7.2 The real deal?: behavioral mimicry in hymenoptera  (Page 3/7)

It has been shown that in P. dominulus, n -alkanes are the common hydrocarbons present on the cuticles of the wasps (Bonavita-Cougourdan et al. 1991, Dani et al. 1996a, Dani et al. 1996b). Studies have shown that application of n -alkanes to residents of P. dominulus does not increase the aggressive response by other residents. However, in experiments applying either 40 μg or 200 μg of synthetic n -alkanes to the bodies of P. dominulus wasps, results showed that with an increase in the amount of synthetic n -alkanes applied, there were significantly more aggressive encounters with control residents, indicating that P. dominulus can recognize higher levels of cuticular hydrocarbons. Furthermore, when residents were treated with methyl alkanes and monoenes, the number of aggressive responses from other control residents was significantly higher, suggesting that the cuticular hydrocarbon profiles are colony-specific for nestmate recognition (Bonavita-Cougourdan et al. 1991, Dani et al. 1996a, Dani et al. 1996b).

Ants also exhibit chemical mimicry, and species of ants have been known to pick up and reproduce colony odors to allow for nestmate recognition (Bagnères et al. 1991, Kaib et al. 1993, Lenoir et al. 1997, Lahav et al. 1999, Monnin et al. 1998). One mechanism by which ants and other Hymenopterans can mimic recognition cues of their hosts is through passive means. Gas chromatographic profiles of hexane soaks of increasingly developed stages in the ectoparasitic wasp’s, Orasema sp. , relationship with the host fire ant, Solenopsis invicta , showed that false nestmate recognition developed passively over time, as the parasitic wasp acquired the ant colony odor via basic contact (Vander Meer et al. 1989). Aphid-parasitoid wasps have also exhibited chemical mimicry as a means to appease the ants that usually protect aphids (Liepert&Dettner 1993). This allows for them to bypass ant attack while they parasitize aphids.

Chemical mimicry has also been shown to be a developed behavior that is achieved during adult life and is not innate or inherited (Lenoir et al. 1997). Besides passive means of chemical mimicry, cuticular hydrocarbon profiles can also be actively synthesized by the mimic (Bagnères et al. 1991). In this study, two ant species that do not share many commonalities in their colony odors were raised in separate and mixed colonies. Formica selysi ants have unsaturated compounds, mainly monoenes and dienes, in their cuticular hydrocarbon profiles, whereas Manica rubida ants have almost exclusively saturated alkanes in theirs. In mixed colonies, a new odor was achieved that was a mix of both saturated and unsaturated hydrocarbons and was an intermediary odor that shared characteristics with both individual profiles. Because the quantities of these mixed hydrocarbons were similar to what the donor ants normally produced, it was suggested that the ants had to have actively synthesized the compounds. If the compounds were passively transferred from the donor ant to the recipient, it was expected that the quantity picked up would be less than what the donor normally produced, but this was not the case (Bagnères et al. 1991). Another study of cuckoo wasps that parasitize beewolves showed that an active synthesis of cuticular hydrocarbons occurs by demonstrating the presence of isomeric forms of compounds on the mimic that are not present on the host (Strohm et al. 2008). These cases serve as behavioral evidence that Hymenopteran insects are versatile chemical mimics and are capable of both passively and actively obtaining chemical recognition cues of their nestmates, by either simple contact or synthesis, respectively (Bagnères et al. 1991, Lahav et al. 1999).