17
Multi-Function Agricultural Biodiversity:
Pest Management and Other Benefits
Geoff M. Gurr, Stephen D. Wratten and John Michael Luna
Introduction
What good are all those species that man cannot eat or sell?
(Odum, 1971)In structurally complex landscapes, parasitism was higher and crop damage
was lower than in simple landscapes ...
(Thies and Tscharntke, 1999)The first quotation above emphasizes the potential value of species for indirect
commercial production benefits (soil fertility maintenance, pollination, pest and
disease suppression, etc). The second, which concerns the effect of non-crop veg-
etation on rape pollen beetle (Meligethes aeneus Fabricius) in oilseed rape (Brassica
napus L.), neatly summarizes the type of outcome now often sought from agricul-
tural biodiversity. In California, for example, no fewer than seven proprietary seed
mixtures – with names like ‘Good Bug Blend’ and ‘Insectary Blend’ – are available
to growers to increase vegetational biodiversity (Bugg and Waddington, 1994). A
proprietary mixture of ‘weed’ species is also available in Switzerland (Nentwig et al,
1998). The consequence sought is pest suppression, ostensibly via an enhance-
ment of the populations (or at least efficacy) of predators and parasitoids. Impor-
tantly, however, increasing biodiversity per se is no guarantee of pest suppression
(van Emden and Williams, 1974; Andow, 1991; Gurr et al, 1998; Landis et al,
2000). An understanding of the mechanisms by which biodiversity may favour
pest management is, therefore, important.
Vegetational diversification may be beneficial via a direct, bottom-up influ-
ence of the first trophic level on the pest. Resource concentration hypothesis effects
Reprinted from Basic and Applied Ecology vol 4, Gurr G M, Wratten S D and Luna J M, Multi-
function agricultural biodiversity: Pest management and other benefits, 107–116, Copyright (2003),
with permission from Elsevier.