Occurrence of Philornis bella Couri in nestlings of Tyrannus melancholicus Vieillot ( Tyranninae ) in the municipal district of Seropédica , Rio de Janeiro

Five nestlings of Tyrannus melancholicus Vieillot, 1819, between nine (n = 2) and twelve days (n = 3) old, were studied from July to September in 2006. A total of 43 larvae was collected, of which 33 (76%) became Philornis bella Couri, 1984. The most infested areas of the nestlings were the wings ! " # # $ & " P. bella parasitizing nestlings of Tyrannus melancholicus.


Introduction
Philornis Meinert, 1890, is a genus of Muscidae that is predominantly neotropical (COURI, 1983).Adults can usually be distinguished from other congeners by the following combination of characters: palpi slightly enlarged at apex; arista with long plumes; mesonotum usually quadrivittate; anepimeron hairy; postalar wall with a tuft of cilia; posterior spiracle with cilia; dorsocentral bristles 2+4; anal vein long; and third and fourth veins divergent, the latter a little bent towards the tip.The presence of hairs on the anepimeron and on the postalar wall can easily distinguish adults of Philornis from those of other muscid genera.According to Couri (1999), P. bella differs from other species of the genus by having the following: yellow antenna and palpi; yellowhaired cheeks; yellowish-brown mesonotum, with greyish pollinosity, and four brown vittae; abdomen with WHUJLWHV DQG \HOORZ ¿UVW VWHUQLWH DQG JHQLWDO VHJPHQWV yellow; hind tibia with 5-6 bristles on anterodorsal surface and 5-6 bristles anteroventral surface.
Apparently, the intimate association of Philornis ÀLHV ZLWK QHRWURSLFDO ELUGV ZDV ¿UVW PHQWLRQHG LQ %UD]LO in the middle of the seventeenth century by George Marcgrave (TEIXEIRA, 1982).The larvae of this genus can be free living on bird nests, with a coprophagous or semi-hematophagous habit, or live intradermally in nestlings, with a hematophagous habit (COURI, 1985).In Brazil, 29 species of Philornis have been recorded, and 10 species are known from the state of Rio de Janeiro (COURI; CARVALHO, 2005).According to Couri (1984), 23 species of Philornis are related to the nestlings of 75 bird species, and two cases are known for adult birds, which were reported by Macquart (1854) and Dodge and Atiken (1968).Teixeira (1999) reported parasitism by Philornis for 105 species of birds that belong to 32 families.,Q WKLV VWXG\ ZH SUHVHQW WKH ¿UVW UHFRUG RI ODUYDH RI Philornis bella on nestlings of Tyrannus melancholicus Vieillot, 1819 (Aves, Tyrannidae), which was observed in the municipality of Seropédica, in the state of Rio de Janeiro.

Materials and Methods
The study was conducted from July to September of 2006 in the municipal district of Seropédica (22º45'49"S, 43º41'19"W, 70m elevation).
The larvae were removed manually from different regions of the body and placed in sterile plastic containers WKDW ZHUH FRYHUHG ZLWK D ¿QH PHVK FORWK 'U\ JUDVV DQG D thin layer of soil were placed in each container to allow pupariation and metamorphosis.After the adult forms of diptera emerged, cotton moistened with water was placed inside each container to maintain the humidity of the environment.
The adults were allowed to die naturally so their life expectancy could be estimated.After death, the adults ZHUH VWRUHG LQ */ HWKDQRO DQG LGHQWL¿HG

Results and Discussion
)URP -XO\ WR 6HSWHPEHU RI ¿YH QHVWOLQJV of Tyrannus melancholicus were found, which were approximately nine (n = 2) and twelve days (n = 3) old.A total number of 43 larvae were collected during this time, of which 33 (76%) became adults and were LGHQWL¿HG DV Philornis bella Couri, 1984.At this time there was no record of P. bella parasitizing nestlings of Tyrannus melancholicus.According to Teixeira (1999), only two species of Philornis, P. downsi (Dodge and Aitken, 1968) and P. trinitensis (Dodge and Aitken, 1968), were known to be parasites of the nestlings of this species.
We observed a higher concentration of larvae in the uropygium, wings and tails of the nestlings.Possati et al. (2001) mentioned that the larvae of P. bella found in nestlings of P. sulphuratus were collected from the wings, head, upper back and near the cloacae, but did not mention which region was parasitized the most.In a study by Luz et al. (2007), the authors mention several areas with parasites, and the most infested regions were the wings and uropygium.Thus, we believe that parasitism in these regions lowers the chance that the host will prey on the larvae.

Occurrence of Philornis bella in nestlings of Tyrannus melancholicus
We did not observe any feces or other organic matter inside the nest that could explain the parasitism.The larvae of P. bella are subcutaneous (biting), feed on blood, and are commonly found in birds that keep clean nest (HIGGINS et al., 2005).According to Guimarães and Papavero (1983), these muscidae deposit their eggs directly on the young or their nests.As for any debilitating effect caused by the parasitism in the present study, no nestlings died.The number of larvae (mean RI ODUYDH SHU QHVWOLQJ ZDV SUREDEO\ QRW VXI¿FLHQW to cause death.However, Smith (1968) mentions that seven larvae would be enough to cause a debilitating effect on a nestling.Higgins et al. (2005) also mentioned that the effect is debilitating and described the death of a nestling of S. slelorum due to severe parasitism by larvae of Philornis.Possati et al. (2001) mentioned that the average number of larvae found on nestlings of P. sulphuratus was seven and that all the nestlings survived.It is important to note that the removal of some larvae IRU LGHQWL¿FDWLRQ PD\ GLUHFWO\ LQÀXHQFH WKH UHFRYHU\ of the hosts so they do not die.However, we do not KDYH VXI¿FLHQW GDWD WR FRQFOXGH WKDW WKLV SURFHGXUH prevented the death of the studied nestlings.According to Aguilar et al. (1999), after collecting some larvae of Philornis, which were living in nestlings of L. euleri, all of the nestlings died, and the following year, in a new study with the same species, the larvae were not removed and all of the nestlings survived.In another study, Luz et al. (2007) reported that the survival of nestlings of X. cinerea could be related to other factors, and not only the number of larvae parasitizing a nestling.Thus, we believe that the debilitating effect on hosts may be linked to two factors: age of the nestling x number of parasites and the behavior of parents while feeding a nestling.It is also possible that different host species have different resistances against this kind of parasite.Based on a study by Smith (1968), seven larvae would be enough to cause the death of a host bird, and a study by Couri (1985), where 32 larvae of a Philornis sp. in a nestling of Pitangus sulphuratus did not kill the bird, we can infer the possibility of host species that are resistant to this type of parasite.Thus, additional studies about the factors that cause the debilitating effect on the hosts are needed, as well as studies about the biology of these parasites and their hosts.The goal of this study ZDV WR UHSRUW WKH ¿UVW UHFRUG RI P. bella parasitizing nestlings of T. melancholicus.