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Ontogenetic origin of mermithogenic Myrmica phenotypes (Hymenoptera, Formicidae)


Entomo-pathogen parasites typically induce alternative ”parasitogenic” phenotypes in ants and other insects. However, the basis of generated developmental changes is poorly understood. Parasitic mermithid nematodes also cause the formation of three discrete and aberrant morphologies within Myrmica ants. These have been called ”worker-like” (”mermithergate”), ”intermorphic” (”gynaecoid mermithergate”) and ”gyne-like” (”mermithogyne”) and their formation has been attributed to infection of worker- and queen-presumptive larvae, respectively. In order to better understand the developmental mechanisms that lead to the formation of these alternative parasitogenic phenotypes we observed allometric patterns of parasitogenic Myrmica gallienii phenotypes in comparison with uninfected workers and gynes from the same nests. It was revealed that the three discrete morphologies of parasitogenic female phenotypes did not differ significantly from each other in their scaling indicating that these were trapped in the same developmental pathway. Infected individuals scaled according to basically gyne-like allometry, however significantly differed from workers in their scaling. Based on the observed scaling patterns we herein raise an alternative explanation according to which both ”mermithergate”, ”gynaecoid mermithergate” and ”mermithogyne” Myrmica phenotypes develop from the same type of larvae, namely from the queen-presumptive larvae and their formation, therefore, is rendered as a diverging process. According to the mechanism we propose effect of nematodes may turn out to be the determining factor in the formation of alternative parasitogenic morphologies.

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Correspondence to S. Csősz.

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Received 16 June 2008; revised 15 September and 7 November 2008; accepted 18 November 2008.

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Csősz, S., Majoros, G. Ontogenetic origin of mermithogenic Myrmica phenotypes (Hymenoptera, Formicidae). Insect. Soc. 56, 70–76 (2009).

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  • Allometry
  • castes
  • intermorphs
  • development
  • parasites
  • Mermis