Seasonal activity and temporal separation of four species of fleas (Insecta: Siphonaptera) infesting Richardson's ground squirrels,Spermophilus richardsonii(Rodentia: Sciuridae), in Manitoba, Canada

Abstract

Fleas were collected from Richardson's ground squirrels (Spermophilus richardsonii) livetrapped in two areas in southern Manitoba. Our objectives were to describe the seasonal activity of the fleas and determine whether peaks in mean infestation parameters for different species of fleas occurred at different times of the year. We also wanted to determine if the seasonal activity of Opisocrostis bruneri was different in the presence of other fleas on the same hosts. Activity of Richardson's ground squirrels at both locations was similar to that observed in previous studies in Canada. Opisocrostis bruneri, Oropsylla rupestris, Neopsylla inopina, and Rhadinopsylla fraterna infested ground squirrels near Darlingford, whereas only O. bruneri occurred at two Winnipeg sites. Females of all species outnumbered males during most weekly collection periods. Mean intensity of N. inopina was highest during April, when prevalence of infestation often exceeded 50%. Prevalence of R. fraterna seldom exceeded 10%; there were peaks of infestation on adult squirrels during early April and on juveniles from mid-August to the end of the season. Oropsylla rupestris was the most abundant species on squirrels at Darlingford, and peaks of prevalence and intensity of infestation occurred during April, July, and September. There were two peaks of infestation for O. bruneri, on adult squirrels in May and on juveniles during August. Patterns of activity of O. bruneri were the same for Darlingford and Winnipeg, despite the occurrence of three additional flea species on ground squirrels at Darlingford.