Do Bot Flies, Cuterebra (Diptera: Cuterebridae), Emasculate their Hosts?

Abstract

Abstract. Asa Fitch, in his description of a new species of Cuterebra that he nzrr'ed, "emaseulator," was the first to suggest that bot flies castrated their mammalian hosts. In recent years several major review papers and parasitology texts have continued to perpetuate this belief. A review of both the literature on bot flies and their hosts and of the life cycles of both bots and hosts provides no evidence to substantiate castration. Eastern Chipmunks (Tamias striatus) experimentally infected with Cuterebra ernascularlor experienced no destruction of testicular tissue. The concept of castration may have been perpetuated by observations of bots in the scotal sac of a host. Suoerficial examination of a host with a bot(s) in the scrotum would suggest that the bot had consumed the testis; this is demonstrated on a White-footed Motse (Peromyscus leucopus). We conclude that there is no evidence to support the notion that bot flies castrate their mammalian hosts. On extremely rare occasions, a bot may slightly displace a testis, and perhaps this temporarily reduces fertility.

Ophthalmomyiasis interna anterior in a cat: surgical resolution

“…The eggs hatch into motile first stage larvae in approximately 1 week with the right temperature and moisture conditions. The larva usually enters the host through its natural body openings such as the nose, mouth, anus, or eyes 16–19 . In rodents and lagomorphs, the larva migrates to the subcutis and cuts warble pores (respiratory holes) where it matures to second‐stage larva.…”

Is Host Castration an Evolutionary Strategy of Bot Flies?

“…Our work on Cuterebra emasculator parasitizing the eastern chipmunk, Tamias striatus, and C. fontinella parasitizing the white-footed mouse, Peromyscus leucopus, demonstrated that bot flies are found exclusively in the subcutaneous region between the skin and underlying muscle (Timm and Cook, 1979;Timm and Lee, 1981). They do not consume muscle or reproductive tissue, but rather feed on "tissue debris and exudate produced" (Payne and Cosgrove, 1966, p. 212).…”

“…First, a capsule that superficially resembles the testis is formed around a developing bot; this capsule may have been mistaken for a "consumed testis." On occasion, bot flies located in the scrotum may displace a testis anteriorly andlor dorsally; the larval bot then occupies the scrotal sac where the casual observer expects to find a testis (see photographs in Timm and Lee, 1981). And finally, bots located in the inguinal region of the female rodent create a pocket of swollen skin that superficially resembles a scrotum.…”

Is Host Castration an Evolutionary Strategy of Bot Flies?

“…(Timm and Cook, 1979;Timm and Lee, 1981). They do not consume muscle or reproductive tissue, but rather feed on "tissue debris and exudate produced" (Payne and Cosgrove, 1966, p. 212).…”

“…On occasion, bot flies located in the scrotum may displace a testis anteriorly and/or dorsally; the larval bot then occupies the scrota! sac where the casual observer expects to find a testis (see photographs in Timm and Lee, 1981). And finally, bots located in the inguinal region of the female rodent create a pocket of swollen skin that superficially resembles a scrotum.…”