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Quantitative differences in nourishment affect caste-related physiology and development in the paper wasp Polistes metricus.

Judd TM, Teal PE, Hernandez EJ, Choudhury T, Hunt JH - PLoS ONE (2015)

Bottom Line: A growing number of studies now indicate that workers emerge with activated reproductive physiology, whereas the future reproductive gynes do not.Here, we present the results of a laboratory rearing experiment in which Polistes metricus single foundresses were held in environmental conditions with a higher level of control than in any previously published study, and the amount of protein nourishment made available to feed larvae was the only input variable.Although the experiment was not designed to test for worker behavior per se, our results further implicate activated reproductive physiology as a developmental response to low larval nourishment as a fundamental aspect of worker behavior in Polistes.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Southeast Missouri State University, Gape Girardeau, MO, 63701, United States of America.

ABSTRACT
The distinction between worker and reproductive castes of social insects is receiving increased attention from a developmental rather than adaptive perspective. In the wasp genus Polistes, colonies are founded by one or more females, and the female offspring that emerge in that colony are either non-reproducing workers or future reproductives of the following generation (gynes). A growing number of studies now indicate that workers emerge with activated reproductive physiology, whereas the future reproductive gynes do not. Low nourishment levels for larvae during the worker-rearing phase of the colony cycle and higher nourishment levels for larvae when gynes are reared are now strongly suspected of playing a major role in this difference. Here, we present the results of a laboratory rearing experiment in which Polistes metricus single foundresses were held in environmental conditions with a higher level of control than in any previously published study, and the amount of protein nourishment made available to feed larvae was the only input variable. Three experimental feeding treatments were tested: restricted, unrestricted, and hand-supplemented. Analysis of multiple response variables shows that wasps reared on restricted protein nourishment, which would be the case for wasps reared in field conditions that subsequently become workers, tend toward trait values that characterize active reproductive physiology. Wasps reared on unrestricted and hand-supplemented protein, which replicates higher feeding levels for larvae in field conditions that subsequently become gynes, tend toward trait values that characterize inactive reproductive physiology. Although the experiment was not designed to test for worker behavior per se, our results further implicate activated reproductive physiology as a developmental response to low larval nourishment as a fundamental aspect of worker behavior in Polistes.

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Plot of the ovary score vs. number of caterpillars eaten within the two weeks after eclosion for individual wasps reared on the restricted (gold circles, N = 9), and unrestricted (blue triangles, N = 23) diets.The trend line includes all of the data.
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pone.0116199.g003: Plot of the ovary score vs. number of caterpillars eaten within the two weeks after eclosion for individual wasps reared on the restricted (gold circles, N = 9), and unrestricted (blue triangles, N = 23) diets.The trend line includes all of the data.

Mentions: Of the individual variables, wing length, lipid levels, ovary score, number of nest cells, and cell height were significantly different between treatments (S2 Table). Wasps reared on the restricted diet had shorter wings, higher ovary scores, higher lipid levels, and lower cocoon heights than those in the unrestricted treatment (Fig. 2). Foundresses in the restricted treatment group produced smaller nests. The ovary score of isolated newly-emerged wasps was positively correlated with the number of caterpillars consumed during the isolation period (logistic regression, F = 10.75, p = 0.0044; Fig. 3).


Quantitative differences in nourishment affect caste-related physiology and development in the paper wasp Polistes metricus.

Judd TM, Teal PE, Hernandez EJ, Choudhury T, Hunt JH - PLoS ONE (2015)

Plot of the ovary score vs. number of caterpillars eaten within the two weeks after eclosion for individual wasps reared on the restricted (gold circles, N = 9), and unrestricted (blue triangles, N = 23) diets.The trend line includes all of the data.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4338145&req=5

pone.0116199.g003: Plot of the ovary score vs. number of caterpillars eaten within the two weeks after eclosion for individual wasps reared on the restricted (gold circles, N = 9), and unrestricted (blue triangles, N = 23) diets.The trend line includes all of the data.
Mentions: Of the individual variables, wing length, lipid levels, ovary score, number of nest cells, and cell height were significantly different between treatments (S2 Table). Wasps reared on the restricted diet had shorter wings, higher ovary scores, higher lipid levels, and lower cocoon heights than those in the unrestricted treatment (Fig. 2). Foundresses in the restricted treatment group produced smaller nests. The ovary score of isolated newly-emerged wasps was positively correlated with the number of caterpillars consumed during the isolation period (logistic regression, F = 10.75, p = 0.0044; Fig. 3).

Bottom Line: A growing number of studies now indicate that workers emerge with activated reproductive physiology, whereas the future reproductive gynes do not.Here, we present the results of a laboratory rearing experiment in which Polistes metricus single foundresses were held in environmental conditions with a higher level of control than in any previously published study, and the amount of protein nourishment made available to feed larvae was the only input variable.Although the experiment was not designed to test for worker behavior per se, our results further implicate activated reproductive physiology as a developmental response to low larval nourishment as a fundamental aspect of worker behavior in Polistes.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Southeast Missouri State University, Gape Girardeau, MO, 63701, United States of America.

ABSTRACT
The distinction between worker and reproductive castes of social insects is receiving increased attention from a developmental rather than adaptive perspective. In the wasp genus Polistes, colonies are founded by one or more females, and the female offspring that emerge in that colony are either non-reproducing workers or future reproductives of the following generation (gynes). A growing number of studies now indicate that workers emerge with activated reproductive physiology, whereas the future reproductive gynes do not. Low nourishment levels for larvae during the worker-rearing phase of the colony cycle and higher nourishment levels for larvae when gynes are reared are now strongly suspected of playing a major role in this difference. Here, we present the results of a laboratory rearing experiment in which Polistes metricus single foundresses were held in environmental conditions with a higher level of control than in any previously published study, and the amount of protein nourishment made available to feed larvae was the only input variable. Three experimental feeding treatments were tested: restricted, unrestricted, and hand-supplemented. Analysis of multiple response variables shows that wasps reared on restricted protein nourishment, which would be the case for wasps reared in field conditions that subsequently become workers, tend toward trait values that characterize active reproductive physiology. Wasps reared on unrestricted and hand-supplemented protein, which replicates higher feeding levels for larvae in field conditions that subsequently become gynes, tend toward trait values that characterize inactive reproductive physiology. Although the experiment was not designed to test for worker behavior per se, our results further implicate activated reproductive physiology as a developmental response to low larval nourishment as a fundamental aspect of worker behavior in Polistes.

Show MeSH