Pathogenic potential, parasitic success and host efficiency of Meloidogyne incognita and M. javanica on cucurbitaceous plant genotypes

The response to Meloidogyne incognita and M. javanica of 29 cucurbitaceous genotypes belonging to the genera Cucurbita, Lagenaria and Luffa was evaluated to determine their relative host suitability and utility as rotational crops in sustainable agriculture. The pathogenic potential, parasitic success and host efficiency were estimated based on the ability of the nematode to form galls and generate egg masses on selected genotypes. Meloidogyne incognita showed higher pathogenic potential (gall formation) than M. javanica across all genotypes except for C. argyrosperma. However, M. javanica had higher parasitic success (egg mass production) than M. incognita on the Cucurbita genotypes. By contrast, on Lagenaria and Luffa, M. incognita had higher pathogenic potential and parasitic success than M. javanica. All genotypes except Luffa spp., showed higher host efficiency (rate of egg masses per gall) for M. javanica than for M. incognita. The genotypes of Cucurbita pepo ssp. pepo will be useful for M. incognita management because they reduce population build-up, but root damage would be more severe due to abundant root galling. The Cucurbita genotypes would be more tolerant to higher Pi when infected by M. javanica as they suffer less root damage, but the residual populations may affect the subsequent crop in the rotation. Lagenaria siceraria showed a good level of resistance to M. javanica and will be useful by itself or for grafting other cucurbitaceous crops. The species of Luffa were poor hosts of M. javanica and can be used also for grafting.