Larval density and feeding success of Ixodes scapularis on two species of Peromyscus

One potential mechanism for the regulation of tick populations is density-dependent feeding success on vertebrate hosts. In a series of laboratory experiments, we tested whether the density of larval Ixodes scapularis on the mice Peromyscus maniculatus and Peromyscus leucopus influenced tick feeding success. For both host species, the proportion of ticks feeding to repletion was constant (approximately 40-50%) over a range of infestation from 5 to 100 ticks per mouse. For P. leucopus, neither mass nor molting success of fed ticks was significantly related to tick density on the host. However, for P. maniculatus, we observed a statistically significant increase in molting success with increasing tick density on hosts, thus demonstrating facilitation rather than density-dependent regulation. Although results were not statistically significant, we observed a tendency for previously exposed P. leucopus to support lower tick feeding success than naive mice; however, even for previously exposed mice, tick feeding success was not density dependent. Our results do not support the notion that density-dependent feeding on hosts regulates density of I. scapularis populations at the numbers tested.