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Article

Insecticidal Effect of Lemongrass Essential Oil Against Megalurothrips usitatus (Bagnall)

by
Yun Han
1,2,
Ming Zhu
3,
Bo Qiu
1,
Shaukat Ali
1 and
Jianhui Wu
1,*
1
College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
2
Zhongshan Lanju Daily Chemical Industry Co., Ltd., Zhongshan 528400, China
3
College of Life Science, South China Agricultural University, Guangzhou 510642, China
*
Author to whom correspondence should be addressed.
Agronomy 2025, 15(7), 1733; https://doi.org/10.3390/agronomy15071733
Submission received: 5 June 2025 / Revised: 10 July 2025 / Accepted: 16 July 2025 / Published: 18 July 2025
(This article belongs to the Special Issue Adaptive Evolution and Resistance Mechanisms in Agricultural Pest Management)
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Abstract

Megalurothrips usitatus is a global pest damaged legume crops, particularly cowpea (Vigna unguiculata). This study aimed to determine the chemical composition of lemongrass essential oil (LEO) and its insecticidal activity against the insect pest M. usitatus. The composition of lemongrass essential oil was analyzed using Gas Chromatography Mass Spectrometry (GC-MS). D-limonene, Neral, and Citral were found to constitute over 30% of the essential oil. LEO exhibited higher insecticidal toxicity than the individual pure components. Based on our results, the optimal formulation of LEO emulsifiable concentrates (ECs) was identified, and their insecticidal activity was further investigated. The mortality rate induced by the LEO did not significantly differ from that of the emamectin benzoate (EB) formulation but was lower than that of spinosad (SP). Additionally, LEO was shown to act as a synergist when combined with EB for controlling M. usitatus. This research offers an alternative strategy for controlling M. usitatus and reducing the reliance on synthetic pesticides.

1. Introduction

Bean thrips, Megalurothrips usitatus Bagnall (Thysanopera: Thripidae), is a major pest damaged leguminous crops (Fabales: Fabaceae) in tropical and subtropical regions [1,2,3]. Cowpea plant, Vigna unguiculata, is a preferred host of M. usitatus [3,4]. M. usitatus can damage V. unguiculata throughout its entire growth cycle, causing leaf deformation, flower and pod drop, and black-head and black-tail symptoms by feeding directly on plant cell sap [5,6]. Chemical insecticides are the primary method of controlling this pest. However, due to the small size and high reproductive rate of thrips, the overuse of chemical pesticides can quickly lead to resistance development and pesticide residues in cowpeas. To date, M. usitatus has shown varying levels of resistance to neonicotinoid and pyrethroids in China [7,8]. Although low levels of resistance to spinetoram have been observed in M. usitatus populations, this insecticide is still commonly recommended in Hainan province, China [8]. Therefore, it is crucial to explore green and efficient management strategies for controlling thrips. Biological pesticides could offer a viable alternative strategy in the future.
Botanical pesticides are safe and environmentally friendly, making them more readily accepted by consumers and applied by farmers [9,10,11]. Much research in this field has focused on essential oils (EOs) [12,13,14]. EOs (such as citronella, lemongrass, clove, thyme, and rosemary oil) have been reported to exhibit insecticidal as well as acaricidal activity [12,15,16,17]. At present, there is a lack of effective chemicals for thrips management. EOs and their pure compounds exhibit specific biological activity on thrips’ feeding and oviposition behavior [18]. For instance, Lamiaceae and citrus EOs have demonstrated strong insecticidal activity against Thrips flavus [18,19]. Pure (R)-linalool and its mixtures with peppermint oil have shown toxic effects on Frankliniella occidentalis and Frankliniella insularis [20]. Furthermore, eugenol may alter the behavior of Thrips tabaci and serve as a novel component in integrated pest management strategies [21]. However, there is a lack of research on the use of EOs for controlling M. usitatus.
Previous studies have shown that lemongrass (Cymbopogon citratus) essential oil (LEO) is a promising acaricidal and insecticidal agent [22,23,24]. LEO from fresh leaves has been evaluated for its insecticide activity against Myzus persicae and Frankliniella schultzei [24]. LEO has also been tested for pesticidal activity against various insect species, including Lepidoptera, Coleoptera, Diptera, etc. [25,26,27,28]. The combination of LEO and insecticides has been shown to enhance toxicity against fruit flies [28]. Plata-Rueda et al. (2022) demonstrated that LEO and its terpenoid components exhibit insecticidal and repellent activities against Ulomoides dermestoides [29]. However, no studies have yet evaluated the use of LEO to control bean thrips affecting cowpeas. In this study, we first analyzed the insect pest species that can be controlled by LEO. To better utilize LEO, we extracted and identified its components and investigated the toxicity of formulated LEO against M. usitatus. In addition, the study evaluated the insecticidal efficacy of LEO in combination with two commonly used insecticides—emamectin benzoate (EB) and spinosad (SP)—against M. usitatus. Our findings provide valuable insights into the development of LEO-based formulations and offer practical guidelines for protecting V. unguiculata from M. usitatus infestations.

2. Materials and Methods

2.1. Gas Chromatography Mass Spectrometry (GC-MS) Analysis

All experiments were performed under controlled laboratory conditions at the Insect Ecology Laboratory of the Guangdong Bio-engineering Research Center during the period from October 2023 to July 2024.
LEO with 99% purity was obtained from Guangzhou Sixiantang Biotech Co., Ltd., Guangzhou, China. The composition of the LEO was analyzed using an HP 7890A gas chromatograph coupled to a HP 5975c mass selective detector (Agilent Technologies, Foster City, CA, USA). The sample was directly injected into the GC-MS for analysis after filtration through a 0.22 μm microporous membrane filter. The oven temperature was initially held at 50 °C for 2 min. Then, it was increased at a rate of 5 °C/min to 150 °C, and subsequently increased at a rate of 10 °C/min to 310 °C. Finally, it was isothermally maintained for 10 min. The electron ionization mode of the mass spectrometer was set at −70 eV. Volatile compounds were identified by comparing their mass spectra to those in the Wiley 7 n mass computer library and the NIST 11 database. These compounds were further analyzed and screened based on a matching factor (MF) greater than 90 and an area ratio (AR) greater than 0.1%. The major components that were identified were investigated for biological activity.

2.2. Preparation of Emulsifiable Concentration (EC)

Polyoxyl 40 hydrogenated castor oil (RH40) is a nonionic surfactant composed mainly of polyethylene glycol ethers of hydrogenated castor oil. The surfactant 203b is prepared by blending 6 parts of polyoxyethylene castor oil ether with 4.5 parts of calcium dodecylbenzenesulfonate, followed by mixing with xylene. The main components of EL20 are castor oil/hydrogenated castor oil condensed with ethylene oxide. BY125 is a nonionic surfactant, with castor oil ethoxylate as its main component. Pesticide emulsifier 0201B is a special nonionic and anionic surfactant, with styrenated phenol polyoxyethylene ether as its main component. LEO was formulated as an EC at a concentration of 10% (w/w) through mixing with 30 g surfactants (RH40, 203b, EL20, BY125, 0201B) and 5 g of methyl oleate. The solvent oil (S200) was then added to bring the final volume to 100 g. To prepare a 10% (w/w) emulsifiable concentrate (EC) formulation of LEO, 10 g of high-purity LEO was accurately weighed and mixed with 5 g of methyl oleate and 30 g of a single type of surfactant. Five separate EC formulations were prepared, each containing one of the following nonionic surfactants: RH40, 203b, EL20, BY125, or 0201B. After thorough homogenization, solvent oil (S200) was added to each mixture to adjust the total mass to 100 g. A 10% concentration of LEO corresponds to 100 mg/g.
The LEO EC formulation was dropped from a height of 10 cm into 70 mL of deionized water, and the dispersion status of the solution in the water was observed. The suitable surfactant was chosen by evaluating the homogeneity and dispersibility of LEO EC formulations with different surfactants. Binary mixtures of surfactants 203b and 0201B were prepared at weight ratios of 3:0, 2:1, 1:1, 1:2, and 0:3, and each blend was incorporated into the formulation of a corresponding LEO EC. These chemical agents were purchased from Jiangsu Haian Petrochemical Co. (Nantong, China).
The specific preparation process is illustrated in Figure 1a. We used EB (78% active ingredient) and SP (≥92% active ingredient), which were provided by the State Key Laboratory of Green Pesticides. A mixture of 1% EB (m/v) or 2.5% (m/v) SP and LEO was prepared. First, EB or SP was dissolved in methanol. Then, the solution was added to EC with or without LEO. The EC was diluted 500-fold before being used in the biological activity assays. The final concentrations of EB and SP in the diluted solutions were 20 mg/L and 50 mg/L, respectively.

2.3. Characterization of EC

The state of the LEO EC solution diluted 200-fold was observed through emulsion droplets under a microscope. The spreadability of the solution (500 mg/L) applied to leaves and petals was recorded at 1, 3, 5, 7, and 9 min using a LEICA DM750 stereo microscope coupled to an ICC50W imaging system (Leica Microsystems, Wetzlar, Hesse, Germany). The contact angle of the LEO EC was measured using the Contact Angle Analyzer Version 3.0.

2.4. Thrips Rearing

M. usitatus were collected from a field of cowpea crops in the Qilin district, South China Agricultural University. The thrips were reared in culture bottles with tissue paper and bean pods under controlled laboratory conditions: 26 ± 1 °C, 60 ± 5% relative humidity, and 12 h light/dark cycle. The bean pods were replaced every two days and consumed beans were transferred to new bottles.

2.5. Measurement of Insecticidal Activity

Five different concentrations (0, 0.5, 1, 1.5, and 2 mg/L) of LEO were prepared by diluting the oil with absolute ethanol, 0.5 mL of Tween-80, and water. The insecticidal activity of LEO was compared with that of its individual compounds, D-limonene and Neral, at concentrations of 1.5 mg/L. A solution without LEO or its components was used as the control. The LEO EC was diluted 100-, 300-, 500-, and 1000-fold to assess its insecticidal activity against M. usitatus. The corresponding working concentrations were 1000 mg/L, 333 mg/L, 200 mg/L, and 100 mg/L, respectively. The effects of the mixture of the LEO EC with pesticides (EB, SP) or their individual components were also evaluated at a 300-fold dilution. Young bean pods (~1 cm in length) and 1.5 mL centrifuge tubes were immersed for 30 s in the treatment solution, then air-dried in the shade. After drying, newly emerged adult M. usitatus were transferred using insect suction apparatus (Figure 1b) onto the treated pods. The mortality rate was recorded after 24 h. The mortality data obtained from bioassays were subjected to nonlinear regression analysis to estimate the median lethal concentration (LC50) values. A four-parameter Logistic model was fitted to the dose-response data using Origin Pro 2024. Each treatment included three replicates. A EC solution without insecticidal components and LEO was used as the control, with all other components being identical to those in the treatment groups.

2.6. Data Analysis

All data were analyzed with one-way analysis of variance (ANOVA) in IBM SPSS 26.0 followed by least significance difference (LSD) among different groups. Preliminary analyses were conducted using Origin Pro 2024. Data are presented as mean ± standard deviation of measurements. Significant differences between treatments were determined at a confidence level of 95% (p < 0.05).

3. Results

3.1. Chemical Composition of LEO

A total of 60 compounds were identified and annotated through database searches based on the mass spectra and reference standards. The primary components of LEO, as shown in the chromatogram graph, were D-limonene (31.20%), Neral (30.90%), and Citral (31.56%) (Figure 2, Table 1). Additionally, other compounds with a match factor greater than 90 and an area ratio (AR) exceeding 0.1% are listed in Table 1. These major components are likely to play a significant role in the oil’s effectiveness against thrips.

3.2. Insecticidal Activity of LEO and Its Compounds

The experimental procedure used to determine the insecticidal activity is illustrated in Figure 1b. The insecticidal activity of LEO and its main components is shown in Figure 3. At a concentration of 1.5 mg/L, the mortality rate of LEO was the highest (46.97%), but no significant differences were found among the treatment groups. However, the control group showed a mortality rate of 10%, which was significantly lower than that of the treatment groups (Figure 3a). The LC50 value of LEO against M. usitatus was estimated using a logistic analysis to be 0.69 ± 0.20 mg/L, with a 95% confidence interval ranging from 0.14 to 1.24 mg/L. The dose-response model exhibited a good fit to the experimental data, as indicated by a coefficient of determination (R2) exceeding 0.90. These results demonstrate the strong insecticidal activity of LEO against M. usitatus and provide a quantitative basis for its potential application in pest management.
We then analyzed the insecticidal activity of D-limonene (18.03%) and Citral (18.43%). Compared to the LEO mixture, the two pure components exhibited a significantly lower mortality rate against M. usitatus, with no significant difference between them (Figure 3b).

3.3. Spreadability of EC

The schematic diagram of the EC is shown in Figure 1a. The diffusion behavior of the ECs, containing different surfactants (RH40, 203b, EL20, BY125, and 0201B), was systematically evaluated upon dilution in deionized water at multiple time points (30 s, 10 min, and after shaking) as shown in Figure 4a. The 203b surfactant demonstrated better dispersibility and emulsification compared to the others. In contrast, the 0201B surfactant exhibited superior lateral diffusivity and emulsification properties. Therefore, five different EC dilutions (203b:0201B in a ratio of 3:0, 2:1, 1:1, 1:2, and 0:3) were investigated for stability over varying time periods (30 s, 1 d, 7 d, 21 d, and 30 d) (Figure 4b). The mixed surfactant systems generally exhibited improved physical stability compared to single-surfactant formulations. Notably, the formulation with a 1:1 ratio exhibited homogeneity without visible phase separation or sedimentation throughout the 30-day period, indicating optimal emulsification synergy between 203b and 0201B (Figure 4b). The balanced combination of 203b and 0201B surfactants significantly enhanced the EC formulation’s resistance to aggregation and sedimentation. These results suggest that the surfactant is a critical factor in optimizing the physical stability and, potentially, the bioavailability of LEO ECs.
To apply these ECs to cowpea, we assessed their spreadability on leaves and flowers. The 1:1 (203b:0201B) EC dilution showed a more uniform distribution and consistent coverage across the flower surfaces (Figure 5a,b). When these ECs were diluted 200-fold and sprayed on both the outer and inner layers of cowpea flowers, the solution spread evenly across the surface without the formation of water droplets (Figure 5b). Over time, the water droplets showed minimal changes, and the EC solutions remained evenly distributed on the cowpea leaves and petals (Figure 5c,d). Such persistent coverage is essential to ensure sustained insecticidal activity through prolonged contact with the target pests. The contact angles of water and the emulsions (in ratios of 3:0, 2:1, 1:1, 1:2, and 0:3) on cowpea leaves were measured at 1 min, with angles ranging from 68.12, 35.03, 47.25, 44.68, 49.14, and 45.58° to 64.57, 28.00, 32.42, 33.52, 30.29, and 32.85°, respectively (Figure 5e,f). Notably, the 1:1 EC formulation demonstrated consistently lower and more stable contact angles compared to the others, reflecting enhanced wetting properties that likely contribute to improved formulation adherence and insecticidal efficacy. These results indicate that the balanced surfactant ratio in the 1:1 EC dilution optimizes physical properties that are critical for effective pest control, making it the most promising candidate for managing M. usitatus infestations on cowpea.

3.4. Insecticidal Activity

As shown in Figure 6, the LEO EC at all dilution concentrations exhibited higher insecticidal activity against M. usitatus. The highest 24 h mortality rate was observed at the 100-fold dilution, which was higher than at other dilution levels. However, the EC solutions of other dilution factors (300, 500, and 1000) did not show significant differences (Figure 6a). The corresponding working concentrations were 1000 mg/L, 333 mg/L, 200 mg/L, and 100 mg/L, respectively. The dose-response curves were well fitted by the four-parameter Logistic model using Origin Pro 2024, with high goodness-of-fit indicators (R2 > 0.89). The estimated LC50 value for the LEO EC was 130 ± 60 mg/L (80% confidence interval: 40–230 mg/L), indicating the concentration required to cause 50% mortality in M. usitatus. These results demonstrate the potent toxic effects of the compounds and provide essential quantitative benchmarks for further toxicological evaluations.
Given the resistance of M. usitatus to EB (20 mg/L) and SP (50 mg/L), we assessed the synergistic effects of the LEO EC and a binary mixture EC, which combined the insecticide with LEO. As shown in Figure 6b, the treatment groups demonstrated significantly higher mortality than the control group. The EC formulations containing a single component did not show significant differences in mortality, while the binary mixture (LEO + EB) exhibited the highest mortality against M. usitatus (Figure 6b). However, LEO did not show synergistic activity with SP. No significant difference in mortality was observed between the mixed EC (LEO + SP) treatment and the SP EC treatment.

4. Discussion

4.1. Research on C. citratus

M. usitatus has rapidly developed resistance to many pesticides under both laboratory and field conditions [9,30]. Bio-pesticides have the potential to mitigate pest resistance [31,32,33]. Numerous studies have shown that C. citratus, commonly known as lemongrass, exhibits insecticidal activity and its EO plays a significant role in integrated pest management [15,34]. LEO has demonstrated the capacity and potential to control maize weevil (Sitophilus zeamais) [32]. Additionally, LEO has shown toxicity against Aedes aegypti and Anopheles dirus larvae [33]. Furthermore, a blend of lemongrass and cinnamon bark EO exhibited synergistic spatial repellency against A. aegypti mosquitoes in field settings [23]. We screened and used lemongrass to protect cowpea plants.
Our results showed a 47% mortality rate of M. usitatus at a concentration of 1.5 mg/L (Figure 3a), whereas F. schultzei exhibited only 1.49% mortality [24]. The mortality of T. tabaci, an onion thrips, treated with lemongrass leaf extract (C. citratus) at a concentration of 1000 mg/L was 63.33% on the seventh day in the laboratory [34]. These thrips species may develop different levels of resistance to LEO.
LEO has been found to be non-toxic to predators and a promising candidate for controlling M. usitatus, potentially helping to reduce the development of resistance to conventional insecticides. Furthermore, volatiles from C. citratus have shown potential in repelling Megalurothrips sjostadti females [35]. Therefore, LEO could be evaluated for use as a repellent in field applications.

4.2. Analysis of Major Components of LEO

LEO and its major components exhibited insecticidal activity against Tuta absoluta, Anopheles sinensis, and Trichoplusia ni [15,36,37]. The main components of LEO are Neral (34.48%), Geranial (34.37%), and β-Myrcene (12.84%) [15]. However, in our study, the prominent components of the EO were D-limonene (31.20%), Neral (30.90%), and Citral (31.56%) (Table 1). The LC50 value of LEO against M. usitatus was estimated to be 0.69 ± 0.20 mg/L, indicating strong insecticidal activity. The chemical analysis revealed that the LEO sample contained nine major compounds, with geranial (49.98%) and neral (37.78%) as the predominant constituents [24]. In comparison, previous studies reported an LC50 value of 1.49% (14,900 mg/L) for lemongrass oil against F. schultzei, highlighting substantial differences in efficacy that are likely attributable to variations in chemical composition and target species sensitivity [24]. Such variation in component concentrations is largely attributed to differences in plant sources, especially regional variations in lemongrass cultivation. For example, LEO from Nepal predominantly contained Neral (35.5%) and Geranial (36.0%) [38]. Similarly, Pinto, et al. (2015) identified 13 and 12 major chemical components in Brazilian and Cuban LEO samples, respectively, with Geranial accounting for 53.2% and 51.14%, and Neral for 36.37% and 35.21% in Brazilian and Cuban oils, correspondingly [39]. These compositional differences significantly affect insecticidal activity. For example, LEO showed LC50 values of 4.25% and 3.24%, and LC90 values of 84.25% and 83.24% for Brazilian and Cuban samples, respectively [39]. Felipe-Victoriano et al. (2023) also reported the limited efficacy of a commercially available and well-established lemongrass oil product against Bagrada hilaris in laboratory bioassays [40]. Therefore, comprehensive characterization of the chemical constituents of LEO is crucial prior to its application as an insecticide.
Conventionally, the insecticidal activity of C. citratus is assigned to Citral, its major component. Citral has demonstrated significant larvicidal activity against Spodoptera littoralis and Culex pipiens quinquefasciatus [25,39]. Tak et al. (2017) identified Citral, Limonene, and Geranyl acetate as major components of LEO and reported two synergistic binary combinations of Citral and Limonene that enhanced toxicity against T. ni larvae [37]. In our study, LEO exhibited greater lethality than D-limonene and Citral alone (Figure 3b). Citral has been shown to inhibit cytochrome P450 (CYP50) activity by binding to cysteine (Cys345), histidine (His343), and glutathione-S-transferase (GST) [25]. Additionally, LEO and its primary components effectively suppress acetylcholinesterase (AChE), resulting in increased knockdown and mortality with citronellal exhibiting the highest potential for binding to the active site of AChE [14].

4.3. Insecticidal Activity of LEO ECs

A mixture of two compounds from LEO has been shown to enhance cuticular penetration activity in the cabbage looper [37]. ECs containing EO may offer an alternative pest control strategy and reduce the risk of insecticide contamination in crops [41]. ECs are a widely used form of pesticidal formulations [42,43]. The environmental sustainability and stability of ECs largely depend on the choice of solvents. In our study, we determined the optimal ratio of EC components (1:1) by analyzing the contact angle (Figure 5). Previous research has shown that the stability and biological activity of ECs can be improved by adjusting the solvent ratio [44]. To enhance the diffusion and penetration of ECs on cowpea plants, this formulation results in a significant reduction in the use of chemicals, ensuring the safety of cowpea products.
Essential oils have been reported to increase the toxicity of insecticides such as β-cypermethrin, deltamethrin, and malathion [41,42,43,44]. LEO has demonstrated excellent activity in bioassays utilizing Drosophila melanogaster [28,45,46]. We compared the insecticidal toxicity of the LEO EC, commonly used insecticides (EB, SP) for thrips control, and their mixtures against M. usitatus. The results showed that the EO ECs significantly enhanced the toxicity of EB EC, but did not improve the efficacy of SP (Figure 6). The LEO EC was found to be effective at a 300-fold dilution. The use of LEO ECs could be considered to be a promising strategy for controlling M. usitatus. The present study aimed to assess the overall insecticidal activity of LEO and to identify its active components under laboratory conditions. In addition, the LC50 values of the LEO and LEO EC were analyzed to provide essential quantitative indicators of its toxicity, thereby strengthening the scientific validity of the results. The results of this study will be further validated under field conditions in future research, providing a theoretical basis for subsequent applications.

5. Conclusions

This study aimed to evaluate the toxicity of LEO against the cowpea thrips M. usitatus under controlled laboratory conditions. The major components of LEO were identified to be D-limonene, Neral, and Citral. LEO exhibited greater toxicity than its individual components. We also determined the composition of the LEO EC. The results indicated that the LEO EC could be used as an additive in EB EC formulations. This offers a viable alternative to solely relying on synthetic insecticides within integrated pest management strategies. Due to differences in the ingredient profiles of LEO from different sources, the results and conclusions derived from this study may not be universally applicable to all LEO extracts. Therefore, further investigation into the extent and impact of such component variations is warranted to ensure consistency and efficacy in future applications.

Author Contributions

Conceptualization, J.W.; investigation, Y.H., M.Z. and B.Q.; writing—original draft, Y.H. and M.Z.; writing—review and editing, J.W. and S.A.; visualization, S.A.; validation, S.A. and B.Q.; data curation, Y.H., M.Z. and B.Q.; supervision, J.W.; project administration, J.W. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the National Key R&D Program of China (Grant No. 2024YFD1400100).

Data Availability Statement

Data are contained within the article.

Conflicts of Interest

Author Yun Han was employed by the company Zhongshan Lanju Daily Chemical Industry Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

References

  1. Xia, G.; Yang, L.; Li, B.L.; Wang, Q.L.; Huang, L.F.; Tian, X.L.; Zhang, G.H. Genome-wide identification and expression profiling of odorant-binding protein genes in the bean flower thrips Megalurothrips usitatus (Bagnall) (Thysanoptera: Thripidae). Insects 2025, 16, 212. [Google Scholar] [CrossRef] [PubMed]
  2. Yasmin, S.; Ali, M.; Rahman, M.M.; Akter, M.S.; Latif, M.A. Biological traits of bean flower thrips, Megalurothrips usitatus (Thysanoptera: Thripidae) reared on mung bean. Sci. Herit. J. 2021, 5, 29–33. [Google Scholar] [CrossRef]
  3. Chi, Y.; Yu, C.; Feng, M.; Zhou, Y.; Li, X.; Zhang, Q. Effects of field releases of Neoseiulus barkeri on Megalurothrips usitatus abundance and arthropod diversity. Sci. Rep. 2024, 14, 14247. [Google Scholar] [CrossRef] [PubMed]
  4. Liu, P.; Qin, Z.; Feng, M.; Zhang, L.; Huang, X.; Shi, W. The male-produced aggregation pheromone of the bean flower thrips Megalurothrips usitatus in China: Identification and attraction of conspecifics in the laboratory and field. Pest Manag. Sci. 2020, 76, 2986–2993. [Google Scholar] [CrossRef]
  5. He, Y.C.; Gao, Y.; Hong, H.N.; Geng, J.M.; Chen, Q.L.; Zhou, Y.; Zhu, Z.R.; Casas, J.L. Megalurothrips usitatus directly causes the black-heads and black-tail symptoms of cowpea along with the production of insect-resistance flavonoids. Plants 2023, 12, 3865. [Google Scholar] [CrossRef] [PubMed]
  6. Wang, H.; Huang, L.; Zheng, X.; Gong, R.; Cao, X.; Yang, L. An age-stage, two-sex life table for Megalurothrips usitatus feeding on eight different crop plants. Agronomy 2024, 14, 2283. [Google Scholar] [CrossRef]
  7. Chen, W.Y.; Li, Z.Y.; Zhou, C.Y.; Ali, A.; Ali, S.; Wu, J.H. RNA interference in cytochrome P450 monooxygenase (CYP) gene results in reduced insecticide resistance in Megalurothrips usitatus Bagnall. Front. Physiol. 2023, 14, 1130389. [Google Scholar] [CrossRef]
  8. Fu, B.L.; Tao, M.; Xue, H.; Jin, H.F.; Liu, K.; Qiu, H.Y.; Yang, S.Y.; Yang, X.; Gui, L.Y.; Zhang, Y.J.; et al. Spinetoram resistance drives interspecific competition between Megalurothrips usitatus and Frankliniella intonsa. Pest Manag. Sci. 2022, 78, 2129–2140. [Google Scholar] [CrossRef]
  9. Zhang, P.; Li, X.W.; Dong, L.L.; Chen, S.L. Study on botanical pesticides and its application in production of traditional Chinese medicine. China J. Chin. Mater. Med. 2016, 41, 3579–3586. [Google Scholar]
  10. Hernández-Moreno, D.; Soffers, A.; Wiratno; Falke, H.E.; Rietjens, I.; Murk, A.J. Consumer and farmer safety evaluation of application of botanical pesticides in black pepper crop protection. Food Chem. Toxicol. 2013, 56, 483–490. [Google Scholar] [CrossRef]
  11. Gostin, I.N.; Popescu, I.E. Evaluation of the essential oils used in the production of biopesticides: Assessing their toxicity toward both arthropod target species and beneficial pollinators. Agriculture 2024, 14, 81. [Google Scholar] [CrossRef]
  12. Narayanankutty, A.; Kunnath, K.; Alfarhan, A.; Rajagopal, R.; Ramesh, V. Chemical composition of Cinnamomum verum leaf and flower essential oils and analysis of their antibacterial, insecticidal, and larvicidal properties. Molecules 2021, 26, 6303. [Google Scholar] [CrossRef] [PubMed]
  13. Jin, C.; Han, H.; Xie, Y.; Li, B.; Zhang, Z.; Zhang, D. Toxicity, behavioral effects, and chitin structural chemistry of Reticulitermes flaviceps exposed to Cymbopogon citratus essential oil and its major constituent citral. Insects 2022, 13, 812. [Google Scholar] [CrossRef] [PubMed]
  14. Jin, C.Z.; Wu, Z.W.; Chen, Y.Y.; Gong, X.; Yang, S.M.; Zhang, Z.L.; Zhang, D.Y.; Xie, Y.J. Insights into the toxicity, behavioral responses, biochemical activity, and molecular docking of three essential oils and their major constituents. Ind. Crops Prod. 2024, 214, 118563. [Google Scholar] [CrossRef]
  15. Ngongang, M.D.T.; Eke, P.; Sameza, M.L.; Mback, M.N.L.N.; Lordon, C.D.; Boyom, F.F. Chemical constituents of essential oils from Thymus vulgaris and Cymbopogon citratus and their insecticidal potential against the tomato borer, Tuta absoluta (Lepidoptera: Gelechiidae). Int. J. Trop. Insect Sci. 2022, 42, 31–43. [Google Scholar] [CrossRef]
  16. Wan, J.; Zhong, S.B.; Schwarz, P.; Chen, B.C.; Rao, J.J. Influence of oil phase composition on the antifungal and mycotoxin inhibitory activity of clove oil nanoemulsions. Food Funct. 2018, 9, 2872–2882. [Google Scholar] [CrossRef]
  17. Koschier, E.H. Essential Oil Compounds for Thrips Control—A Review. Nat. Prod. Commun. 2008, 3, 1171–1182. [Google Scholar] [CrossRef]
  18. Zhou, Y.X.; Pei, T.H.; Zhou, X.C.; Xu, M.L.; Gao, H.X.; Wang, L.L.; Gao, Y. An investigation into the biological activities of four Lamiaceae essential oils against Thrips flavus, crops, and weeds. Plants 2025, 14, 448. [Google Scholar] [CrossRef]
  19. Pei, T.H.; Niu, Y.L.; Liu, B.; Yuan, M.; Zhang, A.G.; Li, X.F.; Wang, L.X.; Xu, M.L.; Gao, Y. Citrus essential oils as potential insecticides against Thrips flavus. Curr. Anal. Chem. 2024, 20, e280224227514. [Google Scholar] [CrossRef]
  20. Gharbi, K.Z. Fumigant toxicity of essential oils against Frankliniella occidentalis, F. insularis (Thysanoptera: Thripidae), and Solanum lycopersicum (Solanaceae) as affected by polymer release and adjuvants. Insects 2022, 13, 493. [Google Scholar] [CrossRef]
  21. Riefler, J.; Koschier, E.H. Behaviour-modifying activity of eugenol on Thrips tabaci Lindeman. J. Pest Sci. 2009, 82, 115–121. [Google Scholar] [CrossRef]
  22. Chahal, K.K.; Singh, B.; Kataria, D.; Dhillon, N.K. Nematotoxicity of lemongrass oil, citral and its derivatives against Meloidogyne incognita. Allelopath. J. 2016, 39, 217–229. [Google Scholar]
  23. Peach, D.A.H.; Almond, M.; Gries, R.; Gries, G. Lemongrass and cinnamon bark: Plant essential oil blend as a spatial repellent for mosquitoes in a field setting. J. Med. Entomol. 2019, 56, 1346–1352. [Google Scholar] [CrossRef]
  24. Costa, A.V.; Pinheiro, P.F.; Rondelli, V.M.; de Queiroz, V.T.; Tuler, A.C.; Brito, K.B.; Stinguel, P.; Pratissoli, D. Cymbopogon citratus (Poaceae) essential oil on Frankliniella schultzei (Thysanoptera: Thripidae) and Myzus persicae (Hemiptera: Aphididae). Biosci. J. 2013, 29, 1840–1847. [Google Scholar]
  25. Moustafa, M.A.M.; Hassan, N.N.; Alfuhaid, N.A.; Amer, A.; Awad, M. Insights into the toxicity, biochemical activity, and molecular docking of Cymbopogon citratus essential oils and citral on Spodoptera littoralis (Lepidoptera: Noctuidae). J. Econ. Entomol. 2023, 116, 1185–1195. [Google Scholar] [CrossRef] [PubMed]
  26. Alves, M.S.; Campos, I.M.; Conde de Brito, D.M.; Cardoso, C.M.; Pontes, E.G.; Alves de Souza, M.A. Efficacy of lemongrass essential oil and citral in controlling Callosobruchus maculatus (Coleoptera: Chrysomelidae), a post-harvest cowpea insect pest. Crop Prot. 2019, 119, 191–196. [Google Scholar] [CrossRef]
  27. Kim, D.I.; Kim, S.I.; Jung, J.W.; Ilyasov, R.A.; Jang, D.; Lee, S.H.; Kwon, H.W. Spatial releasing properties and mosquito repellency of cellulose-based beads containing essential oils and vanillin. J. Asia-Pac. Entomol. 2019, 22, 409–416. [Google Scholar] [CrossRef]
  28. Aljedani, D.M. Effects of some insecticides (deltamethrin and malathion) and lemongrass oil on fruit fly (Drosophila melanogaster). Pak. J. Biol. Sci. 2021, 24, 477–491. [Google Scholar] [CrossRef] [PubMed]
  29. Plata-Rueda, A.; Fiaz, M.; Brugger, B.P.; Canas, V.; Coelho, R.P.; Zanuncio, J.C.; Martinez, L.C.; Serrao, J.E. Lemongrass essential oil and its components cause effects on survival, locomotion, ingestion, and histological changes of the midgut in Anticarsia gemmatalis caterpillars. Toxin Rev. 2022, 41, 208–217. [Google Scholar] [CrossRef]
  30. Pang, R.; Wang, J.B.; Li, H.L.; Zhong, Z.C.; Li, Z.S.; Qiu, B.; Zhou, C.Y.; Ali, S.; Wu, J.H. Identification of the CYPome associated with acetamiprid resistance based on the chromosome-level genome of Megalurothrips usitatus (Bagnall) (Thysanoptera: Thripidae). Pest Manag. Sci. 2025, 81, 3273–3283. [Google Scholar] [CrossRef]
  31. Gupta, A.; Sharma, S.; Naik, S.N. Biopesticidal value of selected essential oils against pathogenic fungus, termites, and nematodes. Int. Biodeterior. Biodegrad. 2011, 65, 703–707. [Google Scholar] [CrossRef]
  32. Radunz, A.L.; Radunz, M.; Bizollo, A.R.; Tramontin, M.A.; Radunz, L.L.; Mariot, M.P.; Tempel-Stumpf, E.R.; Calisto, J.F.F.; Zaniol, F.; Albeny-Simoes, D.; et al. Insecticidal and repellent activity of native and exotic lemongrass on Maize weevil. Braz. J. Biol. 2022, 84, e252990. [Google Scholar] [CrossRef] [PubMed]
  33. Soonwera, M.; Phasomkusolsil, S. Effect of Cymbopogon citratus (lemongrass) and Syzygium aromaticum (clove) oils on the morphology and mortality of Aedes aegypti and Anopheles dirus larvae. Parasitol Res. 2016, 115, 1691–1703. [Google Scholar] [CrossRef]
  34. Mohsin, A.A.; Al-Salami, W.M.; Abid, A.J. Laboratory Study of the Effect of Lemongrass Leaves (Cymbopogon citratus) on an Onion Thrips Insect (Thrips tabaci Thysanoptera: Thripidae). J. Univ. Babylon Pure Appl. Sci. 2018, 26, 182–192. [Google Scholar] [CrossRef]
  35. Diabate, S.; Martin, T.; Murungi, L.K.; Fiaboe, K.K.M.; Subramanian, S.; Wesonga, J.; Deletre, E. Repellent activity of Cymbopogon citratus and Tagetes minuta and their specific volatiles against Megalurothrips sjostedti. J. Appl. Entomol. 2019, 143, 855–866. [Google Scholar] [CrossRef]
  36. Tang, Y.; Li, H.; Song, Q. Lemongrass essential oil and its major component citronellol: Evaluation of larvicidal activity and acetylcholinesterase inhibition against Anopheles sinensis. Parasitol. Res. 2024, 123, 315. [Google Scholar] [CrossRef]
  37. Tak, J.H.; Jovel, E.; Isman, M.B. Synergistic interactions among the major constituents of lemongrass essential oil against larvae and an ovarian cell line of the cabbage looper, Trichoplusia ni. J. Pest Sci. 2017, 90, 735–744. [Google Scholar] [CrossRef]
  38. Baranová, B.; Kudláčková, B.; Baral, R.P.; Svojanovská, L.; Javed, Q.; Amato, G.; Caputo, L.; De Martino, L.; Francolino, R.; Chaudhary, S.K.; et al. Potential herbicidal and insecticidal (Beneficial) properties of Nepalese lemongrass essential oil. Chem. Biodivers. 2025, 22, e01095. [Google Scholar] [CrossRef]
  39. Pinto, Z.T.; Sánchez, F.F.; Santos, A.R.; Amaral, A.C.F.; Ferreira, J.L.P.; Escalona-Arranz, J.C.; Queiroz, M.M.C. Chemical com position and insecticidal activity of Cymbopogon citratus essential oil from Cuba and Brazil against housefly. Rev. Bras. Parasitol. Vet. 2015, 24, 36–44. [Google Scholar] [CrossRef] [PubMed]
  40. Felipe-Victoriano, M.; Villegas-Luján, R.; Treviño-Cueto, D.; Sánchez-Peña, S.R. Combined activity of natural products and the fungal entomopathogen Cordyceps farinosa against Bagrada hilaris (Hemiptera: Pentatomidae). Fla. Entomol. 2023, 106, 154–160. [Google Scholar] [CrossRef]
  41. Shaltiel-Harpaz, L.; Kreimer, T.; Dudai, N.; Kaspi, R.; Ben-Yakir, D.; Rytwo, G. Sepiolite-rosemary oil combination as an environmentally oriented insecticide. Appl. Clay Sci. 2023, 234, 106838. [Google Scholar] [CrossRef]
  42. Abd-Elnabi, A.D.; El-sawy, E.A.F.; Badawy, M.E.I. Plant oil nano-emulsions as a potential solution for pest control in sustainable agriculture. Neotrop. Entomol. 2025, 54, 35. [Google Scholar] [CrossRef] [PubMed]
  43. Pacheco, A.; Attard, T.; Calvert, D.; Bullock, J.; Clark, J.H.; Sherwood, J.; McElroy, C.R. Green solvent selection for emulsifiable concentrate agrochemical formulations. Org. Process Res. Dev. 2024, 28, 132–136. [Google Scholar] [CrossRef]
  44. Wu, J.; Yang, R.; Zheng, Q.; Wei, L.; Wang, B.; Yan, W.; Meng, S.; Cheng, D.; Huang, S.; Zhang, Z.; et al. Effect of Brucea javanica oil on the toxicity of β-cypermethrin emulsifiable concentrate formulation. ACS Appl. Mater. Interfaces 2024, 16, 9713–9724. [Google Scholar] [CrossRef]
  45. Baldacchino, F.; Tramut, C.; Salem, A.; Lienard, E.; Deletre, E.; Franc, M.; Martin, T.; Duvallet, G.; Jay-Robert, P. The repellency of lemongrass oil against stable flies, tested using video tracking. Parasite 2013, 20, 21. [Google Scholar] [CrossRef]
  46. Brugger, B.P.; Martinez, L.C.; Plata-Rueda, A.; de Castro e Castro, B.M.; Soares, M.A.; Wilcken, C.F.; Carvalho, A.G.; Serrao, J.E.; Zanuncio, J.C. Bioactivity of the Cymbopogon citratus (Poaceae) essential oil and its terpenoid constituents on the predatory bug, Podisus nigrispinus (Heteroptera: Pentatomidae). Sci. Rep. 2019, 9, 8358. [Google Scholar] [CrossRef]
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Figure 1. The schematic diagram of the preparation process for the emulsifiable oil formulations is shown in the graph (a), and test process for insecticidal activity is shown in the graph (b).
Figure 1. The schematic diagram of the preparation process for the emulsifiable oil formulations is shown in the graph (a), and test process for insecticidal activity is shown in the graph (b).
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Agronomy 15 01733 g002
Figure 2. The total ion chromatogram (TIC) of lemongrass essential oil (LEO), obtained via GC-MS, is presented. The first three major compounds of D-limonene, Citral, and Nera are highlighted in red.
Figure 2. The total ion chromatogram (TIC) of lemongrass essential oil (LEO), obtained via GC-MS, is presented. The first three major compounds of D-limonene, Citral, and Nera are highlighted in red.
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Agronomy 15 01733 g003
Figure 3. Mortality of Megalurothrips usitatus was recorded at different concentrations of lemongrass essential oil ethanol solution (a) and with different components (b). Different letters indicate significant differences.
Figure 3. Mortality of Megalurothrips usitatus was recorded at different concentrations of lemongrass essential oil ethanol solution (a) and with different components (b). Different letters indicate significant differences.
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Figure 4. The schematic diagram of the preparation process for the emulsifiable oil was diluted in water (a). The state of the diluted emulsifiable oil was observed at 30 s, 1 day, 7 days, 21 days, and 30 days (b).
Figure 4. The schematic diagram of the preparation process for the emulsifiable oil was diluted in water (a). The state of the diluted emulsifiable oil was observed at 30 s, 1 day, 7 days, 21 days, and 30 days (b).
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Agronomy 15 01733 g005
Figure 5. Comparison of dispersion state of emulsified oils in water (a). Adhesion state of emulsifiables concentrated on flowers (b,d) and on leaves (c). Contact angle on leaves was recorded (e,f).
Figure 5. Comparison of dispersion state of emulsified oils in water (a). Adhesion state of emulsifiables concentrated on flowers (b,d) and on leaves (c). Contact angle on leaves was recorded (e,f).
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Agronomy 15 01733 g006
Figure 6. The insecticidal activity of lemongrass essential oil emulsifiable concentrates was analyzed against M. usitatus at different dilution folds (a). The synergistic activity was evaluated by adding emamectin benzoate (b) and spinosad (c). Different letters indicate significant differences.
Figure 6. The insecticidal activity of lemongrass essential oil emulsifiable concentrates was analyzed against M. usitatus at different dilution folds (a). The synergistic activity was evaluated by adding emamectin benzoate (b) and spinosad (c). Different letters indicate significant differences.
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Table 1. The major chemical compounds of lemongrass essential oil (LEO).
Table 1. The major chemical compounds of lemongrass essential oil (LEO).
Retention TimeCompound NameMatching FactorMolecular FormulaCASArea
Ratio (%)
19.154Citral97.66C10H16O141-27-531.56
11.853D-Limonene98.14C10H165989-27-531.20
18.261Neral99.4C10H16O106-26-330.90
10.409β-Myrcene97.82C10H16123-35-31.30
8.735α-Pinene99.38C10H1680-56-80.85
9.901β-Phellandrene98.71C10H16555-10-20.51
16.1323,6-Octadienal, 3,7-dimethyl-98.43C10H16O55722-59-30.42
10.783Octanal97.41C8H16O124-13-00.26
13.693Linalool99.38C10H18O78-70-60.24
17.255(-)-cis-Isopiperitenol98.64C10H16O96555-02-10.23
22.711Caryophyllene99.42C15H2487-44-50.22
15.608Isoneral98.93C10H16O1000414-18-00.21
15.2656-Octenal, 3,7-dimethyl-, (R)-99.24C10H18O2385-77-50.21
10.002β-Pinene99.19C10H16127-91-30.16
21.9572,6,10-Dodecatrien-1-ol, 3,7,11-trimethyl-86.55C15H26O4602-84-00.14
16.3782,6-Octadienal, 3,7-dimethyl-, (E)-87.7C10H16O141-27-50.14
21.4973-Cyclohexene-1-carboxaldehyde, 1,3,4-trimethyl-86.3C10H16O40702-26-90.12
18.534Geraniol94.55C10H18O106-24-10.11
10.9973-Carene98.3C10H1613466-78-90.11
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Han, Y.; Zhu, M.; Qiu, B.; Ali, S.; Wu, J. Insecticidal Effect of Lemongrass Essential Oil Against Megalurothrips usitatus (Bagnall). Agronomy 2025, 15, 1733. https://doi.org/10.3390/agronomy15071733

AMA Style

Han Y, Zhu M, Qiu B, Ali S, Wu J. Insecticidal Effect of Lemongrass Essential Oil Against Megalurothrips usitatus (Bagnall). Agronomy. 2025; 15(7):1733. https://doi.org/10.3390/agronomy15071733

Chicago/Turabian Style

Han, Yun, Ming Zhu, Bo Qiu, Shaukat Ali, and Jianhui Wu. 2025. "Insecticidal Effect of Lemongrass Essential Oil Against Megalurothrips usitatus (Bagnall)" Agronomy 15, no. 7: 1733. https://doi.org/10.3390/agronomy15071733

APA Style

Han, Y., Zhu, M., Qiu, B., Ali, S., & Wu, J. (2025). Insecticidal Effect of Lemongrass Essential Oil Against Megalurothrips usitatus (Bagnall). Agronomy, 15(7), 1733. https://doi.org/10.3390/agronomy15071733

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