I actually don't believe that the husbandry was an issue here - more like stress, or perhaps a genetic pre-disposition? Conditions were very good for a proper molt and 2 others in the same group molted the day after I received them without issues. I think that sometimes it just happens for reasons we'd make ourselves crazy trying to pin-point.
"...it just happens for reasons we'd make ourselves crazy trying to pin-point.."
Not correct, as it has been pinpointed quite often so no need to make ourselves nutty.
It has to be a husbandry practice of yours.
But no big deal, right? Just to point out that you may need to make a minor change,
that's all. I point this out so we can all learn and better our own hobby/collections.
You have made two erroneous assumptions:
One is that because some molt nicely and one or two don't, that there is no husbandry problem. With husbandry problems it is not always an "all or none" result as you indicate; just like any more that I can be 100 percent certain you are autistic because there are autistic humans in this country. Even one is an indicator of a husbandry mistake or need for adjustment.
The second is that this simply does not occur as a genetic pre-disposition (another analogy coming) any more than I can say all red-headed persons are diabetics. There is more involved in a sequence of events and not just one fallible genome producing one effect.
The two top husbandry aspects that affect molting or "ecdysis" would be
food and water- both well within our control.
Food, in that some relevantly proper nutrition is required to produce a successful molt. From the food a roach eats, it extracts and/or produces numerous compounds to use in ecdysis, including vitamins A and D, Zinc, soluable lipids, and enzymes used in digestion.
Water, in that water (from direct consumption) or in retention of from the humidity of the environment, is
required both to synthesize the hormones involved and to produce the hydrostatic pressure to break free of the outer cuticle. (For many roach species, this water pressure is also combined with the intake of air into airsacs to help in this process). Additionally, without the retention of some water the roach would dry out very quickly upon molting as the outer cuticle would not have hardened yet.
As for why it's a husbandry issue:
Here are some quotes and references to help illustrate or imply the importance of dietary requirements and water supply/humidity from various books, articles, papers, and other content that I have handy (if no credit is mentioned it is because I just dont have it, otherwise I indicate the source of the info):
Chung JS, Dircksen H, Webster SG.
School of Biological Sciences, University of Wales, Bangor, Gwynedd, LL57 2UW, United Kingdom.
Molting or ecdysis is the most fundamentally important process in arthropod life history, because shedding of the exoskeleton is an absolute prerequisite for growth and metamorphosis. Though hormonal mechanisms driving ecdysis in insects have been studied extensively, nothing is known about these processes in crustaceans. “… we observed a precise and reproducible surge in hemolymph hyperglycemic hormone (CHH) levels, which was over 100-fold greater than levels seen in intermolt animals. The source of this hormone surge was not from the neurosecretory tissues but from previously undescribed endocrine cells (paraneurons), in defined areas of the foregut and hindgut. During premolt (the only time when CHH is expressed by these tissues), the gut is the largest endocrine tissue…” The CHH surge, which is a result of an unusual, almost complete discharge of the contents of the gut endocrine cell,
regulates water and ion uptake during molting, thus allowing the swelling necessary for successful ecdysis and the subsequent increase in size during postmolt. This study defines an endocrine brain/gut axis in the arthropods. We propose that the ionoregulatory process controlled by CHH may be common to arthropods, in that, for insects, a similar mechanism seems to be involved in antidiuresis. It also seems likely that
a cascade of very precisely coordinated release of (neuro) hormones controls ecdysis.
PMID: 10557280 [PubMed - indexed for MEDLINE]
PMCID: PMC23907
Molting in arthropods and related groups (ecdysis)
In arthropods, such as insects, arachnids and crustaceans, molting is the shedding of the exoskeleton, or cuticle, typically to let the organism grow. The exoskeleton is a hard, inert, outer structure that supports and protects the animal. For some arthropods, it is referred to commonly as a shell.
The molting process is often termed ecdysis. Ecdysis can be defined as the molting or shedding of the cuticula in arthropods and the related groups that together make up the Ecdysozoa. The Ecdysozoa are a group of protostome animals that includes Arthropoda, Nematoda, and several smaller phyla. The most notable characteristic shared by ecdysozoans is a three-layered cuticle composed of organic material, which is periodically molted as the animal grows. This process gives the group its name.
The exoskeleton, or cuticle, is well-defined and is secreted by, and strongly attached to, the underlying epidermal cells
(Ewer 2005) . Since the cuticula of these animals is also the skeletal support of the body and is inelastic, unable to grow like skin, it is shed during growth and a new, larger covering is formed. The new exoskeleton that is secreted by the epidermis is initially soft and remains so until the outer cuticle is shed at ecdysis. The new cuticle expands and hardens after the molting of the old exoskeleton.
After molting, an arthropod is described as teneral—it is fresh pale, and soft-bodied. Within a short time, sometimes one or two hours, the cuticle hardens and darkens following a tanning process similar to that of the tanning of leather. It is during this short phase that the animal grows, since growth is otherwise constrained by the rigidity of the exoskeleton.
Ecdysis may also enable damaged tissue and missing limbs to be regenerated or substantially re-formed, although this may only be complete over a series of molts, the stump being a little larger with each molt until it is of normal, or near normal size again.
Process
In preparation for ecdysis, the arthropod becomes inactive for a period of time, undergoing apolysis (separation of the old exoskeleton from the underlying epidermal cells). For most organisms, the resting period is a stage of preparation during which the secretion of fluid from the molting glands of the epidermal layer and the loosening of the underpart of the cuticula occur.
Once the old cuticle has separated from the epidermis, the digesting fluid is secreted into the space in between them. However, this fluid remains inactive until the upper part of the new cuticule has been formed.
While the old cuticula is being digested, the new layer is secreted. All cuticular structures are shed at ecdysis, including the inner parts of the exoskeleton, which includes terminal linings of the alimentary tract and of the tracheae if they are present.
Then, by crawling movements, the animal pushes forward in the old integumentary shell, which splits down the back allowing the animal to emerge. Often, this initial crack is caused by an increase in blood pressure within the body (in combination with movement), forcing an expansion across its exoskeleton, leading to an eventual crack that allows for these organisms to extricate themselves.
Molting in insects
*(I would put a pic of a molting small nymph into a medium nymph here if I had one.)
Each stage in the development of an insect between molts is called an instar, or stadium. Higher insects tend to have fewer instars (four to five) than lower insects (anywhere up to about 15). Higher insects have more alternatives to molting, such as expansion of the cuticle and collapse of air sacs to allow growth of internal organs.
The process of molting in insects begins with the separation of the cuticle from the underlying epidermal cells (apolysis) and ends with the shedding of the old cuticle (ecdysis). In many of them, it is initiated by an increase in the hormone ecdysone. This hormone causes:
• apolysis - the separation of the cuticle from the epidermis
• excretion of new cuticle beneath the old
• degradation of the old cuticle
After apolysis, molting fluid is secreted into the space between the old cuticle and the epidermis (the exuvial space). This fluid contains inactive enzymes that are activated only after the new epicuticle is secreted. This prevents them from digesting the new procuticle as it is laid down. The lower regions of the old cuticle—the endocuticle and mesocuticle—are then digested by the enzymes and subsequently absorbed. The exocuticle and epicuticle resist digestion and are hence shed at ecdysis.
References:
Ewer, J. How the ecdysozoan changed its coat. PLos Biology 3(10): e349, 2005. Retrieved July 23, 2007.
Lowry, L. Beluga whale. Wildlife Notebook Series (Alaska Dept. of Fish and Game). 1994.
Ling, J. K. “Pelage and molting in wild mammals with special reference to aquatic forms.” The Quarterly Review of Biology 45(1): 16-54, 1970.
Authors: Schofield R.M.S.1; Nesson M.H.; Richardson K.A.; Wyeth P.
Source: Journal of Insect Physiology, Volume 49, Number 1, January 2003 , pp. 31-44(14)
Publisher: Elsevier
Text References:
The American Cockroach By William J. Bell, K. G. Adiyodi
Clinical Techniques of Invertebrates .
Veterinary Clinics of North America: Exotic Animal Practice, Volume 9, Issue 2, Pages 205 - 221 M. BRAUN
Emergency Care of Invertebrates
Daniel Dombrowski MS, DVMa and Ryan De Voe DVM, MSpVM, DACZM, DABVP-Avianb
aNorth Carolina Museum of Natural Sciences, 11 West Jones Street, Raleigh, NC 27601, USA bNorth Carolina Zoological Park, Asheboro, NC 27205, USA
Invertebrate care
John E. Cooper FRCVS, FRCPath
The University of the West Indies, School of Veterinary Medicine, Faculty of Medical Sciences, St. Augustine, Trinidad and Tobago
Invertebrate Medicine
Published Online: 18 Feb 2008
Author(s): Gregory A. Lewbart
Print ISBN: 9780813818443 Online ISBN: 9780470344606
Article:
The chemical control of arthropod molting
E. David Morgan, Ian D. Wilson, Peter M. Bebbington, Colin F. Poole
Department of Chemistry, University of Keele, Keele, Staffordshire ST5 5BG
Synopsis of a contribution to a symposium Regulation of arthropod growth and development on 25 November 1977 organized by the Pesticides Group, Society of Chemical Industry.
Reference Authors:
Truman, JW.
Department of Biology, University of Washington, Seattle, Washington 98195, USA.
PMID: 16399406
Links:
http://www.bio.umass.edu/biology/kunkel/bgmolt.html
...and to many others to count.
If you require further proof you may need to make a simple adjustment in your husbandry practices, there are several science related sites where you can purcase online copies of the research for yourself.
