Divergent Preferences for Song Structure between a Field Cricket and its Phonotactic Parasitoid

Abstract

In many animals, males produce signals to attract females for mating. However, eavesdropping parasites may exploit these conspicuous signals to find their hosts. In these instances, the strength and direction of natural and sexual selection substantially influence song evolution. Male variable field crickets, Gryllus lineaticeps, produce chirped songs to attract mates. The eavesdropping parasitoid fly Ormia ochracea uses cricket songs to find its hosts. We tested female preferences for song structure (i.e., chirped song vs. trilled song) in crickets and flies using choice experiments. Female crickets from a parasitized and a non-parasitized population significantly preferred the species-typical chirped song, whereas flies significantly preferred a trilled song, which is expressed by other hosts in different regions. Sexual selection due to female choice and natural selection due to fly predation both appear to favor the chirped song structure of G. lineaticeps in the parasitized population, whereas sexual selection favors the chirped structure in the non-parasitized population.

Parasitoid infestation changes female mating preferences

“…We collected adult female O. ochracea at Rancho Sierra Vista in the Santa Monica Mountain National Recreation Area (near Newberry Park, CA, U.S.A.) in the summer of 2011, using broadcasts of G. lineaticeps song (Wagner & Basolo 2007b; Beckers & Wagner 2011b, 2012a). We collected adult female G. lineaticeps from Cayucos, California (35°28′23.16″N, 120′52′16.68″W) in the summers of 2008 and 2009 to establish laboratory populations.…”

A silent orchestra: convergent song loss in Hawaiian crickets is repeated, morphologically varied, and widespread

“…2A), we designed playbacks to mimic natural conditions by placing three traps 11 m apart in a triangle: one typical Nw song, one CwNw song, and a third without playback as a negative control. Trials lasted 5 min and were performed in dry weather between sunset (~18:10) and 20:30 when the fly is active (Beckers and Wagner 2012). All pairings of typical Nw and CwNw song models were repeatedly tested over 4 nights and rotated among speakers between trials.…”

Darwinian balancing selection: Predation counters sexual selection in a wild insect

“…There is some evidence of trade‐offs between attractiveness and survival. For example, song parameters of Gryllus species most attractive to acoustically orienting flies whose larvae kill their hosts (Cade ; Zuk et al ) were also preferred by females—in both field (Gray and Cade ) and laboratory (Beckers and Wagner ) studies. Even in the absence of predation, there is viability selection against high‐quality singing male T. commodus ; laboratory males in high condition sing more, and thus attract more mates, “but die young” (Hunt et al ).…”