Bacterial metabolites.

Abstract

An outcome of research into the biology of the symbiosis of entomopathogenic nematodes and their associated bacteria has been the discovery of the diversity of chemical substances, some of them new to science, produced by bacterial symbionts. This paper focuses on these secondary metabolites, especially the organically soluble, small-molecule ones, and highlights their source, production and potential utility.

Determination of the efficacy of some entomopathogenic nematodes against Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) under laboratory conditions

“…through the cuticle, and enter the hemocoel of the host releasing their symbiotic bacteria into the haemolymph of their host. These bacteria propagate and produce toxins (Dowds & Peters, 2002) and other metabolites (Webster et al, 2002) to suppress the defense mechanisms of the host, which usually dies within 48 h of invasion by the nematode. The cadaver provides food for the nematode for up to three generations (Poinar, 1990;Kaya & Gaugler, 1993).…”

Microbial control of diamondback moth, Plutella xylostella L. (Lepidoptera: Yponomeutidae) using bacteria (Xenorhabdus nematophila) and its metabolites from the entomopathogenic nematode Steinernema carpocapsae

“…The bacterial cells carried by the IJs of nematodes are released from insect cadavers to infect larvae and pupae in the soil, so their environmental impact needs to be investigated in detail, particularly if the treatments were applied in soil. S. carpocapsae which carries X. nematophila is currently exempt from pesticide regulations in Europe and the U.S.A., but efforts to use the bacterial symbionts themselves or their toxic metabolites may need to proceed cautiously because of the nature of the broad spectrum of the symbiont's bioactivity (Webster et al, 2002), particularly in the rhizosphere.…”

Effects of Paenibacillus nematophilus on the entomopathogenic nematode Heterorhabditis megidis

“…The presence of non-symbiont bacteria may reduce Heterorhabditis yields in vitro (Ehlers, 2001) and in vivo , while certain contaminant species may also induce morphological and behavioral abnormalities in Heterorhabditis (Poinar, 1988). Rapid growth rate and secretion of antibiotics by Photorhabdus prevent microbial contamination of the cadaver, mainly from the insect intestinal microXora (Jarosz, 1996;Webster et al, 2002). Shedding by infective juveniles of their protective sheath (the molted cuticle of the previous developmental stage) prior to entry into the host or host hemocoel (Bedding and Molyneux, 1982;Peters et al, 1997) may also help reduce the number of contaminants introduced into the hemocoel by the invading nematodes.…”