Effect of soil nematode functional guilds on plant growth and aboveground herbivores

Abstract

Soil multitrophic interactions are the keystone of understanding mechanisms of ecological function. In order to test the effect of nematode functional guilds on rice growth and Nilaparvata lugens abundance, a pot experiment was conducted by growing rice with a complete factorial design manipulating microbivores (microbivorous nematodes), herbivores (herbivorous nematodes) and omnivore-carnivores (omnivore-carnivorous nematodes). Results showed that compared with no nematodes, herbivores significantly increased rice root biomass (P < 0.05) and total shoot phenolic content (P < 0.05). The microbivores significantly increased N. lugens abundance and significantly reduced root biomass (P < 0.05). Omnivore-carnivores promoted rice shoot growth (P < 0.05), decreased the number of N. lugens (P < 0.05). Higher total phenolic content occurred in treatment receiving all three nematode functional guilds, suggesting stronger potential for insect resistance. In conclusion, organisms at higher trophic levels, such as omnivore-carnivores, could promote plant defense and suppress aboveground herbivory via regulating the herbivores and microbivores. Soil biota managements play central roles in control of trophic level diversity.