Does brood presence affect exploratory behaviour in Reticulitermes lucifugus (Isoptera, Rhinotermitidae)?

Little is known about the division of labour during searching for food in the order Isoptera. Moreover, the cryptic lifestyle of subterranean termites such as Reticulitermes spp.(Isoptera, Rhinotermitidae), makes behavioural studies particularly difficult to perform. Nevertheless, studies on foraging patterns in R. santonensis, showed that workers are the caste involved in food searching (Reinhard et al. 1997). A previous investigation on the exploratory behaviour of R. lucifugus was performed in laboratory conditions, collecting behavioural data by individual marking and scan-sampling techniques (Pedroni and Maistrello 2007), and allowed to describe the searching patterns of termites in presence or absence of food sources and to identify the existence of scout termites, which were recognized as the largest and oldest workers. The present study aimed at investigating whether and how the presence of brood in the experimental groups could affect the exploratory behaviour of the workers and was performed in laboratory, comparing groups composed by workers only and mixed groups, with both workers and larvae. Results showed that, when larvae were present, it took a longer time to scout workers to reach the food source for the first time. Moreover, when a food source is available, after the scouts have located it, both “mixed” and “workers only” groups are observed to gradually shift to the food source from the original nest area, however, in groups with larvae, this moving takes a longer time. In absence of food in both “mixed” and “workers only” groups, the majority of termites remained in the nest area, whereas a few scout workers continued to explore the apparatus. From these observations it emerged that brood presence lead to a delay both in starting exploratory behaviour and in organizing the response to food detection.