SEASONAL OCCURRENCE AND REPRODUCTIVE STATUS OF OPISOCROSTIS-BRUNERI (SIPHONAPTERA, CERATOPHYLLIDAE), A FLEA ON FRANKLIN GROUND-SQUIRREL, SPERMOPHILUS-FRANKLINII (RODENTIA, SCIURIDAE) NEAR BIRDS HILL PARK, MANITOBA

Eight hundred and forty-nine and 1,503 Opisocrostis bruneri (Baker) we re removed from Spermophilus franklinii (Sabine) in 1982 and 1983, res pectively. Two discrete peaks in mean intensity of infestation were ob served, one in early May and one in late August to early September. Ov erall prevalence of O. bruneri on S. fanklinii was greater-than-or-equ al-to 0.75. The observed biweekly prevalence on adult male and female squirrels was always greater-than-or-equal-to 0.73 and greater-than-or -equal-to 0.67, respectively. All juvenile squirrels were infested. Fe male fleas with undeveloped ovarioles, and with or without sperm in th e spermatheca, were predominant during the first 6 wk that squirrels a ppeared above ground after hibernation. Parous females predominated th ereafter. Peaks of nulliparous female fleas were observed in early May and early july. Female fleas were favored in each trapping period exc ept during a 2-wk period from the beginning of May to the end of June. The mean biweekly sex ratio (male/female) of fleas removed from S. fr anklinii was 0.70 and 0.72 in 1982 and 1983, respectively. Oogenesis i n O. bruneri was not dependent upon the estrous cycle of female S. fra nklinii. It appeared that O. bruneri completed at least two generation s per year in Manitoba.