Increasing biodiversity to improve insect pest management in agro-ecosystems.
M. A. Altieri's 1991 conference paper reviewed how biodiversity and vegetation structure could support natural enemies, reduce pest pressure and contribute to more stable agroecosystems, while stressing that outcomes depend on local ecological and socio-economic conditions.
What the study did and found
M. A. Altieri's 1991 paper “Increasing biodiversity to improve insect pest management in agro-ecosystems.” examined how biodiversity loss in simplified farming systems can affect pest regulation. Published in the proceedings of the First Workshop on the Ecological Foundations of Sustainable Agriculture, it reviewed experimental evidence and case studies on the role of vegetation diversity and natural enemies in pest management. The paper argued that monocultures can reduce ecological services that help restrain pests, while more diverse vegetation can provide alternative prey or hosts, food and refuges for predators and parasitoids. It also emphasized that no single vegetation design is universally effective: each agroecosystem requires separate assessment, and long-term strategies must consider both ecological and socio-economic conditions.
Why it is cited
The chapter is cited in later work on agroecology, biological control and diversified farming because it set out an early ecological framework linking crop and habitat diversity with natural-enemy activity. Later reviews and textbooks have referenced Altieri's 1991 chapter when discussing the history of biodiversity-based pest management and the development of integrated pest management approaches.
Subsequent research broadly supports the idea that diversification can improve biological pest control, but the effects are variable. Recent meta-analyses report that diversified farming tends to increase beneficial species and reduce pest abundance, while crop-diversity studies often find lower herbivore abundance. However, outcomes depend on crop combinations, pest traits, natural-enemy communities and surrounding landscape complexity. This supports Altieri's emphasis on context rather than a universal prescription.
The topic today
Current pest-management research treats biodiversity as one component of integrated and agroecological strategies rather than as a stand-alone solution. Modern work evaluates intercropping, cover crops, flower strips, non-crop habitats and landscape structure alongside pesticide use and crop productivity. The central question has shifted from whether diversity can help to which forms of diversification work best, for which pests and natural enemies, and under which landscape and farming conditions.