Behavioural specialization among populations of the acoustically orienting parasitoid fly Ormia ochracea utilizing different cricket species as hosts

Abstract

Tightly coupled evolutionary associations between parasites and their hosts are well known. What is less well characterized is the behavioural specialization of parasites that exploit different hosts in different parts of the parasite's geographical range. Here we examine behavioural specialization among populations of a parasitoid fly, Ormia ochracea, that exploit different host species of crickets in different parts of the fly's range. We conducted a field experiment to compare phonotactic attraction of flies from Florida, Texas, California and Hawaii (U.S.A.) to the songs of their local host species of cricket versus their attraction to the songs of species of crickets utilized as hosts elsewhere within the flies' range. We found strong behavioural specialization of fly populations, with preferential phonotaxis towards the song of the local host species of cricket. These results suggest strong behavioural specialization of flies, but that specialization does not constrain or preclude the rapid adoption of novel hosts.

The cost of assuming the life history of a host: acoustic startle in the parasitoid fly Ormia ochracea

“…However, these experiments compared Ormia flies native to one region (Florida) with crickets introduced to another (Hawaii). Ormia throughout the USA and Hawaii adapts to parasitize the local field cricket population, demonstrating behavioral preferences for its chosen host's song (Gray et al, 2007). These songs vary widely in temporal pattern but all have a carrier frequency of 4-5kHz.…”

A precedence effect resolves phantom sound source illusions in the parasitoid fly Ormia ochracea

“…Ormia thus face 2 important auditory tasks: (1) correctly identifying the song of a suitable host and (2) successfully locating the potential host. Behavioral evidence indicates that flies rely on temporal parameters within songs to identify suitable host crickets (19)(20)(21)(22)(23). Recognition of host calling songs initiates phonotactic behavior in gravid female Ormia.…”

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

“…Cade 1975;Lloyd 1981;Tuttle and Ryan 1981). Behavioral specializations of the predators and parasites, such as preferences for host-specific mating signals (Gray et al 2007), likely reduce the costs of searching for prey or hosts (reviews in Stephens and Krebs 1986;Godfray 1994). As a consequence, prey or host species may evolve counteradaptations to avoid eavesdropping by unintended receivers, such as the use of different signaling modalities (Belwood and Morris 1987), a reduction in signaling activity (Cade 1975(Cade ,1979(Cade , 1981Cade and Wyatt 1984;Zuk et al 2006), or a shift in the timing of signaling to a less risky time of day (e.g.…”

“…The parasitoid fly, Ormia ochracea, localizes its host species by orienting to the host's mating songs (Cade 1975;Gray et al 2007). The fly deposits its larvae on the cricket, and the larvae enter the cricket, where they feed and grow.…”