Pathogen- and diet-dependent foraging, nutritional and immune ecology in mealworms
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Date
2011
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Abstract
Background: Feeding habits and dietary nutritional content may play a key role in pathogen-dependent foraging ecology, because mounting an effective immune response is costly for the host.
Hypothesis: Since immune defence is the final line of protection against infective aggression, an adequate provision of dietary macromolecules through a selective foraging behaviour is required to maintain immunocompetence in infected hosts.
Goal: We studied dietary switching and its consequences on immune response performance after an immune challenge using mealworms (Tenebrio molitor) as a model host.
Methods: We evaluated diet selection and body mass balance (proxy of fitness) of larvae following a lipopolysaccharide challenge under three experimental nutritional treatments: an isocaloric low-protein/high-carbohydrate or high-protein/low-carbohydrate diet offered either independently (no-choice experiment) or simultaneously (dual-choice experiment). Furthermore, we studied the effect of diet composition on three immune traits: antibacterial activity, phenoloxidase activity, and total haemocyte count.
Results: Immune-challenged larvae ate almost five times more than did control larvae in the dual-choice experiment. In addition, 50.7% of total food intake by immune-challenged larvae corresponded to the high-protein/low-carbohydrate diet, significantly higher than challenged or unchallenged control larvae (3.7% and 2.3% respectively). However, no significant differences in body mass change were observed. In contrast, in the no-choice diet condition, immune-challenged larvae lost body mass compared with naive mealworms. Furthermore, we found that dietary protein had a positive effect on antibacterial activity and total haemocyte count but not phenoloxidase activity, and that mealworms feeding on a balanced diet did not have a better immune performance.
Conclusions: The immune response activation triggers a compensatory shift in host foraging behaviour that is not necessarily associated with the prevailing physiological state, but can have considerable influence on Darwinian fitness.
Hypothesis: Since immune defence is the final line of protection against infective aggression, an adequate provision of dietary macromolecules through a selective foraging behaviour is required to maintain immunocompetence in infected hosts.
Goal: We studied dietary switching and its consequences on immune response performance after an immune challenge using mealworms (Tenebrio molitor) as a model host.
Methods: We evaluated diet selection and body mass balance (proxy of fitness) of larvae following a lipopolysaccharide challenge under three experimental nutritional treatments: an isocaloric low-protein/high-carbohydrate or high-protein/low-carbohydrate diet offered either independently (no-choice experiment) or simultaneously (dual-choice experiment). Furthermore, we studied the effect of diet composition on three immune traits: antibacterial activity, phenoloxidase activity, and total haemocyte count.
Results: Immune-challenged larvae ate almost five times more than did control larvae in the dual-choice experiment. In addition, 50.7% of total food intake by immune-challenged larvae corresponded to the high-protein/low-carbohydrate diet, significantly higher than challenged or unchallenged control larvae (3.7% and 2.3% respectively). However, no significant differences in body mass change were observed. In contrast, in the no-choice diet condition, immune-challenged larvae lost body mass compared with naive mealworms. Furthermore, we found that dietary protein had a positive effect on antibacterial activity and total haemocyte count but not phenoloxidase activity, and that mealworms feeding on a balanced diet did not have a better immune performance.
Conclusions: The immune response activation triggers a compensatory shift in host foraging behaviour that is not necessarily associated with the prevailing physiological state, but can have considerable influence on Darwinian fitness.
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Keywords
antibacterial activity, dietary nutrients, ecoimmunology, feeding, haemocytes, phenoloxidase activity, Tenebrio molitor