Experimental hybridization of Rhizoglyphus robini and R. echinopus (Acari: Acaridae)

Rhizoglyphus robini Claparede and R. echinopus Fumouze et Robin are the most common species of the genus. They are distinguished on the basis of the Sci setae length (short in R. robini, long in R. echinopus) and the shape of the penal base, but these diagnostic features may vary within species, and both species were reported from the same habitats. We carried out experimental hybridization of R. robini and R. echinopus in reciprocal crosses to see if they are reproductively isolated. The results showed strong genetic incompatibility in the parental generation, more pronounced in R. robini females mated to R. echinopus males (7% fecund) than in R. echinopus females mated to R. robini males (20% fecund). We recorded complete sterility in F1 hybrids, confirming the reproductive isolation of these species.