Updated: Apr 19
April 25, 2020
By Dr. Jonathan Lundgren
Director of Ecdysis Foundation
When you were growing up, how often did you have to clean your windshield? And how often do you have to do that now?
The universal answer is that there are remarkably few insects today gooing up our windshields even relative to a few decades ago.
The insect apocalypse is worldwide in scope, and is directly related to how we produce our food. One study estimates that we have lost 76% of insect biomass over the past 27 years (1). Two primary drivers of this staggering biodiversity loss are habitat loss and unintended consequences of agrichemical use, and both are associated with the industrialization of our food system (2). Reforming our food system gives us a powerful tool for combatting this broadscale biodiversity loss, and regenerative food systems can overcome many of these drivers for insect loss.
Integrated pest management (IPM) fought a battle that it could never win. In 1959, it became clear that over-reliance on chemical pesticides was failing, and some scientists in California devised a systematic approach to pest management that could reduce chemical use, increase crop yield, and increase the oneness of the agroecosystem (3, 4). Silent Spring then provided the fuel for widespread promotion of IPM that continues to this day. But it didn’t work. More pesticides than ever are put into the environment. And arguably, pests are as big a problem today as they were 60 years ago. Regenerative farmers around the world are dispelling one of the central myths that IPM was trying to solve: that pests in agriculture are inevitable, and that pesticides are an effective management tool (5, 6).
Pests are not inevitable. Outbreaks are typically caused by monoculture cropping conditions, and by removing diversity and network connectivity from an agroecosystem (7, 8). Most pests are early successional organisms and take advantage of stressed crops grown in monocultures that are devoid of biotic resistance to the pest (9). Practices that eliminate life give a platform for continual pest resurgence. Essentially, IPM said “you produce food in this way; here is a better way to manage a problem that is produced by this production method”. Farmers practicing regenerative agriculture say “industrialized food production food doesn’t work. And when we fix the way we produce food, pests are no longer a problem”.
Regenerative agriculture has roots in conservation agriculture and adaptive management (8, 10-12), and relies on four central principles to achieve pest-free crops and livestock. These are 1) eliminate tillage, 2) never leave bare soil (always have living roots on the ground), 3) some plant diversity is better than none, and more is better than less, 4) integration of plants and animals on farms, and 5) eliminate or reduce synthetic agrichemicals. These five underlying principles are achieved through myriad practices that are adapted to the local or regional environment to attain a functioning farm system. Regenerative is organic, but organic isn’t necessarily regenerative. The end result is that by focusing on soil health and promoting biodiversity on farms, regenerative farms produce healthy food profitably. Regenerative principles fundamentally restore diversity and reduce disturbance to an agroecosystem within a functioning farm operation. As such, the effect of regenerative principles on pest populations are well founded in ecology. Here is how regenerative principles fight pests.
Life in the soil. Soil disturbance (e.g., tillage) removes life from the soil, and disrupts the balance among organisms that remain in the soil, reducing their ability to function (13, 14). The functions of soil life that are related to pest management include making the crop able to resist pest pressure (e.g., increasing the immune function of the plant, and the vigor of the resulting crop plant) (15), and increasing the biotic resistance to pest proliferation (e.g., entomopathogens, predators, parasitoids, and competitors). Although tillage has been espoused as a tool for managing soil insect pests for generations, there is little evidence that it actually works, and in many cases it increases pest pressure (10, 16).
Living roots to replace BS (bare soil). In 2009, we ran a study in which we planted a winter cover crop (slender wheatgrass), and killed it directly before corn planting. This was back when cover crops were still regarded as “fringe” to mainstream land managers. Then we infested the corn plants with corn rootworms and monitored biodiversity. As the name suggests, the little beetle grubs live in the corn roots. The result was fewer pests compared to the corn plots preceded by BS (17). This surprising result was produced because insect predators were much more abundant in the cover-cropped field. But the corn plants were also different in this study; the root structure was changed. So as the rootworms aged, they had to leave the corn root to find more suitable host roots, and when they did so they were attacked by legions of predators (18). Just having roots in the ground from one plant species, and some residue on the surface (and it wasn’t a lot) was enough to completely tip the balance to allow insect communities to work. We now know that the ways that insect communities function are difficult to understand, but we know that these complex communities…well, they work. And their function all starts with having as many plant species on the ground all year long (18-21).
Saturating plant communities. Restoring diversity to farmland is essential for pest suppression. The diversity of most other organisms is directly tied to plant diversity, abundance, and biomass within a habitat (22, 23). Thus, practices that encourage plant diversity on a farm provide clear benefits to pest management (24-27). The number of plant species and whether specific species are needed pest management are practical questions frequently requested by farmers. One study suggests that other ecosystem services start to maximize around 10-16 plant species in a community, but we don’t have good data on insect pest management in this regard. Insect communities are complex and that complexity challenges the selection of the perfect suite of plants for conserving the “best” insects. Certainly, it has never been demonstrated that there can be TOO MANY plant species in a habitat, from an ecosystem service perspective.
There are a lot of ways of getting plant diversity onto a farm in agronomically feasible ways. It begins with crop diversity. Varying the varieties of a crop is a first step, and long crop rotations and including intercropping schemes are great ways to increase plant diversity in cropland. Diverse cover crop mixes and interseeded cover mixes help to cover BS and add diversity. Diversifying field margins, shelterbelts and wetlands offer an additional source of plant diversity on a farm whose effects can spill over into adjacent cropland.
Livestock in the toolbelt. Animals (livestock) are essential to a healthy biological community on the land, especially a healthy plant community (28). Their dung recycles nutrients and feeds the next generation of plants (29). Livestock, through stimulation of plant growth (28), direct consumption of plants and pests (30), and trampling action (31, 32), are an effective management tool for many pests when crop plants and pastures are directly grazed. In addition to reducing costs associated with pest management, well managed livestock integration in cropland also increases the resilience and natural resource base of a farm (33-37). Integrating different livestock species into a single field has many benefits for the agroecosystem (38); the benefits of mixed livestock systems on pest management remain to be demonstrated, although anecdotal reports from farmers suggest that this is the future of livestock integration.
In the end, regenerative food systems are one of the most effective and best approaches we have for battling planetary scale problems like pollution, climate change, human health problems, and biodiversity conservation. Although the pest management benefits of regenerative principles have a strong scientific basis in ecology, it is the farmers that have learned how to put these ecological fundamentals into practical and functional farm systems. This illustrates the crucial importance of how these two sectors of the agricultural community need to work together for regenerative agriculture to rise to dominance in our society.
Dr. Jonathan Lundgren
is director of the Ecdysis Foundation that uses science and education to fuel the regenerative agriculture movement. He also runs the regenerative Blue Dasher Farm in Estelline, SD. www.ecdysis.bio and www.bluedasher.farm
1. C. A. Hallmann et al., More than 75 percent decline over 27 years in total flying insect biomass in protected areas. PLoS ONE 12, e0185809 (2017).
2. F. Sanchez-Bayo, K. A. G. Wyckhuys, Worldwide decline of the entomofauna: A review of its drivers. Biological Conservation232, 8 (2019).
3. V. M. Stern, R. F. Smith, R. van den Bosch, K. S. Hagen, The integrated control concept. Hilgardia 29, 81 (1959).
4. J. H. Perkins, Insects, Experts, and the Insecticide Crisis., (Plenum Press, New York, 1982).
5. C. E. LaCanne, J. G. Lundgren, Regenerative agriculture: merging food production and natural resource conservation in a profitable business model. PeerJ 6, e4428 (2018).
6. J. R. Pecenka, J. G. Lundgren, Effect of cattle management systems on dung arthropod community structure. Basic and Applied Ecology 40, 19 (2019).
7. J. G. Lundgren, S. W. Fausti, Trading biodiversity for pest problems. Science Advances 1, e1500558 (2015).
8. M. A. Altieri, The ecological role of biodiversity in agroecosystems. Agriculture, Ecosystems and Environment 74, 19 (1999).
9. R. N. Wiedenmann, J. W. J. Smith, Attributes of natural enemies in ephemeral crop habitats. Biological Control 10, 16 (1997).
10. B. R. Stinner, G. J. House, Arthropods and other invertebrates in conservation-tillage agriculture. Annual Review of Entomology 35, 299 (1990).
11. H. E. Birgé, C. R. Allen, A. S. Garmestani, K. L. Pope, Adaptive management for ecosystem services. Journal of Environmental Management 183, 343 (2016).
12. B. B. Lin, Resilience in agriculture through crop diversification: Adaptive management for environmental change. BioScience 61, 183 (2011).
13. P. F. Hendrix et al., Detritus food webs in conventional and no-tillage agroecosystems. BioScience 36, 374 (1986).
14. M. J. I. Briones, O. Schmidt, Conventional tillage decreases the abundance and biomass of earthworms and alters their community structure in a global meta-analysis. Global Change Biology 23, 4396 (2017).
15. R. L. Vannette, M. D. Hunter, Mycorrhizal fungi as mediators of defence against insect pests in agricultural systems. Agricultural and Forest Entomology 11, 351 (2009).
16. E. K. Rowen, K. H. Regan, M. E. Barbercheck, J. F. Tooker, Is tillage beneficial or detrimental for insect and slug management? A meta-analysis. Agriculture, Ecosystems and Environment 294, 106849 (2020).
17. J. G. Lundgren, J. K. Fergen, The effects of a winter cover crop on Diabrotica virgifera (Coleoptera: Chrysomelidae) populations and beneficial arthropod communities in no-till maize. Environmental Entomology 39, 1816 (2010).
18. J. G. Lundgren, J. K. Fergen, Enhancing predation of a subterranean insect pest: A conservation benefit of winter vegetation in agroecosystems. Applied Soil Ecology 51, 9 (2011).
19. G. Tillman et al., Influence of cover crops on insect pests and predators in conservation tillage cotton. Journal of Economic Entomology 97, 1217 (2004).
20. L. Philippot, J. M. Raaijmakers, P. Lemanceau, W. H. van der Putten, Going back to the roots: the microbial ecology of the rhizosphere. Nature Reviews Microbiology 11, 789 (2013).
21. M. Damien et al., Flowering cover crops in wintere increase pest control but not trophic link diversity. Agriculture Ecosystems and Environment 247, 418 (2017).
22. D. R. Zak, W. E. Holmes, D. C. White, A. D. Peacock, D. Tilman, Plant diversity, soil microbial communities, and ecosystem function: are there any links? Ecology 84, 2042 (2003).
23. D. Salazar, A. Jaramillo, R. J. Marquis, The impact of plant chemical diversity on plant-herbivore interactions at the community level. Oecologia 181, 1199 (2016).
24. D. K. Letourneau et al., Does plant diversity benefit agroecosystems? A synthetic review. Ecological Applications 21, 9 (2011).
25. F. J. J. A. Bianchi, C. J. H. Booij, T. Tscharntke, Sustainable pest regulation in agricultural landscapes: a review on landscape composition, biodiversity and natural pest control. Proceedings of the Royal Society B 273, 1715 (2006).
26. P. Barbosa et al., Associational resistance and susceptibility: having right or wrong neighbors. Annual Review of Ecology, Evolution & Systematics 40, 1 (2009).
27. A. Ebeling et al., Plant diversity effects on arthropods and arthropod-dependent ecosystem functions in a biodiversity experiment. Basic and Applied Ecology 26, 50 (2018).
28. W. R. Teague et al., Grazing management impacts on vegetation, soil biota and soil chemical, physical and hydrological properties in tall grass prairie. Agriculture, Ecosystems and Environment 141, 310 (2011).
29. G. T. Fincher, The potential value of dung beetles in pasture ecosystems. Journal of the Georgia Entomological Society16, 301 (1981).
30. G. D. Buntin, J. H. Bouton, Alfalfa weevil (Coleoptera: Curculionidae) management in alfalfa by spring grazing with cattle. Journal of Economic Entomology 89, 1630 (1996).
31. R. East, R. P. Pottinger, Use of grazing animals to control insect pests of pasture. New Zealand Entomologist 7, 352 (1983).
32. P. G. Hatfield et al., Incorporating sheep into dryland grain production systems I. Impact on over-wintering larva populations of wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae). Small Ruminant Research 67, 209 (2007).
33. B. F. Tracy, Y. Zhang, Soil compaction, corn yield response, and soil nutrient pool dynamics within an integrated crop-livestock system in Illinois. Crop Science 48, 1211 (2008).
34. L. W. Bell et al., Impacts of soil damage by grazing livestock on crop productivity. Soil and Tillage Research 113, 19 (2011).
35. A. J. Franzluebbers, J. A. Stuedemann, Crop and cattle responses to tillage systems for integrated crop-livestock production in the Southern Piedmont, USA. Renewable Agriculture and Food Systems22, 168 (2007).
36. M. P. Russelle, M. H. Entz, A. J. Franzluebbers, Reconsidering integrated crop-livestock systems in North America. Agronomy Journal 99, 325 (2010).
37. K. Hilimire, Integrated crop/livestock agriculture in the United States: A review. Journal of Sustainable Agriculture 35, 376 (2011).
38. G. Martin et al., Potential of multi-species livestock farming to improve the sustainability of livestock farms: A review. Agricultural Systems 181, 102821 (2020).