Australian Journal of Entomology (2004) 43, 138–147 Blackwell Science, LtdOxford, UKAENAustralian Journal of Entomology1326-67562004 Australian Entomological SocietyMay 2004432138147Original ArticleOpiusattacking leaf-mining AgromyzidaeSA Belokobylskij et al. *Author to whom correspondence should be addressed (Email: hymenopt@zin.ru). Australian species of the genus Opius Wesmael (Hymenoptera: Braconidae) attacking leaf-mining Agromyzidae, with the description of a new species from South-east Asia Sergey A Belokobylskij, 1 * Robert A Wharton 2 and John La Salle 3 1 Zoological Institute Russian Academy of Sciences, St. Petersburg 199034, Russia and Museum and Institute of Zoology PAN, Wilcza 64, Warsaw, Poland. 2 Department of Entomology, Texas A & M University, College Station, Texas 77843, USA. 3 CSIRO Entomology, GPO Box 1700, Canberra, ACT 2601, Australia. Abstract The species of Opius Wesmael that attack leaf-mining Agromyzidae in Australia are discussed, and a key provided for their separation. Opius cinerariae Fischer is redescribed based on specimens reared from Liriomyza chenopodii (Watt) (Agromyzidae), and its subgeneric placement is discussed in light of newly discovered morphological features. Opius (Opiothorax) chromatomyiae Belokobylskij & Wharton sp. n. is described from specimens reared from Chromatomyia horticola (Goureau) and Liriomyza huidobrensis (Blanchard) (Agromyzidae) in Malaysia, Indonesia and Vietnam. Opius insu- licola Tobias nom. n. is proposed for Opius insularis Tobias (1998), a junior primary homonym. Key words Agromyzidae, Australia, Braconidae, Hymenoptera, Opius, Oriental Region, parasitoids. INTRODUCTION Leaf-mining flies in the family Agromyzidae are among the more important pests worldwide of vegetables and floricul- tural crops. Several species can cause extensive economic damage to a broad range of host plants under both field and greenhouse conditions. Knowledge of the parasitoids of Agromyzidae has become increasingly important as interest in utilisation of biological control tactics for these pests expands beyond the traditional areas of western Europe and the USA (Konishi 1998; Ku et al. 1998; Murphy & La Salle 1999). In addition to numerous chalcidoid genera from the families Eulophidae (mostly) and Pteromalidae, several genera of Braconidae and eucoiline Figitidae have been recorded as parasitoids of Agromyzidae (Murphy & La Salle 1999). Opius Wesmael s.l. (including Phaedrotoma of Achterberg & Salvo 1997) is one of the largest genera in the family Bra- conidae, and more than half of the recorded hosts belong to the Agromyzidae. Several species of Opius have been utilised in biological control and pest management in general (Cameron 1941; Muesebeck 1963; Fischer 1971a; Greathead 1975; Woets & van der Linden 1982; Wharton 1984; Neuenschwander et al. 1987; Schuster & Wharton 1993; Salvo & Valladares 1995). Previous host records for agromyzid parasitoids from the Australian and Oriental regions are limited (Fischer 1987). In Australia, Opius (Opiothorax) atricornis Fischer, Opius (Gerius) cinerariae Fischer and O. (Phaedrotoma) oleracei Fischer attack a diverse assemblage of agromyzids in crops and weedy vegetation (Fischer 1963; Lardner 1991). In the Oriental region, O. (Phaedrotoma) phaseoli Fischer has been recorded as a parasitoid of several agromyzid species. The African species O. (Gastrosema) importatus Fischer and O. (Merotrachys) melanagromisae Fischer were introduced purposefully to Hawaii (Fischer 1971a), and Opius dissitus Muesebeck, described originally from Hawaii (Muesebeck 1963), may have been an accidental introduction (Wharton 1984). Opius (Gastrosema) lantanae Bridwell, reared from leaf-miners on an introduced weed, also was described from Hawaii and may represent similarly an accidental introduction. The well-known European species, O. exiguus Wesmael, was recorded from Korea by Papp (1981). This paper contributes to the knowledge of Australasian Opius species that may control leaf-mining agromyzid pests. Opius cinerariae is redescribed here based on specimens reared from Liriomyza chenopodii (Watt) developing on fat hen, chick weed, red chard, and silver beet in Australia. This species has two previously overlooked features that consider- ably facilitate its identification. Existing keys to this species are difficult to use because O. cinerariae does not readily fit in the subgeneric classification used by Fischer (1972, 1987). Thus, a key to Australian species of Opius reared from leaf- mining agromyzids is provided to enable identification of these economically important species. Opius (Opiothorax) chromatomyiae Belokobylskij & Wharton sp. n., from Malaysia, Indonesia and Vietnam, was reared from mines of Chromatomyia horticola (Goureau) on potato, sweet pea, gar- den pea, and cucumber, and swept from cucumber plants heavily infested with Liriomyzae huidobrensis (Blanchard).