SEASONAL ACTIVITY AND TEMPORAL SEPARATION OF 4 SPECIES OF FLEAS (INSECTA, SIPHONAPTERA) INFESTING RICHARDSON-GROUND-SQUIRRELS, SPERMOPHILUS-RICHARDSONII (RODENTIA, SCIURIDAE), IN MANITOBA, CANADA

Fleas were collected from Richardson's ground squirrels (Spermophilus richardsonii) livetrapped in two areas in southern Manitoba. Our objec tives were to describe the seasonal activity of the fleas and determin e whether peaks in mean infestation parameters for different species o f fleas occurred at different times of the year. We also wanted to det ermine if the seasonal activity of Opisocrostis bruneri was different in the presence of other fleas on the same hosts. Activity of Richards on's ground squirrels at both locations was similar to that observed i n previous studies in Canada. Opisocrostis bruneri, Oropsylla rupestri s, Neopsylla inopina, and Rhadinopsylla fraterna infested ground squir rels near Darlingford, whereas only O. bruneri occurred at two Winnipe g sites. Females of all species outnumbered males during most weekly c ollection periods. Mean intensity of N. inopina was highest during Apr il, when prevalence of infestation often exceeded 50%. Prevalence of R . fraterna seldom exceeded 10%; there were peaks of infestation on adu lt squirrels during early April and on juveniles from mid-August to th e 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 tw o peaks of infestation for O. bruneri, on adult squirrels in May and o n juveniles during August. Patterns of activity of O. bruneri were the same for Darlingford and Winnipeg, despite the occurrence of three ad ditional flea species on ground squirrels at Darlingford.