First Record of Cuterebra fontinella (Diptera: Oestridae) Larvae Infesting a Florida Rat (Rodentia: Muridae)

Abstract

The host relationships of Cuterebra spp. bot flies (D?ptera: Oestridae) are of interest from both the perspective of parasite/host coevolution (Col well et al. 2006; Slansky 2007a) and the context of these insects causing a type of myiasis (cuterebro sis) in cats, dogs, humans, and other mammals (Safdar et al. 2003; Slansky 2007b,c; 2008). Cute rebra spp. larvae typically parasitize either indig enous lagomorphs (rabbits and hares) or rodents (e.g., mice, rats and tree squirrels) in the Ameri cas (Sabrosky 1986; Slansky & Kenyon 2003), with each generally restricted to one or a few closely related host species. Occasionally they in fest other mammals ('atypical' hosts; Sabrosky 1986; Slansky & Huckabee 2006; Slansky 2007b,c; Slansky 2008). Whether the latter repre sent aberrant cases, as categorized by Sabrosky (1986), or reflect incipient broadening of the host spectrum of these flies, is uncertain. Thus, studies are required to help define these flies' host rela tionships. Here we describe an unusual case of an eastern woodrat, Neotoma floridana (Ord) (Ro dentia: Muridae), parasitized by larvae o? Cutere bra fontinella Clark, which typically infest mice. In late Apr 2007, a severely emaciated rat in Sebastian, Indian River county, Florida, was killed in a suburban area adjacent to a 0.3 ha plot of dense scrub, including Brazilian pepper (Schi nus terebinthifolius Raddi, palmetto (Sabal spp. and Serenoa repens (Bartr.) Small, oak (Quercus spp.) and pine (Pinus spp.). Upon the animal's death, 5 larvae emerged from its lower abdomen, leaving large holes that exposed the underlying muscle fascia. Four larvae were placed in a glass jar with vented lid containing moist sandy soil, and a thin layer of soil was sprinkled over them. The jar was kept in a shaded area outdoors for ap proximately 3 weeks, after which it was main tained indoors at approximately 21-24?C; 2 fe male flies eventually emerged, 1 in late Jun and the other in early Jul, 2007. Subsequently, they died and were pinned for preservation. One larva was preserved in isopropanol. These specimens are deposited in the Medical & Veterinary Insect Collection, Department of Entomology & Nema tology, at the University of Florida, Gainesville, as voucher specimens UF070501, UF070502 and UF070503, respectively. The first fly was photo graphed with a Nikon? model D200 digital cam era, and images of the larva were made with an Automontage? digital photomicroscopy system (Synchroscopy, Frederick, Maryland). The rat was tentatively identified as an eastern woodrat but the specimen was not retained. Another rat was therefore collected from the same population and confirmed to be N. floridana; it is deposited as voucher specimen UF 31368 in the mammal col lection of the Florida Museum of Natural History at the University of Florida, Gainesville. Based upon information in Sabrosky (1986), the flies (Fig. la,b) were determined to be C. fon tinella. The larva (Fig. lc) appears to have par tially pupariated. Some of the mostly flattened, exterior platelets are raised slightly and have multiple points (Fig. Id), a characteristic of third instars of rodent-infesting Cuterebra species; in contrast, lagomorph-infesting species have cone shaped spine-like platelets (Slansky & Huckabee 2006; Slansky 2007b). The lack of 2 button-like anterior spiracles typically extruded by Cuterebra spp. larvae during pupariation (Sabrosky 1986; Slansky & Kenyon 2003) indicates this process was incomplete. The pupal durations and dates of emergence for these specimens support records indicating that C. fontinella has 2 or more gener ations per year in the southeastern US (Sabrosky 1986; Durden 1995, 2008; Slansky 2006). This species apparently has not been reported previ ously from Indian River County, although there are records from other eastern counties north (Or ange and Volusia) and south (Broward and St. Lu cie) of this county (Slansky 2006). Only 2 published studies have reported Cutere bra spp. infesting N. floridana in Florida, and in neither was the species of Cuterebra identified (Johnson 1930; Worth 1950a). Outside Florida, only Cuterebra americana (Fabricius) has been reared from N. floridana (Sabrosky 1986; L. A. Durden, personal communication to F. S.). Thus, the case described here appears to be the first con firmed report o? a. Cuterebra species other than C. americana, and of C. fontinella, reared from N. floridana. This appears to be the first published, substantiated record for Florida of a Cuterebra species reared from any of the 3 indigenous rat species (N. floridana, the rice rat, Oryzomys palustris (Harlan) and the hispid cotton rat, Sig modon hispidus Say and Ord) or 2 non-indigenous