The society of nematologists at 50, and where to from here?

Nathan Cobb, as the father figure of the Society of Nematologists, set an example to later generations of nematologists in his studies of nematode biology. In the 50 years of the Society's existence nematological research has greatly expanded that knowledge base. Opportunities over the next 50 years are boundless in view of advancing technologies and emerging challenges, and this leads to speculation as to what future nematological research advances will enhance peoples' quality of life.

The antioxidants dimethylsulfoxide and dimethylthiourea affect the immediate adhesion responses of larval haemocytes from 3 lepidopteran insect species.

Antioxidants, dimethylsulfoxide (DMSO) and dimethylthiourea (DMTU), at concentrations not affecting the viability of blood cells (haemocytes) from the larval stage of 3 lepidopteran insects - Galleria mellonella, Lymantria dispar, and Malacosoma disstria - differed in their influence on the innate binding of haemocytes to glass, bacteria to haemocytes, and on humoral responses to alien materials. In vitro DMSO had little effect, whereas DMTU substantially impaired the adhesion of the haemocyte types, the plasmatocytes and granular cells, to slides as well as the attachment of Bacillus subtilis to these haemocytes. Although both antioxidants increased lysozyme and phenoloxidase activities, there was no correlation of enzyme activity and haemocyte adhesion responses, possibly reflecting sequestered radicals. Nitric oxide and hydroxyl radicals offset the DMTU effect. In the absence of antioxidants, inactivate protein kinases A (PKA) and C (PKC) enhanced haemocyte aggregation. In general, DMSO, as opposed to DMTU, did not alter the effects of PKA and PKC activators and inhibitors on haemocyte aggregation or of PKC and PKA activities. High concentrations of DMSO and all levels of DMTU, although inhibiting PKA and PKC, inhibited haemocyte adhesion to slides. Comparable results occurred for DMTU-treated haemocytes incubated with B. subtilis. In vivo DMSO, unlike DMTU, did not impair plasmatocyte or granular cell responses to foreign materials, including bacterial removal from the haemolymph and nodulation.

A novel antimicrobial epoxide isolated from larval Galleria mellonella infected by the nematode symbiont, Photorhabdus luminescens (Enterobacteriaceae).

A novel antimicrobial epoxide, 2-isopropyl-5-(3-phenyl-oxiranyl)-benzene-1,3-diol (1), was identified from larval Galleria mellonella infected by a symbiotically associated bacterium-nematode complex (Photorhabdus luminescens C9-Heterorhabditis megidis 90). Its structure was determined with spectroscopic analysis and confirmed by chemical synthesis starting from a known antibiotic, 2-isopropyl-5-(2-phenylethenyl)-benzene-1,3-diol (2). Epoxide 1 was active against Bacillus subtilis, Escherichia coli, Streptococcus pyogenes, and a drug-resistant, clinical strain of Staphylococcus aureus (RN4220) with minimum inhibitory concentrations in the range of 6.25-12.5 microg/ml. Epoxide 1 was cytotoxic against human cancer cell lines, MCF-7 wt, H460, and Jurkat, with GI(50) of 2.14, 0.63, and 0.42 microM, respectively, but was less toxic on normal, mouse splenic lymphocytes with a GI(50) of 45.00 microM.

Target Host Finding by Steinernema feltiae and Heterorhabditis bacteriophora in the Presence of a Non-Target Insect Host.

The ability of Steinernema feltiae or Heterorhabditis bacteriophora infective juveniles (IJ), when applied to the soil surface, to infect a Galleria mellonella larva at the base of a soil-filled cup (276 cm(3)) was evaluated in the presence and absence of 100 larvae of a non-target insect, the aphid midge Aphidoletes aphidimyza, near the soil surface. In all four trials with either S. feltiae or H. bacteriophora, A. aphidimyza presence did not affect the number of IJ finding and infecting a G. mellonella larva. Steinernema feltiae and H. bacteriophora IJ movement (as measured by the percentage of IJ aggregating on either side of an experimental arena) in the presence of one or many A. aphidimyza larvae was evaluated in agar- and soil-filled petri dishes, respectively. Infective juvenile movement in the presence of A. aphidimyza did not differ from random, indicating that IJ were not attracted to A. aphidimyza. It is suggested, therefore, that A. aphidimyza does not reduce IJ efficacy when these two forms of biological control agent are present together in a field situation even though it is known that A. aphidimyza is susceptible to IJ of these species.

Interaction of microbial populations in Steinernema (Steinernematidae, Nematoda) infected Galleria mellonella larvae.

Infection of Galleria mellonella larvae with the entomopathogenic nematodes Steinernema feltiae (A21 and R strains) and Steinernema glaseri (Dongrae) resulted in several species of bacteria, including the respective bacterial symbiont, Xenorhabdus spp., growing in the infected insect cadavers. These other bacteria were Enterococcus in all three nematode infections studied and Acinetobacter in the S. feltiae infections. The respective populations of these bacteria changed with time. Following infection of G. mellonella larvae with any one of the Steinernema sp., only Enterococcus bacteria were detected initially in the dead larvae. Between 30 and 50h post-infection Xenorhabdus bacteria were detected and concurrent with this Enterococcus population declined to zero. This was probably due to secondary metabolites with antibacterial properties that were produced by Xenorhabdus. In the S. feltiae (both R and A21 strains) infections a third bacterium, Acinetobacter, appeared at about 130h (in S. feltiae A21 infections) or 100h (in S. feltiae R infections) and increased in population size to approximately that of Xenorhabdus. It was demonstrated that Enterococcus, orginating from the G. mellonella digestive tract, was sensitive to the organically soluble antimicrobials produced by Xenorhabdus but Acinetobacter, which was carried by the nematode, was not.