Pasteuria penetrans Sayre & Starr parasitizes several nematode species and is considered a promising biocontrol agent of the root-knot nematode, Meloidogyne spp. (1,7). Numerous plant-parasitic nematodes, including Tylenchulus semipenetrans, however, are seldom if ever infected by this biocontrol agent (3). Tylenchulus semipenetrans Cobb is the most economically important and widespread nematod...

Pratylenchus penetrans suppressed the tuber yields of potato cultivars 'Katahdin', 'Kennebec', and 'Superior', but did not affect yields of 'Russet Burbank'. In comparison with noninfested controls, all initial nematode densities (P(i)) of P. penetrans (P(i) = 38, 81, 164, 211/ 100 cm(3) of soil) suppressed yields of Superior; a moderate P(i) (81/100 cm(3) soil) suppressed yields of Kennebec; a...

Parasite prevalence shows tremendous spatiotemporal variation. Theory indicates that this variation might stem from life-history characteristics of parasites and key ecological factors. Here, we illustrate how the interaction of an important predator and the schedule of transmission potential of two parasites can explain parasite abundance. A field survey showed that a noncastrating fungus (Met...

Strong selection on parasites, as well as on hosts, is crucial for fueling coevolutionary dynamics. Selection will be especially strong if parasites that encounter resistant hosts are destroyed and diluted from the local environment. We tested whether spores of the bacterial parasite Pasteuria ramosa were passed through the gut (the route of infection) of their host, Daphnia magna, and whether ...

The effect of nematode population density at the time of application and formulations of in vitro-produced Pasteuria spp. endospores on the final population density of Belonolaimus longicaudatus was studied in an 84-d-long pot bioassay. The experiment utilized a factorial design consisting of 30 or 300 B. longicaudatus /100 cm of sandy soil and three formulations of in vitro-produced Pasteuria ...

Stress conditions have been found to change the susceptibility of hosts or their offspring to infection. The usual method of testing at just one parasite dose level does not allow conclusions on the distribution of susceptibility. To better understand the epidemiology and evolution of host-parasite systems, however, knowledge about the distribution of host susceptibility, the parameters that ch...

Previous pathogen exposure is an important predictor of the probability of becoming infected. This is deeply understood for vertebrate hosts, and increasingly so for invertebrate hosts. Here, we test if an initial pathogen exposure changes the infection outcome to a secondary pathogen exposure in the natural host-pathogen system Daphnia magna and Pasteuria ramosa. Hosts were initially exposed t...

A simple method for atomic force microscopy (AFM) of nematode cuticle was developed to visualize the external topography of Helicotylenchus lobus, Meloidogyne javanica, M. incognita, and Xiphinema diversicaudatum. Endospores of two isolates of the nematode parasite, Pasteuria penetrans, adhering to M. incognita and X. diversicaudatum were also visualized and measured by this technique. Scanning...