ERUCA VESICARIA (ARUGULA) EXTRACT: POSSIBLE ACARICIDAL EFFECT AGAINST RED PALM MITE

Purpose: Therefore, this study aimed to use the crude extract of Eruca vesicaria (arugula) leaves in the management of Raoiella indica . Theoretical reference: The red palm mite is an invasive species and is considered a pest of great importance for coconut and banana trees and other plants in the Arecaceae family. Therefore, this study aimed to use the crude extract of Eruca vesicaria (arugula) leaves in the management of Raoiella indica . Method: For this, fine powder from arugula leaves was used diluted in water and Tween® adhesive spreader, in concentrations of 1.0; 1.58; 2.51; 3.98; 6.31, and 10.0 %. These extracts were sprayed on 10 adult females of R. indica per sample unit, with 10 replicates for each concentration. The acaricidal effect was evaluated at different time intervals after spraying: 12, 24, 36, 48, 60, and 72 hours. Results and conclusion: The results demonstrate that mortality of the R. indica mite increases as the concentration of arugula vegetable extract increases, with lethal concentrations above 3.98 % being indicated for control. Research implications: The aqueous arugula extract, in its different concentrations, demonstrated acaricidal efficacy against the red palm mite under laboratory conditions. Originality/value: This text adds value to fields of study such as alternative insect control in crops and sustainability, proposing a change in the ecologically responsible behavior of farmers.


INTRODUCTION
The red palm mite, Raoiella indica Hirst, 1924 (Prostigmata: Tenuipalpidae), first documented in India in 1924, is a phytophagous species that inhabits plants belonging to the Arecaceae family (BARROSO et al., 2019).The species R. indica was initially documented in the state of Espírito Santo in January 2018, infesting coconut palm and pygmy date palm plants (Phoenix roebelenii O'brien, Arecaceae) (MARSARO JÚNIOR et al., 2018).According to Nuvoloni (2020), the feeding behavior of the red palm mite entails scraping leaf surfaces and extracting cellular fluids, resulting in the yellowing and subsequent desiccation of coconut and banana leaves.Upon reaching elevated population densities, these mites have the potential to induce mortality in juvenile plants.The predominant approach for red palm mite management in various global regions has been the application of synthetic chemical products.Despite the availability of several effective products for mite control, only two synthetic chemical products are officially registered for this pest species in Brazil (AGROFIT, 2023).
Owing to escalating environmental apprehensions regarding the utilization of insecticides and acaricides, particularly concerning non-target organisms, substantial advancements have been achieved in researching alternative methods for pest control.Improper application of chemical products may instigate social, economic, and ecological issues.Moreover, the excessive utilization of agrochemicals can foster resistance in pest populations and diminish the presence of natural enemy species (SILVA et al., 2023).In this context, specific plants possess insecticidal/acaricidal properties, offering a potential and promising alternative for managing pest populations (PIFFER et al., 2023).Arugula, a member of the Brassicaceae family, is gaining significance in Brazil due to its expanding economic prospects (LIMA et al., 2021).This plant is recognized for harboring numerous secondary metabolites, serving diverse functions, ranging from herbivory deterrence to conferring a bitter taste to its leaves, as elucidated by Lobo et al. (2020).In this context, the aim of this study was to assess the acaricidal impact of the E. vesicaria species (arugula) on the red palm mite in a laboratory setting.

METHODOLOGY
The experiment was conducted in the Agricultural Entomology and Acarology laboratory at the Federal Institute of Espírito Santo -Campus Itapina, situated in the rural area of the municipality of Colatina -ES, with coordinates 19°29'52.7"S40°45'38.5"W(Figure 1).The experimental units were maintained in climate-controlled chambers at a temperature of 25 ± 1 ºC, relative humidity of 70 ± 10%, and a 12-hour photophase.

Obtaining Extracts and Breeding Raioella indica
To carry out the experiments, Eruca vesicaria (arugula) plants were collected from an organic vegetable farm, located in the municipality of Rio Bananal, ES at coordinates 19°27'85.81''S,40°31'70.71''W.In the experimental procedure, focus was directed towards the plant leaves, subjecting them to meticulous sanitation through immersion in a sodium hypochlorite solution followed by rinsing with distilled water.Subsequently, the plant leaves underwent desiccation in a forced-air circulation oven, sustained at a controlled temperature of 60 ºC for a duration of 72 hours.
After this procedure, the arugula leaves were crushed in a Willey model SL-31 knife mill, this machine has a rotor with fixed knives and a chamber where the solid vegetable materials are ground, obtaining a fine powder that was stored in an amber glass bottle (1 L), covered with laminated paper, in order to avoid light penetration, where it was later used to prepare the solutions.
To establish mite populations, leaflets harboring R. indica were brought into contact with dwarf coconut seedlings.Upon manifestation of prominent mite infestation symptoms, such as leaf yellowing and necrosis, the affected plants were positioned in proximity to new, mite-free plants.This facilitated the colonization of the new plants by R. indica, thereby sustaining the propagation of the mite population.The seedlings were planted within a greenhouse environment and received irrigation through an automated drip system.Cultural treatments were applied as deemed necessary.Notably, no chemical interventions were employed for pest and disease control throughout the course of the experimental process.

Direct Application Test
Initially, a pre-test was conducted to assess the mortality rate of R. indica at a 95% confidence level, considering concentrations of 1 % and 10%.Subsequently, a logarithmic scale interval was systematically devised to derive the following concentrations of arugula leaf extract: 1 %, 1.5 %, 2.51 %, 3.98 %, 6.3 %, and 10 %.This methodology adhered to the model proposed by Carvalho et al. (2017).
For the preparation of each concentration, an amount equivalent to the percentage indicated on the logarithmic scale in grams of arugula was transferred to a 100 mL Erlenmeyer flask.The flask was then filled with distilled water and Tween® 80 adhesive spreader (0.05 % v/v), the quantities of which were pre-determined to achieve the final concentration of the extract solution.Subsequently, the solutions were homogenized using a transversal shaker at 240 rpm for 30 minutes.
Each concentration was applied to R. indica adults, sourced from the breeding colony, with 10 replicates, each comprising 10 individuals.Each individual was considered a separate repetition.For each experimental unit, a Petri dish (10.0 x 1.2 cm) containing palm leaf discs approximately 4 cm in diameter was employed.Moistened cotton was placed around the leaf discs to maintain leaf turgor and prevent mite escape.Spraying was conducted using an Alfa 2 model airbrush connected to a calibrated compressor, maintaining a constant pressure of 1.3 psi, and utilizing 1 mL of solution for each repetition.The control treatment involved the application of distilled water and the adhesive spreader Tween® 80 (0.05% v/v).
The experimental units were maintained in climate-controlled chambers at a temperature of 25 ± 1 ºC, relative humidity of 70 ± 10%, and a 12-hour photophase.The acaricidal effect was evaluated at intervals of 12, 24, 36, 48, 60, and 72 hours after spraying.
The statistical design used in this experiment was completely randomized.For each arugula aqueous extract, mortality data were corrected using the Abbott formula (1925) and subsequently subjected to the Tukey test (p≤0.05)using the R statistical program.

RESULTS
With an increase in the concentration of arugula extract, the mortality of adult individuals of R. indica showed a corresponding increase, reaching a point with no statistical difference from a concentration of 3.98% (Figure 2).Utilizing the model derived from statistical analyses, Figure 2 depicts the results of the toxicity test, demonstrating a proportional rise in the mortality of R. indica with increasing concentrations of the aqueous extract of E. vesicaria.Remarkably, significant differences in mortality rates were observed from a concentration of 3.98% onwards.However, it is crucial to highlight that all concentrations tested demonstrated effectiveness in controlling the pest organism, as they achieved at least 60 percent mortality.This suggests that the higher the concentration of the extracts, the greater the control effectiveness.These results are indicative of the promising capacity of arugula extracts as an effective alternative in the management of red palm mites, with even the lowest concentrations showing some degree of control over the infestation.
Chemical analyses of the aqueous extract of E. vesicaria corroborated the findings of previous studies that highlighted the significant presence of phenolic compounds in this plant (FILHO et al., 2021), as demonstrated in (Table 1).

DISCUSSION
Plants are recognized for their capacity to synthesize a diverse array of chemical compounds, which can be categorized into two main groups: primary metabolites and secondary metabolites.Primary metabolites are crucial for the growth and development of plants, participating in fundamental metabolic pathways essential for their sustenance (FILHO et al., 2021).In contrast, secondary metabolites, which are more intricate, are not universally synthesized by all plant species.These compounds serve diverse functions, encompassing the interaction of plants with their surrounding environment and acting as a defense mechanism against pests and pathogens.Their multifaceted roles present promising avenues for agricultural research and development (GARCÍA;CARRIL, 2009;BORGES;AMORIM, 2020).
Secondary metabolites constitute a category of highly specialized compounds that play crucial roles in the evolution of plants and their intricate interactions with other species.They are categorized into three main classes of molecules: terpenes, phenolic, and nitrogenous compounds, each serving multiple functions.These functions include safeguarding plants against biotic and abiotic stresses, as well as finding commercial applications in the pharmaceutical industry, dye production, and flavor development (RASKIN et al., 2002;BORGES;AMORIM, 2020).
The synthesis of these secondary metabolites is governed by complex metabolic pathways, originating from primary metabolites, and is typically present in limited quantities.They confer a bitter taste to leaves, functioning as a defense mechanism against herbivores, generate toxins to shield against pathogens and pests, and can also play a significant role in plant interactions with the environment, such as attracting pollinators (PINHEIRO et al., 2022).
As evident from the results, extracts derived from E. vesicaria leaves exhibit significant potential in the control of R. indica, presenting a promising natural alternative due to the notable percentage of mortality observed.Notably, the post-application state of the mites revealed a distinctive change, with individuals exhibiting a grayish color along with adjacent structures, leading to immobility and rigidity of the mite (Figure 3).The alterations witnessed in the mites, including changes in color, immobility, and rigidity following the application of the extract, serve as pivotal indicators of the efficacy of this residue in managing these arthropods-an aspect of great significance in agriculture.Consistent with the findings of Segalla et al. (2022), these observed changes imply the activation of toxic compounds within the extract that impact the nervous system or musculature of the mites, underscoring the extract's potential as a tool for pest control.According to Holtz et al. (2020), the elevated mortality observed is likely attributed to the presence of specific toxic compounds referred to as secondary metabolites, including tannins, phenolic acids, and flavonoids (see Table 1).Secondary metabolites are inherent substances synthesized by plants, primarily serving to shield them against both abiotic and biotic stresses (BORGES, 2020).Tannins, for instance, function as a deterrent to phytophagous insects and mites, rendering the leaves unpalatable due to their astringent effect.They are considered significant compounds due to their interference with specific metabolic pathways or physiological processes of pests (FRANÇA et al., 2020).
Phytochemicals, the secondary metabolites inherent in plants responsible for their therapeutic properties, are synthesized in a manner greatly influenced by numerous factors, including seasonality, soil characteristics, irrigation levels, and sun exposure, among others (NETO et al., 2022).As noted by the same author, this intricate interplay of environmental and genetic factors contributes to the diversity and specificity of secondary metabolites present in various plant species.This phenomenon results in a broad array of bioactive compounds, showcasing significant potential for pharmaceutical and nutritional applications.
According to Huber et al. (2008), vegetables consumed in Brazil mainly contain flavonoids (Lobo et al., 2020), a compound that acts on pest organisms.Supporting the findings of the conducted research, where arugula extract exhibited significant efficacy in controlling palm mites and aligning with the aforementioned authors, Oliveira et al. (2021) similarly observed the toxicity of the hydroalcoholic extract of chili pepper seeds on the white mite Polyphagotarsonemus latus (Banks, 1904) (Acari: Tarsonemidae) in a greenhouse.In their study, the authors speculate that the abundance of secondary compounds in chili pepper is responsible for its biological activity.Thus, the previously mentioned study substantiates the positive impact of plant extracts on arthropod control, further reinforcing the results presented in this study.

CONCLUSION
The investigation unveiled the acaricidal efficacy of the aqueous extract of E. vesicaria at various concentrations against the red palm mite in laboratory conditions.This finding presents a promising alternative for pest management, offering an effective solution while reducing costs with chemical insecticides and mitigating environmental damage.Moreover, it underscores the significance of tapping into the extensive potential of biodiversity within our natural ecosystems.Plants like E. vesicaria possess elevated concentrations of compounds such as phenolic acids, flavonoids, and tannins, recognized for their acaricidal properties.Hence, this study not only signifies a noteworthy advancement in pest management but also underscores the ongoing imperative to explore and responsibly utilize natural resources.Valuing the biological richness of our environment remains crucial for the mutual benefit of agriculture and the environment.

Figure 2 :
Figure 2: Mortality of Raoiella indica Hirst adults with aqueous extract of Eruca vesicaria, at different concentrations.Letters followed by the same letters there is no significant difference between them (Tukey test).Source: Author.

Figure 3 :
Figure 3: Adults of Raoiella indica Hirst after 3 days of application of the aqueous extract of Eruca vesicaria.Source: Author.

Table 1 :
Chemical analysis of the aqueous extract of Eruca vesicaria.