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INVITATION PAPER (C.P. ALEXANDER FUND): CLASSICAL BIOCONTROL OF WEEDS: ITS DEFINITION, SELECTION OF EFFECTIVE AGENTS, AND ADMINISTRATIVE–POLITICAL PROBLEMS

Published online by Cambridge University Press:  31 May 2012

Peter Harris
Peter Harris
Affiliation:
Agriculture Canada Research Station, PO Box 440, Regina, Saskatchewan, Canada S4P 3A2
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Abstract

Dilemmas in weed biocontrol are wide ranging. Even the term biological control is confusing as meanings may be restricted to the use of parasites and predators or extend to the use of all non-chemical means of control. Another problem is that two-thirds of the agents released do not become numerous enough to inflict major damage to the weed population, although this statistic is misleading as it includes agents costing little in pre-release studies where failure is of little consequence and those costing about two scientist years each, or currently about $400,000. Many of the suggestions for improvement are costly and time consuming. Delay is unacceptable where agent release is seen by sponsors as a mark of progress in a program likely to require 20 years and funding is difficult. Analysis of previous biocontrol attempts for attributes of "success" have been disappointing, partly because there are a number of steps involved, each with its own attributes. This paper recognizes four graded "success" steps and discusses many agent selection methods.

There are public demands for a change in emphasis from chemical to biological control; but in the absence of effective enabling legislation, the practice of biocontrol can be legally and politically hazardous; biocontrol should be carried out by a multidisciplinary team but it is usually assigned to a single scientist; it needs to branch in new directions to remain scientifically stimulating, but this increases the risk of failure. Possible solutions for these dilemmas are discussed.

Résumé

Les problèmes reliés au contrôle biologique des mauvaises herbes sont de tous ordres. Le terme même de contrôle biologique peut porter à confusion, puisque, s’il désigne l’utilisation de parasites et de prédateurs, il peut aussi bien s’appliquer à toutes les méthodes non chimiques de contrôle. Un autre problème réside dans le fait que deux tiers des agents libérés dans la nature ne prolifèrent pas assez pour endommager la population de mauvaises herbes; cette statistique n’est cependant pas tout à fait juste, puisqu’elle tient compte à la fois des agents qui occasionnent peu de coûts au cours des essais préalables où l’insuccès a peu de conséquences, et de ceux qui coûtent environ deux années-recherche chacun, soit environ $400,000. Plusieurs des améliorations à apporter aux méthodes sont coûteuses en argent et en temps. Les retards sont inacceptables lorsque l’application d’un agent de contrôle est considérée par les commanditaires comme un signe tangible de progrès au sein d’un programme qui peut demander 20 ans de travail et, de plus, l’obtention de fonds est difficile. L’analyse des tentatives de contrôle biologique pour en reconnaître les facteurs de "succès" s’est révélée un exercice décevant, en partie parce qu’il faut les décomposer en un grand nombre d’étapes, chacune avec ses propres particularités. On reconnaît ici quatre étapes progressives de "succès" et plusieurs méthodes de choix d’un agent de contrôle font l’object d’une discussion.

Le public réclame que l’attention soit davantage tournée vers des contrôles biologiques que vers des contrôles chimiques; cependant, en l’absence d’une législation définie, la pratique du contrôle biologique peut s’avérer dangereuse légalement et politiquement; les contrôles biologiques devraient être régis par des équipes multidisciplinaries, mais sont ordinairement mis entre les mains d’un seul expert; il faudrait que le contrôle biologique s’ouvre sur de nouvelles avenues pour que la rechreche reste stimulante scientifiquement, mais cela augmente les risques d’insuccès. Des solutions à tous ces problèmes sont envisagées.

[Traduit par la rédaction]

Type
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Information
The Canadian Entomologist , Volume 123 , Issue 4 , August 1991 , pp. 827 - 849
Copyright
Copyright © Entomological Society of Canada 1991

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