Sunday, November 6, 2011

Larval Diapause

Probably the most thorough, although not entirely scientifically accurate article relating to Iris diapause was published in “The Entomologist's record and journal of variation” back in 1954, by F.V.L. Jarvis. The article was quite comprehensive and can be read via the “Biodiversity Heritage Library” website at the following URL:

Pages 212-217 and 234-240.

Similar articles associated with the subject matter (amongst many others, I am sure) were also published by, C.J. Luckens (1976) and H.G.Short (1977) also in “The Entomologist's record and journal of variation” and can also be read at the following ULR’s respectively:

In spite of the findings reported in these articles however, more accurate research has shown that larval diapause is actually controlled by photoperiod and temperature in an absence of the normal ‘moulting’ hormone ecdysone.
Larval pigmentation/camouflage in response to diapause is a subject matter which is still under debate, although it is again thought to be under hormonal control. Consistent with the findings reported by Jarvis (and also Dennis, below), however there is still some evidence (Chippendale, 1972) which supports the idea that pigmentation is influenced by hydration levels and ingested host/food plant material(s). Chippendale 1972, abstract URL link as follows:

In contrast to the statement by Dennis however regarding the irreversibility of larval pigmentation, his statement (unless I have misunderstood it?) is unfortunately not correct (otherwise the larvae would never rouse from their diapausal states) and has been documented by many researchers (such as Bell 1983 and Rock 1983). Again the factors controlling arousal from diapause, are known to be temperature and photoperiod influencing hormonal balances. Bell 1983 and Rock 1983 abstract links can also be read at the following ULR’s respectively:

I hope the information above is of interest to some of you?


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