Mycophagous ladybirds of <i>Macroilleis hauseri</i>: mass‐rearing artificial diet development, fungicide‐insecticide toxicity assessment and release in orchard of <i>Rosa roxburghii</i> to control powdery mildew

BACKGROUND: Mycophagous ladybirds of Macroilleis hauseri play a vital role in the biological control of plant pathogenic fungi. However, little is known about mass-rearing of M. hauseri and its application in agroforestry ecosystems to control powdery mildew in the characteristic plant Rosa roxburghii producing edible medicinal fruits. RESULTS: Combining Podosphaera xanthii with artificial diet I (AD I), which comprised glucose, fructose, soybean powder, silkworm pupa powder, feed-grade vitamin and sterile water, facilitated M. hauseri development and propagation. Macroilleis hauseri developed well when fed on P. xanthii and AD I at 12 L:12D, 20-25°C, and 75-80% relative humidity. The <25% mortality rate of M. hauseri larvae and adults exposed to four common fungicides at 72 h was observed, but it raised to 28-83% and 23-58%, respectively, when exposed to six common insecticides. Macroilleis hauseri (10 adults per tree) release had the 83-86% control efficiency against R. roxburghii powdery mildew at 21 days, which is close to that (85-89%) of under 30% pyraclostrobin SC treatment, increasing fruit yields and economic benefits by 48-62% and 45-59%, respectively, compared with the bank control, although they were not higher than those (51-65% and 51-66%) of pyraclostrobin treatment. CONCLUSION: Mass-rearing of M. hauseri could be achieved by feeding AD I and P. xanthii. Fungicide use in orchards minimally threatened adults of M. hauseri. These adult individuals could serve as biocontrol agents to effectively control the spread of R. roxburghii powdery mildew, which highlights its application potential of controlling plant powdery mildew. © 2025 Society of Chemical Industry.