupal diapause in a diapausing form of Antheraea pernyi. The levels of arginine, lysine, proline, and threonine increased gradually during metamorphosis; alanine and glutamine concentrations increased in the pupal stage before decrease during adult development, while glutamic acid decreased at the larval-pupal transformation before rising during adult development. The intervention of diapause resulted in increased levels of these amino acids (except glutamic acid) and histidine. Except for proline and histidine, the patterns of changes during metamorphosis in the levels of the affected amino acids were almost identical in both the non-diapausing and diapausing forms of the silkworm. Alanine and proline showed abnormal accumulation throughout the induction and maintenance of diapause before being depleted during post-diapause development. The increases in the levels of these amino acids appear to be secondary in nature, associated with physiological and biochemical adjustments during induction of diapause and cold-hardiness in A. pernyi.

PHYSIOLOGY OF INSECT DIAPAUSE. XIV. AN ENDOCRINE MECHANISM FOR THE PHOTOPERIODIC CONTROL OF PUPAL DIAPAUSE IN THE OAK SILKWORM, ANTHERAEA PERNYI

1. In the oak silkworm,Antheraea pernyi, photoperiod controls not only the onset of pupal diapause (as previously demonstrated by Tanaka) but also the termination of pupal diapause.2. At 25° C., short-day conditions (4-to 12-hour photophases) strongly inhibit the termination of pupal diapause; maximal inhibition is by a 12-hour photophase.3. Long-day conditions (15-to 18-hour photophases) promote the termination of diapause; a 17-hour photophase is the most effective.4. A 14-hour photophase is transitional between short-days which sustain diapause and long-days which terminate diapause.5. By various experimental maneuvers, sensitivity to photoperiod was localized in the head-end of the pupa. Short-day illumination of the head-end inhibited the termination of diapause even when the hind-end was exposed to long-day conditions. In like manner, long-day illumination of the head-end was fully effective even when the abdomen received short-day illumination.6. When the brain was removed from the head and implant...

PHYSIOLOGY OF INSECT DIAPAUSE. XIII. DNA SYNTHESIS DURING THE METAMORPHOSIS OF THE CECROPIA SILKWORM

1. DNA synthesis at stages in the life-cycle of the Cecropia and Cynthia silkworms was examined by radioautographic survey of the incorporation of tritiated thymidine.2. In sections of pupae previously injected with tritiated thymidine, incorporation of the nucleotide into DNA, as well as cell division, was observed in several tissues as late as one week after pupation.3. In diapausing pupae, incorporation of thymidine occurred in spermatogonia hemocytes, a few midgut regenerative cells, and a few cells of the testicular walls. Neither incorporation nor mitotic figures were observed in diapausing epidermal tissues.4. Large epidermal injury increased DNA synthesis in the blood cells of diapausing pupae and induced incorporation in a few epidermal cells in the immediate vicinity of the wound. Epidermal cells outside the wound periphery did not incorporate thymidine after injury.5. A generalized incorporation of thymidine was observed in synchrony with the termination of pupal diapause. The first cells to sh...

Termination of Pupal Diapause in the Cinnabar Moth and the Reproductive Capacity of the Resulting Females

MANY thousands of pupae of the cinnabar moth, Tyria jacobaeae L., from southern England, and a smaller consignment from central Italy, were introduced into Australia for the control of the noxious weed, ragwort (Senecio jacobaea L.), in southern Victoria. In England this moth has a strictly uni-voltine life-cycle1 that includes an obligatory pupal diapause2 lasting for an average of 270 days. Because of this diapause3, difficulties were expected in synchronizing emergence of the moths with the Australian summer—for this would require diapause to be terminated in less than 150 days or extended to at least 450 days.

THE PHYSIOLOGY OF INSECT DIAPAUSE. IX. THE CYTOCHROME OXIDASE SYSTEM IN RELATION TO THE DIAPAUSE AND DEVELOPMENT OF THE CECROPIA SILKWORM

1. The effects of mixtures of carbon monoxide and oxygen on the growth and metamorphosis of the Cecropia silkworm were examined at successive stages of embryonic and post-embryonic development.2. Embryos, mature larvae, and adults are killed by five days of exposure to carbon monoxide/oxygen ratios of 20:1 or 25:1. Diapausing pupae, by contrast, survive at least 21 days of exposure to carbon monoxide/oxygen ratios as high as 33:1.3. While failing to interfere with the viability of diapausing pupae, carbon monoxide blocks or greatly retards the termination of the pupal diapause; it also inhibits the healing of experimental wounds in the pupal integument.4. The ability to survive in the presence of high pressures of carbon monoxide persists throughout the early stages of adult development. Exposure of the developing, post-diapausing insect to suitable pressures of carbon monoxide establishes and enforces an artificial diapause which is reversed upon return to air.5. The inhibition of adult development by carbon monoxide is light-reversible; the degree of inhibition is a function of the carbon monoxide/oxygen ratio. These findings indicate that the effects of carbon monoxide are due to the poisoning of cytochrome oxidase.6. Resistance to carbon monoxide, as in the diapausing pupa, signals the presence and utilization of an oxidase other than cytochrome oxidase.7. On the basis of these several lines of evidence, it is concluded that growth and metamorphosis, at all stages in the life history, are dependent on metabolism catalyzed by cytochrome oxidase. The function of cytochrome oxidase is likewise prerequisite for the maintenance of life of the embryo, larva, and adult.8. Only the diapausing pupa survives without regard to the presence or function of cytochrome oxidase, the maintenance metabolism of the pupae being served by an unidentified oxidase which is insensitive to carbon monoxide.9. With the termination of pupal diapause the growth and differentiation of the adult moth again requires the function of the cytochrome oxidase system. This fact is considered in relation to the endocrine control of the pupal diapause.