Production of Ganaspidium utilis (Hymenoptera: Eucoilidae) for biological control of Liriomyza spp. (Diptera: Agromyzidae)

A method for rearing the Liriomyza leafminer parasitoid Ganaspidium utilis Beardsley (Hymenoptera: Eucoilidae) is described. 'Henderson' bush lima beans, Phaseolus limensis var. limenanus L. H. Bailey, were planted in vermiculite in six 20 × 14 × 35.5-cm² plastic bags. After 10 to 11 days the plants were exposed to 500 to 600 adult Liriomyza trifolii (Burgess) (Diptera: Agromyzidae) for 24 h and then placed in a holding cage for 4 days at 22°C. Plants containing second instar L. trifolii were exposed to G. utilis for 48 h. Emergence of parasitoids occurred 24 to 33 days after exposure. The number of G. utilis emerging per bag of beans was 403 ± 29 (X ± SEM; n = 15); 51% of these were females. Recurring cost of production of 5000 parasitoids per day was estimated at $36 for G. utilis compared with $97 for another leafminer parasitoid, Diglyphus begini Ashmead (Hymenoptera: Eulophidae).