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. 2015 Feb 10;54:e30.
doi: 10.1186/s40555-015-0105-z. eCollection 2015.

Infection Behavior, Life History, and Host Parasitism Rates of Emblemasoma erro (Diptera: Sarcophagidae), an Acoustically Hunting Parasitoid of the Cicada Tibicen dorsatus (Hemiptera: Cicadidae)

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Free PMC article

Infection Behavior, Life History, and Host Parasitism Rates of Emblemasoma erro (Diptera: Sarcophagidae), an Acoustically Hunting Parasitoid of the Cicada Tibicen dorsatus (Hemiptera: Cicadidae)

Brian J Stucky. Zool Stud. .
Free PMC article

Abstract

Background: 'Eavesdropping' parasitoids find their hosts by homing in on the communication signals of other insects. These parasitoids often exploit chemical communication, but at least some species of the sarcophagid genusEmblemasomaeavesdropon the acoustic communications of cicadas. Despite considerable scientific interest in acoustic parasitoids, we know remarkably little about most species of Emblemasoma. To better understand the ecology and behavioral diversity of these flies, I used a combination of field and laboratory techniques to elucidate theinfection behavior and life history of E.erro,which uses the cicada Tibicen dorsatusasa host, and I also investigated parasitoid loads and parasitism rates of T.dorsatus inmultiple host populations in the central United States.

Results: Female E. erro used the acoustic signals of male T. dorsatus as the primary means of locating hosts, but they also required physical movement by the host, usually either walking or flight, to provide visual cues for the final larviposition attack. Larvae were deposited directly on the host's integument and burrowed through intersegmental membrane to enter the host's body. On average, E. erro larvae spent 88.0 h residing inside their host before leaving to pupariate, but residence time was strongly dependent on both ambient temperature and effective clutch size. Adult flies eclosed about 18 days after pupariation. Across all study sites, the mean parasitoid load of infected male T. dorsatus was 4.97 larvae/host, and the overall parasitism rate was 26.3%. Parasitism rates and parasitoid loads varied considerably amonghost population samples, and high parasitism rates were usually associated with high parasitoid loads.

Conclusions: Previously, detailed information about the infection behavior, life history, and host parasitism rates of sarcophagid acoustic parasitoids was only available for one species, E. auditrix. This study reveals that the infection behavior of E. erro is quite different from that of E. auditrix and, more broadly, unlike that known for any other species of acoustic parasitoid. The life histories of these two Emblemasoma are also divergent. These differences suggest that sarcophagid acoustic parasitoids are more behaviorally and ecologically diverse than previously recognized and in need of further study.

Keywords: Eavesdropping; Emblemasoma; Host defense; Host location; Infection behavior; Parasitoid; Parasitoid load; Phonotaxis; Superparasitism; Tibicen.

Figures

Fig. 1.
Fig. 1.
Figure 1 Male Tibicen dorsatus, Harvey Co., KS.
Fig. 2.
Fig. 2.
Figure 2 Female Emblemasoma erro, Ellsworth Co., KS.
Fig. 3.
Fig. 3.
Figure 3 Locations of study sites. Filled circles indicate the primary sites used for estimating host parasitism rates, and open circles indicate secondary sites used for additional collections of cicadas and flies. Primary sites are referenced in the text by the counties in which they were located: 1) Harvey Co., 2) McPherson Co., 3) Reno Co., 4) Ellsworth Co., 5) Hamilton Co., and 6) Prowers Co. Both T. dorsatus and E. erro were found at all 11 sites. The inset map indicates the location of the main map in the United States.
Fig. 4.
Fig. 4.
Figure 4 Larviposition by E. erro. A first-instar larva of E. erro on the right fore wing of a T. dorsatus moments after larviposition (larva indicated by blue arrow). The cicada’s head and foreleg are at top center.
Fig. 5.
Fig. 5.
Figure 5 Relationship of effective clutch size and temperature to larval residence time. Each data point represents the mean residence time of the parasitoid larvae inside a single host cicada along with the effective clutch size (number of larvae emerging from the host) and the mean air temperature experienced by the host during parasitoid development. The planar surface represents the multiple linear regression model of the effects of temperature and effective clutch size on larval residence time. Lines connected to the data points indicate the vertical distance of each data point from the regression surface (i.e., the residuals).
Fig. 6.
Fig. 6.
Figure 6 Emergence of E. erro from its host. A mature larva of E. erro emerges from between the left operculum and the abdomen of a deceased male T. dorsatus from Prowers Co., CO.
Fig. 7.
Fig. 7.
Figure 7 The distribution of parasitoid loads (larvae per host) of infected cicadas in the field.
Fig. 1.
Fig. 1.
Figure 8 Relationship between host parasitism rate and mean parasitoid load per host. Each data point represents 1 year of host population sampling data for a single study site. The solid line (blue in the color figure) represents the linear regression model for the data.

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