Surveys of tephritid fruit flies and their parasitoids are a first step to a better understand of the ecology of these economically important taxa (Zucchi 2000a). The major natural enemies of the fruit flies in Brazil belong to the families Braconidae, Figitidae, and Pteromalidae (Hymenoptera). Pteromalidae, mainly Pachycrepoideus vindemiae Rondani, are sporadically collected and specimens of Figitidae are collected in small numbers throughout the country. Typically the most frequent parasitoids collected in Brazil are members of the Braconidae family (Canal & Zucchi 2000).

In Santa Catarina state, Nora et al. (2000) previously found, in order of abundance, Doryctobracon areolatus (Szèpligeti), Doryctobracon bra-siliensis (Szèpligeti), Opius bellus Gahan, and Opius tomoplagiae Lima. In addition, they obtained unidentified Diapriidae, Eulophidae, Figitidae, and Pteromalidae. Guimarães et al. (2000) added to this list the figitids Aganaspis pelleranoi (Brèthes) and Odontosema anastrephae Borgmeier, and Leonel, Jr. et al. (1995) and Canal & Zucchi (2000) obtained braconids Microcrasis lonchaea (Lima) and Utetes (Bracanastrepha) anastrephae (Viereck).

The present paper describes the parasitoids of fruit flies from the western portion of Santa Catarina state, an area which is a growing producer of citrus in the state (Koller et al. 1999) and which has not been surveyed thoroughly in the past. We collected 9,197 mature fruit from trees or on the soil comprising 46 species belonging to 25 families in the six towns Anchieta (26°53′S and 53°33′W), Chapecó (27°06′S and 53°16′W), Cunha Porã (26°07′S and 53°16′W), Palmitos (27°06′S and 53°16′W), São Carlos (27°07′S and 53°00′W), and Xanxerê (26°87′S and 52°40′W), Santa Catarina. Each fruit was weighed and put in a plastic container with about seven centimeters of sterilized sand, and covered with a net. The containers were kept in the entomology laboratory of the Agricultural and Environmental Science Center at the Universidade Comunitária Regional de Chapecó at 25 ± 3°C, 70 ± 10% and a 12-h photoperiod. After five days, the sand with pupae was transferred to lab Petri dishes containing filter paper dampened with distilled water. Flies and parasitoids were counted after seven days.

The relationship between a fly species and its parasitoids was determined only when a single species of fly was held in an emergence container (Canal et al. 1994).

The total index of parasitism (TIP) was calculated as the number of parasitoids emerged × 100/number of flies emerged + number of parasitoids emerged. The relative frequency of fly species and parasitoids (RF) was defined as number of samples of a given species collected × 100/total number of collected species according to Matrangolo et al. (1998), and the parasitism percentage was calculated as %P = total parasitism × 100/total pupae, which was modified from Silveira Neto et al. (1997).

Species of Anastrepha were identified with Steyskal’s key (1997) and Zucchi’s key (2000b), which includes only Brazil species. The Braconidae were identified according to the key of Canal & Zucchi (2000). The flies and parasitoids belonging to other families were sent to Prof. Dr. Manoel Araécio Uchôa Fernandes, Biologist Jorge Anderson Guimarães, Dr. Allen Norrbom, and Prof. Dr. Roberto Antonio Zucchi for identification.

Of the 46 fruit species collected, 35 were infested by fruit flies, but only 14 of these fruit species contained parasitoids (Table 1). A total of 682 samples of parasitoids belonging to nine species and three families were obtained, as follows: D. areolatus, D. brasiliensis, O. bellus, Opius sp., U. anastrephae (Braconidae), A. pelleranoi, O. anastrephae (Figitidae), and Trichopria anastrephae Lima (Diapriidae).

Of the 461 hymenopterans associated with a particular fruit fly, A. pelleranoi was the most common and represented 25.6% of the total, followed by D. brasiliensis (21.1%) and D. areolatus (18.6%). These figures differ from those obtained by Salles (1996) for the state of Rio Grande do Sul and Leonel Jr. (1995), Leonel et al. (1996) for the state of São Paulo. However, the relative abundance of parasitoids collected in the valley of Rio do Peixe, state of Santa Catarina by Nora et al. (2000) are similar to ours.

All the parasitoids developed in A. fraterculus, except for L. anastrephae, which was associated only with Neosilba sp. Also a lonchaeid was obtained in the samples (Table 2). D. areolatus and U. anastrephae also parasitized Neosilba sp. De Santis (1980) catalogued eleven species of Trichopria for Brazil, and believed that only T. anastrephae parasitized the genus Anastrepha. Aguiar-Menezes et al. (2001) previously reported A. fraterculus as the host of T. anastrephae. L. anastrephae has been recorded previously only in the southern part of the country, in the state of São Paulo and central Mato Grosso do Sul (De Santis 1980).

Parasitoids attacked fruit flies in 14 host-plant species, one Fabaceae, five Rosaceae and eight Myrtaceae (Table 1). Myrtaceae contained 79.6% of the parasitoids and Rosaceae had 21.2%. The total parasitism index and the parasitism percentage were greatest in Eugenia involucrata, followed by Prunus avium and Myrcianthes pungens. These indexes are higher than those obtained by Leonel, Jr. et al (1996), Salles (1996) and Matrangolo et al. (1998), but are similar to those of Guimarães et al. (1999).

The high percent parasitism in E. involucatra was previously found by Salles (1996) in the Rio Grande do Sul state, and may be due, as he suggested, to the thin peel and small size of the fruit. Guimarães et al. (2000) previously observed affinity of A. pelleranoi to the Myrtaceae fruit, which we confirmed. Sivinski (1991), Sivinski et al. (1997), Sivinski et al. (2000) and Hickel (2002) found that braconid parasitism was negatively correlated to fruit pulp thickness, and we showed that weight data correlated to parasitism.