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Unraveling the ecology behind the success of traditional Milpa intercropping in Mesoamerica

English title Unraveling the ecology behind the success of traditional Milpa intercropping in Mesoamerica
Applicant Benrey Betty
Number 197463
Funding scheme Project funding (Div. I-III)
Research institution Institut de Biologie Faculté des Sciences Université de Neuchâtel
Institution of higher education University of Neuchatel - NE
Main discipline Ecology
Start/End 01.10.2020 - 31.01.2024
Approved amount 526'667.00
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All Disciplines (2)

Discipline
Ecology
Agricultural and Forestry Sciences

Keywords (6)

Plant defence; parasitoids; Soil feedback; indirect plant-mediated effects; Agricultural Ecosystems; Traditional Agriculture

Lay Summary (French)

Lead
La Milpa est une culture intercalaire traditionnelle du Mexique qui associe le maïs (Zea mays), les courges (Cucurbita spp.) et les haricots (Phaseolus spp.). Elle est considérée comme hautement productive et peu vulnérable aux ravageurs et aux maladies. Nous souhaitons examiner les mécanismes écologiques peu connus qui mènent au succès de cette pratique culturale.
Lay summary

Nous testerons notre hypothèse selon laquelle la combinaison des caractéristiques végétales de chaque plante de la Milpaentraîne des avantages mutualistes pour les plantes associées. Ainsi, les tiges du maïs servent de tuteurs pour les haricots, qui à leur tour améliorent la fertilité du sol par leur association avec des bactéries fixatrices d'azote. Quant aux courges, leurs grandes feuilles couvrent le sol, empêchant son dessèchement. Nous nous intéresserons principalement aux traits végétaux qui améliorent la qualité du sol et aux traits végétaux qui contribuent à la défense des plantes contre les ravageurs. Nous étudierons deux types de défenses : les défenses directes et indirectes. Les défenses directes, telles que les métabolites secondaires, confèrent une résistance aux plantes en affectant directement leurs ravageurs. Les défenses indirectes quant à elles favorisent la présence d’ennemis naturels des ravageurs  (par exemple, les substances volatiles attirent ou le nectar extra-floral). Les questions suivantes seront abordées :

  • Comment les plantes de la Milpainfluencent-elles la composition abiotique et biotique du sol et comment cela affecte-t-il leurs performances respectives ?
  • Dans quelle mesure la défense et la performance d’une plante de la Milpaprofitent-t-elles des traits de défense directs et indirects des autres espèces associées ?

Pour répondre à ces questions, nous effectuerons une combinaison d'expériences en laboratoire et sur le terrain au Mexique. Nous accomplirons notamment des tests de comportement et de performance, ainsi que des analyses chimiques et moléculaires.

Le transfert de pratiques d'une agriculture traditionnelle peut procurer des solutions aux défis de l'agriculture moderne, tels que la perte de fertilité des sols ou les changements climatiques. Nous nous attendons à ce que cette étude fournisse une meilleure connaissance des interactions écologiques qui sont à la base du succès de l'agroécosystème traditionnel de la Milpaet que ces informations s’avèrent précieuses pour promouvoir la protection des cultures et la sécurité alimentaire.

 

Direct link to Lay Summary Last update: 01.11.2020

Responsible applicant and co-applicants

Employees

Associated projects

Number Title Start Funding scheme
162860 Agricultural practices and the cascading effects of apparent competition: A case study of trophic interactions on cultivated maize and wild lima bean plants. 01.10.2016 Project funding (Div. I-III)

Abstract

The Milpa, a traditional Mesoamerican intercropping system involving maize (Zea mays), squash (Cucurbita spp.) and beans (Phaseolus spp.), has, for thousands of years, proven to be highly productive and relatively invulnerable to pests. Little is known about the ecological mechanisms that make Milpa so successful and how the interactions among the three-plant species may mediate the protection from pests. With the proposed project I aim to unravel the mutualistic Milpa ecology by studying the interactions among the three crop plants and associated organisms above- and belowground. The main objective is to determine how specific plant traits mediate associational facilitation and resistance and thus are the basis for the success of the Milpa cropping system.Three types of plant traits will be considered: 1) traits that enhance soil quality for plant growth; 2) traits that provide direct resistance against pests, and 3) traits that serve as indirect defenses by promoting the presence of the natural enemies of pests. For instance, soil quality may be enhanced by the large soil-covering leaves of squash plants that prevent soil desiccation, whereas nitrogen-fixing bacteria of bean plants can enhance soil fertility. Defensive trichomes, as well as plant-produced toxins such as cucurbitacins (squash), benzoxazinoids (maize), and isoflavonoids (beans), which also leach into the soil, are expect to provide direct protection against pests. Indirect defense may be provided by extrafloral nectar (beans) and the emissions of herbivore-induced volatiles (particularly strong in maize), which are attractive to insect predators and parasitoids. We will test our general hypothesis that the combination of these plant traits drive the mutualistic benefits that the Milpa plants derive from each other. Three questions will be addressed:1.How do the Milpa plants influence the abiotic and biotic composition of the soil and how does this affect their respective performance? 2.To what extent do the direct and indirect defense traits of one crop benefit the defense and performance of the other crops in the Milpa?3.Do the combined plant-mediated effects on soil conditions and plant defense traits enhance plant performance in a mutually beneficial manner?To answer these questions, we will conduct a combination of laboratory, field cage and open field experiments, using state-of-the-art behavioral, performance, molecular and metabolomics assays. Besides advancing our fundamental knowledge on the ecology of plant-insect interactions, we envision that the knowledge that we generate may lead to novel strategies for sustainable crop protection. This is particularly pertinent in the context that of the many challenges that modern-day agriculture faces, such as loss of soil fertility, a changing and fluctuating climate and increases in attacks by invasive pathogens and insects. Transferring successful strategies from traditional agricultural systems may provide solutions for these challenges. Hence, the primary objective is to provide unique insight into the ecological processes that underlie the success of traditional Milpa agroecosystem and to ultimately transfer this insight to sustainable pest management strategies that will help to ensure long-term food security.
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