Agroecological Crop Protection Research Articles

Modeling the effect of multiple pests on ecosystem services provided by fruit crops: Application to apple

CONTEXTIn agroecosystems, crop pests have long been controlled by the intensive use of synthetic pesticides. To lower the dependency on pesticides, alternative crop protection strategies such as Integrated Pest Management (IPM) and Agroecological Crop Protection (ACP) have been proposed. In this context, it is crucial to consider multiple pests and their effects on host plant functioning and, ultimately, on system performance. OBJECTIVEWe aim to develop a pest-crop model to account for the effect of multiple pests on fruit tree functioning and the resulting ecosystem services provided by an orchard, using apple as a case study. METHODSFirst, we identified possible mechanisms of pest disturbance on apple tree for ten major pests: rosy and woolly apple aphid, codling, oriental and tortrix moths, red mite, powdery mildew, European canker, fire blight and apple scab. We classified them into seven functional groups: resource stealers, leaf area reducers, assimilation rate reducers, water transport reducers, assimilate sappers, fruit senescence accelerators and fruit marketability depreciators. Second, we defined coupling functions for each functional group. These describe the reduction of target variables in an existing fruit tree model (QualiTree), i.e. the variables to which the pest disturbances directly apply, as a function of pest abundances. Parameter values of the coupling functions were estimated based on the literature. Third, we used simulations in standard cultural conditions and a Monte Carlo Bayesian Sensitivity Analysis to test and hierarchize the effect of pests on the variation of nine indicators of four classes of ecosystem services (namely fruit production, climate regulation, soil nitrogen availability and water cycle maintenance and regulation).RESULTS AND CONCLUSIONSOnly four indicators were affected by the considered pests: refractometric index (measuring fruit sugar content), marketable yield, carbon sequestration and water drainage. The variations in refractometric index and in marketable yield were largely explained by the main effects of water transport reducers and fruit senescence accelerators, respectively. The latter also contributed the most to carbon sequestration variation. The variation in water drainage was largely explained by the main effect of mildew, an assimilation rate reducer. SIGNIFICANCEOur approach provides an operational tool to assess the impact of multiple pests on orchard ecosystem services. The model also opens up the possibility of studying the impact of pests in different ecological and technical contexts. For this, it must be coupled with models capable of predicting pest abundances as a function of cultivation practices and biotic and abiotic conditions.

Crop protection practices and risks associated with human fungal infectious diseases: a One Health perspective

We review interactions between crop protection practices (developed to control plant pathogens and invertebrate pests) and human fungal infectious diseases. Unlike viral, bacterial and parasitic infections, fungal infections in humans are usually only superficial in healthy individuals, but can become invasive and pose serious risks to immunosuppressed individuals. Although their global impact is less than that of other infectious diseases, human fungal infections still pose serious public health issues. For instance, the use of synthetic agricultural fungicides, particularly the azole class, under conventional intensive, or efficiency improvement-based crop protection practices, is at risk as far as antimicrobial resistance is concerned, due to cases of cross-resistance to clinical azoles used to treat pulmonary aspergillosis, candidiasis and cryptococcocis. In this respect, the One Health approach, originally designed for other types of human pathogens, looks relevant for human pathogenic fungi. Additionally, some entomopathogenic fungi used as biocontrol products against crop pests in a substitution-based approach, may be potentially pathogenic to humans. Very few examples of redesign-based practices (i.e. Agroecological Crop Protection) emerged from our analysis on human fungal diseases. However, discontinuing agricultural azole fungicides (as practiced on organic farms, and which may to some extent be related to the redesign strategy) appears to be the best way to reduce selection pressure and hence the level of azole-resistant human pathogenic fungal strains in the environment.

Tracking down coupled innovations supporting agroecological vegetable crop protection to foster sustainability transition of agrifood systems

CONTEXTHigh pesticide use causes environmental and human health hazards. Yet, the change to alternative crop protection practices faces a web of interacting barriers that results in a sociotechnical lock-in. Designing “coupled innovation” has been proposed by agricultural scientists to overcome the barriers that prevent change in practices. Coupled innovations consist of developing jointly innovations both at the farm and the agrifood system level to overcome the lock-in. OBJECTIVEIn this study, we aim at characterizing how existing coupled innovations foster the implementation of agroecological crop protection in French vegetable systems. METHODS‘Tracking down coupled innovation’ method consisted of six steps: (i) identification of the existing coupled innovations in vegetable systems across France; (ii) interview of their stakeholders; (iii) identification, based on the interviews and an analytical framework, of the sociotechnical levers involved in the coupled innovations and the functions the levers perform to foster agroecological crop protection; (iv) characterization of the conditions for the coupled innovation implementation based on 20 categorical variables; (v) typology of the innovations based on the lever functions they performed, using a multiple correspondence analysis followed by hierarchical cluster analysis on principal components; (vi) comprehensive analysis of one typical innovation per cluster, to understand in-depth how it was implemented. RESULTS AND CONCLUSIONSWe identified 40 coupled innovations, 17 sociotechnical lever functions and 5 consistent clusters of coupled innovations each implementing a specific combination of lever functions. The five clusters consist of: (1) co-developing and diffusing new inputs and related knowledge through specific knowledge infrastructure, (2) facilitating farmers' peer-exchange of knowledge, (3) (re)structuring the food value chain to support the implementation of agroecological crop protection, (4) pooling material and cognitive resources and (5) renting or exchanging fields to support crop diversification. Key conditions for innovation success were the support of intermediaries, a shared vision and trust between stakeholders, their active involvement, and a limited physical distance between them. The comprehensive analysis of the typical innovations illustrated, for each cluster, the complex relation between the sociotechnical levers, the functions they perform, the network involved, the ACP practices implemented and the conditions for successful implementation. SIGNIFICANCETracking down coupled innovation produced knowledge that can support the coupled innovation design in other contexts, hence the sustainability transition of the agrifood systems. It can complement the study of innovative farmers' practices with capitalizing knowledge on the means to overcome barriers to the implementation of these practices.

Evaluation of Equisetum arvense (Horsetail Macerate) as a Copper Substitute for Pathogen Management in Field-Grown Organic Tomato and Durum Wheat Cultivations

Effective pathogen management, as an aspect of agroecological crop protection (ACP) necessitates the replacement of copper (Cu) fungicides, but there is little knowledge relating to the performance of potentially suitable alternatives in large-scale, open-field agricultural settings. The present study was aimed at investigating the potential of Equisetum arvense (horsetail macerate) compared to Cu-based treatments for the control of Solanum lycopersicum. and Triticum turgidum ssp. durum fungal pathogens in established organic commercial farms located in Emilia Romagna (Italy) over a three-year period (2017–2019). Both the Cu-based and horsetail foliar sprays were routinely applied as preventative treatments and in the event of pathogen establishment as curative treatments. The Cu-based and horsetail macerate treatments were both equally effective at significantly reducing Phytophthora infestans (late blight) and increasing yield in tomato compared to the untreated control. For durum wheat, the horsetail macerate and Cu-based treatments were successful at significantly reducing Puccinia triticina (brown rust) infection and increasing yield under moderate infection, but unsuccessful under unfavorable meteorological conditions resulting in the combined and severe spread of Puccinia triticina, Fusarium graminearum, and Zymoseptoria tritici. From the present results, horsetail macerate is a promising and suitable Cu-free ACP alternative for late blight management of tomato.

Challenges of complying with both food value chain specifications and agroecology principles in vegetable crop protection

To meet the challenges of sustainability in agricultural system design, reducing the dependency on synthetic plant protection products has become a core issue. There are currently two major reasons for farmers' decision to reduce their use of synthetic products: public policies, and the extralegal requirements of food supply chains. To reduce or eliminate synthetic plant protection products, agroecological crop protection (ACP) relying on the development of agroecology science and practices is a promising holistic approach focused on crop health overall. ACP requires a consistent combination of various agronomic practices at different spatiotemporal and trophic levels. Vegetable crops are minor crops facing the major challenges of producing high-quality produce and of controlling sanitary pressure on yields. Thus, agroecological vegetable systems must not only be adapted to official regulations and environmental parameters but must also comply with the specifications of the targeted food value chains (FVC), which are variable: marketing standards regarding cosmetic issues are very strict in long value chains, whereas they are more flexible in local short chains. Whereas fresh vegetable production is strongly challenged by the reduction of synthetic plant protection products, there are few studies that show how to design, manage and assess agroecological crop protection strategies for such systems, considering the main specifications and criteria of the FVC as a whole. This article reports on the challenges of complying with both FVC specifications and agroecology principles in protected vegetable crop protection. This study relies on four cropping systems implemented in an experimental station for 4.5 years, each of which had a specific strategy of crop protection management and was devoted to a particular FVC. The four FVCs are “local direct sale in low-pesticide farming”, “local direct sale in organic farming”, “super- and hypermarket value chain in low-pesticide farming” and “super- and hypermarkets value chain in organic farming”. Results consist in the description of combination of agronomic practices used, as well as the corresponding decision-making processes. They then present the performance of the four systems tested, showing that agroecological crop protection strategies are successful in reducing or eliminating synthetic plant protection products. We then discuss failure and success factors highlighted by this multi-year experiment. It illustrates that agroecological crop protection and compliance with the FVC's expectations can be compatible but involve specific trade-offs, depending on the targeted food value chain. We finally stress key areas to investigate further in order to achieve still challenging objectives in vegetable systems.

Qualitative modeling of fruit fly injuries on chayote in Réunion: Development and transfer to users

Intensive chayote cultivation in Réunion almost disappeared in the 2000s due to significant yield losses from fruit fly attacks on this historically important crop (Dacus ciliatus, Zeugodacus cuurbitae and Dacus demmerezi). Since the late 2000s, the adoption of agroecological crop protection practices have led to the effective management of fruit fly populations, a significant reduction in pesticide use, an increase in chayote production and plantations, and the development of organic production. To assist in fruit fly management, a qualitative model which simulates fruit fly damage to chayote crops, known as IPSIM-chayote, was developed, providing satisfactory prediction results. It has a user-friendly interface and is now available free of charge online, in three languages (French, English and Spanish): https://pvbmt-apps.cirad.fr/apps/ipsim-chayote/?lang=en. The IPSIM-chayote modeling platform can be used by farmers as a diagnosis to simulate fruit fly damage to their crops and as a decision-making tool for their agricultural practices. The model can be used as a training resource in agroecological crop protection. Public authorities and local government can use it as a tool in planning and forecasting agricultural development. Finally, researchers can use it as a prediction tool and a resource for the exchange of information, allowing them to review scientific knowledge or identify new, relevant research areas suited to the context and challenges. IPSIM-chayote can be considered as a forum for exchange and can stimulate collaborative work between individuals. It is a flexible model, as it allows variables to be added. IPSIM-chayote is the first qualitative model developed for crop pests in a tropical environment. It could serve as a basis for the development of other similar models simulating crop pest incidence, thus contributing significantly to the development of agroecological crop protection.

Leaf Eh and pH: A Novel Indicator of Plant Stress. Spatial, Temporal and Genotypic Variability in Rice (Oryza sativa L.)

A wealth of knowledge has been published in the last decade on redox regulations in plants. However, these works remained largely at cellular and organelle levels. Simple indicators of oxidative stress at the plant level are still missing. We developed a method for direct measurement of leaf Eh and pH, which revealed spatial, temporal, and genotypic variations in rice. Eh (redox potential) and Eh@pH7 (redox potential corrected to pH 7) of the last fully expanded leaf decreased after sunrise. Leaf Eh was high in the youngest leaf and in the oldest leaves, and minimum for the last fully expanded leaf. Leaf pH decreased from youngest to oldest leaves. The same gradients in Eh-pH were measured for various varieties, hydric conditions, and cropping seasons. Rice varieties differed in Eh, pH, and/or Eh@pH7. Leaf Eh increases and leaf pH decreases with plant age. These patterns and dynamics in leaf Eh-pH are in accordance with the pattern and dynamics of disease infections. Leaf Eh-pH can bring new insight on redox processes at plant level and is proposed as a novel indicator of plant stress/health. It could be used by agronomists, breeders, and pathologists to accelerate the development of crop cultivation methods leading to agroecological crop protection.

Agroecological management of cucurbit-infesting fruit fly: a review

Conventional crop protection with pesticides has limitations such as resistance of pests to pesticides and faunal imbalance. Agroecological crop protection is an attractive alternative based on the principles of agroecology. We present here this strategy using the case of Cucurbitaceae flies, which are the most important agricultural pests in Reunion. Research has been carried out on the bioecology of these insects and on the effectiveness of agroecological techniques. The main points are the following: the number of species of vegetable flies increased in the southern summer. Adult flies spend more than 90 % of their time on nonhost plants, with specific circadian rhythms. Several original agroecological techniques were designed, such as sanitation using augmentoria; trap plants, e.g., maize; adulticide bait; and the creation of habitats for predatory arthropods. Local growers are very satisfied with the results. They have reduced insecticide use with substantial cost savings and they have observed a decrease in losses and a lower phytosanitary workload. The education and training of students, professionals, and the general public has been a major aspect of this project. Increased knowledge of flies and agroecological management strategies of their populations can now be combined with modeling tools to facilitate the extension of the program to other areas or for educational purposes. Practices are currently being extended to other areas of the island and other countries of the Indian Ocean. This project is both a significant milestone for organic farming in Reunion and a precedent for other initiatives aimed at reducing or eliminating pesticides.

The augmentorium, a tool for agroecological crop protection. Design, implementation and evaluation on farm conditions on Reunion Island

A La Reunion, la protection des cultures contre les mouches des fruits et des legumes (Diptera, Tephritidae) a pris un virage agroecologique. Dans cette demarche, les mesures prophylactiques reposent sur l’utilisation d’un augmentorium. Il s’agit d’une structure ressemblant a une tente fermee dans laquelle on depose regulierement les fruits infestes ramasses au champ. L’augmentorium empeche ainsi la re-infestation de l’agroecosysteme par une nouvelle generation d’adultes de mouches qui emergent dans l’augmentorium, alors qu’un filet a la maille adaptee, place sur le toit de l’augmentorium, permet de relâcher dans la nature les parasitoides des mouches. L’objectif de l’etude est de mettre au point et d’evaluer la technique de l’augmentorium adaptee au contexte de La Reunion. En premier lieu, une enquete montre que, des qu’elle est correctement presentee et expliquee, la technique de l’augmentorium recoit un tres bon accueil, non seulement de la part des agriculteurs produisant des legumes, mais aussi de la part des particuliers possedant des arbres fruitiers dans leur jardin. Les deux types d’augmentorium qui ont ete concus en concertation avec des agriculteurs, puis fabriques localement, se revelent faciles d’emploi et adaptes a la diversite des situations de production. Plusieurs dizaines d’agriculteurs utilisent l’augmentorium depuis 2009 : ils considerent cette technique simple, efficace, respectueuse de l’environnement et peu consommatrice en coUt et en temps. A terme, l’utilisation de ce type de technique peut etre envisagee aussi bien en ville qu’a la campagne, reliant ainsi protection agroecologique des cultures et ecologie urbaine.