Document Detail

How well do specialist feeders regulate nutrient intake? Evidence from a gregarious tree-feeding caterpillar.
MedLine Citation:
PMID:  16547301     Owner:  NLM     Status:  MEDLINE    
Nutritional regulation is a powerful mechanism used by generalist feeders to obtain the balance of nutrients they require from nutritionally diverse, perhaps unbalanced, foods. We examined nutritional regulation in a species with a narrow individual diet breadth: the forest tent caterpillar, Malacosoma disstria. Fourth instar caterpillars were provided with artificial foods consisting of different ratios of protein to digestible carbohydrate in no-choice, choice and compensatory feeding experiments. In the no-choice test, caterpillars were confined to a single food source of varying protein/carbohydrate ratio for the duration of the fourth larval stadium. Caterpillars performed best on equal-ratio and slightly protein-biased diets. Significant reductions in performance were only observed on extremely protein- or carbohydrate-biased diets. Daily consumption of the three acceptable intermediate diets was consistent with volumetric regulation, but the timing of the moult to the next instar appeared linked instead to protein intake. In the choice test, caterpillars were provided with two complementary foods, one biased toward protein and the other toward carbohydrate, for the duration of the stadium. The caterpillars fed randomly from the two food sources presented to them, except for the extremely protein-biased diet (P:C ratio of 35:7), which they avoided. The compensatory feeding experiment tested whether forest tent caterpillars deprived of either protein or digestible carbohydrate would select a food containing the deficient nutrient. Insects were conditioned on either protein-only, carbohydrate-only, protein-and-carbohydrate or no-nutrient foods, then offered a choice between protein-only and carbohydrate-only foods. Unlike previously studied generalist feeders, our caterpillars did not compensate for protein deficiency and showed only very weak evidence of compensation for carbohydrate deficiency. Forest tent caterpillars are colonial trail-laying forest folivores that are generally confined to a single host plant and hence do not experience much diversity in food nutrient ratios. We show that forest tent caterpillars do not independently regulate protein and carbohydrate intake. These findings are consistent with predictions that nutritional regulation abilities should be less important in animals with narrower diet breadths.
Emma Despland; Meghan Noseworthy
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of experimental biology     Volume:  209     ISSN:  0022-0949     ISO Abbreviation:  J. Exp. Biol.     Publication Date:  2006 Apr 
Date Detail:
Created Date:  2006-03-20     Completed Date:  2006-06-13     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0243705     Medline TA:  J Exp Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  1301-9     Citation Subset:  IM    
Department of Biology, Concordia University, 7141 Sherbrooke West, Montréal, Québec, H4B 1R6, Canada.
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MeSH Terms
Animal Nutritional Physiological Phenomena*
Dietary Carbohydrates / administration & dosage
Dietary Proteins / administration & dosage
Feeding Behavior / physiology*
Food Preferences
Larva / growth & development,  physiology*
Lepidoptera / growth & development,  physiology*
Reg. No./Substance:
0/Dietary Carbohydrates; 0/Dietary Proteins

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