Leveraging Adventive and Endemic Parasitoids Against Polyphagous Agromyzid Leafminers in Australia

The recent incursions of three agromyzid leafminers (Liriomyza huidobrensis, L. sativae, and L. trifolii) into Australia pose a significant threat to horticultural production. Outbreaks of these polyphagous pests are consistently associated with the disruption of their parasitoids caused by the widespread use of non-selective insecticides and to increasing pesticide resistance in these agromyzids. An analysis of the international literature for records of parasitoids associated with L. huidobrensis, L. sativae, and L. trifolii revealed that they are attacked by a similar profile of parasitoid families: Eulophidae (63% of records), Braconidae (19%), Pteromalidae (9%), and Figitidae (8%). Diglyphus isaea, Neochrysocharis formosa and Hemiptarsenus varicornis (all already recorded in Australia) were the most commonly reported parasitoids worldwide. These species, along with Australia's broader parasitoid fauna, will play an important role in managing invasive Liriomyza species, provided insecticide use does not disrupt their populations. However, key knowledge gaps remain, especially regarding the taxonomy of local parasitoids, their potential use in conservation biocontrol programs, and the local landscape features that support parasitoid populations. The use of various species in augmentative releases is considered, including constraints and opportunities related to strain selection, including the potential use of thelytokous strains for mass-rearing.