Relationships between the parthenogenetic cockroach Pycnoscelus surinamensis (Dictyoptera : Blaberidae) and ants (Hymenoptera : Formicidae)
Résumé
During field studies conducted in southern Cameroon, we gathered arguments permitting us to assert that Pycnoscelus surinamensis, a parthenogenetic cockroach species, is frequently associated with ants, mostly Pheidole megacephala (Myrmicinae) and Paratrechina longicomis (Formicinae). Both latter species have a pantropical distribution and are known as tramp species (transported by boats, their nesting mode is associated with human activity). Moreover, adult P. surinamensis associated with Camponotus brutus (Formicinae) were noted as following the scent trails of their host leading to a food source. They then fed on the food sources without being attacked in most of the cases, while the observed attacks never resulted in the cockroaches being injured. The same was noted for adults and larvae tolerated by Pheid. megacephala workers while feeding on their prey. As we also noted P. surinamensis not associated with ants, this species is rather a temporary ant nest commensal, or synoekete, rather than a true myrmecophile. We suggest that the association with ants could have influenced the geographical distribution of this parthenogenetic cockroach species (worldwide) compared to the more restricted distribution of the sexual form, A indicus, only known in South-East Asia and Hawaii, human transport being the major dispersal agent for both species. Moreover, P. surinamensis is mostly associated with tramp ant species that are also largely distributed thanks to human transport.