Biology and Ecology of Bat Flies (Diptera: Streblidae) on Bats in the Genus Carollia1

Abstract

The biology and ecology of bat flies found on Carollia perspicillata were investigated in Heredia Province, Costa Rica. Only Trichobius joblingi, Speiseria ambigua , and Strebla guajiro were found on Carollia . These streblids were absent from 9 species of bats in 7 other genera. Although streblids transfer readily among bats in a roost, flies had a clumped distribution on foraging bats. Female bats had significantly higher numbers of flies (3.5 ± 3) than did male bats (2.1 ± 2). The ratio of female to male flies was 1:1.3, 1:1.4, and 1:1.7 for T. joblingi, Sp. ambigua , and St. guajiro , respectively. Pupiposition occurred between 1730–1930 h, coinciding with the time when bats leave their roosts. Pupae eclosed during the morning, providing teneral flies with maximum time for cuticle hardening and host searching. Mean pupal developmental times (in days) for caged T. joblingi, Sp. ambigua , and St. guajiro were 17.4 ± 1, 19.8 ± 0.66, and 18.8 ± 0.75, respectively; pupal mortality was 22, 48, and 62%, respectively. Trichobius joblingi pupae monitored in a tree roost had 37% mortality. Streblids fed frequently and voided fecal droplets containing masses of intact red blood cells. When removed from hosts, fly defecation rates dropped to 0 after 1 h. Fed T. joblingi had a mean survivorship off the host of 2.79 ± 0.88 h, whereas teneral flies lived significantly longer (4.0 ± 0.47 h). Mean survival time off the host for Sp. ambigua and St. guajiro was less than 7 h. Streblids copulated on the host, and males would often “ride” fully parous females. Laboulbeniomycete fungi were found on all 3 bat fly species; this is the first record of them on New World streblids.