Mode of reproduction and interbreeding capabilities of two host races of reniform nematode, Rotylenchulus reniformis*

The interbreeding capabilities of two geographical populations representing different host races (race 1 from Delhi and race 4 from Andhra Pradesh) of reniform nematode, Rotylenchulus renifomis were studied under laboratory conditions. The data on root population showed that the absence of males did not prevent bud did affect-the penetration by females. The hvo populations were indicated to be amphimictically reproducing since males were essential for reproduction. Furthermore, females of Delhi population (race 1) could not reproduce with the males of A.P. population (race 4, while females of the latter could successfully reproduce with males of the former, thus exhibiting the phenomenon of partial reproductive isolation. Hence, it is hypothesised that the two host races of different geographical origin, are perhaps in the process of speciation, but not yet to the extent of complete reproductive isolation.