Density-Dependent Factors Regulating Feeding Success of Ixodes scapularis Larvae (Acari: Ixodidae)

We studied the effects of different parasite and host densities on the feeding success of larval Ixodes scapularis ticks upon white-footed mice Peromyscus leucopus. Mice were infested daily with 10, 25, 50, or 100 larvae and kept individually or in groups of 2 and 3 to simulate co-nesting in the field. Engorgement weight and molting success of replete larvae did not change during more than 3 wk of continuous infestation, but overall larval feeding success decreased from 24% to 12% with increased infestation density. Grooming was observed in response to unattached, crawling larvae, and grooming of unfed ticks increased with infestation density. Nearly all larvae completed engorgement once attached, although a few were groomed accidentally along with unattached ticks. Co-nesting mice fed 2-3 times fewer ticks than did solitary mice because of increased frequency of self-grooming in the presence of nest-mates, but differences between groups of 2 or 3 mice were not significant. Thus, increased mouse density may reduce the density of the tick population at first, but further increase in the number of co-nesting mice does not affect the feeding success of larval I. scapularis and increased mouse density will increase tick density.