Spatial-Temporal Evolution of Scientific Production about Genetically Modified Maize

agriculture Review Spatial-Temporal Evolution of Scientific Production about Genetically Modified Maize Alberto Santillán-Fernández 1,2 , Yolanda Salinas-Moreno 3,*, JoséRenéValdez-Lazalde 4and Santiago Pereira-Lorenzo 5   Citation: Santillán-Fernández, A.; Salinas-Moreno, Y.; Valdez-Lazalde, J.R.; Pereira-Lorenzo, S. Spatial-Temporal Evolution of Scientific Production about Genetically Modified Maize. Agriculture 2021,11, 246. https:// doi.org/10.3390/agriculture11030246 Academic Editor: Mark O. Winfield Received: 15 February 2021 Accepted: 8 March 2021 Published: 12 March 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Catedrático-Conacyt, Colegio de Postgraduados Campus Campeche, Champotón 24450, Campeche, Mexico; [email protected] 2International Doctorate Program of Agricultural and Environmental Sciences, Escuela Politécnica Superior, Universidad de Santiago de Compostela, Galicia, 27002 Lugo, Spain 3Department of Genetic, Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Campus Altos de Jalisco, Tepatitlán de Morelos 47600, Jalisco, Mexico 4Department of Forestry, Colegio de Postgraduados Campus Montecillo, Texcoco 56230, Estado de México, Mexico; [email protected] 5Department of Plant Production and Engineering Projects, Escuela Politécnica Superior, Universidad de Santiago de Compostela, Galicia, 27002 Lugo, Spain; santiago.pereira.lor[email protected] *Correspondence: [email protected]; Tel.: +52-33-2219-7627 Abstract: Maize is the grain cereal that is the basis of human and animal diets in Mexico and Latin America; it constitutes an essential crop for global food security. The objective of this study was to analyze the spatial–temporal evolution of scientific production on the theme of GMO maize, through a bibliometric analysis of the texts available in the main editorial houses (Elsevier, Scopus, and Springer), open access journal articles database (Conricyt, Scielo, Redalyc, Latindex, Claryvate Analytics, Periodica, and DOAJ), and freely accessible web search engine Google Scholar, to determine the factors that influence the impact of the studies. From 1991 to 2019, 917 texts were found whose spatial–temporal evolution showed a linear growth that concentrated in Latin America (58.56%). The low impact (measured by the number of bibliographic citations) of scientific studies developed in countries of Latin America was related to their publication in journals edited in their own countries and in Spanish, which restricts the constructive criticism of peer review. For the case of Mexico, a spatial discrepancy was also found between research centers and production areas, which limits the transference of technology; and no specialized author in theme of GMO maize was found; the researchers responded to “scientific trends” in agreement with the agrarian policies of the time. Keywords: Zea mays L.; academic endogamy; scientific article; scientific trends 1. Introduction Maize (Zea mays L.) is the cereal with highest worldwide production level, above wheat (Triticum aestivum L.) and rice (Oryza sativa L.), and it constitutes the basis of the human diet for countries of Latin America, especially Mexico, where it is considered a strategic crop for the country’s food security [ 1 ]. With the development of biotechnology, GMO maize varieties have been created with resistance to insects and herbicides, which allows productivity to increase by area [2]. Maize is originally from Mexico, territory where 64 races are cultivated derived from the millenary domestication process of its wild relatives, Teocintle and Tripsacum, in combination with different environments, agricultural systems and ethnic groups [ 3 ]. However, despite this diversity of maize races, Mexico is not the main maize producer in the world. Of global production, 70.06% is concentrated in five countries, with USA (35.42%) and China (21.93%) as the leading producers, followed by Brazil (7.22%), Argentina (3.01%), and Mexico (2.48%) [1]. Agriculture 2021,11, 246. https://doi.org/10.3390/agriculture11030246 https://www.mdpi.com/journal/agriculture Agriculture 2021,11, 246 2 of 14 Unlike Mexico, USA, China, Brazil, and Argentina base their productivity on the use of GMO maize varieties, which provide higher yields in the field than the conventional varieties [ 4 ]. Reference [ 5 ] found that the agricultural competitiveness of a country is directly related with the quality of the research performed in this sector. To measure the quality of research, [ 6 ] suggest a methodology of bibliometric analysis that allows studying and analyzing the evolution of scientific activity through its publications. The publication of a scientific study is the most effective way to transmit knowledge acquired as consequence of the research, and its visibility is important for the researchers themselves, for the institutions where they work, and for the organizations that finance the research [ 7 ]. The growth of scientific production in recent decades and their indexation in automatized bibliographic databases have strengthened the use of bibliometry and the generation of indicators to measure the results of scientific and technological activity [8]. Bibliometric studies based on the scientific articles published are supported by the application of quantitative methods, generation of indicators and mathematical models, which allow characterizing their development and evolution [ 9 ]. Through bibliometric indicators, the journals and other periodic publications can be evaluated objectively, and the trends that they follow can be observed to generate useful information to improve their management [7]. Understanding the scientific information that is developed around a topic allows making decisions in relation to its improvement [ 10 ]. Bibliometric studies have been developed in the agricultural sector to evaluate general themes of agronomy [ 6 ], specific themes such as ecological agriculture [ 11 ], fruits and vegetables [ 12 ], and even for agronomists in particular [ 13 ], agricultural journals [ 14 ], national agricultural sectors [ 8 ], and specific crops such as wheat and barley [15], and rice [9,16]. However, despite the growth in the number of publications that has taken place in the agricultural sector and specifically in themes related to transgenic maize, there is scarce research to assess the evolution and the impact of these publications at the level of the user [ 17 ]. Considering this, the objective of the present study was to analyze the spatial–temporal evolution of scientific production on the theme of GMO maize at the global level, and with emphasis for Mexico, through text mining (bibliometry) and Social Network Analysis (SNA) to determine the factors that impact the quality of the studies. 2. Materials and Methods 2.1. Origin of the Information and Data Preparation Scientific articles about transgenic maize available in the principal editorial houses (Elsevier, Scopus, and Springer), open access journal articles database (Conricyt, Scielo, Redalyc, Latindex, Claryvate Analytics, Periodica, and DOAJ), and freely accessible web search engine Google Scholar were considered in this study. They were compiled from January to April 2020. It was considered all scientific articles available up 2019. The keywords used in the search were “maíz transgénico”, “maíz genéticamente modificado”, “genetically modified corn” and “transgenic corn”, identifying them in the titles and keywords of the publications. In addition, the “snowball” technique was used to obtain the missing articles, from the reference list of the articles initially found. However, it has to be considered that the technique of “snowball” as being non-probabilistic, has the possibility of incurring in bias, while recovering the scientific articles, favoring the documents in English. For upcoming this bias, in the search of the scientific articles, the keywords used were both in English and Spanish, what let to obtain the great majority of important publications [18]. In order to establish the bibliometric indicators, the variables analyzed from each of the articles were "name of the journal, editing institution, country of edition", and "language of publication", which served to determine the profile of the journals that publish studies related to the theme of "GMO maize; first author and collaborators" which served to understand the network of actors involved in the research; "year" used in order to place the Agriculture 2021,11, 246 3 of 14 information in a time line; "institution of the first author" and "the first author’s country of origin" to evaluate the frequency of publications of institutions by country. The "postal code of the institution of the first author" served to perform a geographic localization of the information’s institution of origin; in the cases when the postal address did not appear, the name of the institution was searched with Google Earth ® tools and in the official pages of the institutions. The "title, abstract" and "keywords" were used to categorize the topic addressed by the publication in agreement with the classification by the National Resource Consortium of Scientific and Technological Information [ 19 ] for genetically modified maize. Finally, the usefulness of the publications was determined with the "number of citations". Capturing the variables was done in a worksheet, in which they were systematized and classified in thematic areas according to their content; in addition, the original language of each of the texts was respected. While capturing all the information, some records were standardized because the information available in the articles was sometimes incomplete or presented with variations [ 20 ]. In addition, special characters were eliminated or changed to ease the analysis, such as: ñ (by n), accent marks, superindex, subindex, ® , © , among others. Due to interpretation reasons, the information for the case of Mexico was separated into three periods that coincide with the periods of three government administrations: 2001–2006, 2007–2012, and 2013–2018. 2.2. Analysis with Text Mining With the help of the RcmdrPlugin.temis complement of the statistical software R [ 21 ], the number of articles per year and journal, the institution where the research originated, and the articles where the main author is from the same institution of the journal were obtained. 2.3. Network Analysis With the Sci2tool software [ 22 ] the interactions present between the first authors and collaborators were analyzed with the aim of understanding the consistency of the researcher’s work; that is, to assess whether the author has published just in one year or else has been publishing constantly throughout time, which gives an idea of the author’s consolidation on the topic of GMO maize. The syntaxis used with the Sci2tool software was Extract bipartite Network, and for its visualization the Gephi software was used [23]. Finally, with the help of the variable "postal code" and Google Earth ® tools, the geographic coordinates in tenths of degree were obtained (Longitude, Latitude) of each of the articles published. The spatial representation of the number of articles per institution was carried out with the geographic package ARGIS®[24]. 3. Results and Discussion 3.1. Scientific Production on GMO Maize in the International Context From 1991 to 2019, a total of 917 scientific articles were published, which resulted in 20,997 bibliographic citations (Figure 1). The first study recorded dates from 1991; however, since 2000 a growing production was seen for the topic of “GMO maize”. The period of highest productivity was from 2008 to 2018 with 76.23% of the total (699 articles). The most frequently cited studies were those published in 2003, 2004, and 2005 which together resulted in 6245 citations (29.74%). Based on the first author’s country of origin in the scientific articles, 917 studies originated in 53 countries. Of these, 74.81% (686) were concentrated in seven countries: Mexico (24.24%, 225 articles), USA (17.99%, 165), Brazil (8.40%, 77), Colombia (8.40%, 77), Argentina (5.56%, 51), Spain (5.34%, 49), and China (4.58%, 42). The fact that the countries with highest scientific production are the countries with greatest maize grain production globally stands out (Figure 2). Figure 2also shows that the countries with highest number of publications are located in Latin America, which explains that 55.29% (507 articles) are Agriculture 2021,11, 246 4 of 14 published in Spanish, 39.59% (363) in English, 3.93% (36) in Portuguese, and 1.20% (11) in other languages (primarily French, Mandarin, and Russian). Agriculture 2021, 11, x FOR PEER REVIEW 4 of 16 Figure 1. Temporal evolution of scientific production and bibliographic citations on the topic of GMO maize worldwide from 1991 to 2019. Based on the first author’s country of origin in the scientific articles, 917 studies originated in 53 countries. Of these, 74.81% (686) were concentrated in seven countries: Mexico (24.24%, 225 articles), USA (17.99%, 165), Brazil (8.40%, 77), Colombia (8.40%, 77), Argentina (5.56%, 51), Spain (5.34%, 49), and China (4.58%, 42). The fact that the countries with highest scientific production are the countries with greatest maize grain production globally stands out (Figure 2). Figure 2 also shows that the countries with highest number of publications are located in Latin America, which explains that 55.29% (507 articles) are published in Spanish, 39.59% (363) in English, 3.93% (36) in Portuguese, and 1.20% (11) in other languages (primarily French, Mandarin, and Russian). Figure 2. Spatial relation of the production of scientific articles on the topic of GMO maize with productivity indicators in the field from 1991 to 2019 (* millions t, ** millions ha) adapted from [1] with permission from FAOSTAT (2020). Figure 1. Temporal evolution of scientific production and bibliographic citations on the topic of GMO maize worldwide from 1991 to 2019. Agriculture 2021, 11, x FOR PEER REVIEW 4 of 16 Figure 1. Temporal evolution of scientific production and bibliographic citations on the topic of GMO maize worldwide from 1991 to 2019. Based on the first author’s country of origin in the scientific articles, 917 studies originated in 53 countries. Of these, 74.81% (686) were concentrated in seven countries: Mexico (24.24%, 225 articles), USA (17.99%, 165), Brazil (8.40%, 77), Colombia (8.40%, 77), Argentina (5.56%, 51), Spain (5.34%, 49), and China (4.58%, 42). The fact that the countries with highest scientific production are the countries with greatest maize grain production globally stands out (Figure 2). Figure 2 also shows that the countries with highest number of publications are located in Latin America, which explains that 55.29% (507 articles) are published in Spanish, 39.59% (363) in English, 3.93% (36) in Portuguese, and 1.20% (11) in other languages (primarily French, Mandarin, and Russian). Figure 2. Spatial relation of the production of scientific articles on the topic of GMO maize with productivity indicators in the field from 1991 to 2019 (* millions t, ** millions ha) adapted from [1] with permission from FAOSTAT (2020). Figure 2. Spatial relation of the production of scientific articles on the topic of GMO maize with productivity indicators in the field from 1991 to 2019 (* millions t, ** millions ha) adapted from [ 1 ] with permission from FAOSTAT (2020). According to the classification by [ 19 ], with 34 theme areas regrouped into six categories, the following results were obtained: (1) Productivity (agriculture, botany, and ecology), 36.21% of the total articles; (2) Competitiveness (economy and social sciences), 17.34%; (3) Pests and diseases (zoology and biology), 15.81%; (4) Public health (medicine and nutrition), 8.72%; (5) Cultural (anthropology, history, and archaeology), 4.25%; and (6) Others (engineering, geography, chemistry, law, and various topics), 17.67%. In the case of the main countries that recorded scientific production about GMO maize, the themes of productivity (26.28%, 241 articles), pests and diseases (12.65%, 116), and com- Agriculture 2021,11, 246 5 of 14 petitiveness (12.10%, 111) had the highest frequencies in scientific articles (Figure 3). [ 25 ] found that the policy that the USA adopted to encourage the development of technological innovations, allowed it to become the principal maize producer in the world. In contrast with Mexico, where the development of research consisted mostly in demonstrating the irrelevance of transgenic maize [17,25]. Agriculture 2021, 11, x FOR PEER REVIEW 5 of 16 According to the classification by [19], with 34 theme areas regrouped into six categories, the following results were obtained: (1) Productivity (agriculture, botany, and ecology), 36.21% of the total articles; (2) Competitiveness (economy and social sciences), 17.34%; (3) Pests and diseases (zoology and biology), 15.81%; (4) Public health (medicine and nutrition), 8.72%; (5) Cultural (anthropology, history, and archaeology), 4.25%; and (6) Others (engineering, geography, chemistry, law, and various topics), 17.67%. In the case of the main countries that recorded scientific production about GMO maize, the themes of productivity (26.28%, 241 articles), pests and diseases (12.65%, 116), and competitiveness (12.10%, 111) had the highest frequencies in scientific articles (Figure 3). [25] found that the policy that the USA adopted to encourage the development of technological innovations, allowed it to become the principal maize producer in the world. In contrast with Mexico, where the development of research consisted mostly in demonstrating the irrelevance of transgenic maize [17,25]. Figure 3. Principal nations and research they address, according to the first author’s country of origin in scientific articles on GMO maize from 1991 to 2019. In the 917 articles analyzed, 703 first authors were found, between author and collaborators they were 2360 different individuals in total. The mean of co-authorship was 2.57 and the mode (160) of 3 authors per article, with extreme values of a single author (29 articles) and 6 studies with more than 12 authors. The network of authors and collaborators (Figure 4) was made up of 2360 nodes (authors) and 2132 aspects (links). The links in a SNA are important because it is through them that an author can reach certain ideas, knowledge and information that is socially distant for him [26]. The density of the network had a value of 0.001, implying that for the topic of GMO maize there is not much collaboration between authors in the international context. This is evident since there are 501 institutions (from 917 studies) indicated as the ascription of the first author. The density is an indicator of the SNA that implies that both the nodes interact (are linked) between one another, mathematically it is a value within the interval (0 to 1), the closer to 1 the higher the interaction in the network [27]. The institutions with highest frequency (≥19 scientific articles) were: (1) UAM, Mexico, 36 articles, principal author Massieu_Trigo_Y; (2) UNAM, Mexico, 34, Cortes_Flo- res_JI; (3) UNC, Colombia, 33, Chaparro_Giraldo_A; and (4) COLPOS, Mexico, 19, Castillo_González_F. It should be noted that Chaparro_Giraldo_A from the UNC was the author with most contributions, with a total of 20 (seven as first author and 13 as coauthor). A subnetwork formed by Mexican researchers was detected (Figure 4): Espinosa_Cal- deron_A, Mejia_Andrade_H and Turren_Fernandez_A from INIFAP; Cortes_Flores_JI (UNAM); Serratos_Hernandez_JA (UACM) and Massieu_Trigo_Y (UAM). As a whole, the Figure 3. Principal nations and research they address, according to the first author’s country of origin in scientific articles on GMO maize from 1991 to 2019. In the 917 articles analyzed, 703 first authors were found, between author and collaborators they were 2360 different individuals in total. The mean of co-authorship was 2.57 and the mode (160) of 3 authors per article, with extreme values of a single author (29 articles) and 6 studies with more than 12 authors. The network of authors and collaborators ( Figure 4 ) was made up of 2360 nodes (authors) and 2132 aspects (links). The links in a SNA are important because it is through them that an author can reach certain ideas, knowledge and information that is socially distant for him [26]. Agriculture 2021, 11, x FOR PEER REVIEW 6 of 16 researchers in the subnetwork are part of the Union of Scientists Committed with Society in the Agriculture and Food Program (Transgenic Maize Group) [28]. Figure 4. Network of authors and coauthors worldwide that have published scientific articles on GMO maize from 1991 to 2019. The size of the node corresponds to their productivity. The arrow connections refer to the association among authors. The arrows thickness is related with the frequency of which the authors interact. The ellipse identifies a sub-network formed by Mexican researchers. 3.2. Bibliometric Indicators The 917 studies analyzed were published in 449 scientific journals. A total of 248 articles, 27.05% and 8628 bibliographic citations, 41.09%, were found in 20 journals (Table 1). Among these 20 main journals, 13 are from Latin American countries: Mexico (5), Colombia (4), Argentina (1), Cuba (1), Venezuela (1), and Brazil (1); they publish mostly in Spanish and do not have a JCR impact factor or a very low factor (Q4), which according to [29] limits the number of bibliographic citations since English is the language adopted as universal by the scientific community. Figure 4. Network of authors and coauthors worldwide that have published scientific articles on GMO maize from 1991 to 2019. The size of the node corresponds to their productivity. The arrow connections refer to the association among authors. The arrows thickness is related with the frequency of which the authors interact. The ellipse identifies a sub-network formed by Mexican researchers. Agriculture 2021,11, 246 6 of 14 The density of the network had a value of 0.001, implying that for the topic of GMO maize there is not much collaboration between authors in the international context. This is evident since there are 501 institutions (from 917 studies) indicated as the ascription of the first author. The density is an indicator of the SNA that implies that both the nodes interact (are linked) between one another, mathematically it is a value within the interval (0 to 1), the closer to 1 the higher the interaction in the network [27]. The institutions with highest frequency ( ≥ 19 scientific articles) were: (1) UAM, Mexico, 36 articles, principal author Massieu_Trigo_Y; (2) UNAM, Mexico, 34, Cortes_Flores_JI; (3) UNC, Colombia, 33, Chaparro_Giraldo_A; and (4) COLPOS, Mexico, 19, Castillo_González_F. It should be noted that Chaparro_Giraldo_A from the UNC was the author with most contributions, with a total of 20 (seven as first author and 13 as coauthor). A subnetwork formed by Mexican researchers was detected (Figure 4): Espinosa_ Calderon_A, Mejia_Andrade_H and Turren_Fernandez_A from INIFAP; Cortes_Flores_JI (UNAM); Serratos_Hernandez_JA (UACM) and Massieu_Trigo_Y (UAM). As a whole, the researchers in the subnetwork are part of the Union of Scientists Committed with Society in the Agriculture and Food Program (Transgenic Maize Group) [28]. 3.2. Bibliometric Indicators The 917 studies analyzed were published in 449 scientific journals. A total of 248 articles, 27.05% and 8628 bibliographic citations, 41.09%, were found in 20 journals ( Table 1 ). Among these 20 main journals, 13 are from Latin American countries: Mexico (5), Colombia (4), Argentina (1), Cuba (1), Venezuela (1), and Brazil (1); they publish mostly in Spanish and do not have a JCR impact factor or a very low factor (Q4), which according to [ 29 ] limits the number of bibliographic citations since English is the language adopted as universal by the scientific community. The low impact (bibliographic citations) of the scientific studies developed in countries of Latin America is related to the fact that the researchers publish their studies in national journals (Table 2), edited in Spanish; meanwhile, the journals of highest impact are found in English-speaking countries (United Kingdom and USA) [ 31 ], published in English. This explains the high impact of articles from USA, with 63.03% of their studies published in journals of their own country, and the remaining percentage in journals of other countries also edited in English. Among the 20 most cited studies about GMO maize themes, 14 belong to a first author whose institution of ascription is localized in USA and only one study corresponds to a researcher in Latin America (Mexico); they have all been published in English and in journals of English-speaking origin (Table 3). According to [ 5 ] the economic development of a country is directly related to the quality of the research it performs; countries with consolidated economies (USA, Switzerland, Italy, and China) invest more in their research centers, which allows them higher technological development, compared to underdeveloped economies like the Latin American where investment in research is lower. In addition, some of these consolidated economies (Switzerland, Italy, and China), whose native language is not English, also publish their studies of higher impact in this language, the same in which most of the indexed journals included in the Journal Citation Report are edited, which is included in the Web of Science (WoS) and belongs to an information company in USA, Thomson Reuters [30]. Agriculture 2021,11, 246 7 of 14 Table 1. Bibliometric indicators of the main journals that published scientific articles on GMO maize at the global level from 1991 to 2019, ordered according to the number of articles published. Journals Number Name Country Institution JCR [30]Language Articles Citations Journal of economic entomology UK Oxford University Press 1.970/Q2 English 34 1581 PLoS ONE USA Public Library of Science 3.057/Q1 English 29 1127 Revista Mexicana de Ciencias Agrícolas Mexico INIFAP No JCR Spanish/English 19 92 Environmental entomology USA Entomological Society of America 1.802/Q2 English 15 1038 Cultivos Tropicales Cuba Instituto Nacional de Ciencias Agrícolas No JCR Spanish 14 56 Mundo Agrario Argentina Universidad Nacional de la Plata No JCR Spanish 13 381 Revista Colombiana de EntomologíaColombia Universidad del Valle 0.166/Q4 Spanish 13 106 El Cotidiano Mexico UAM No JCR Spanish 12 67 American Journal of Agricultural Economics UK Oxford University Press 1.436/Q2 English 10 2995 Interciencia Venezuela Asociación INTERCIENCIA 0.219/Q4 Spanish 10 38 Revista Colombiana de Biotecnologia Colombia UNC No JCR Spanish 10 64 Agrociencia Mexico COLPOS 0.370/Q3 Spanish/English 9 73 Revista Fitotecnia Mexicana Mexico Sociedad Mexicana de Fitogénetica A.C. 0.326/Q3 Spanish 9 204 Scientific reports UK Nature Publishing Group 5.228/Q1 English 9 235 Southwestern Entomologist USA Society of Southwestern Entomologists 0.478/Q4 English 8 39 Acta Biológica Colombiana Colombia UNC 0.220/Q3 English 7 29 Agronomía Colombiana Colombia UNC 0.180/Q4 English 7 137 Ciencia rural Brazil Universidade Federal de Santa Maria 0.376/Q4 English 7 95 Florida Entomologist USA Florida Entomological Society 0.975/Q3 English 7 233 Agricultura, Sociedad y Desarrollo Mexico COLPOS No JCR Spanish/English 6 38 Others (429) 669 12,369 Agriculture 2021,11, 246 8 of 14 Table 2. Matrix that relates the percentage and the number of scientific articles published in journals of the main countries with scientific production on GMO maize from 1991 to 2019. Country Country from Journal: % (Number of Scientific Articles) Scientific Production on GMO Maize Argentina Brazil China * Colombia Spain USA ** Mexico Sum Other Country Total Argentina 64.71 (33) 5.88 (3) 15.69 (8) 86.27 (44) 13.73 (7) 100 (51) Brazil 1.30 (1) 59.74 (46) 2.60 (2) 9.09 (7) 6.49 (5) 79.22 (61) 20.78 (16) 100 (77) China 7.14 (3) 2.38 (1) 2.38 (1) 26.19 (11) 2.38 (1) 40.48 (17) 59.52 (25) 100 (42) Colombia 2.60 (2) 62.34 (48) 2.60 (2) 2.60 (2) 1.30 (1) 71.43 (55) 28.57 (22) 100 (77) Spain 4.08 (2) 4.08 (2) 55.10 (27) 4.08 (2) 6.12 (3) 73.47 (36) 26.53 (13) 100 (49) USA 0.61 (1) 63.03 (104) 1.21 (2) 64.85 (107) 35.15 (58) 100 (165) Mexico 2.67 (6) 0.44 (1) 3.56 (8) 2.67 (6) 4.89 (11) 78.67 (177) 92.89 (209) 7.11 (16) 100 (225) * 9.52 (4) in journals of the Netherlands and 26.19 (11) in journals of the UK. ** 7.27 (12) in journals of the Netherlands, and 9.70 (16) in journals of the UK. Table 3. Bibliometric indicators of the main scientific articles on GMO maize worldwide from 1991 to 2019, ordered according to the number of bibliographic citations. First Author Journals Author Institution Country Name Country Language Citations Theme Area Lusk, J.L. [32] Purdue University USA American Journal of Agricultural Economics UK English 714 Public health Saxena, D. [2] New York University USA American Journal of Botany USA English 402 Productivity Zwahlen, C. [33] University of Bern SW Molecular Ecology USA English 331 Productivity Jarvis, D.I. [34] International Plant Genetic Resources Institute Italy Molecular Ecology USA English 230 Productivity Zwahlen, C. [35] University of Bern SW Molecular Ecology USA English 224 Productivity Gianessi, L.P. [36] CropLife Foundation USA Pest Management Science USA English 199 Competitiveness Ortiz-García, S. [37] Instituto Nacional de EcologíaMexico Proceedings of the National Academy of Sciences USA English 173 Productivity Dively, G.P. [38] University of Maryland USA Environmental entomology USA English 147 Pests and diseases Lundgren, J.G. [39] University of Illinois USA Environmental entomology USA English 129 Pests and diseases Faria, C.A. [40] University of Neuchátel SW PloS One USA English 116 Pests and diseases Daly, T. [41] University of Georgia USA Environmental entomology USA English 110 Pests and diseases Davis, P.M. [42]Monsanto Company USA Journal of economic entomology USA English 109 Pests and diseases Buntin, G.D. [43] University of Georgia USA The Florida Entomologist USA English 105 Pests and diseases Pilcher, C.D. [44]Iowa State University USA Environmental entomology USA English 103 Pests and diseases Storer, N.P. [45] North Carolina State University USA Journal of economic entomology USA English 103 Pests and diseases Onstad, D.W. [46] Illinois Natural History Survey USA Journal of economic entomology USA English 92 Productivity Dyer, G A. [47] University of California USA PloS One USA English 88 Productivity He, K. [48] Chinese Academy of Agricultural Sciences China Journal of economic entomology USA English 86 Pests and diseases Pilcher, C.D. [49]Iowa State University USA Journal of economic entomology USA English 82 Pests and diseases Bitzer, R.J. [50]Iowa State University USA Environmental entomology USA English 79 Pests and diseases Agriculture 2021,11, 246 9 of 14 3.3. Scientific Production on the Theme of GMO Maize in Mexico From 1991 to 2019 Mexican researchers published 225 scientific articles on the topic of GMO maize. From the 225 studies, 163 (72.44%) were developed in 11 of 50 institutions, taking as reference the institution of ascription of the first author. The institutions with highest productivity were UAM (36 studies), UNAM (34), COLPOS (19), CHAPINGO (15), INIFAP (14), and IPN (12). Due to tradition, in CHAPINGO (founded in 1854), COLPOS (1959) and INIFAP (1985), the studies published stemmed from the initiatives to develop agricultural research. The spatial distribution of the institutions with scientific productivity on GMO maize (1991–2019) (Figure 5) allows deducing that research on this topic is located in the center of the country, while in terms of the states with highest maize grain production in Mexico from 2000 to 2019, the areas with highest production are in the north (Sinaloa and Chihuahua), east (Jalisco, Michoacán, Guanajuato, and Estado de México), northeast (Tamaulipas and Veracruz), and southeast (Chiapas) of Mexico. This aspect of the centralization of research has been addressed by [ 10 ], who found that the discrepancy between the production areas and the research centers makes the transference of technology difficult. Agriculture 2021, 11, x FOR PEER REVIEW 11 of 16 3.3. Scientific Production on the Theme of GMO Maize in Mexico From 1991 to 2019 Mexican researchers published 225 scientific articles on the topic of GMO maize. From the 225 studies, 163 (72.44%) were developed in 11 of 50 institutions, taking as reference the institution of ascription of the first author. The institutions with highest productivity were UAM (36 studies), UNAM (34), COLPOS (19), CHAPINGO (15), INIFAP (14), and IPN (12). Due to tradition, in CHAPINGO (founded in 1854), COLPOS (1959) and INIFAP (1985), the studies published stemmed from the initiatives to develop agricultural research. The spatial distribution of the institutions with scientific productivity on GMO maize (1991–2019) (Figure 5) allows deducing that research on this topic is located in the center of the country, while in terms of the states with highest maize grain production in Mexico from 2000 to 2019, the areas with highest production are in the north (Sinaloa and Chihuahua), east (Jalisco, Michoacán, Guanajuato, and Estado de México), northeast (Tamaulipas and Veracruz), and southeast (Chiapas) of Mexico. This aspect of the centralization of research has been addressed by [10], who found that the discrepancy between the production areas and the research centers makes the transference of technology difficult. Figure 5. Spatial distribution of academic and research institutions in Mexico that published articles on GMO maize from 1991 to 2019, and main production areas. The language preferred by Mexican researchers to publish their results on GMO maize was Spanish with 88.44% (199) of the studies, followed by English for the remainder 11.56% (26). The themes of most interest were those related with competitiveness (56 studies, 24.89%) and productivity (49, 21.78%) directed at showing the irrelevance of GMO maize in the Mexican farmland. The 225 studies were published in 123 different journals, 86 of which were edited by national institutions that in total published 177 articles (78.67%). In Mexico, most of the researchers published their studies about GMO maize in journals edited by their institution of ascription (Table 4), which restricts the constructive criticism of peer review and, according to [51,52], is indicator of the low impact of the publications, since it limits the feedback from interdisciplinary groups regarding the relevance of the research. In this regard, [10,53] found that research in Mexico not only presents “academic endogamy” but also that the researchers in their eagerness to remain in the Sistema Nacional de Investigadores—Consejo Nacional de Ciencia y Tecnologia (SNICONACYT) tend to replicate the same methodologies in different study areas, which limits innovation in research and allows the circularity (redundancy in the study object) of the publications. Figure 5. Spatial distribution of academic and research institutions in Mexico that published articles on GMO maize from 1991 to 2019, and main production areas. The language preferred by Mexican researchers to publish their results on GMO maize was Spanish with 88.44% (199) of the studies, followed by English for the remainder 11.56% (26). The themes of most interest were those related with competitiveness (56 studies, 24.89%) and productivity (49, 21.78%) directed at showing the irrelevance of GMO maize in the Mexican farmland. The 225 studies were published in 123 different journals, 86 of which were edited by national institutions that in total published 177 articles (78.67%). In Mexico, most of the researchers published their studies about GMO maize in journals edited by their institution of ascription (Table 4), which restricts the constructive criticism of peer review and, according to [ 51 , 52 ], is indicator of the low impact of the publications, since it limits the feedback from interdisciplinary groups regarding the relevance of the research. In this regard, [ 10 , 53 ] found that research in Mexico not only presents “academic endogamy” but also that the researchers in their eagerness to remain in the Sistema Nacional de Investigadores—Consejo Nacional de Ciencia y Tecnologia (SNI-CONACYT) tend to replicate the same methodologies in different study areas, which limits innovation in research and allows the circularity (redundancy in the study object) of the publications.