Introduction

Fipronil is a broad-spectrum and efficient systemic insecticide, with easy and flexible application and dispersion in plantations (Seydi et al. 2019). It is widely used in agriculture, being applied in various types of crops and in veterinary uses to control a variety of pests (Cappelini et al. 2018; Eadie et al. 2020; Seydi et al. 2019). This insecticide acts by contact or ingestion; insects submitted to its action suffer inhibition of chloride uptake in GABAergic receptors and glutamate-chloride channels (Gupta and Anadón 2018). Chloride ions that are not captured in the receptors will be accumulated and the difference in grouping inside and outside the cell causes excitation of the central nervous system which will result in neurasthenia and, consequently, the death of the insect (Holder et al. 2018).

Brazil is a notorious example of the effects of rampant use of pesticides as it has been one of the world leaders (the 3rd second data of FAO 2019) in the use of pesticides since 2008, and recently, 474 pesticides were launched, the highest rate ever observed (Nunes et al. 2021). In Brazil, fipronil has been widely used for some years to control pest infestations such as termites (Heterotermes tenuis, Cornitermes cumulans, Neocapritermes opacus and Procornitermes triacifer), Cane borer (Diatraea saccharalis), beetle (Migdolus fryanus) brown leaf (Atta capiguara), pin larva (Diabrotica speciosa), chicken bread (Diloboderus abderus), and rootworm or aquatic weevil (Oryzophagus oryzae), in sugarcane, corn, and rice crops, respectively (Gibbons et al. 2015).

However, the indiscriminate use of pesticides causes damage to a variety of non-target species (Nunes et al. 2021). Fipronil is intended for the control of class Insecta, but all these organisms represent more than half of the biological diversity in the world; it is estimated that it includes approximately 5.5 million species including for example pollinators, bedbugs, mosquitoes, fleas, and other non-pest insects (Stork 2018). Due to the long persistence of fipronil in the environment, its applications in cultivated areas end up contaminating land surfaces and water bodies by leaching and surface runoff, resulting in imbalance and alteration of soil quality and water network in the environment. This contamination harms an even wider range of non-target species (Ucar et al. 2020).

Bees are a wide diversity, around 20,000 species are known worldwide, and they are essential insects in preserving ecosystems and human welfare by both pollination and increasing the productivity of crops. However, there are high mortality rates, due to a variety of causes, including management practices, Varroa mite infestation, stress, pathogens, and pesticide exposure; therefore, bees are threatened in agroecosystems from different countries; this disappearance is known as “bee collapse syndrome” (Bovi et al. 2018; de Morais et al. 2018; Holder et al. 2018; Munoz-Capponi et al. 2018; Pires et al. 2016). The unruly use of pesticides is the main factor for this decline (Nunes et al. 2021; Sgolastra et al. 2020). Over a period of 5 years, a loss of ~ 1 billion bees was estimated in Brazil, including stingless and solitary bees. The São Paulo State accounted for 45.7% of the total reports of bee mortality, where among the causes 55.9% were attributed to neonicotinoids and pesticides derived from fipronil that are widely used in plantations (Castilhos et al. 2019).

Many reports have indicated that fipronil in bees is found to be highly toxic regardless of the route of exposure (Castilhos et al. 2019; de Morais et al. 2018). Moreover, it has been demonstrated the toxicity of fipronil on aquatic invertebrates (Schaaf 2015). Fipronil can also cause direct and indirect toxic effects to terrestrial and aquatic vertebrates, for example, lizards, birds, fish (Gibbons et al. 2015), pre-metamorphic tadpoles Silurana tropicalis (Saka and Tada 2021), and mice (Seydi et al. 2019). Fish exhibit high sensitivity to the effects caused by pesticides, due to they frequently absorb contaminants from the environment leading to be important bioindicators of aquatic pollution, and being also used on studies about toxicological and genotoxic effects by pesticides (Eadie et al. 2020; Gripp et al. 2017).

Fipronil bioaccumulates in fish (Deiu et al. 2021) and, combined with its misuse, its residues can be also detected in other organisms or matrixes as was reported in chicken eggs and meat in some European Union countries, in spite of fipronil commercialization and use had been forbidden in many of those countries (Reich et al. 2018). Biodegradation of fipronil lead to the main metabolites fipronil desulfinyl, fipronil sulfone, fipronil sulphide, and fipronil amide by the processes of photolysis, oxidation, reduction, and hydrolysis, respectively (Bobé et al. 1998; Gripp et al. 2017; Simon-Delso et al. 2015; Weston and Lydy 2014). These characteristics of the compounds cause the production of more toxic intermediate metabolites when a complete degradation is not performed (Tomazini et al. 2021). Toxic effects of fipronil cause also population imbalance in terrestrial organisms, such as Folsomia candida, an arthropod with a high influence on microbial ecology and soil fertility (Oliveira Filho and Baretta 2016).

The website Pesticide Action Network (PAN 2022) has a list of banned pesticides, including fipronil, which use and sale have been prohibited in 36 countries, including Cape Verde and Mauritania from Africa, UK, Vietnam, and 27 countries in the European Union. An overview of publications related to this pesticide can inform new research projects, innovations of determination, and degradation methods as well as guide environmental policies. In order to support scientific development, this study aimed to conduct a scientometric analysis to assess global research trends on the insecticide fipronil in order to identify trends and gaps in scientific research and thus contribute to future research efforts and analyses. It also provides a global overview of some of the discussions surrounding the use of fipronil.

Materials and methods

The information for this article was obtained from the Web of Science (WoS) database owned by Clarivate Analytics. Currently, it is considered one of the most relevant databases in the scientific world, due to the provision of several subsets of data and more than two hundred scientific categories (Liu 2019). The search was carried out by selecting basic search, topic “fipronil,” which corresponded to 4369 results, between the years 1945 and 2021 in all databases, as we can see in Fig. 1. The first step after the search was the refinement, where 2471 studies were selected, the eligibility criterion was to present the term “fipronil” in the title and/or abstract, but patent registrations were disregarded.

Fig. 1
figure 1

Flow of information through the different phases of the systematic review and selection of studies included. Flowchart according the PRISMA statement

According to the results, 2362 documents belonged to the main WoS database; these were the articles selected by eligibility to compose the dataset. The other studies were from other databases, Scielo Citation Index (40), KCI-Korean Journal Database (31), and Russian Science Citation Index (37), and these databases do not provide enough information for the analysis held on CiteSpace. In the WoS database, the tools “Analyze Results” and “Create Citation Report” were used; the number of publications and citations registered per year and the H-index were investigated. In a second step, the article data were extracted to analysis in Microsoft Office Excel, CiteSpace Software, and the Bibliometrix tool.

In Microsoft Office Excel, it was provided the graphs by combination to express the results of related data and a geographic map that allows a broad visualization of the publications number at a global level. To identify the main trends and gaps over time, information was extracted from the main articles (10 most cited) by time period (Supplementary Table).

The Bibliometrix tool is programmed in R and has an open code, so it makes it possible to carry out comprehensive bibliometric analyses to obtain the scientific mapping (Aria and Cuccurullo 2017). Thus, we obtained with Bibliometrix a correlation graph between the country of origin, authors, and keywords.

CiteSpace Software provides infographics with connection networks between items selected for analysis, such as countries, cited authors, and journals, categories, references, and keywords. In this way, it allows groupings through the similarity between title terms and keywords using different studies, providing clusters for the observation of subjects that stand out in the addressed theme. Networks are represented by links between the terms selected for analysis. Moreover, the thickness of the links demonstrates the intensity of collaboration between nodes, which can be expressed, for example, by frequency, centrality, and number of citations. The colors of the links correspond to temporality and are also expressed in the groupings, indicating that over the years, the focus of research may change (Chen 2020).

When selecting the analysis item, the CiteSpace maps and labels the terms according to the information provided by the dataset. In this way, the items are represented by colored circles, called “node,” which vary in size according to the number of citations of the item. The outermost ring of the node, when viewed in purple, represents the centrality of the topic. Centrality is a very relevant measure used for the analysis of infographics, as it represents the influence and prominence of the item within the issue (Chen 2020). Its intermediation is measured by the sum of the links that pass-through node (i) divided by the total of shorter links between circle j and k, as shown in Eq. (1):

$$\mathrm{Centrality}\;(\mathrm{node}\;i){\textstyle\sum_\mid^\mid}(i\neq j\neq k)\;''Pjk''\;(''i'')/''Pjk''$$
(1)

Results and discussion

Temporal and geographic patterns

Fipronil is an insecticide that was developed in 1987 by Rhône-Poulenc Agro, placed on the market in 1993 and registered as a pesticide in the USA in 1996 (Gunasekara et al. 2007). The first publication on fipronil in the dataset was from 1992, and the rate of publications and citations per year continues to grow (Fig. 2). The H index is used as a broad measure of the impact of the scientific contribution of an area or researcher. One of its advantages is to combine the publication numbers with the citation rate, since it is calculated as the “h” number of articles with the same “h” number of citations (Hirsch 2005). The H index of the dataset was 91, reflecting the great impact of articles in this area of research.

Fig. 2
figure 2

Number of fipronil publications and citations by year

As fipronil is used for both commercial and domestic applications, concerns have arisen about the risks to public health (Gunasekara et al. 2007; Tingle et al. 2003) and the need to develop more research with this pesticide. The supplementary table presents the main objectives, conclusions, and suggestions of the most cited articles in a given period of time; in this way, we can see the development of this field of research over time.

In the 1990s, the objectives of the ten most cited studies were mainly to evaluate the toxicity of fipronil and its by-products (4 studies). Toxicity was evaluated in mammals, mainly rodents, and in insects. These studies on toxicity have mainly concluded that fipronil and its product desulfinyl have similar toxicity to mice and flies (Hainzl and Casida 1996). The greater potency of the parent compound in the insect versus the mammalian GABA receptor explains the selective toxicity of this pesticide (Hainzl and Casida 1996). In rodents, fipronil disrupts thyroid-pituitary homeostasis, and is not just mutagenic (Hainzl et al. 1998). The GABA system was studied in 3 of these 10 articles. GABA is a very important inhibitory neurotransmitter in the nervous system of invertebrates and vertebrates, and the GABA receptor is a target of insecticides, including fipronil (Gant et al. 1998). Abiotic degradation of fipronil was the subject of a study which concluded that this process involved desulfination and oxidation (Bobe et al. 1998). In addition, insecticide-targeted ion channels and the behavior of fipronil in soils were also studied (Supplementary Table).

Among the main suggestions of the top 10 articles from this period are the need to elucidate the mechanism of the fipronil degradation reaction, study the molecular basis of convulsive/insecticidal antagonist actions on GABA receptors from homooligomeric RDL receptors, and perform molecular analysis continuation of mammalian and insect sodium channels to aid in the development of new synthetic compounds or toxins.

Between 2000 and 2010, the study with the highest number of citations addressed methods for the detection of insecticides (Liu et al. 2009). Among the ten most relevant works, there are two studies that deal with the effect of fipronil on Appis melifera bees, including toxicity and neurotoxic effects, such as reduced learning in organisms surviving exposure (Aliouane et al. 2009; Decourtye et al. 2005). Another study determined the presence of insecticides in pollen, where fipronil overlapped the others, bringing the need for studies that investigate the effect of insecticides on bee colonies (Chauzat et al. 2006). The toxicity of fipronil was addressed in two review studies, depicting the environmental ecotoxicity and the risks that the insecticide presents to human health, insects such as bees, and highly toxic to aquatic organisms and terrestrial birds (Tingle et al. 2003). Fipronil metabolites were also detected, even in prohibited places (Gunasekara et al. 2007).

Fipronil is a neurotoxic insecticide that acts on chloride channels, a review of these channels and the physiological role they play was one of the most cited studies of the 2000s, considering that these channels are targets of GABA receptors in insects and can be targeted for antiparasitics and insecticides, aiming at the selective control of insect pests (Buckingham et al. 2005). Currently, the scientific community is already aware that insects are developing mechanisms of insecticide resistance; thus, another study from the 2000s covers ion channels, bringing combined computational and site-directed mutagenesis approaches to understand the structural basis of the disease, channel function, and insecticide resistance for the development of new efficient insecticides (Bloomquist 2003).

Between the years 2010 and 2019, the most cited publication objectives were mainly reviews on the risks associated with the effects of fipronil and its metabolites to the environment and toxicity to non-target organisms (7 studies). A comprehensive review of the risks of neocotinoid insecticides and fipronil to ecosystems and their biofauna was carried out (Chagnon et al. 2015). These review studies mainly concluded that fipronil and its metabolites negatively impact ecosystem services and may be threatening to wildlife and food security.

The most cited paper in this decade identified 121 different pesticides and metabolites in 887 samples of wax, pollen, honeybee, and associated hives in North American apiaries; due to the ecological importance of bees and because they are non-target organisms, it becomes an extremely concerning issue (Mullin et al. 2010). Three papers have addressed cysts and pesticide toxicity to bees (Mullin et al. 2010; Sanchez-Bayo et al. 2016; Vidau et al. 2011). Toxicity has been assessed in non-target invertebrates from terrestrial, freshwater and marine environments (Pisa et al. 2015), and vertebrates (Gibbons et al. 2015). Among the 10 studies, one addressed the status of pyrazoles (Kucukguzel and Senkardes 2015). The most cited papers point out as future directions that it is necessary to specifically address the unique toxicology of these neurotoxic chemicals, including their non-lethal, indirect effects, and synergistic effects with other compounds to a variety of terrestrial, aquatic, and marine organisms.

The most cited articles in the last few highlighted that more research is needed in this area. Further research is needed on the toxic effects of pesticides on soil organisms and on the impact of these pesticides on marine and coastal ecosystems. More research is needed to study the therapeutic applications of resveratrol and curcumin. In addition, research is needed on new methods of environmental abatement and remediation.

Academic collaboration favors the development of science and the dissemination of knowledge (Zhang et al. 2020). To better analyze the role of countries in contributing to research on fipronil, a collaborative network was established based on the affiliation of the authors (Fig. 3A). Each node represents a country, the font size is proportional to the publication volume, and the thickness of lines between countries is proportional to the intensity of cooperation between them. The centrality (purple rings) represents the influence of the country and shows that such countries are acting as a link, connecting other countries in the network (Chen 2014). The country with the greatest centrality was the USA, while the countries with the highest number of publications were the USA (30.6%), followed by China (15.7%), Brazil (10.9%), and France (8.9%).

Fig. 3
figure 3

A Collaborative countries network of co-authors countries. B Total fipronil publication number of world countries

The countries with the highest volume of published articles about fipronil (Fig. 3B) were just the biggest consumers of pesticides in the world. In 2019, China pesticides use achieved 1,763,000 tons, and the USA and Brazil consumed 407,779 and 377,176 tons, respectively (FAO 2019). France ranks sixth (85,072 tons), behind Argentina (20,455 tons) and Canada (87,632 tons) in pesticides use (FAO 2019). China banned the use of fipronil in 2008 because of the increasing of insecticide resistance by pests and severe environmental pollution; however, it is usually illicitly added to other pesticides (Li et al. 2019). The USA and France also banned the fipronil use due to its high degree of toxicity (Li et al. 2015). Nevertheless, the illegal use of fipronil has been detected by contamination of chicken eggs in several countries of the European Union, including France (Reich et al. 2018). Currently, fipronil is used in more than 50 countries (Shakya et al. 2020).

Subject category analysis

The analysis of categories co-occurrence can be seen in Fig. 4A. The ranking of publications by category is as follows: entomology (27.7%), environmental sciences and ecology (18.7%), environmental sciences (18.1%), agriculture (13.8%), chemistry (12.7%), and veterinary sciences (12.4%). However, the categories that showed the greatest centrality of intermediation were chemistry (0.30), environmental sciences and ecology (0.17), and toxicology (0.17) (Fig. 4B). Frequency represents the area with greater visibility, and centrality represents the area with greater influence, so the area with greater visibility will not always be the most influential area (Ghisi et al. 2020). Thus, even if it is not the most frequent area, chemistry was the area with the greatest influence in research on fipronil.

Fig. 4
figure 4

A Network of co-occurring subject categories. B Top 10 subjects in terms of frequency and centrality

Publishing journals

Researches on fipronil have been published in several journals. The co-citation network map of journals that published articles on fipronil is shown in Fig. 5A. Each node stands for one journal; the larger the node, the more publications it represents. The journals with the highest citation frequency were Journal of Economic Entomology and Pesticide Biochemistry and Physiology. Burst detection is an efficient and reliable method to verify publications that have received greater attention from the scientific community in certain periods of time; thus, citation surges are high-level indicators of intellectual impact (Azam et al. 2021). Journal of Economic Entomology, besides being the most frequent journal, also had the most robust citation explosion (57.36), which continued for 12 years, from 1996 to 2008. Other journals such as Environmental Science and Pollution Research and Scientific Reports featured the latest biggest, since 2017 with 40.06 and 29.48, respectively, representing emerging trends in this research area as shown in Fig. 5B.

Fig. 5
figure 5

A Map of the journal co-citation network of fipronil articles. B Top 25 cited journals with the strongest citation burst

Top 10 publications

Table 1 lists the 10 most cited references and their citation frequencies. Although time contributes to a higher number of citations, these are the most influential papers on fipronil studies, as the most cited articles are generally considered baseline references for their innovative contributions (Chen et al. 2012). The countries of the corresponding authors of the 10 most cited papers are those represented in Fig. 3, as being the most representative fipronil research; six of them are from Europe (Netherlands, France, UK — 2 each), three of them from the USA, and one from China.

Table 1 The top 10 publications in the field of fipronil research, ranked by citations

Among the top 10 publications, 9 were published by journals presented in Fig. 5. It can be observed that most of the papers addressed the toxicity and effects of fipronil on non-target organisms. It highlights the importance of studies on this insecticide, since it is still used on a large scale in more liberal countries, such as Brazil and Australia, and probably illegally in countries where its commercialization and use is prohibited. It can be also observed several published reviews about fipronil. However, no one of them is a systematic review as the present study. In this sense, this work represents the first scientometric review about fipronil.

The most cited article was “High levels of miticides and agrochemicals in North American apiaries: implications for bee health” with 847 citations. This paper carried out an extensive survey of pesticide residues in samples of beehive matrixes from beekeepers from twenty-three different states during the years 2007 and 2008. The analyses were performed using a modified QuEChERS method, and 121 different pesticides and metabolites were found in 887 samples of wax, pollen, bee, and associated hives, showing highly toxic levels of pesticides in bee brood and adult feed (Mullin et al. 2010).

The second most cited article was “Systemic insecticides (neonicotinoids and fipronil): trends, uses, mode of action and metabolites”. This research carried out a review of fipronil and neonicotinoids. The reasons for the success of these insecticides such as the mode of action, their metabolic pathways, their toxic effects, and the serious environmental risks caused by both were addressed (Simon-Delso et al. 2015). Third in the ranking was “Destination and environmental exposure; neonicotinoids and fipronil.” This article also reviews the literature describing the environmental fate and exposure routes of systemic insecticides, with an emphasis on neonicotinoids and fipronil (Bonmatin et al. 2015).

Keywords

Keywords can summarize and compile the content of a research field. The analysis of keywords frequently used in research on fipronil can be useful to determine the characteristics of this domain of knowledge (Yu et al. 2017). The co-occurrence network of keywords reflects the direction of research in a study field, the research topics, and the connection between different scientific concepts (Qin et al. 2021; Yu et al. 2017). Regarding research on fipronil, the most frequent keywords were insecticide (12.8% publications) and toxicity (12.8%), followed by fipronil (10.4%), pesticide (7.5%), and efficacy (5.1%) (Fig. 6A). Insecticide, besides being the most frequent keyword, was also the one with the highest centrality (0.30).

Fig. 6
figure 6

A Knowledge mapping of the keyword co-occurrence network on fipronil research. B The keywords with the strong citation bursts in articles related to fipronil research

Comparative keywords analysis allows to explore search directions and changes in search directions/topics over certain time periods (Wei 2019), as can be seen in Fig. 6B which reveals the 25 keywords with the highest citation burst. “Oxidative stress” is the word with the highest citation burst (strongest of 12.59), starting in 2016 to date. “Neonicotinoid” was the second word (strongest of 11.74) from 2018 to the present day, and “metabolite” was the third one (strongest of 9.83), which started in 2019 and continues to this day. The most representative words are correlated with the top 10 papers mentioned above.

These words are the most representative and closely related to fipronil. Oxidative stress can be induced by chemical substances, such as fipronil, which damages the antioxidant system and causes damage to macromolecules (Weidinger and Kozlov 2015). Insects can neutralize the action of insecticides through the development of several mechanisms of resistance, such as metabolic detoxification, increased excretion and behavioral changes (Wilson 2001). The development of resistance to insecticides is one of the biggest problems in pest control; more than 500 species of insects and mites are resistant to at least some insecticides (Mota-Sanchez and Wise 2019). This fact promotes a reduction in the efficiency of the compound, requiring a reformulation to a more aggressive compound, or one that uses other forms of action.

The current bursts “oxidative stress”, “neonicotinoid”, “exposure”, “environmental fate”, “water”, “fipronil insecticide”, “liver”, “wastewater” and “metabolite” are representing the top searches and current publications on fipronil and may be representing trends in future research related to the topic. These words have appeared since the beginning of the publications, although the combinations of these words have been heavily increased recently. These words are related to environmental issues, contamination, effects and mode of action of fipronil, and pesticide behavior in the environment (Bovi et al. 2018; de Morais et al. 2018; Ucar et al. 2020), persistence in the environment (Tomazini et al. 2021), and effects on non-target organisms (Nunes et al. 2021). Due to its physicochemical characteristics, fipronil toxicity increases the environmental risk, and the extensive use becomes an aggravating factor for environmental conservation and sustainability.

Figure 7 shows the network of interactions among the most productive countries, authors, and keywords. Among countries, the USA, China, Brazil, and France showed relatively important author contributions. Beugnet F., Rust M. K., and Montagner C.C. were the top contributing authors. Fipronil, permethrin, and pesticides were the most cited keywords, although the word “fipronil” was cited at least once by 95% of the authors. It can be observed that the links between countries and authors are more prominent than between authors and keywords. This is due to the fact that authors hardly keep changing affiliations frequently, whereas keywords are random and can vary constantly and therefore have thinner links. Figure 7 was built with the Bibliometrix software, while Figs. 3, 4, and 6 were made in CiteSpace, and it is possible to observe that the most frequent items correspond between the figures, demonstrating the reliability of this methodology.

Fig. 7
figure 7

Relations between countries (left), authors (middle), and keywords (right) for fipronil research

A cluster analysis based on the co-occurrence of keywords was performed to identify the search hotspots (Fig. 8). The clusters obtained through the keywords give us insight into the trends, gaps, and possible future directions of the topic of interest. The first ranked cluster (#0) was “metabolites”, followed by (#1) “dog” and (#2) “insecticide resistence”. The first cluster is related to the concern about the metabolization of this compound, since it can give rise to intermediate molecules with greater toxicity, and when its degradation does not occur completely, because part of it is bioaccumulated, results in a chronic exposure of non-target organisms in the environment (Bonmatin et al. 2015). The second cluster represented by dogs corresponds to the widespread domestic use of fipronil as an acaricide and insecticide to control insects, ticks, lice, and mites in pets (Cochran et al. 2015).

Fig. 8
figure 8

Co-occurring keywords-based knowledge clusters

Insecticide resistance was also the keyword with the biggest citation explosion as it is shown in Fig. 6b, because much research permeates this topic. In this sense, fipronil is widely used due to its efficiency in combating insect pests, but it is known that organisms can develop defense mechanisms against insecticides, becoming resistant (Wazir and Shad 2022). Fipronil causes neurotoxicity and subsequent death of the organisms (Awad et al. 2021b). In some cases, insects have gene mutations that control chloride channels, and therefore, the action of the insecticide is blocked, nullifying its effect (Casida and Durkin 2013; Ffrench-Constant et al. 2016). This fact occurs mainly in amino acids that bind to genes controlling the GABA receptor, preventing fipronil action (Bloomquist 2003; Casida and Durkin 2013; Hainzl et al. 1998). For this reason, there are several studies on the modulation of fipronil and mechanisms of action.

Another trend concerning fipronil is studies related to pesticide exposure in different organisms and the promotion of oxidative stress. In this sense, several biomarker responses are evaluated as a useful tool to understand the effect of oxidative stress in biota (Awad et al. 2021a; Seydi et al. 2021). The metabolization of this compound can give rise to intermediate molecules with greater toxicity, and when its degradation does not occur completely, because part of it is bioaccumulated, results in a chronic exposure of non-target organisms in the environment (Bonmatin et al. 2015).

All results are closely related; as an example, the categories with the most influence are “chemistry”, “environmental sciences and ecology” and “biochemistry and molecular biology”, which relate to the keywords and citation bursts, indicating that the trends of studies on fipronil in recent years are focused on its effects on non-target organisms, resistance by insect, and environmental contamination risks. It can be inferred that there are some gaps to be filled by future research with this insecticide, as little is found on protocols that aim to degrade this compound without intermediate compounds synthesis, which are mainly responsible of relevant environmental impacts. Alternative methods to control fipronil release in the environment are also needed, aiming for more sustainable use considering both the commercial and environment faces. Future studies should meet these demands, through methods with greater viability and lower ecosystem impact.

Conclusion

This scientometric analysis systematically displays the main dispositions and distributions of research on fipronil, considering the countries, keywords, areas of knowledge, articles and journals, and their collaboration networks with the greatest influence and visibility on this insecticide. The final dataset included 2362 documents with an H index of 91, a total of 50,053 citations, and an average of 21.29 citations per item. The USA, China, and Brazil were the countries of affiliation of the authors who published the most on the subject and, coincidentally, they are also the largest pesticide consumers in the world with allowed fipronil use.

In the last decades, several reviews have been carried out on fipronil, including studies on its lethal and non-lethal effects on organisms, studies on the metabolism, transport, and fate of pesticides and studies on alternatives to systemic insecticides. Among the trends in studies on fipronil in recent years, we can highlight “oxidative stress,” “neonicotinoid,” “exhibition,” “environmental destination,” “Water,” “fipronil insecticide,” “liver,” “wastewater,” and “metabolite.” The main articles published in recent years highlight that further research is needed investigating the toxic effects of pesticides on soil organisms and the impact of these pesticides on marine and coastal ecosystems. The data presented provide an overview of the use and research related to fipronil, showing gaps and future directions for further studies.