Laboratory Colonization, Life History Observations, and Desiccation Tolerance of the Canyon Fly Fannia conspicua (Diptera: Fanniidae)

Abstract

"Canyon flies" are flies within the Fannia benjamini Malloch species complex. These flies can be considerable pests to humans and animals due to their habit of feeding on animal body secretions such as tears, mucus, sweat, and blood. Adult "canyon flies" (Fannia conspicua Malloch) were collected from the coastal mountain community of La Habra Heights in Los Angeles County, CA, during late spring and early summer of 2011. Canyon flies were colonized in the laboratory and maintained for over two years. Larval growth, sex-specific adult emergence, and fecundity were evaluated quantitatively. At 25°C, male flies required a minimum of 22 d postoviposition to develop from egg to adult, with peak emergence occurring at 24-26 d; female flies required a minimum of 25 d postoviposition, with peak emergence occurring at 26-28 d. Female flies were capable of oviposition starting at 7 d postemergence, and produced a mean of 90.6±54.7 eggs over a 19-41-d life span. Canyon fly eggs were quite resistant to desiccation, with hatching rate of eggs reduced only after ≥12 wk of desiccation, and some successful hatching even when eggs were desiccated up to 28 wk. When immature flies were removed from their food source and subjected to continuous desiccation and starvation, flies at 3-d-old posthatching did not survive, and only 8% of flies at 5-d posthatching survived and completed development to the adult stage. Immature flies that were 7- or 11-d-old posthatching survived to adulthood in good numbers, having reached the mid to late L3 stage at the time of food removal. Exposure to desiccation in either the egg or larval stage had no effect on fecundity of surviving females. This extreme level of desiccation tolerance is likely an adaptation to increase survival in desert climates of the southwestern United States with long, hot summers and little precipitation, where Fannia conspicua are typically distributed.