Survey of 15 sites over 28 months for entomopathogenic nematodes (Rhabditida: Steinernematidae)

Abstract

SUMMARYThe presence of entomopathogenic nematodes in soil from 15 sites on 10 sampling occasions over a period of 28 months was documented. Sites were chosen to represent habitats classified as heathland, hedgerow, roadside verge, pasture or woodland. Bioassays utilized Galleria larvae and most of the nematodes obtained were identified asSteinernema (= Neoaplectana) bibionis (Bovien). A sibling species which fails to interbreed with S. bibionis was also found at 2 of the sites. Bioassays were at 15 and 20°C and there was no significant difference in the results at these temperatures. There was no evidence for seasonality in the presence of the nematodes and at 2 sites they were found on every sampling occasion. Otherwise, sites converted unpredictably from positive to negative or negative to positive over the 28-month sampling period.

Seasonal dynamics of entomopathogenic nematodes of the genera Steinernema and Heterorhabditis as a response to abiotic factors and abundance of insect hosts

“…In some cases, the cause may be the sampling error, because EPNs indicate an aggregated distribution in soil (Stuart and Gaugler, 1994), and a large amount of soil is necessary for proper EPN quantiWcation. Hominick and Briscoe (1990) observed unpredictable alternations of EPN presence and absence over 2 years in several localities in Great Britain. An absence of seasonal pattern is reported by Campbell et al (1995) and Glazer et al (1996).…”

Parasite transmission: reconciling theory and reality

“…However, it has been shown previously that the addition of a highly susceptible host into the glasshouse allows the nematodes to maintain themselves when pest densities are low, thereby enabling their persistence (Kaya 1990). It is only in natural populations in the field where there are other factors, including the presence of alternative hosts, that entomopathogenic nematodes have persisted for any length of time (Hominick & Briscoe 1990;Parkman et al 1993). It appears that these nematodes cannot be linked inextricably to a single host species and this may explain partly why they have such a vast host range.…”

Entomopathogenic Nematodes in the Soil Environment: Distributions, Interactions and the Influence of Biotic and Abiotic Factors

“…However, there is considerable variability across seasons, habitats and geographic regions; and factors such as soil texture, moisture content, temperature, and availability of hosts are important in determining local distributions (Akhurst & Brooks, 1984;Campos-Herrera, Escuer, Labrador, Robertson, Barrios, et al, 2007;Campos-Herrera, Pathak, El-Borai, Stuart, et al, 2013;Ehlers, Deseö, & Stackebrandt, 1991;Hominick & Briscoe, 1990aStuart & Gaugler, 1994). Unfortunately, EPN surveys typically only assess occurrence, involve a relatively small number of samples, and provide little quantitative information on relative abundance or distribution at various scales of measurement or across different kinds of sites or habitats.…”

“…Local extinctions and reintroductions are probably important aspects of the distribution of these species, and populations could often be extremely transitory in space and time (Hominick & Briscoe, 1990a;Ram, Gruner, McLaughlin, Preisser, & Strong, 2008;. Passive dispersal by water or phoretic dispersal within or upon hosts (Lacey, Kaya, & Bettencourt, 1995;Timper, Kaya, & Gaugler, 1988) or other organisms (e.g., mites, (Epsky, Walter, & Capinera, 1988); earthworms, (Shapiro, Berry, & Lewis, 1993); isopods, (Eng, Preisser, & Strong, 2005)) likely play important roles.…”