Adhering Pasteuria penetrans endospores affect movements of root-knot nematode juveniles

Abstract

Pasteuria penetrans is a biological control agent of root-knot nematodes (Meloidogyne spp.), preventing root invasion by second-stage juveniles (J2s), and eventually causing females sterility and death. greatest control effects for P. penetrans depend on the numbers of endospores attached to nematode cuticles. a method based on digital image analysis was used to record the effects of endospore attachment on the movements of juvenile root-knot nematodes, using a model based on the centroid point. Data showed that the numbers of endospores attached to the cuticle influenced nematode movement. At high endospore attachment levels (20‒30 per J2), nematodes did not show directional movement, whereas nematodes encumbered with five to eight spores showed limited directional movement, compared to those without endospores. nematode cephalic region turns were modelled using a markov chain, showing that P. penetrans endospores affected movements. Less nematodes invaded and established on tomato root systems when encumbered with low (five to eight) or high numbers (20‒30) of P. penetrans endospores, compared with unencumbered nematodes.