The effect of inoculation with Selenophoma donacis at different growth stages on spring barley cultivars

A technique used for 3 yr to produce 15 000–20 000 nematode-free adult Megaselia halterata/v/k is described and its potential for future mass-production of nematode-parasitised flies, for use in biological control, is assessed. Gravid female phorids preferred to oviposit in compost in which mushroom mycelium had grown for 7–12 days. At 20 ± 1 °C flies began to emerge 24 days after adults of the previous generation had been released on the compost. By day28, 88% of the total population had emerged. In laboratory experiments using different densities of parental flies, fly yield per female was highest when 200 flies infested each 1 kg of compost. At higher densities, competition between larvae affected survival of larvae and pupae, and probably resulted in the mean egg content of emerging flies being reduced by as much as 16-4%. Theoretically, 250 kg compost should yield 1 150 000 phorids.