Olfactory response of Sancassania polyphyllae (Acari: Acaridae) to its phoretic host larva killed by the entomopathogenic nematode, Steinernema glaseri (Rhabditida: Steinernematidae)

Abstract

Using a Y-tube olfactometer, we assessed whether Sancassania polyphyllae (Acari: Acaridae) female mites showed a differential preference when offered a choice between odors from various sources. The combinations of odor sources included the following: (1) no odor source (blank), (2) dissected larval tissues of uninfected Polyphylla fullo (Coleoptera: Scarabaeidae), (3) P. fullo killed by Steinernema glaseri (Rhabditida: Steinernematidae), (4) intact freeze-killed, uninfected P. fullo, (5) free-living infective juveniles (IJs) of S. glaseri, or (6) living uninfected P. fullo. When offered a choice between (1) blank and dissected tissues of uninfected P. fullo or (2) blank and P. fullo killed by S. glaseri or (3) blank and intact freeze-killed, uninfected P. fullo, S. polyphyllae showed a significant preference for the odor sources compared to the blank. S. polyphyllae showed no preference when offered a choice (1) between S. glaseri IJs and blank or (2) between living uninfected P. fullo and blank. When offered two different odor sources, S. polyphyllae showed a significant preference for volatiles from (1) dissected tissues of uninfected P. fullo, (2) P. fullo killed by S. glaseri, or (3) intact freeze-killed, uninfected P. fullo compared to S. glaseri IJs or living P. fullo. However, when the (1) dissected tissues of uninfected P. fullo versus P. fullo killed by S. glaseri, (2) intact freeze-killed, uninfected P. fullo versus P. fullo killed by S. glaseri, or (3) living uninfected P. fullo versus S. glaseri IJs were tested, there was no significant difference in mite distribution.