The effect of opposing sexual and natural selective pressures on the mating calls of parasitized katydids

Project Abstract

Male katydids produce conspicuous acoustic signals to attract mates but these signals also attract phonotactic parasitoids. The parasitoid fly, Ormia lineifrons, eavesdrops on these signals and deposits larvae onto the calling male. Continued calling by infested males increases their exposure to additional flies, resulting in costly superparasitism. Superparasitism intensifies competition among unrelated larvae within the host, and because the first clutch of larvae emerges after ~ 8 days, which kills the host, larvae from subsequent parasitism events die with the host. These dynamics set up an arms race driven by opposing selective pressures on male signals and signaling behavior. Natural selection exerted by the parasitoid should favor changes in host calls and/or reduce calling activity, indicating the parasitism status of the host, which could aid in preventing superparasitism. Sexual selection exerted by female mates would favor no changes in calls and calling activity of parasitized males, keeping the signals attractive to females. We hypothesized that the combination of these pressures would determine call characteristic and activity of parasitized hosts. To test this, we recorded and analyzed calls from unparasitized and parasitized males of three Neoconocephalus host species. In N. robustus & N. velox, call features remained attractive and recognizable after infestation, which suggest that sexual selection may be the reason for keeping call features unchanged. N. velox increased its calling effort after infestation, which is consistent with a terminal investment strategy to increase reproduction before death. In contrast, N. robustus reduced calling effort, which aligns with natural selection exerted by the parasitoid to reduce risk of superparasitism. The third species, N. retusus, ceased calling immediately after infestation, indicating strong selection from the parasitoid against signaling. We discuss the contrasting results in the context of a complex evolutionary arms-race between one parasitoid and multiple hosts.

Conference

87th Annual Meeting of the Association of Southeastern Biologists

Dates: March 25 - 28 , 2026

Sponsoring Body: Association of Southeastern Biologists

Website: sebiologists.org

Funding Type

Travel Grant

Academic College

Jesse D. Jones College of Science, Engineering and Technology

Area/Major/Minor

Biology

Degree

Masters of Science

Classification

Graduate

Name

Oliver Beckers, PhD

Academic College

Jesse D. Jones College of Science, Engineering and Technology

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