Widening the window of persistence in seasonal pathogen-host systems.
Local instability of exploiter-victim systems is well-known in both theory and in nature. Victims can be too sparse to support exploiter reproduction (under-exploitation) or they can be too readily driven to extinction (over-exploitation). Exploiters of seasonal resources face the additional challenge of surviving periods when victims are rare or unavailable. We formulate a fully stochastic model of highly seasonal pathogen-host dynamics and explore the interactions between an entomopathogenic nematode and its lepidopteran host. Our model suggests that if nematode populations experience the high rates of mortality predicted by short-term laboratory experiments, the paired threats of under- and over-exploitation should preclude the long-term persistence of this exploiter-victim system. We measured nematode mortality rates in the field and found that long-term mortality is lower than that predicted by short-term experiments. Incorporation of this new data into our model produces long-term persistence of local nematode populations across a range of initial nematode densities.
Dugaw
Christopher J
CJ
Department of Mathematics, University of California Davis, One Shields Avenue, Davis, CA 95616, USA. cjdugaw@ucdavis.edu
Preisser
Evan L
EL
Hastings
Alan
A
Strong
Donald R
DR
D000818:Animals; D006790:Host-Parasite Interactions; D009348:Nematoda / Q000469:parasitology; D010271:Parasites / Q000472:pathogenicity*; D012621:Seasons; D013269:Stochastic Processes; D013534:Survival