Behavioral evidence for host fidelity among populations of the parasitic wasp, Diachasma alloeum (Muesebeck)

Abstract

The concept of "host fidelity," where host-specific mating occurs in close proximity to the oviposition site and location of larval development, is thought to impart a pre-mating isolation mechanism for sympatric speciation (sensu members of the genus Rhagoletis). The apple maggot fly, Rhagoletis pomonella, and the blueberry maggot fly, R. mendax, are morphologically similar sibling species thought to have speciated in sympatry by divergence of host plant association. Both of these fly species are attacked by the specialist braconid parasitoid, Diachasma alloeum. The current study demonstrates that both male and female D. alloeum exhibit a behavioral preference for the odor of the fruit of their larval Rhagoletis host species. Specifically, those D. alloeum emerging from puparia of R. pomonella are preferentially attracted to hawthorn fruit and those emerging from puparia of R. mendax are preferentially attracted to blueberry fruit. However, male D. alloeum reared from either R. pomonella or R. mendax were equally attracted to females originating from both Rhagoletis species. We suggest that the data herein present evidence for "host fidelity," where populations of D. alloeum exhibit a greater tendency to mate and reproduce among the host plants of their preferred Rhagoletis hosts. Furthermore, host fidelity may have resulted in the evolution of distinct host races of D. alloeum tracking the speciation of their larval Rhagoletis prey.

Selection by parasitoid females among closely related hosts based on volatiles: Identifying relevant chemical cues

“…This acquired behavior would allow females hatching from the susceptible host to retain the same susceptible host species for their offspring, but without dropping the resistant host from the host repertoire. A similar acquired host selection behavior has been observed in other parasitoid species (van Emden et al., ; Stelinski & Liburd, ) and may be influential in host race formation (Konig et al., ). Host race formation would require that cues inducing host searching behavior for the less accepted host are no longer recognized or avoided (Goldman‐Huertas et al., ).…”

Divergent host plant preference causes assortative mating between sympatric host races of the ladybird beetle,Henosepilachna diekei

“…'Habitat isolation' occurs when genetically based divergent habitat preferences between populations reduce the likelihood of heterogeneous encounters (Rice & Salt, 1990). This is one of the reasons for the vast diversity of specialist parasites (Stelinski & Liburd, 2005;Giraud, Gladieux & Gavrilets, 2010;Skoracka et al, 2013). Specifically, phytophagous insects also provide powerful model systems to address speciation mechanisms via divergent host plant specialization (Funk, 1998;Berlocher & Feder, 2002;Drés & Mallet, 2002;Matsubayashi, Ohshima & Nosil, 2010).…”

Intimate Rendezvous in a Tritrophic Context? Nothing but the Girls for Male Lysiphlebus testaceipes

“…; Nadel & Luck ; Ruther & Steidle ) or synomones (McAuslane et al. ; Stelinski & Liburd ) by males. In particular, McAuslane et al.…”

“…Plant volatiles may either increase the production and release of sex pheromones by females or enhance the response of males (Landolt & Phillips 1997;Ruther et al 2001). In parasitoids, only a few studies have reported the use of kairomones (Vandijken et al 1989;Nadel & Luck 1992;Ruther & Steidle 2000) or synomones (McAuslane et al 1990;Stelinski & Liburd 2005) by males. In particular, McAuslane et al (1990) and Metzger et al (2010) showed that volatiles from hosts acted synergistically with pheromones to increase male response.…”