Differential Attractive Response of Bradysia impatiens Larvae to Volatiles from Fusarium solani –Infected Kidney Beans

ABSTRACT The fungus gnat, Bradysia impatiens Johannsen, is a primary root pest of plants, resulting in significant losses in crop production. Here, we evaluated the odor preference of 1st–2nd and 3rd–4th instar larvae on nine test materials (enoki mushroom EM, king oyster mushroom KOM, oyster mushroom OM, white mushroom WM, kidney bean KB, potato PTT, Fusarium solani FS, F. solani –infected kidney bean FSK, and cheonggukjang CGJ) using two‐ and multiple‐choice bioassays. In two‐choice bioassays, EM, KOM, OM, WM, KB, PTT, FSK, and CGJ attracted both 1st–2nd and 3rd–4th instar larvae of B. impatiens significantly more than the control. FSK attracted a high number of 1st–4th instar larvae when the results from both larval stages were combined. In subsequent experiments, 1st–2nd instar larvae were more attracted to the odor of FSK than FS, whereas 3rd–4th instar larvae showed a stronger attraction to FS than FSK. Moreover, 1st–2nd instar larvae were significantly more attracted to FSK extract than FS extract, whereas FS extract attracted significantly more 3rd–4th instar larvae than FSK extract. The specific attraction of 1st–2nd and 3rd–4th instar larvae suggests that each substrate contains stage‐specific attractant compounds, supporting the olfactory‐mediated host selection of B. impatiens larvae. These findings suggest that FS and FSK volatiles may be useful semiochemicals for monitoring and environmentally friendly management of B. impatiens .