2004. Effect of average worker size on tunneling behavior of Formosan subterranean termite colonies

The effect of a colony’s average worker size on tunneling behavior of Cop-totermes formosanus Shiraki (Isoptera: Rhinotermitidae) in laboratory for-aging arenas was investigated. Large groups of foragers from four colonies were added to arenas and allowed to tunnel for a period of 22 days. Var-ious aspects of the resulting tunnel galleries were analyzed using ANOVA and regression analysis. After the exclusion of one colony due to high mor-tality, the only parameters shown to differ significantly were tunnel width and tunnel segmentation. Larger workers tended to construct less segmented gal-leries with wider tunnels. Tunnel length was positively correlated to size on the first 2 days, but the relationship reversed by day 4. Tunneling on day 1 was positively correlated to the discovery of food items. Our results indi-cate that a foraging group’s average worker size can affect tunnel pattern and that groups composed of larger workers are better tunnelers, but groups of smaller sized workers are able to make up the difference over time. Possible explanations for size-related variation in tunneling behavior are discussed. KEY WORDS: Coptotermes formosanus; intercolony variation; tunneling behavior; subter-ranean termites