The COVID-19 problem

At the end of November 2019, in Wuhan, Hubei province, China, there were reports of cases of pneumonia whose clinical picture differed from those known locally. Quick etiological studies confirmed a previously unknown virus in humans. The disease was called severe acute respiratory syndrome (SARS) or coronavirus disease 2019 (COVID-19). The causative agent is the coronavirus of zoonotic origin SARS-CoV-2 (^{Ludwing and Zarbock, 2020}). On January 30, 2020, the World Health Organization (^WHO) declared the outbreak of a public health emergency of international concern (^{Harapan et al., 2020}). In March, the WHO declared a pandemic. According to the Mexican Ministry of Health (^{SSA, 2020}), the first COVID-19 case detected in Mexico was reported on February 27, 2020. The following month, the government implemented preventive measures to stall the spread of infections in the country. These measures included the National Healthy Distance Campaign (Jornada Nacional de Sana Distancia), which originally ran from March 23 to May 30, 2020. This strategy involved a suspension of non-essential activities in the public, social and private sectors, which had a great socioeconomic impact (^{García, 2020}). Other countries adopted similar or even more severe measures such as forced family and community confinement, urban patrols, fines, total isolation of cities, and border closures. Preventive measures continued to be applied until the second semester of 2020. In 2021, up to press time, preventive measures affecting productive activities were relatively relaxed, but in-person educational activities continued to be restricted (Editor’s Note). Although agriculture was classified as an essential activity in Mexico, the social environment and the need for inputs and labor affected the rhythm of production. The present work aimed to assess the status of Integrated Pest Management (IPM) as a way to promote sustainability and proper environmental management in the agricultural production carried out in Mexico City (CDMX), and the impact of COVID-19 in the IPM activities of technicians and producers during the first SARS-CoV-2 epidemic cycle in 2020.

Integrated Pest Management as a sustainability strategy

In Mexico, agriculture is a primary activity of great economic, political and socio-cultural importance (^{Galindo, 2011}). The great demand for food and its market value has fueled a rapid evolution towards intensive and extensive production models throughout the world. These models have involved the development of technology and inputs to promote, protect or add value to agricultural production. The pesticide industry has provided toxic solutions for pest and disease control since the 1930s. The biological effectiveness of pesticides has led to their excessive use, many times outside of any rational framework. This has had detrimental effects on the environment as well as on the health of flora, fauna, and humans, paradoxically without eradicating the targeted pests. A vicious circle has thus emerged in which pests mutate to adapt to pesticides and the chemical formulations of pesticides are modified in response to prolong their useful and profitable life. There are many proposed approaches to solve this circular biological-chemical ‘game’. Integrated Pest Control emerged in the 1970s, one of the first approaches with wide acceptance due to its systemic approach. Conceptually, it was simple: it consisted of the sum of practices, techniques, and methods that complement each other to improve the efficiency and effectiveness of pest control. The concept was soon modified to Integrated Pest Management (IPM), dispensing with the intention of eradicating one pest and targeting instead a pest complex. For this purpose, the concept of pest is used broadly following the definition recognized by the International Plant Protection Convention (IPPC) of FAO, which includes insects, pathogens, weeds, etc. (Editor’s Note). These strategies had a positive effect on agricultural practices by changing the focus from eradicating to managing various phytopathogens, arthropod pests, weeds, etc. (^{Pérez, 2004}). Even though this strategy requires a technical-scientific assessment of the characteristics of each region, its simplicity allows it to be empirically implemented by producers, using different techniques and achieving different results, in a continuous trial-error process. In the 1990s, the demand for safe agricultural products, and later, with the beginning of the new century, for healthy products, which has intensified during the COVID-19 pandemic, reactivated the IPM strategy as a viable alternative for small and medium producers looking to add value to their products and reduce production losses. This strategy can also help reduce the negative impact of agrochemicals on agricultural assets (soil, water, cultivars) and the health of agricultural workers. The need to lower the environmental impact of agricultural production came later in the face of social pressure due to the effects on the health of the community (Editor’s Note). At present, IPM is a strategy with many variations and objectives that is widely known and applied throughout the world. Its implementation in organic agriculture, which has made great progress in our country, mainly among small producers and in urban and community agricultural systems, has become almost mandatory due to the restrictions on the use of synthetic pesticides. For this reason, agricultural producers should be educated and trained to improve their knowledge of their crops, pest biology, and the techniques and actionability criteria associated with IPM (^{Mora-Aguilera et al., 2009}).

An agricultural survey in Mexico City

The present work was planned and carried out in the summer-autumn of 2020, during the first phase of the COVID-19 pandemic, under restrictions that limited academic work to virtual activities using institutional and personal digital tools. The work was carried out by a team of agronomy students from UAM-X, an academic unit located southeast of Mexico City in the ancient pre-Hispanic agricultural region of Xochimilco (which means ‘flower chinampa’ in Nahuat). Two questionnaires were applied to agricultural technicians and producers according to their job profiles. The questionnaires were prepared using the Google Forms platform. They consisted of 36 questions for producers and 33 questions for technicians regarding their understanding and application of IPM and how COVID-19 affected their work. All surveys were sent to agricultural technicians and producers who supervised or worked on crops grown in the municipalities of Xochimilco, Milpa Alta, Tláhuac, Tlalpan, Magdalena Contreras, and Cuajimalpa, all inside Mexico City (Figure 1). These agricultural production units are classified as urban due to their interaction with a territorial environment integrated into Mexico City and with socioeconomic activities predominantly oriented to satisfy the needs of a diverse population through the industrial, services, and tourism sectors, agriculture being a marginal activity. The surveys were sent and answered via email, WhatsApp or telephone. The collected data were analyzed and plotted in Excel 2010.

Survey of agricultural technicians

Out of a total of 30 agricultural technicians who were asked to participate in the survey, 21 did. Of these, 12 were male and nine females. Forty-eight percent of them worked in the mayor’s office of Xochimilco. This is an important urban agricultural region in Mexico City due to its horticultural, floricultural, and ornamental contributions. It contains small family production units, some of which still use the chinampa system, an ancestral agricultural technique for intensive production based on wetland management (^{Mendoza, 2018}). During the period in which the surveys were taken, in the summer-autumn cycle of 2020, the technicians were training producers in the growing of different crops. The surveyed technicians reported having at least three years of work experience (57%). Regarding their knowledge of IPM, the technicians expressed knowledge about the economic damage caused by pests, monitoring strategies, recognition of pests and diseases, prevention methods, and control treatments. Most of them (more than 60%) were also aware of the definition of pests according to the FAO IPPC.

Figure 1 Vegetable production in urban production units in Mexico City. A. Maize production in chinampa, Xochimilco. B. Production of vegetables leafy in chinampa, Xochimilco. C. Tomato crop variety El Cid, San Luis Tlaxialtemalco, Xochimilco. D. Nursery of spinach, San Gregorio Atlapulco, Xochimilco. E. Nursery of tomato, chili and ornamentals, Caltongo, Xochimilco. F. Epazote plant with symptoms of mildew interacting with tomato crop. 

Before the pandemic, technicians made at least three visits (76%) to farmers’ plots per production cycle. Likewise, they followed up on the management practices implemented by producers. The main pest control method recommended or carried out by the producers was chemical control (57%), while the rest (43%) used other methods (biological, mechanical, cultural, mixed control). This type of pest management, combining chemical control and other alternatives with less environmental impact, including IPM (identified as ‘mixed’) contrasts with the pest control practices of an important agricultural region such as the Bajío Michoacano, where 98% of producers used chemical control (^{Ávila-Alistac, 2010}). This may be due to the productive typology of urban agricultural production, which relies on small production units that may not be able to afford costly chemical products, using instead traditional management methods and artisanal products such as plant extracts. The urban setting may also influence the producer’s decision not to use chemical products with toxic effects that could contaminate the environment where his own family lives. The use of chemical products in urban agricultural production units is probably reserved, either as a first control option or as part of a MIP scheme, for highly profitable crops or for infections (diseases) or infestations (insects or mites) too severe to be controlled with the use of other methods. These scenarios are common in agriculture and have been widely documented (^{González et al., 2014}). Regarding the proclivity of producers to accept technical recommendations, it is significant that only 50% of the surveyed producers implemented recommendations of the technicians. The producers who didn’t follow the technical recommendations were still able to grow healthy crops. In a traditional productive model, where community knowledge is deep and effective, as is the case of Xochimilco, which has an ancient agricultural vocation, this result is not surprising. The transfer of innovative technologies must be based on a sociocultural analysis of the effectiveness of pre-existing technologies. Needless to say, this aspect has profound philosophical implications for academia and research.

As expected, in Xochimilco agricultural production is destined to the local and regional markets and only marginally for self-consumption. This indicates the great opportunities that agricultural producers can have in an urban environment, where population density guarantees demand, there is quick access to points of sale, transport and storage costs are low, and production can be planned based on the dynamics of the local market, on which macroeconomic factors have little influence.

The COVID-19 pandemic severely affected supply chains throughout the world by causing production deficits or disrupting transport networks. The negative economic effects of the pandemic were aggravated by the globalization of the world economy, based on the fragmentation of production chains across countries. In this context, forecasts for agriculture were discouraging (^{Seleiman et al., 2020}). However, agricultural production is generated by heterogeneous production systems. Highly technified agricultural production systems were the most affected due to their need for large volumes of highly specialized inputs such as agrochemicals, planting seeds, packaging material, and transportation systems. In urban (or rural) agricultural systems with small productive units, input chains were not so severely affected. For example, 62% of the surveyed producers use their own seeds or exchange them, while 33% purchase seed from local distributors or agrochemical stores, informal businesses, distributors, sub-distributors, collectors, and SADER programs. With variations, this scheme works in the same way throughout the country (^{CEDRSSA, 2015}). In other words, the supply of agricultural inputs becomes diversified by relying on small-scale retailers for small-scale production units (Figure 2). Similar results were observed with fertilizer and agrochemicals regarding the diversity of service providers. Some amount of self-sufficiency was also reported, maybe due to the use of compost or artisanal products. The traditional chinampa system is characterized by the intense use of organic matter produced in the wetlands on which the system is based.

Source: own, based on a survey applied through digital means.

Figure 2 Mechanisms for the acquisition or appropriation of three types of agricultural inputs used by producers in urban agricultural production units of six Mexico City municipalities.  

Impact of COVID-19 on the agricultural technical service

The health emergency created by COVID-19 affected the continuity of the agricultural technical service. However, knowledge and advice continued to be provided to agricultural producers through digital technologies such as virtual platforms, video tutorials, video calls, phone calls, and WhatsApp. Although the risk of an erroneous diagnosis in the identification of pests was recognized by 29% of the surveyed technicians, digital photography was very useful, especially when technicians had previous knowledge of the productive systems they were working with and when there was sufficient knowledge about the pests and diseases of local incidence (47%). It can be inferred that digital work was effective in at least 76% of the cases since the density of pests and/or diseases did not increase in the same percentage of the plots attended by agricultural technicians. The diagnosis of pests plays a crucial role in the treatment and management of sanitary problems and it is one of the fundamental elements of phytosanitary management. Reliance on the diagnosis of plant pests and disease can be abused, however, creating the false conception that diagnosis is sufficient for controlling plant health, and agrochemical stores can prescribe solutions for any phytosanitary problem. This reductionist approach is behind the irrational use of pesticides under the pretext of protecting the crops and justifies the use of IPM as a holistic and systemic phytosanitary approach. It is worth noting the parallelism between the virtual diagnosis of plants and humans during the COVID-19 epidemic. Although telemedicine already existed in an incipient way, mainly in the surgical field, it was popularized worldwide due to the risk of contagion with SARS-CoV-2 in hospital and clinical systems. As an example, Medica Sur, a recognized private medical company based in Mexico City, is developing the Telemedicina Médica Sur program, and it already provides virtual consultations.

Digital tools have proved very valuable for communicating relevant data and instructions between agricultural technicians and producers during the COVID-19 pandemic, especially in an urban agriculture environment with a high risk of contagion and lax prevention protocols, as is the case of Mexico City. Since March 2020, Xochimilco’s local authorities promoted prevention strategies against COVID-19 due to the high risk of contagion associated with its intense economic and tourist activity (http://www.xochimilco.cdmx.gob.mx/alista-xochimilco-mega-jornada-to-prevent-covid-19/). Mexico City and the State of Mexico, which together comprise 21.5% of the national population, were the entities with the highest number of positive cases and deaths from COVID-19 throughout the epidemic process, which explains their higher use of digital tools compared with rural production environments. In the agricultural regions of the country, phytosanitary and training activities continued to be carried out in person, although with certain restrictions, with no use of digital systems (González-Gaona et al., and Castañeda-Cabrera et al., in this Special Issue) (^{CGLU, 2020}). The different perceptions of the gravity of the COVID-19 pandemic between rural and urban areas may also explain why 47% of urban agricultural producers considered it ‘imprudent’ to carry out in-person training activities, while in rural areas in-person training was a recurring demand from producers (G. Mora-Aguilera 2021. Personal Communication). The rapid understanding by urban technicians of the risks posed by COVID-19 allowed them to innovate their communication processes as a technical but also as a professional need.

Survey of urban agricultural producers

Eighty-seven producers responded to the survey out of a total of 100 who were invited to participate. Of these, 64 (74%) were male and 23 (26%) female. Their age was between 20 and 30 years old (23%), 31 and 50 years (35%), and over 50 years old (42%). These data suggest a positive transgenerational trend, with preponderant participation of producers under 50 years of age and greater participation of women (+ 9%) compared to national data. One of the current problems of agriculture is the aging of the rural population (>46 years, 83.5%) and with it the loss of agricultural knowledge (https://www.inegi.org.mx/programas/ena/2019/). Urban agriculture in Mexico City is rooted in strong ancestral values ​​and traditions, which possibly explains the generational replacement dynamics in family productive activities. However, the survey used in the present study did not make an in-depth evaluation of this aspect nor of the trends in land use, which are greatly affected by urban pressure. As a megalopolis, Mexico City offers complementary job opportunities without the need to migrate and break up the family group. The surveyed producers were located in the seven municipalities of Mexico City with urban agricultural activity but were mainly represented by Xochimilco and Tlalpan (Figure 3).

Figure 3 Mexico City municipalities where the surveyed producers lived and had their agricultural production units during the COVID-19 pandemic. 

Most of the surveyed producers had basic or intermediate education. Only 6% had university studies. This coincides with the findings of ^{Zepeda-Jazo (2018)}, who mentioned that more than 50% of the agricultural producers of Mexico City had only basic education. Most producers (88%) owned their land (less than three hectares). This is an indicator of the productive vocation of the original landowners and proof of the strength of the transgenerational family model. Land fragmentation is a characteristic of family farming due to the continuous division of the land between heirs. ^{Torres-Lima and Rodríguez-Sánchez (2007}) reported that 90% of agricultural producers in Cuajimalpa, A. Obregón and Milpa Alta have properties of one hectare or less. In an urban system, land fragmentation can benefit intensive cultivation with low investment, enabling the producer to sustain his productive vocation. For example, during the peak (July 20) of the first epidemic wave in Mexico, only 14% of the surveyed producers declined to plant their fields during the summer-fall of 2020. Most of them planted mainly corn (Figure 1A) and, to a lesser extent, vegetables (Figure 1B-E and Table 1). Although Mexico City has a tradition of corn cultivation, with a total of 2,397 producers who planted together up to 23 native types of corn in 2016 (^{SEDEREC, 2016}), the predominance of this crop during the COVID-19 pandemic could be due to its lower requirements of labor and low production costs compared to vegetables or ornamental plants. These characteristics of corn cultivation helped producers to overcome the potential operational problems created by the health emergency, and provided them enough corn for self-consumption, ensuring a source of food for persons and animals. Corn is also easy to preserve and store, and more versatile, in culinary terms, than vegetables (^{Vera-Sánchez, 2016}). The survey found that during this productive cycle, the harvested grain and vegetables were used for self-consumption and sale in local markets. This change in the production pattern from more profitable crops to crops that provide food security demonstrated the versatility and resilience of small producers in the face of crises such as that created by SARS-CoV-2. It also shows the potential of urban production units to guarantee the local food supply with low or limited dependence on foreign products. Despite their high purchasing power, European countries suffered from food restrictions due to the effect of the COVID-19 pandemic on supplier countries, (https://www.agronegocios.co/agricultura/productos-frescos-seran-mas-esrazas-in-Europe-on-account-of-the-crisis-of-covid-19-2984253). At the macroeconomic level, countries or regions with strong agricultural activity had a lower food security risk from COVID-19 (^{FAO and ECLAC, 2020}). Even Mexico increased its agricultural exports due to the global demand for food. This sector was the only one that had positive growth in 2020 (P. Rivas, in this Special Issue).

The producers corroborated the technicians’ appreciation that the seeds are usually obtained by purchase or exchange (65%), while 35% of the producers used seeds from previous harvests. Between 2008 and 2009, a series of surveys applied in different rural areas of Mexico City found that 90% of farmers used their own seeds, while 9% used seeds from other producers in other communities (^{Vera et al., 2014}). This is an example of empirical knowledge applied by producers to avoid productive ‘erosion’ by mixing the genotype of their crops with foreign genotypes. This is a viable strategy for small producers, who, with this practice, also preserve their agricultural genetic resources in situ, as opposed to large producers, who use seed varieties created by private companies that can genetically restrict the possibility of reusing the seeds after harvest. This is precisely the case of hybrid maize. This type of knowledge must be preserved and improved under a sustainable agricultural system.

Regarding IPM, 82% of the producers were unaware of its technical principles. However, they were able to describe it as the use of various methods to control a pest or disease, which means that they had an empirical understanding of the system. This group of producers also define “pests” in a broad way when referring to any insect or organism that causes damage to their crops, be it insects, fungi, bacteria, etc. (Figure 1F). They also identified the various pests that affect their crops, most of them (65%) stating that insects are their greatest problem (Table 2) but recognized the existence of beneficial insects that can contribute to pest control.

Pests affect 99% of producers, so they all apply some control method (Figure 4). However, as already indicated, the urban agricultural model imposes the need for pest control strategies with the least effect on the environment. Interestingly, the main strategy is mechanical control for preventive purposes (67%) followed by chemical control (52%) for curative purposes. This preventive-curative strategy is the basis of a rational management that is hardly ever applied in extensive agriculture, which favors chemical control due to the high level of investment and the market demand for products with specific organoleptic properties that are produced using total active ingredients of great impact to the environment. Another notable result is the use of biological controls for both preventive (8%) and curative (25%) processes. Less than 10% of the surveyed producers combined more than one technique. These control scenarios indicate that IPM has great chances to be implemented holistically and systemically together with other environmental strategies. Mechanical or cultural control pest control, which is very costly in large productive units due to the need for labor, is viable in small production units. Mechanical control includes pruning of damaged plant parts, manual pest collection, soil management, types of planting beds, the cleaning and sanitization of seeds, etc. Many of these practices have an ancient origin, such as manual pest elimination, which could be associated with the consumption of insects (e.g. grasshoppers and maguey worms) and fungi (huitlacoche), ingredients that are widely used in the cuisine of large rural and urban sectors of the Mexican highlands.

Source: own, with survey applied by digital means during the COVID-19 epidemic.

Figure 4 Control strategies used by producers to control pests in urban agricultural production systems of seven municipalities of CDMX.  

It is thus possible to state that there is an intuitive understanding of the benefits of IPM for producers in the region. However, the establishment of IPM systems must be carried out through cooperative research with producers to generate the actionability criteria for each pest and determine the biological effectiveness of possible control strategies suitable for an urban environment. That is, a correct application of the IPM (^{Kogan and Bajwa, 1999}). Once a technological innovation is generated, it is transferred to producers. IPM is not a combination of strategies based on published recipes. Each productive system must be studied from a regional perspective, integrating the traditional knowledge of each community. Producers are willing to use the IPM strategy because they perceive its usefulness in an urban environment that has limited productive resources, expectations for healthy food, and ecological concerns. Producers recognize that the healthiness of their products can provide added value. Various organic nopal production programs in Milpa Alta have had this aim, even if their results have been modest (https://noticieros.televisa.com/ultimas-noticias/cdmx-impulsa-cultivo-organico-nopal/). The COVID-19 pandemic made more people aware of the need to improve their health through the consumption of a healthy diet consisting of fresh and innocuous products. Coinciding with the COVID-19 pandemic, the Mexican Ministry of Health promoted an improved food labeling system as a result of the high incidence of chronic metabolic, cardiovascular and other diseases, which are associated with greater mortality from SARS-CoV-2. Urban agriculture faces great prospects for comprehensive optimization but requires the accompaniment of public and institutional policies.

Health emergency due to COVID-9 and agricultural producers

Despite the health emergency created by the SARS-CoV-2 in 2020, most agricultural producers (72%) in Mexico City continued with their daily activities in plots and chinampas, complying with the preventive measures established by the Secretary of Health of Mexico City (^{Garcia, 2020}). Thanks to this, the incidence of pests did not increase (Table 2, Figure 3). Although 75% of the producers reported production losses, these were not less than 20% and were not considered significant. An extensive producer would certainly consider this a significant loss.

The main problem during the period under study was the scarcity of labor since 50% of producers hire agricultural workers. To guarantee the health of its workers and generate labor confidence, proper sanitary measures were implemented at the production unit level. Despite this, the laborers did not go to work, which is understandable because the maximum peak of positive cases in Mexico City occurred in the summer-autumn of 2020, and for several months Mexico City was classified into the red traffic light category. Agricultural workers would have had to use a public transport system, which, in addition to the risk of contagion posed by it, has a limited number of transport units. Confinement was never mandatory in Mexico, which led to the concentration of people in certain essential areas such as markets, supply centers, pharmacies, and self-service stores. These areas were frequently identified with COVID-19 outbreaks in Mexico City. In that period, it was frequent to read journalistic reports of COVID-19 outbreaks among agricultural workers due to the overcrowded conditions in work areas, transportation, migrant flows, and lack of medical services (^{Valadez, 2020}; González-Gaona and Col. in this Special Issue). Agriculture was considered essential in Mexico, but agricultural workers were exposed to a greater risk of the disease.

Conclusions

A survey was digitally generated and applied to a total of 108 urban agriculture technicians and producers from seven municipalities of Mexico City during the first COVID-19 epidemic wave in Mexico in 2020. The results showed that agricultural technicians kept providing advice and training in person, attending to the sanitary measures established by the Ministry of Health, and using digital technologies with good acceptance from producers. Agricultural technicians knew IPM and its possible benefits for the environment and human health. Although producers were unaware of the main aspects of the IPM strategy, they had an empirical understanding of it, implementing different pest control methods, the least frequent being chemical pest control. It is important to delve into the impact of the COVID-19 epidemic and the opportunities for urban agriculture given the growing social demand for sustainable agriculture, with low environmental impact, as a source of healthy, unprocessed food, the consumption of which constitutes a preventive health strategy. The resilience of urban agriculture in productive, cultural, and social terms, in the face of the COVID-19 pandemic, demonstrated that this type of agricultural production units can be part of a holistic food security system for large cities with a high incidence of disease. Such a system could be put in place with the explicit support of public institutions.