Document Detail


Canalization of development and ecdysteroid timing during the last instar in lubber grasshoppers.
MedLine Citation:
PMID:  12770018     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Development in many phytophagous, holometabolous insects is flexible at the beginning but inflexible at the end of the last larval instar. A prominent feature of the inflexible period is a peak in hemolymph levels of ecdysteroids. We tested whether this pattern holds true for the final molt of a phytophagous, hemimetabolous insect, Romalea microptera (the Eastern lubber grasshopper). We fed one group of grasshoppers a high quantity diet (H) throughout the 5th (final) instar and a second group a low quantity diet (L) throughout the instar. Three other diet treatments involved starting the instar on the high diet and then abruptly switching to the low diet at 3, 8, or 13 days (H3L, H8L, and H13L respectively) and continuing the low diet until adult molt. Diet treatment did not affect the maximum hemolymph level of ecdysteroids (E(max)); this peak typically reached ~4000 ng/ml. Ecdysteroid levels were elevated for ~4 days in all groups. In contrast, diet significantly affected age at adult molt and age at E(max) such that H = H13L = H8L < H3L = L. We identified estimates of thresholds for weight gain (20% initial weight) and hemolymph ecdysteroids (100 ng/ml), after which diet did not affect the time to the adult molt. The weight gain threshold was less precise than the ecdysteroid threshold. These results suggest that R. microptera has an extended period of inflexible (canalized) development during the final instar that includes a peak of ecdysteroids. We hypothesize this pattern holds for many phytophagous, hemimetabolous insects.
Authors:
J D Hatle; W A Miller; D W Borst
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Journal of insect physiology     Volume:  49     ISSN:  0022-1910     ISO Abbreviation:  J. Insect Physiol.     Publication Date:  2003 Jan 
Date Detail:
Created Date:  2003-05-28     Completed Date:  2003-07-07     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  2985080R     Medline TA:  J Insect Physiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  73-80     Citation Subset:  IM    
Affiliation:
Department of Biological Sciences, Illinois State University, Normal, IL 61790-4120, USA. jhatle@ilstu.edu
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MeSH Terms
Descriptor/Qualifier:
Animals
Diet
Ecdysteroids / physiology*
Feeding Behavior
Grasshoppers / growth & development*
Larva
Male
Molting
Time Factors
Chemical
Reg. No./Substance:
0/Ecdysteroids

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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