Because research on nematode involvement in trophic interactions, foodweb structure, and biodiversity is constrained by lack of an overview of nematode feeding habits, this outline presents a consensus of current thought on nematode feeding habits. The source of food is fundamental to trophic interactions and provides the basis for our definitions of the essential feeding types: 1) plant feeder, 2) hyphal feeder, 3) bacterial feeder, 4) substrate ingester, 5) predator of animals, 6) unicellular eucaryote feeder, 7) dispersal or infective stage of parasites, and 8) omnivore. Lists of families and genera with their presumed feeding types are given. Major gaps in knowledge of feeding in the smaller tylenchids and many dorylaims are noted.

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Feeding habits in soil nematode families and genera-an outline for soil ecologists.

Roles of organic soil amendments and soil organisms in the biological control of plant-parasitic nematodes: a review.

Bacterivorous nematodes and organic matter decomposition

Bacteria Used in the Biological Control of Plant-Parasitic Nematodes: Populations, Mechanisms of Action, and Future Prospects

The potato cyst nematode Globodera rostochiensis is an important pest of potato (Solanum tuberosum). Pseudomonas fluorescens F113, which produces 2,4-diacetylphloroglucinol (DAPG), was investigated as a potential biocontrol agent against G. rostochiensis. Exposure of nematode cysts to the pseudomonad, under in vitro conditions or in soil microcosms, almost doubled the ability of the eggs to hatch. The percentage of mobile juveniles was reduced threefold following their incubation in the presence of the pseudomonad, both in vitro and in soil. Results obtained with a transposon-induced DAPG-negative biosynthetic mutant of F113 and its complemented derivative with restored DAPG synthesis showed that the ability of strain F113 to produce DAPG was responsible for the increase in hatch ability and the reduction in juvenile mobility. Similar effects on egg hatch ability and juvenile mobility of G. rostochiensis were obtained in vitro by incubating nematode cysts and juveniles, respectively, in the presence of synthetic DAPG. DAPG-producing P. fluorescens F113 is proposed as a potential biocontrol inoculant for the protection of potato crops against the potato cyst nematode.

Role of 2,4-Diacetylphloroglucinol in the Interactions of the Biocontrol Pseudomonad Strain F113 with the Potato Cyst Nematode Globodera rostochiensis.

+3741 Various aspects of biological control of plant-parasitic nematodes have been reviewed a number of times (5, 9, 16, 39, 56, 75), but the numerous recent developments in this area and the impending loss of several of the most widely used nematicides for reasons of hazards to human health have prompted this examination of the status of natural enemies for control of nematode pests. It is not my intent to list or consider all organisms in this category because little information has been acquired on many of them since previous reviews. This review deals only with the most important and promising natural enemies on which there is sufficient information to make at least preliminary interpretations of their value and potential role in biological control. It also attempts to analyze recent studies, compile re­ ports of new organisms and, I hope, stimulate and guide future research in this important field.

R Mankau

Papers

Biological Control of Nematode Pests by Natural Enemies