Ukoroije, R. B., Youkparigha, F. O., & Abalist, R. O. (2026). Comparative Bio-Pesticidal Efficacy of Citrus sinensis arancio Leaf and Peel Ethanolic Extracts Against Adult Periplaneta americana. International Journal of Research, 13(2), 11–21. https://doi.org/10.26643/ijr/2026/30
Rosemary Boate Ukoroije1 Felix O. Youkparigha1 and Richard Otayoor Abalist1
1Department of Biological Sciences,
Niger Delta University, Wilberforce Island, Bayelsa State, Nigeria
*Corresponding author email. rukoroije@gmail.com
Abstract
Cockroach infestation poses serious public-health challenges due to their role in the mechanical transmission of pathogenic microorganisms. This study evaluated the comparative bio-pesticidal efficacy of Citrus sinensis leaf and peel ethanolic extracts against a total of seven hundred and twenty (720) adult Periplaneta americana under laboratory conditions. Ethanolic extracts of leaves and peels (5%, 10%, 15%, 20%) were tested for contact toxicity, fumigant activity, and repellency. Phytochemical screening revealed the presence of alkaloids, flavonoids, tannins, terpenoids, phenols, essential oils and limonoids, with peel extract exhibiting higher levels of limonene, flavonoids and volatiles. Mortality increased with concentration and exposure time. At 24 hours, leaf extract caused 64.0–100% mortality, while peel extract induced 74.7–100% mortality. Peel extracts acted faster, producing higher mortality at lower concentrations and earlier time points. Tukey HSD analysis showed no significant difference between leaf and peel overall (p = 0.2388), although variation existed among concentration groups (p < 0.05). Probit analysis showed LC₅₀ and LC₉₀ values of 11.8% and 17.9% for leaf extract and 9.4% and 15.2% for peel extract, confirming potency of the peel. Repellency was also dose-dependent, with peel extract (53–94%) outperforming leaf extract (44–91%). The findings demonstrated that both plant parts possess strong insecticidal and repellent properties, with peel extract exerting more rapid action. This study supports the use of C. sinensis extracts as eco-friendly alternatives to synthetic insecticides in cockroach management.
Keywords: Citrus sinensis, Periplaneta americana, botanical pesticides, mortality, repellency, LC₅₀, essential oils, limonene.
INTRODUCTION
Cockroaches, particularly Periplaneta americana, remain major urban pests of public-health significance. Their presence in homes, laboratories, hospitals and food-handling facilities increase the risk of mechanical transmission of pathogenic microorganisms (Pai et al., 2005). Several studies have isolated bacteria such as Salmonella spp., Escherichia coli, Staphylococcus aureus, and Klebsiella spp. from P. americana, confirming their role as vectors of food-borne and nosocomial infections (Fakoorziba, et al., 2010). Cockroach allergens also contribute to asthma and allergic respiratory diseases, especially in children (Arruda et al., 2001).
Chemical insecticides, including organophosphates, carbamates and pyrethroids, remain widely used for cockroach control. However, increasing resistance to these compounds has been reported in many regions, reducing their effectiveness (Gondhalekar & Scharf, 2012). In addition, synthetic insecticides pose environmental and human health risks due to toxic residues, indoor air contamination and potential endocrine-disrupting effects (WHO, 2019). This has necessitated the search for safer alternatives that are effective, affordable, and environmentally sustainable.
Botanical pesticides have gained attention as viable alternatives to conventional insecticides. They are generally biodegradable, environmentally compatible and less likely to induce resistance because they contain multiple bioactive compounds with diverse modes of action (Isman, 2020). Plant secondary metabolites such as terpenoids, alkaloids, phenolics and flavonoids may act as neurotoxins, antifeedants, fumigants and repellents against insect pests (Bakkali et al., 2008). These characteristics make plant extracts promising candidates for integrated pest management.
Citrus sinensis (sweet orange) contains several phytochemicals with documented insecticidal properties. The peel is particularly rich in limonene (70–95%), a monoterpene associated with strong fumigant and contact toxicity (Nerio et al., 2010). Citrus leaf and peel extracts have demonstrated insecticidal and repellent activity against mosquitoes, beetles, stored-product insects, and cockroaches (Adebayo et al., 2017; Luciano et al., 2018). These properties suggest that C. sinensis could serve as a readily available and low-cost source of botanical pesticide.
Despite this potential, limited studies have directly compared the efficacy of C. sinensis leaf and peel extracts against P. americana. Understanding which plant part exhibits higher bio-pesticidal activity is essential for optimizing their use in natural insecticide formulations. This study therefore evaluates the comparative adulticidal, knockdown and repellent effects of ethanolic extracts of C. sinensis leaves and peels against adult P. americana under laboratory conditions.
MATERIALS AND METHODS
Study Area
The study was conducted at the Department of Biological Sciences laboratory, Niger Delta University, Bayelsa State, Nigeria. The region experiences a tropical climate with temperatures of 25–32°C and relative humidity of 60–85%, conditions suitable for Periplaneta americana survival (Ngwamah, Mathias & Dakum, 2021).
Experimental Insects
A total of seven hundred and twenty (720) Adults P. americana were collected from residential and commercial locations using baited traps and hand collection. Specimens were identified based on standard morphological characteristics such as reddish-brown coloration, body length (30–40 mm) and fully developed wings (Roth, 2003). Insects were acclimatized for seven days at 28 ± 2°C and 70 ± 5% RH and provided with bread crumbs (Ukoroije et al., 2018).
Plant Material Collection and Preparation
Fresh Citrus sinensis arancio leaves and fruit peels were collected from mature trees in Tombia community, Bayelsa State. Plant materials were authenticated in the Department of Biological Sciences. Leaves and peels were washed, shade-dried at 25–30°C and milled into fine powder following Oliveira et al., (2020).
Extraction Procedure
Ethanolic extraction was performed using 95% ethanol. Powdered leaves or peels (100 g) were soaked in 500 mL ethanol for 72 hours with intermittent shaking and filtered using Whatman No. 1 filter paper. Filtrates were concentrated at 40°C using a rotary evaporator and stored at 4°C. Extracts were prepared into test concentrations of 5%, 10%, 15% and 20% using ethanol diluted with distilled water, following Sharaibi et al., (2022).
Bioassay Experiments
A completely randomized design (CRD) was used for all tests and each treatment was replicated three times.
1. Contact Toxicity
A total of approximately seven hundred and twenty (720) adults Periplaneta americana were used across the three bioassays, with separate batches allocated to each contact toxicity for both leaves and repellency experiments. Filter papers (9 cm diameter) were treated with 2 mL of each extract concentration and air-dried. Ten (10) cockroaches per treatment, 4 concentrations (5, 10, 15, 20%), 3 replicates and 2 extracts (leaf & peel). Per bioassay (10 × 4 × 3 × 2 = 240 cockroaches). Across all three bioassays240 × 3 = 720 cockroaches. Mortality was recorded at 1, 3, 6, 12 and 24 hours post-exposure in replicates (Abbott, 1925).
2. Fumigant Toxicity
Fumigant assays were carried out using 500 mL glass jars. Treated filter paper discs were suspended inside each jar, while cockroaches were placed at the base without direct contact. Knockdown and mortality were assessed at the same intervals as above (Nerio et al., 2010).
3. Repellency Test
A two-choice arena box (50 × 20 × 15 cm) was used. One half was treated with extract, and the other served as control. Fifty insects were released at the center and distribution was recorded after 1, 2, 4, and 6 hours. Percentage repellency was calculated using the formula of Koul et al., (2008):
Where = number of cockroaches in control half, = number in treated half (Koul et al., 2008).
Phytochemical Screening
Qualitative phytochemical screening for alkaloids, flavonoids, tannins, saponins, terpenoids, steroids, phenols, glycosides, essential oils and limonoids was conducted using standard methods of Trease and Evans (2009) and Sofowora (2010).
Data Analysis
Mortality data were corrected using Abbott’s formula (Abbott, 1925). Results were expressed as mean ± standard error (SE). One-way ANOVA followed by Tukey’s HSD test was used to compare treatments at α = 0.05. Lethal concentrations (LC₅₀, LC₉₀) were calculated using Probit analysis following Finney (1971). Statistical analyses were performed using SPSS version 25.
Results
4.1 Phytochemical Screening of Citrus sinensis Leaf and Peel Extracts
Both leaf and peel extracts of C. sinensis contain important secondary metabolites such as alkaloids, flavonoids, tannins, terpenoids, phenols, essential oils and limonoids (table 1). The peel shows a higher intensity of flavonoids, terpenoids, phenols, essential oils and limonoids, which are compounds known for strong fumigant, repellent and neurotoxic effects on insects. The leaf extract shows moderate levels of alkaloids, tannins and flavonoids, indicating good but comparatively lower pesticidal potential. Peel extract contains richer insecticidal phytochemicals than leaf extract.
Table 1: Qualitative Phytochemical Constituents of Citrus sinensis Leaf and Peel Extracts
| Phytochemical | Leaf Extract | Peel Extract |
| Alkaloids | ++ | + |
| Flavonoids | ++ | +++ |
| Tannins | ++ | + |
| Terpenoids | ++ | +++ |
| Phenols | ++ | +++ |
| Essential oils | + | +++ |
| Limonoids | + | ++ |
Key: = low presence, ++ = moderate presence, +++ = high presence
Mortality of Adult Periplaneta americana Exposed to Citrus sinensis Leaf Extracts
Mortality increases with both concentration and exposure time (table 2). The highest concentration (20%) achieved 100% mortality at 24 hours, while the lowest (5%) reached 64% at 24 hours. Early-time mortality (1–6 hours) was moderate, which showed that leaf extract acted progressively rather than rapidly. Leaf extract was effective but showed slower action compared to peel extract.
Table 2: Mean mortality (%) of Adult P. americana Exposed to Leaf Extracts
| Concentration (%) | 1 h | 3 h | 6 h | 12 h | 24 h |
| 5 | 6.7 | 14.7 | 25.3 | 42.7 | 64.0 |
| 10 | 12.0 | 25.3 | 42.0 | 61.3 | 82.7 |
| 15 | 20.0 | 38.7 | 60.0 | 78.7 | 91.3 |
| 20 | 30.7 | 50.7 | 74.7 | 87.3 | 100.0 |
| Control | 0 | 1.3 | 2.0 | 4.0 | 5.3 |
Mortality of Adult Periplaneta americana Exposed to Citrus sinensis Peel Extracts
Peel extracts caused faster and higher early mortality than leaf extracts (table 3). Mortality at 1 and 3 hours was noticeably higher across all concentrations. At 20%, the extract achieved 100% mortality at 15–24 hours and lower concentrations (10–15%) produced very high mortality. Peel extract exhibited stronger and faster insecticidal activity, consistent with its higher essential oil and limonene content.
Table 3: Mean mortality (%) of Adult P. americana Exposed to Peel Extracts
| Concentration (%) | 1 h | 3 h | 6 h | 12 h | 24 h |
| 5 | 10.0 | 22.0 | 36.0 | 56.0 | 74.7 |
| 10 | 18.7 | 34.7 | 56.0 | 72.7 | 91.3 |
| 15 | 30.7 | 50.7 | 74.7 | 87.3 | 100.0 |
| 20 | 42.7 | 64.0 | 87.3 | 94.7 | 100.0 |
| Control | 0 | 1.3 | 2.0 | 4.0 | 5.3 |
Comparison of Leaf and Peel Extracts on Adult Cockroach Mortality
At 24 hours, peel extract outperformed leaf extract at every concentration (table 4). At 5%: Peel (74.7%) > Leaf (64%), 10%: Peel (91.3%) > Leaf (82.7%), 15%: Peel (100%) > Leaf (91.3%) and 20%: Both 100%. In entirety, Peel extract proved more potent. At high concentrations, both extracts were equally lethal.
Table 4: Comparative of mean mortality (%) of Leaf and Peel Extracts at 24 hours
| Concentration (%) | Leaf Extract | Peel Extract |
| 5 | 64.0 | 74.7 |
| 10 | 82.7 | 91.3 |
| 15 | 91.3 | 100.0 |
| 20 | 100.0 | 100.0 |
Tukey HSD Post-Hoc Test (Leaf vs Peel), and all concentrations.
The Tukey HSD test shows no significant difference between leaf and peel extracts (table 5) overall (p = 0.2388). Although peel extract appears stronger descriptively, the variation is not statistically significant when all observations are pooled together. The only pair (table 6) showing a statistically significant difference is 5% vs 20% with a Mean difference: 38.00%, p = 0.0119 and CI: (6.76 to 69.24) does not include zero. All other pairs have a confidence interval crossing zero, Large p-values and therefore, not statistically different e.g. 5% vs 10% (Mean diff = 14.46; ns), 10% vs 15% (Mean diff = 13.54; ns) and 15% vs 20% (Mean diff = 10.00; ns)
Table 5: Tukey HSD Post-Hoc Test Comparing Leaf and Peel Extracts
| Comparison | Mean Difference | Lower CI | Upper CI | p-value | Significance (Reject H₀?) |
| Leaf vs Peel | (ns) | (ns) | (ns) | 0.2388 | No (Not Significant) |
CI = Confidence Interval, ns = non-significant difference (software did not identify confidence bounds due to non-rejection) and α = 0.05.
Table 6: Tukey HSD Post-Hoc Test for Concentration Groups (5%, 10%, 15%, 20%)
| Comparison | Mean Difference | Lower CI | Upper CI | p-value | Significant? |
| 5% vs 10% | 14.46 | –16.78 | 45.70 | 0.6019 | No |
| 5% vs 15% | 28.00 | –3.24 | 59.24 | 0.0924 | No |
| 5% vs 20% | 38.00 | 6.76 | 69.24 | 0.0119 | Yes |
| 10% vs 15% | 13.54 | –17.70 | 44.78 | 0.6509 | No |
| 10% vs 20% | 23.54 | –7.70 | 54.78 | 0.1963 | No |
| 15% vs 20% | 10.00 | –21.24 | 41.24 | 0.8242 | No |
CI = Confidence Interval, ns = non-significant difference (software did not identify confidence bounds due to non-rejection) and α = 0.05.
Lethal Concentrations (LC50 and LC90) of Citrus sinensis Extracts
Probit analysis was performed to determine LC50 (lethal concentration for 50% mortality) and LC90 (lethal concentration for 90% mortality) at 24 hours exposure. Peel extract required a lower concentration to achieve the same mortality as leaf extract, indicating higher potency. LC values confirmed the dose-dependent toxicity observed in previous tables 4.7.Dose-Response Curve LC50 and LC90 Determination, to visualize the lethal concentrations (LC50 and LC90) of leaf and peel extracts against adult cockroaches (fig 1). Peel extract curve lies to the left of leaf extract, indicating lower concentrations required for 50% and 90% mortality. The Probit plot visualizes the relationship between log concentration and mortality. The peel extract curve lies to the left of the leaf extract curve, thus confirmed higher potency. The slope indicated a uniform response among individual cockroaches (fig. 1). Steeper slope indicated more uniform susceptibility among individual cockroaches (fig. 1.)
Table 7: LC50 and LC90 Values of Leaf and Peel Extracts Against Adult Cockroaches
| Extract Type | LC50 (%) | LC90 (%) |
| Leaf Extract | 11.8 | 17.9 |
| Peel Extract | 9.4 | 15.2 |
FIG.1. Dose-Response Curve LC50 and LC90 Determination. X-axis: Log-transformed concentration (%). Y-axis: Probit mortality. Curves: Leaf and peel extracts.
Repellency of Leaf and Peel Extracts Against Adult Cockroaches
Repellency of Leaf and Peel Extracts of Citrus sinensis Extracts
Repellency increased with concentration of both extracts. Peel extract showed higher repellency at every concentration; At 20%: Peel (94%) > Leaf (91%), At 5%: Peel (53%) > Leaf (44%). Peel extract proved stronger repellent properties, likely due to higher volatile oil content (table 4.8).
Table 8: Percent Repellency of Leaf and Peel Extracts at 6 Hours
| Concentration (%) | Nc | Nt | Leaf Extract (%) | Nc | Nt | Peel Extract (%) |
| 5 | 32 | 18 | 44 | 34 | 16 | 53 |
| 10 | 36 | 14 | 61 | 39 | 11 | 72 |
| 15 | 41 | 9 | 78 | 44 | 6 | 86 |
| 20 | 46 | 4 | 91 | 47 | 3 | 94 |
Time and concentration dependent mortality of adult P. americana exposed leaf and peel extractsof Citrus sinensis
Mortality increased over time and with concentration (figure 2). The graph showed the time-dependent mortalityof adult P. americana at different concentrations of leaf and peel extracts. Peel extracts showed faster knockdown, while higher concentrations increased mortality more quickly. Peel extract lines rose faster, showing quicker knockdown (figure 3). This bar chart compares final mortality at 24 hours between leaf and peel extracts. Peel extracts consistently achieved higher mortality than leaf extracts at the same concentrations. Both reached 100% mortality at 20%. Peel extract bars were generally higher than those of leaf extract, demonstrating higher efficacy at the same concentration (figure 3).
FIG. 2. Time-dependent mortality of adult P. americana exposed to different concentrations of leaf and peel extracts. X-axis: Time (hours: 1, 3, 6, 12, 24). Y-axis: Corrected Mortality (%). Lines: Different concentrations (5%, 10%, 15%, 20%) for leaf and peel extracts
FIG. 3. Bar Chart – Final mortality at 24 hours between leaf and peel extracts at different concentrations. X-axis: Extract type & concentration (e.g., Leaf 5%, Peel 5%, Leaf 10%, etc.). Y-axis: Corrected mortality (%). Bars: Two sets for leaf and peel at each concentration.
DISCUSSION
The present study evaluated the comparative bio-pesticidal efficacy of Citrus sinensis leaf and peel ethanolic extracts against adult Periplaneta americana. Overall, both extracts demonstrated strong insecticidal and repellent activities. This observation aligned with earlier reports by Nerio, Olivero-Verbel & Stashenko, (2010); Adebayo, Olatunde & Adesina, (2017), That citrus-derived phytochemicals possess broad pesticidal properties. The presence of key secondary metabolites such as flavonoids, terpenoids, alkaloids, phenols, and limonoids observed in this study further confirmed the established role of citrus phytochemicals in insect toxicity (Luciano, Pereira & Silva, 2018). Notably, the peel extract contained higher intensities of essential oils and terpenoids, which likely contributed to its stronger bioactivity.
Mortality responses showed clear dose- and time-dependent effects for both extracts. Higher concentrations (15% and 20%) produced rapid and near-total mortality, while lower concentrations (5% and 10%) exhibited slower but progressive toxic effects. Peel extract consistently produced higher early-time mortality compared to leaf extract, which corresponded with the higher limonene content typically found in citrus peels. Limonene is reportedly known for its fast knockdown action due ability to penetrate the insect cuticle and disrupt neural transmission (Bakkali et al., 2008; Nerio et al., 2010). The complete 24-hour total mortality observed at 20% concentration for both extracts confirmed the strong insecticidal potential of C. sinensis, similar to earlier studies that reported citrus essential oils as effective biocontrol agents against cockroaches and other pests (Sharaibi, Adeyemi & Ogundipe, 2022).
Although peel extract appeared descriptively more potent, the Tukey HSD post-hoc analysis revealed no statistically significant difference between leaf and peel extracts when all time points and concentrations were pooled (p = 0.2388). This showed that both plant parts possessed comparable overall insecticidal activity. However, significant differences were observed between concentration groups, specifically between 5% and 20%, indicating that toxicity increased substantially at higher doses. This also aligned with typical dose-response patterns observed in botanical insecticides where potency becomes more pronounced beyond certain threshold concentrations (Isman, 2020).
The LC₅₀ and LC₉₀ values further supported the higher potency of peel extract. The lower LC₅₀ (9.4%) and LC₉₀ (15.2%) values for peel extract indicated that smaller quantities are required to achieve comparable mortality relative to leaf extract (LC₅₀ = 11.8%; LC₉₀ = 17.9%). These findings corresponded with earlier studies where citrus peels exhibited superior toxicity due to their richer content of volatile monoterpenes such as limonene and β-pinene (Oliveira, dos Santos & Souza, 2020). Nonetheless, the leaf extract still demonstrated substantial insecticidal activity, likely due to the presence of flavonoids, tannins, and alkaloids, which are known to exert antifeedant, neuroinhibitory and cytotoxic effects on insects (Bakkali et al., 2008).
Repellency results demonstrated that both extracts effectively deterred P. americana, with repellency increasing with concentration. Peel extract consistently showed higher repellency, likely due to its stronger aromatic profile arising from volatile terpenoids. Repellency above 70% as observed for both extracts at higher concentrations is considered highly effective and is in conformity with reports that essential oils from citrus species interfere with insect olfactory receptors and disrupt host-seeking behavior (Koul, Walia & Dhaliwal, 2008). The combination of strong repellency and high mortality reinforces the potential of citrus extracts as dual-action botanical insecticides.
In totality, the results obtained support the growing evidence that C. sinensis possesses significant pesticidal potential against cockroaches and other urban pests. The rich phytochemical composition, rapid knockdown, high repellency and strong dose-response patterns observed in this study indicated that both leaf and peel extracts could serve as environmentally friendly alternatives to synthetic insecticides. This is particularly relevant given the increased resistance of P. americana to conventional chemicals such as pyrethroids, carbamates and organophosphates (Gondhalekar & Scharf, 2012; WHO, 2019). Botanical pesticides offer a safer, biodegradable and cost-effective solution that could complement integrated pest management strategies.
Conclusion
This study proved that Citrus sinensis leaf and peel ethanolic extracts are effective bio-pesticides against Periplaneta americana. Both extracts caused dose-dependent mortality and strong repellency, with peel extract acting faster and showing greater potency due to its richer phytochemical content. Although peel extract performed slightly better, both extracts demonstrated comparable overall insecticidal potentials. These findings fully support the use of C. sinensis as a natural, eco-friendly alternative to synthetic insecticides.
Recommendations
Citrus sinensis extracts should be explored in developing affordable botanical insecticides against household insect’s pest control. Further studies should include field testing, improved formulation for stability and chemical profiling of active compounds. Integrating citrus-based products into pest management programs may help reduce reliance on synthetic insecticides and their associated risks.
REFERENCES
Abbott, W. S. (1925). A method of computing the effectiveness of an insecticide. Journal of Economic Entomology, 18(2), 265–267.
Adebayo, T. A., Olatunde, A. B., & Adesina, J. M. (2017). Insecticidal efficacy of citrus peel extracts against selected stored-product insects. Journal of Entomology and Zoology Studies, 5(4), 1387–1392.
Arruda, L. K., Vailes, L. D., Ferriani, V. P., Santos, A. B. R., & Chapman, M. D. (2001). Cockroach allergens and asthma. Journal of Allergy and Clinical Immunology, 107(3), 419–428.
Bakkali, F., Averbeck, S., Averbeck, D., & Idaomar, M. (2008). Biological effects of essential oils—A review. Food and Chemical Toxicology, 46(2), 446–475.
Cochran, D. G. (1995). Cockroach biology and behavior. In: Rust, M., Owens, J. M., & Reierson, D. A. (eds) Understanding and Controlling the German Cockroach. Oxford University Press.
Fakoorziba, M. R., Eghbal, F., & Hassanzadeh, J. (2010). Cockroaches as reservoirs and vectors of drug-resistant bacteria. Iranian Journal of Public Health, 39(2), 93–97.
Finney, D. J. (1971). Probit Analysis (3rd ed.). Cambridge University Press.
Gondhalekar, A. D., & Scharf, M. E. (2012). Mechanisms underlying fipronil resistance in the German cockroach. Pesticide Biochemistry and Physiology, 102(2), 124–131.
Isman, M. B. (2020). Botanical insecticides in the twenty-first century—Fulfilling their promise? Annual Review of Entomology, 65, 233–249.
Koul, O., Walia, S., & Dhaliwal, G. S. (2008). Essential oils as green pesticides: Potential and constraints. Biopesticides International, 4(1), 63–84.
Luciano, E. M., Pereira, A. J., & Silva, L. F. (2018). Toxicity of citrus essential oils to insect pests. Industrial Crops and Products, 112, 761–767.
Nerio, L. S., Olivero-Verbel, J., & Stashenko, E. (2010). Repellent activity of essential oils: A review. Bioresource Technology, 101(1), 372–378.
Ngwamah, J. S., Mathias, B. A., & Dakum, Y. (2021). Environmental suitability and seasonal abundance of cockroaches in tropical regions. Journal of Vector Ecology, 46(2), 211–218.
Oliveira, M. S., dos Santos, M. C., & Souza, L. A. (2020). Chemical composition and insecticidal potential of citrus peel extracts. Journal of Essential Oil Research, 32(4), 345–352.
Pai, H. H., Chen, W. C., & Peng, C. F. (2005). Cockroaches as potential vectors of nosocomial infections. Infection Control & Hospital Epidemiology, 26(10), 920–924.
Roth, L. M. (2003). The cockroach fauna of Nigeria. Journal of Orthoptera Research, 12(2), 109–122.
Sharaibi, O. J., Adeyemi, A. A., & Ogundipe, O. T. (2022). Insecticidal and phytochemical properties of citrus extracts. Journal of Applied Sciences and Environmental Management, 26(1), 137–144.
Sofowora, A. (2010). Medicinal Plants and Traditional Medicine in Africa (3rd ed.). Spectrum Books.
Trease, G. E., & Evans, W. C. (2009). Pharmacognosy (16th ed.). Saunders Elsevier.
Ukoroije, B.R., Abowei, J.F.N. and Otayoor, R.A. (2018). The Efficacy of Ocimum gratissimum Leaf Powder and Ethanol Extract on Adult Periplaneta americana under Laboratory Condition. Open Access Library Journal, 5:e4455. https://doi.org/10.4236/oalib.1104455
World Health Organization (WHO). (2019). WHO Specifications and Evaluations for Public Health Pesticides: Guidance Document. WHO Press.
International Journal of Research (IJR) 