Fitting the negative binomial distribution to Pasteuria penetrans spore attachment on root-knot nematodes and predicting probability of spore attachments using a Markov chain model
2013
Vagelas, Ioannis | Dennett, Mike D. | Pembroke, Barbara | Gowen, Simon R.
Pasteuria penetrans controls root-knot nematodes (Meloidogyne spp.) either by preventing invasion or by causing female sterility. The greatest control of P. penetrans occurred when an appropriate quantity of P. penetrans spores attached to the cuticle of a juvenile nematode. The number of spores attaching to juveniles within a given time increased with increasing the time of exposure to spores. Based on this, numbers of encumbered nematodes were recorded 1, 3, 6 and 9 h after placing nematodes in standard P. penetrans spore suspensions. From the count data obtained, P. penetrans attachment was modelled using the Poisson and negative binomial distributions. Attachment count data were observed to be overdispersed with respect to high numbers of spores attaching on each J2 at 6 and 9 h after spore application. It was concluded that the negative binomial distribution was shown to be the most appropriate model to fit the observed data-sets considering that P. penetrans spores are clumped; this could be further refined with a Markov process.
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