|WANG, KOON-HUI - University Of Hawaii|
|SRIVASTAVA, AKHIL - University Of Hawaii|
|SIPES, BRENT - University Of Hawaii|
Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/20/2015
Publication Date: 5/18/2015
Citation: Wang, K., Myers, R.Y., Srivastava, A., Sipes, B. 2015. Evaluating the predatory potential of carnivorous nematodes against Rotylenchulus reniformis and Meloidogyne incognita. Biological Control. 88:54-60.
Interpretive Summary: Predatory nematodes have potential to be biological control agents of plant-parasitic nematodes. Limited information exists on the role these organisms play in the soil ecosystem. The feeding behavior of predatory nematodes varies and may influence prey choices. When developing an organism as a biological control agent it is necessary to document that the potential predator readily consumes the targeted plant-parasitic nematode. This study examined the feeding behavior of five predatory nematodes commonly found in Hawaii. Two economically important plant-parasitic nematodes, root-knot and reniform, were added to natural soil communities containing a mixture of nematodes and other soil microorganisms. Using water dish and soil feeding tube assays, predation was determined by a combination of prey counts and molecular gut analysis of predatory nematodes. The results showed that prey preferences did exist and were influenced by other prey nematodes existing in the soil community.
Technical Abstract: Predatory behavior of a nematode is usually determined through gut content observation or prey delimitation counts. In this experiment, Mononchus and Neoactinolaimus predation of Rotylenchulus reniformis or Meloidogyne incognita was determined using a PCR-based nematode gut content analysis. Soil samples naturally infested with Mononchus were placed in tubes and potential prey nematodes R. reniformis, M. incognita, or a mixture of both were introduced. The gut contents of Mononchus were assayed for the DNA from R. reniformis or M. incognita using PCR specific primers. A higher % of Mononchus tested positive for DNA of R. reniformis than for M. incognita when the prey were added alone. However, when provided with both prey species, Mononchus tested positive for DNA of M. incognita more frequently than for R. reniformis. Percent Mononchus testing positive for DNA of R. reniformis correlated positively with the abundance of R. reniformis, but this relationship was not observed between Mononchus and M. incognita. Neoactinolaimus was added to aqueous solution containing a mixture of free-living nematodes and R. reniformis. More Neoactinolaimus tested positive for DNA of R. reniformis than other predatory or omnivorous nematodes in the same samples. Based on regression analysis, the presence of fungivorous and other predatory nematodes in the soil could distract Neoactinolaimus from predation on R. reniformis. Our results suggested that Prismatolaimus, Mesodiplogasteroides and Eudorylaimus could also prey on R. reniformis. Although less than 40% of the predatory or omnivorous nematodes tested preyed on R. reniformis, this level of predation could contribute to reducing the population densities of plant-parasitic nematodes in the soil.