INJURY INDUCED MOLTING IN<i>GALLERIA MELLONELLA</i>LARVAE

Krishnakumaran, A.

doi:10.2307/1540231

Cited by 47 publications

(3 citation statements)

References 20 publications

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“…One possible mechanism by which the JH remains high is that the deformed appendage tissue elicits a wound healing response that is known to elevate JH in some insects (Needham, 1965; Krishnakumaran, 1972). In many insects, including Tribolium reported here, wounding results in the formation of supernumerary instars, presumably to allow larvae to heal the injury before pupating (reviewed in Esperk et al , 2007).…”

Section: Discussionmentioning

confidence: 99%

Larval leg integrity is maintained by Distal-less and is required for proper timing of metamorphosis in the flour beetle, Tribolium castaneum

Suzuki

Squires

Riddiford

2009

Developmental Biology

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The dramatic transformation from a larva to an adult must be accompanied by a coordinated activity of genes and hormones that enable an orchestrated transformation from larval to pupal/adult tissues. The maintenance of larval appendages and their subsequent transformation to appendages in holometabolous insects remains elusive at the developmental genetic level. Here the role of a key appendage patterning gene Distal-less (Dll) was examined in mid- to late- larval stages of the flour beetle, Tribolium castaneum. During late larval development, Dll was expressed in appendages in a similar manner as previously reported for the tobacco hornworm, Manduca sexta. Removal of this late Dll expression resulted in disruption of adult appendage patterning. Intriguingly, earlier removal resulted in dramatic loss of structural integrity and identity of larval appendages. A large amount of variability in appendage morphology was observed following Dll dsRNA injection, unlike larvae injected with dachshund dsRNA. These Dll dsRNA-injected larvae underwent numerous supernumerary molts, which could be terminated with injection of either JH methyltransferase or Methoprene-tolerant dsRNA. Apparently, the partial dedifferentiation of the appendages in these larvae acts to maintain high JH and, hence, prevents metamorphosis.

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Section: Discussionmentioning

confidence: 99%

Larval leg integrity is maintained by Distal-less and is required for proper timing of metamorphosis in the flour beetle, Tribolium castaneum

Suzuki

Squires

Riddiford

2009

Developmental Biology

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“…Indeed, imaginal disc injuries that extend the period of rapid divisions of the discs extend the time spent in the last larval instar in a variety of insects (25)(26)(27)(28)(29)(30). Consequently, to assess the state of imaginal tissue development, we determined the time when the leg imaginal primordia formed and initiated growth in the two groups of larvae.…”

Section: Resultsmentioning

confidence: 99%

A molt timer is involved in the metamorphic molt inManduca sextalarvae

Suzuki

Kaburagi

Hiruma

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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Manduca sexta larvae are a model for growth control in insects, particularly for the demonstration of critical weight, a threshold weight that the larva must surpass before it can enter metamorphosis on a normal schedule, and the inhibitory action of juvenile hormone on this checkpoint. We examined the effects of nutrition on allatectomized (CAX) larvae that lack juvenile hormone to impose the critical weight checkpoint. Normal larvae respond to prolonged starvation at the start of the last larval stage, by extending their subsequent feeding period to ensure that they begin metamorphosis above critical weight. CAX larvae, by contrast, show no homeostatic adjustment to starvation but start metamorphosis 4 d after feeding onset, regardless of larval size or the state of development of their imaginal discs. By feeding starved CAX larvae for various durations, we found that feeding for only 12-24 h was sufficient to result in metamorphosis on day 4, regardless of further feeding or body size. Manipulation of diet composition showed that protein was the critical macronutrient to initiate this timing. This constant period between the start of feeding and the onset of metamorphosis suggests that larvae possess a molt timer that establishes a minimal time to metamorphosis. Ligation experiments indicate that a portion of the timing may occur in the prothoracic glands. This positive system that promotes molting and the negative control via the critical weight checkpoint provide antagonistic pathways that evolution can modify to adapt growth to the ecological needs of different insects.size regulation | ecdysone | biochronometry

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“…In an optimal environment most insect larvae develop at a fairly constant, species-specific rate, but adverse environmental conditions can affect both the number of molts and the length of individual instars. For example, the larval development of the wax moth, Galleria mellonella, can be altered by the quality of food and by population density [l] and is also profoundly affected by chilling [2-51, space deprivation [6,7l, and injury [8,9]. When these treatments are applied during the last larval instar, they can cause either accelerated molting and extra larval ecdyses [3] or suppression of molting and delay of pupation [8].…”

Section: Introductionmentioning

confidence: 99%

Effects of starvation, chilling, and injury on endocrine gland function in Galleria mellonella

Malá¹,

Sehnal²,

Kumaran

et al. 1987

Arch Insect Biochem Physiol

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Starvation, chilling, and injury of last instar Galleria mellonella larvae typically elicit extra larval molts or a delay in pupation. The primary sites of action and the nature of the signals by which these treatments affect development are not known. However, since the connections of the brain to the nerve cord are crucial for the effects of starvation and chilling, these signals apparently affect the brain-centered program of developmental regulation via the nerve cord. Chilling, and occasionally starvation, cause extra larval molts in last instar larvae treated prior to the nervous inhibition of their corpora allata; release of a cerebral allatotropin, which stimulates the production of juvenile hormone, appears to be involved in this effect. After this time, a delay in pupation is the principal effect of starvation and chilling, and is apparently due to a temporal inhibition of the release of the prothoracicotropic hormone. Chilling also appears to inhibit unstimulated ecdysteroid production by the prothoracic glands.The effect of injury is not mediated by the nerve cord, but appears to involve an inhibitory humoral factor that affects either the brain or the prothoracic glands themselves. Injury also stimulates juvenile hormone production, an effect which is enhanced when the brain is separated from the nerve cord and which is evidenced by a delay of ecdysis and the occasional retention of some larval features in the ecdysed insects.None of the effects of these various treatments on the brain and the endocrine glands persist when the brains or glands are implanted into untreated hosts.

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INJURY INDUCED MOLTING INGALLERIA MELLONELLALARVAE

Cited by 47 publications

References 20 publications

Larval leg integrity is maintained by Distal-less and is required for proper timing of metamorphosis in the flour beetle, Tribolium castaneum

Larval leg integrity is maintained by Distal-less and is required for proper timing of metamorphosis in the flour beetle, Tribolium castaneum

A molt timer is involved in the metamorphic molt inManduca sextalarvae

Effects of starvation, chilling, and injury on endocrine gland function in Galleria mellonella

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