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Agroecosystem Diversity and Pest Control: Data, Tentative Conclusions, and New Research Directions
509
Citations
0
References
1983
Year
Ecological TheoryEngineeringEntomologyAgricultural EconomicsPublic HealthBiodiversityAgroecologyPlant-insect InteractionAgroecosystemPest ManagementAgroecological SystemsNew Research DirectionsPest AbundanceAgricultural DiversificationAgroecosystem DiversityEvolutionary BiologyCrop ProtectionPest ControlPlant-animal InteractionAgrobiodiversity ConservationAgroecological PathwaysBiotic InteractionResource Partitioning
Criticism of the diversity‑stability theory has fostered skepticism about using ecological theory to guide agro‑diversification for pest control, because studies rarely link pest abundance to yield and seldom examine underlying mechanisms. The authors aim to develop a predictive theory of how agricultural diversification affects insect pests by elucidating the ecological mechanisms involved. Across 150 studies of 198 herbivore species, 53% were less abundant, 18% more abundant, 9% unchanged, and 20% variable in diversified systems, with evidence that host‑finding behavior to resource patterns—not natural enemies—often drives these differences, supporting the use of within‑field plant diversity to improve pest management.
Recent criticism of the theory that increased diversity leads to increased stability has led to widespread skepticism about the value of using ecological theory to suggest strategies of agricultural diversification to better control insect pests. A total of 150 published studies which examine the effect of diversifying an agroecosystem on insect pest abundance are summarized; 198 total herbivore species were examined in these studies: 53% of these species were found to be less abundant in the more diversified system, 18% were more abundant in the diversified system, 9% showed no difference, and 20% showed a variable response. Two major problems with the studies were: (1) proper experiments were not conducted to show that differences in pest abundance between more and less diverse systems resulted in yield differences; (2) the ecological mechanisms accounting for the differences in pest abundance were carefully examined in only a few of the studies. A fundamental understanding of these ecological mechanisms is critical to the development of a predictive theory of how agricultural diversification affects insect pests. Empirical data and several theoretical arguments are presented which suggest that differences in pest abundance between diverse and simple systems can frequently be accounted for by the response of herbivore host-finding behavior to the patterns of resource availability, rather than the activities of natural enemies. The development of ecologically sound agroecosystems may well utilize within-field plant diversity, both in developing and in developed regions.