Interactions between Pochonia chlamydosporia and Meloidogyne chitwoodiin a crop rotation scheme
Keywords: biological control, integrated pest management, potato, rhizosphere colonization, root-knot nematodes
AbstractStudies on the use of Pochonia chlamydosporia isolates as biological control agents of root-knot nematodes (RKN, Meloidogyne spp.), showed that their efficacy relies on selected key factors such as fungal proliferation in soil, establishment in the rhizosphere, and ability to parasitize RKN eggs. A pot experiment was conducted to evaluate the performance of a Portuguese P. chlamydosporia isolate (Pc2) and of a non-native isolate (Pc10) against M. chitwoodi in a potato-maize-potato-potato crop rotation. The growth of P. chlamydosporia in soil and roots was monitored throughout the experiment by assessing the numbers of colony forming units (cfu). The prevalence in M. chitwoodi eggs and nematode reproduction was measured at the end of each crop. The cfu/g of soil varied over time and was particularly low for both isolates during the spring and summer 2009, when temperatures above 30ºC were registered. Native isolate Pc2 was more effective in establishing in soil than Pc10. Growth and survival of the fungus did not seem to depend on the presence of nematode or host plant species. Establishment of P. chlamydosporia in soil was slow and was only achieved after the full cropping sequence. The two P. chlamydosporia isolates revealed subtle differences in host preference, plant compatibility, or tolerance to abiotic conditions that may affect their efficacy as biocontrol agents in a long-lasting management program.