CALLING SONGS OF FIELD CRICKETS (TELEOGRYLLUS OCEANICUS) WITH AND WITHOUT PHONOTACTIC PARASITOID INFECTION

Area of Science:

• Ecology
• Evolutionary Biology
• Behavioral Ecology

Background:

• The field cricket Teleogryllus oceanicus is an invasive species in Hawaii.
• This cricket is parasitized by the acoustically orienting fly Ormia ochracea.
• Previous studies indicated that parasitism by O. ochracea alters T. oceanicus call parameters.

Purpose of the Study:

• To investigate the specific song characteristics of T. oceanicus males that are parasitized by O. ochracea.
• To determine if T. oceanicus males with specific song traits are more likely to be parasitized.
• To explore the potential for conflicting selective pressures (natural vs. sexual selection) on T. oceanicus song.

Main Methods:

• Field collection of T. oceanicus males.
• Recording and analysis of cricket calling songs.
• Comparison of song characteristics between parasitized and unparasitized males.

Main Results:

• Significant differences in song characteristics were observed between parasitized and unparasitized T. oceanicus males.
• Males with longer "long chirps" and shorter inter-pulse intervals were more likely to harbor parasitoid larvae.
• These findings suggest that O. ochracea preferentially parasitizes males with specific acoustic signals.

Conclusions:

• The acoustically orienting parasitoid fly O. ochracea exerts significant selective pressure on the Hawaiian field cricket T. oceanicus.
• Specific song traits, particularly the "long chirp," are associated with higher parasitism rates, indicating fly attraction.
• Evolutionary changes in T. oceanicus song may be influenced by a conflict between natural selection (by flies) and sexual selection (by females).