Temperature Effects on the Attachment of Pasteuria penetrans Endospores to Meloidogyne arenaria Race 1

L. G. Freitas, D. J. Mitchell, D. W. Dickson

Abstract


Pasteuria penetrans is a gram positive bacterium that prevents Meloidogyne spp. from reproducing and diminishes their ability to penetrate roots. The attachment of the endospores to the cuticle of the nematodes is the first step in the life cycle of the bacterium and is essential for its reproduction. As a preliminary study to a field solarization test, the effects of temperature on the attachment of P. penetrans on Meloidogyne arenaria race 1 were investigated. Preexposing second-stage juveniles (J2) of M. arenaria to approximately 30ºC in water before exposing them to endospores increased their receptivity to endospore attachment when compared to treating J2 at 25ºC or 35ºC. In tests with soil, highest attachment occurred when J2 were incubated in soil infested with endospores and maintained at 20ºC to 30ºC for 4 days. Heating J2 in soil to sublethal temperatures (35ºC to 40ºC) decreased endospore attachment. Incubating P. penetrans endospores in soil at 30ºC to 70ºC for 5 hours a day over 10 days resulted in reductions of endospore attachment to nematodes as temperatures of incubation increased to 50ºC and higher. Key words: attachment, bacteria, biological control, cuticle, endospore, Meloidogyne arenaria, nematode, Pasteuria penetrans, root-knot nematode, temperature

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