Prospects for ecological engineering against rice pests

By Geoff Gurr

Though traditional pest management methods such as companion planting, trap cropping and other forms of polyculture have a long history, it is only in recent years that researchers have attempted to underpin such practices with ecologically-driven research.  ‘Ecological engineering’ for pest management has emerged from conservation biological control and habitat manipulation and is characterised by being based more comprehensively on ecological theory and by being developed via rigorous experimentation on the strategic use of biodiversity.  Of course, the very term ‘ecological engineering’ is also provocative counterpoint to its more controversial cousin: ‘genetic engineering’.  Though these two pest management approaches are not necessarily mutually exclusive, an advantage of ecological engineering is that it can be highly effective in its own right.  It can, thereby, avoid the need to take the genetic engineering route with its attendant risks of consumer backlash, farmer dependence on big business and expensive inputs; maybe even environmental impact.

A recent letter to the journal, Nature, by Josef Settele of the Helmholtz Centre for Environmental Research in Germany (vol 456, page 570) made this point clearly in the context of rice pest management.   Many issues will influence the decision of whether to grow genetically engineered rice commercially in China and elsewhere.  Some will be emotive, such as the heightened levels of consumer concern over food safety prompted by recent melamine contamination of milk products, whilst other issues are more technical. For example, engineered rice grown experimentally performs well against moth pests such as stem borer but is completely ineffective against planthoppers which are generally far more serious pests.  This illustrates a weakness of genetically engineered crops for pest management: they are effective against only certain pest types and even these pests can rapidly evolve resistance against engineered traits unless GE crops are very carefully regulated.  In contrast, ecological engineering can simultaneously suppress a wide range of pests by enhancing biological control and making farms less hospitable for pest colonisation and reproduction.  As Josef Settele suggests, a shift in resources to support ecological engineering could rapidly pay handsome dividends for food security.

Further reading:

Gurr GM, Wratten SD, Altieri MA. 2004. Ecological Engineering: Advances in Habitat Manipulation for Arthropods. Collingwood (Australia):  CSIRO Publishing.