The abundance and phenology of four common agromyzid leafmining flies (Diptera: Agromyzidae) and their associated parasitoid wasps in southern Victoria

Abstract

Three polyphagous agromyzid leafminers, Liriomyza sativae Blanchard, Liriomyza huidobrensis (Blanchard) and Liriomyza trifolii (Burgess), have recently invaded mainland Australia, posing a threat to horticultural crops. Overseas, these species are often effectively controlled by local hymenopteran parasitoids. It is important to assess the abundance and composition of the existing parasitoid community capable of impacting these pests as they spread across Australia. We surveyed three adventive agromyzids, Liriomyza brassicae (Riley), Phytomyza plantaginis Goureau and Phytomyza syngenesiae (Hardy), and one endemic species, Liriomyza chenopodii (Watt), at six sites around Melbourne, Victoria, between August 2018 and January 2020. In all, 4748 agromyzids and 2474 identified parasitoids were reared. Eleven wasp species were identified: seven eulophids, three braconids and one pteromalid. Four eulophid species—Asecodes sp., Diglyphus isaea (Walker), Closterocerus mirabilis Edwards & La Salle and Hemiptarsenus varicornis (Girault)—and one braconid species, Opius cinerariae (Fischer), were reared from all agromyzid hosts. Three eulophid species—Chrysocharis pubicornis (Zetterstedt), Neochrysocharis formosa (Walker) and Zagrammosoma latilineatum Ubaidillah—and one pteromalid species, Trigonogastrella parasitica (Girault), were reared from three host agromyzids. C. pubicornis (Zetterstedt), a pupal parasitoid, was the most abundant parasitoid overall but was almost entirely reared from the two Phytomyza spp. at only one site. Peaks in parasitism were observed in late spring and late autumn, depending on the host. These results show that a diversity of local agromyzids persists throughout the year in southern Victoria, supporting a stable parasitoid community that should help control invasive Liriomyza spp. in the future.