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Submitted to: Sociobiology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 6/20/2005 Publication Date: 6/20/2005 Citation: Morales Ramos, J.A., Rojas, M.G. 2005. Growth of young colonies of coptotermes formosanus (isoptera: rhinotermitidae) feeding on single versus multiple wood species. Sociobiology 46:155-173. Interpretive Summary: Formosan subterranean termites are the most destructive urban pests in the USA producing Billions of dollars in damage annually. The main reason they are so damaging is because of their ability to consume wood at a faster rate than other native subterranean termite species. In part, this is the result of Formosan termites having much larger colonies. Because colony growth is fueled by food consumption, it is generally assumed that Formosan termite workers feed at a faster rate than other termite species providing more food for their queen and brood. Previous studies have shown that Formosan termites have strong preferences for certain wood species, which they consume more readily than others. Studies have also shown that some wood species seem to provide better nutrition than others to the Formosan termite colony by stimulating faster colony growth. As part of a series of studies on the Formosan subterranean termite nutrition, the objectives of this study were to determine if termite workers would make “intelligent” choices if provided with a diverse diet, thereby showing faster colony growth than colonies feeding on single wood species. The growth of young colonies was compared among groups feeding on a single wood species and groups feeding on a combination of 3 wood species. Five wood species were chosen including ponderosa pine, loblolly pine, birch, sugar maple, and pecan. Colony growth was measured by counting all the colony members at the beginning of the experiment and at the end of 1 year period. Colonies were monitored monthly to observe wood consumption and to replace wood pieces as needed. Colonies feeding exclusively on loblolly pine grew at a slower rate than colonies feeding combinations of 3 wood species that included loblolly pine. Colonies feeding on combinations that included pecan grew faster than colonies feeding on combinations that excluded it. When presented with 3 choices, termites fed on all of the wood species; however, some wood species were consumed faster than others. The presence of pecan in the 3 choices stimulated colony growth, but, a diet of pecan alone was also beneficial. This seems to indicate that pecan wood possesses greater nutritional value to the termites than the other woods tested. Colonies feeding on diet combinations that included both loblolly and ponderosa pines had a higher proportion of soldiers than colonies feeding on combinations that included only one of the pine species or none. This study shows that termites choose a diverse diet when presented with choice, and that this diet impact colony growth and caste structure. Technical Abstract: The impact of diet diversity on growth of Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae) colonies was studied. Groups of 22 one-year-old colonies of C. formosanus were fed different combinations of 3 wood species or one of 5 single species of wood including loblolly pine (Pinus taeda L.), ponderosa pine (P. ponderosa Laws.), sugar maple (Acer saccharum Marsh.), pecan (Carya illinoensis (Wangenh.)), and birch (Betula alleghaniensis Briton). The colonies were allowed to grow for 14 mo at 27 ± 1ºC and 93 ± 5% RH. The effect of diet diversity on colony growth was measured and compared. Colonies feeding on a diverse diet exhibited a slightly faster growth than colonies feeding on single wood species; however, those differences were not statistically significant. Only colonies feeding on loblolly pine alone showed significantly lower growth than colonies feeding on a diverse diet that included loblolly pine. Statistical comparison of colony growth between groups feeding diets with and without pecan showed a significantly greater growth in colonies feeding on diets that included pecan. Colonies feeding on diets that included both loblolly pine and ponderosa pine had a significantly higher soldier proportion than colonies feeding on diets that included only one of these species or none. Diverse diets appear to benefit the growth of C. formosanus colonies as long as these diets include wood species that are beneficial by themselves. Termite workers fed on all the wood species presented, but, at different rates showing that workers choose a diverse diet when available. The role of food diversity and feeding choices on termite nutrition is discussed. |
