Abstract: Aggregation is an ecological strategy for some animals adapting various adversities. Pyrrhocoris apterus will aggregate significantly during overwintering by adult diapause. In order to make out whether the aggregation affects rates of energy metabolism, we have directly measured the respiration of P. apterus with five different aggregation degrees using the LI-COR LI-6400, and calculated the rates of respiration (Rr) and the rates of energy metabolism (Rm). The five different aggregation degrees were shown by five different group sizes of the firebugs (1, 5, 10, 20 and 50 individuals). The results indicated that there were significant differences in the values of Rm among the five different aggregation levels. The values of Rm and the aggregation degrees had a negative correlation relationship. The values of Rm were 0.052, 0.044, 0.041, 0.037 and 0.033 W/g, respectively. The results suggested that aggregation of the firebugs can lower the metabolic rates, which may be advantageous for their overwintering successfully.

Key words: Pyrrhocoris apterus, overwintering, aggregation, energy metabolism, rates of respiration