Title: Detection of plant-parasitic nematode DNA in the gut of predatory and omnivorous nematodes Authors
Submitted to: Nematropica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 11, 2013
Publication Date: September 30, 2013
Citation: Cabos, R.Y.M., K.H. Wang, B.S. Sipes, W.P. Heller, T.K. Matsumoto. 2013. Detection of plant-parasitic nematode DNA in the gut of predatory and omnivorous nematodes. Nematropica. 43:44-48. Interpretive Summary: Predatory and omnivorous nematodes have potential as biological control agents against damaging plant-parasitic nematode pests. However these predators feed on many types of nematodes and other soil microorganisms and information is lacking on the percentage of plant-parasitic nematodes that make up their diet. Previous data was obtained by examining the gut contents of fixed specimens and observations from in vitro cultures. We developed a protocol for molecular gut analysis as a more efficient method of determining the feeding habits of predatory nematodes. Species-specific primers for reniform, root-knot, and burrowing nematodes were tested in PCR reactions to detect plant-parasitic nematode prey in the gut contents of different predatory and omnivorous nematodes collected from the field. The results confirmed that the predatory nematodes assayed were feeding on plant-parasitic nematodes in their natural environment. Neoactinolaimus had the highest rate of positive detections (55%) for plant-parasitic nematode DNA. This is the first documentation of predatory nematode feeding habits using a PCR-based approach.
Technical Abstract: A protocol for molecular gut analysis of nematodes was developed to determine if predatory and omnivorous nematodes from five different guilds prey on Rotylenchulus reniformis, Meloidogyne incognita, and Radopholus similis. Mononchoides, Mononchus, Neoactinolaimus, Mesodorylaimus, and Aporcelaimellus were collected from Hawaii agroecosystems. Gut contents were released by slicing nematodes and pipetted into a PCR tube. Appropriate species-specific primers for the PCR reaction were determined by the predominant plant-parasitic nematodes associated with the source of the predatory and omnivorous nematodes. Predator and omnivore samples containing ingested R. reniformis, M. incognita and R. similis amplified a band of the desired size of 224, 342, and 269 bp, respectively. All predator and omnivore genera tested were positive for plant-parasitic nematode DNA in at least 22% of the specimens assayed. The highest percentage of positive detections (55%) was in Neoactinolaimus. This study confirmed that species-specific PCR primers could detect targeted plant-parasitic nematode prey in the gut of excised nematodes. This protocol could be adopted to further our understanding of the role of nematodes in soil food web interactions.