Assessing the Efficacy of Steinernema carpocapsae for Biological Control of Megaselia halterata on Mushroom Farms

ABSTRACT Mushroom phorid flies ( Megaselia halterata ; MPF) are a major pest of commercial mushroom production, where larval feeding in compost and casing can reduce crop yield and quality. Effective and sustainable larval control options in these substrates remain limited. The potential of the entomopathogenic nematode Steinernema carpocapsae for MPF larval control in the mushroom production system has not been well established. The present study evaluated the infectivity of S. carpocapsae against larval MPF and entomopathogenic nematode persistence in mushroom compost under laboratory conditions. In compost‐only arenas, applications of nematodes applied at a rate of 167 Infective Juveniles (IJs)/cm 2 caused 60% larval mortality within 48 h, significantly higher than water (32%) and untreated controls (15%). In casing‐layer arenas, nematode applications resulted in 41% mortality at 72 h, compared to 10% and 16% in water and untreated control treatments, respectively. Nematode survival in compost declined over time, with approximately 50% of the initial population alive at 4–5 days post application. These results indicate S. carpocapsae can infect and kill MPF larvae in substrates representative of the mushroom production system. However, persistence results suggest that repeated nematode applications at approximately 5‐day intervals may be required to maintain consistent control. The findings support the potential incorporation of entomopathogenic nematodes as a component of integrated pest management programs for commercial mushroom production.