Insecticidal plant oil’s toxicity activities on the larval and adult stages of a major malaria vector (Anopheles gambiae Giles 1920)

doi:10.21203/rs.3.rs-2327938/v1

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Insecticidal plant oil’s toxicity activities on the larval and adult stages of a major malaria vector (Anopheles gambiae Giles 1920)

https://doi.org/10.21203/rs.3.rs-2327938/v1

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published 09 Mar, 2023

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Despite increasing reports and concerns about resistance development to public-health insecticides in malaria vectors, significant steps have been put into the quest for novel strategies to disrupt the disease transmission cycle by targeting insect vectors hence sustaining vector management. This study evaluates the toxicity potential of oils of insecticidal plants shortlisted in an ethnobotanical survey on the larvae and adult stages of Anopheles gambiae. Oils from leaves of Hyptis suaveolens, Ocimum gratissimum, Nicotiana tabacum, Ageratum conyzoides and fruit-peel of Citrus sinensis were extracted by steam-distillation using a Clevenger apparatus. Larvae and female adults of deltamethrin-susceptible Anopheles gambiae were gotten from an already established colony in the Entomological Research Laboratory, University of Ilorin. Twenty-five third instar stage larvae were used for larvicidal assays while twenty 2-5 days old adults were used for the adulticidal assays in five replicates. A. gambiae exposed to H. suaveolens and C. sinensis demonstrated significantly higher larval toxicity (94.7-100%) after 24 hours. At 48 hours, the mortality induced by the oils of the four plants peaked at 100%. N. tabacum (0.50 mg/ml) induced the highest percentage of adult mortality (100%) on A. gambiae which was compared favourably with the positive control Deltamethrin (0.05%). The lowest KdT₅₀ was observed with 0.25 mg/ml of N. tabacum (20.3 minutes) while the lowest KdT₉₅ was observed with 0.10mg/ml of A. conyzoides (35.97 mins) against adult A. gambiae. The significant larval and adult mortality rates, lower lethal concentration and knockdown times demonstrated by the evaluated plant oils showed promising outcomes that can be further developed for vector control management.

Anopheles gambiae

Plant oils

Toxicity

Mortality

Mosquito-borne disease burdens account for seventeen percent of all infectious diseases and seven hundred thousand deaths yearly (WHO 2019). Malaria, whose mosquito vector is Anopheles spp., frank the highest with approximately 229 million cases in 2021 resulting in 409,000 deaths globally, 95% of which occurred in Africa and 23% in Nigeria (WHO 2021).

In Nigeria, Anopheles gambiae s.l. (Giles); is a complex with numerous sibling species including A. gambiae, A. arabiensis, A. coluzzii, A. quadriannulatus, A. amharicus, A. bwambae, A. merus and A. melas have been documented as malaria vectors. The first three sibling species have however been incriminated as responsible for the high malaria transmission, morbidity and mortality statistics in Nigeria (Okorie et al. 2011; Olayemi et al. 2011; Oduola et al. 2016; Obi et al. 2017).

The prime choice mosquito control tactic in Africa remains the selective application of residual synthetic insecticides through either Indoor Residual Spraying (IRS) or Long-Lasting Insecticide Nets (LLIN) use (WHO 2019). To this end, Pyrethroids are members of the prequalified classes of the active ingredients of the World Health Organisation (WHO) vector control product (Omotayo et al. 2021; WHO 2021; Ande et al. 2022). However, insecticide resistance development in mosquitoes poses a serious threat to sustainable synthetic insecticide-based vector control programmes in many African countries (Youmsi et al. 2017; Oduola et al. 2019) and necessitates the search for natural, sustainable and eco-friendly alternatives.

Cultural practices over the years coupled with research outputs have shown that plants are rich sources of active constituents that have been used successfully and persistently against mosquitoes (Youmsi et al. 2017; Ogban et al. 2020; Adelaja et al. 2021). In many rural communities in Africa, plants are being used efficiently for the management of insects of concern including mosquitoes (Karunamoorthi et al. 2009; Nzelibe and Chintem 2015) and they have been reported to be readily accessible, available, affordable and biodegradable (Kamaraj et al. 2010). Plants, therefore, constitute a potential source of natural and sustainable agents that will stand the test of time as mosquito control agents.

In Nigeria, numerous plants and plant parts have been reportedly used in the management of larvae or adult mosquitoes across various cultures and over the years (Ivoke et al. 2009; Mgbemena 2010; Okigbo et al. 2010; Ileke et al. 2015; Musa et al. 2015; Nzelibe and Chintem 2015; Ayange-Kaa et al. 2015; Owoeye et al. 2016; Adelaja et al. 2021). The potentials and modes of action of these plants have been scientifically validated through research reports (Ogban et al. 2020; Adelaja et al. 2021). Crude extracts of some of such plants reported include Ageratum conyzoides (L.), Hyptis suaveolens (L.), Ocimum gratissimum (L.) and Nicotiana tabacum (L.) (Ivoke et al. 2009; Mgbemena 2010; Okigbo et al. 2010; Ileke et al. 2015; Musa et al. 2015; Nzelibe and Chintem 2015; Ayange-Kaa et al. 2015; Owoeye et al. 2016; Adelaja et al. 2021). There is however a dearth of knowledge in respect of the toxicity potentials of the oils obtained from each of these botanicals and Citrus sinensis (L.) against A. gambiae. This study, therefore, provides valuable baseline information on the toxicity potentials of each of the above-mentioned plant oils on A. gambiae.

Plant Materials, Oil Extraction and Serial Dilution Procedures

The leaves of Hyptis suaveolens (Lamiaceae), Ocimum gratissimum (Lamiaceae), Nicotiana tabacum (Solanaceae), Ageratum conyzoides (Asteraceae) and fruit peel of Citrus sinensis (Rutaceae) previously identified as most frequently used insecticidal plants from an ethnobotanical survey carried out among locals from different villages in North-central Nigeria (Adelaja et al. 2021) were sourced individually from fresh growing plants around Ilorin. Each collection was identified at the herbarium of the Plant Biology Department by accessory detail and air dried under shade for one week before hydro-distillation. The respective plant oils obtained from each pulverized plant sample were isolated by steam-distillation using a Clevenger apparatus. Each isolated oil was dried over anhydrous sodium sulphate and stored in amber-coloured vials at 4⁰C until required for subsequent assays. Each of the five plant oils to be evaluated was serially diluted using technical grade acetone into eight concentrations, viz: 5% (vol: vol) – 0.05mg/ml, 10% (vol: vol) – 0.10 mg/ml, 15% (vol: vol) – 0.15 mg/ml, 20% (vol: vol) – 0.20mg/ml, 25% (vol: vol) – 0.25 mg/ml, 30% (vol: vol) – 0.30 mg/ml, 40% (vol: vol) – 0.40 mg/ml and 50% (vol: vol) – 0.50 mg/ml. These concentrations were determined based on previously unpublished data.

Mosquito Collection And Rearing

The larvae and female adults of deltamethrin susceptible Anopheles gambiae mosquitoes were gotten from an already established colony at the insectary of the Entomological Research Laboratory, University of Ilorin which was maintained at 27 ± 20^oC and 85 ± 5% RH. Mosquito larvae were fed a diet of non-fatty biscuits mixed with yeast at a ratio of 3:1 while emerged adults were confined in adult holding cages (50 x 50 x 50cm) and provided with a 10% sugar solution. Adult mosquitoes were sorted into males and females using morphological keys by Gillies and DeMeillon (1987).

Larvicidal Bioassay

The larvicidal activity of each of the plant oils at each of the serial dilution concentrations was evaluated according to the protocol of the World Health Organisation (WHO 2005) with slight modifications. Twenty-five (25) third instar larvae of A. gambiae mosquitoes were introduced into test cups containing 100ml of distilled water and allowed to acclimatise for 1 hour. After which 2ml of the various plant oil concentrations described earlier were introduced. Distilled water with and without acetone was used as negative and positive controls respectively. The number of dead larvae was recorded after 24 and 48 hours of exposure and the percentage mean mortality was calculated. The larvae were considered dead if they did not move when prodded with a needle in the siphon or cervical region. Each treatment was tested in five replicates. If the negative control mortality was between 5% and 20%, the mortalities of treated groups were corrected according to Abbott’s formula (Abbott 1925).

Adulticidal Bioassay

The adulticidal activity of the plant oils was evaluated against female adult A. gambiae mosquitoes following the World Health Organisation standard method (WHO 2013) with slight modifications. Two and a half millilitres (2.5 ml) of oil dilution concentration to be tested was impregnated on 12 × 15 cm Whatman paper (Dua et al. 2008). Deltamethrin (0.05%) was used as the positive control while acetone was used as the negative control. The impregnated papers were air-dried for 5 min and then inserted to line the interior of the exposure tube in the WHO test kit. Twenty (20), 2-5-day-old, blood-starved adult female mosquitoes were introduced into the holding tube and held for 1h to acclimatize. The mosquitoes were transferred gently into the exposure tube and knocked down was monitored and determined for 60 minutes and percentage knockdown was calculated afterwards. After 1 hour in the exposure tube, all mosquitoes were gently transferred back to the holding tube for recovery. A small ball of cotton wool soaked with 10% glucose solution was placed on the mesh screen for recovering mosquitoes to feed on. The number of dead mosquitoes was recorded at the end of the 24 hours recovery period, and the percentage of mortality was calculated. The bioassay was replicated five times. If the negative control mortality was between 5% and 20%, the mortalities of treated groups were corrected according to Abbott’s formula (Abbott 1925).

Data Analysis

Percentage knockdown and mortality were calculated using the formulae below:

$\text{%} \text{K}\text{n}\text{o}\text{c}\text{k} \text{D}\text{o}\text{w}\text{n}=\frac{\text{T}\text{o}\text{t}\text{a}\text{l} \text{n}\text{u}\text{m}\text{b}\text{e}\text{r} \text{o}\text{f} \text{k}\text{n}\text{o}\text{c}\text{k}\text{d}\text{o}\text{w}\text{n} \text{m}\text{o}\text{s}\text{q}\text{u}\text{i}\text{t}\text{o}\text{e}\text{s} \text{a}\text{f}\text{t}\text{e}\text{r} 60 \text{m}\text{i}\text{n}\text{u}\text{t}\text{e}\text{s} }{\text{T}\text{o}\text{t}\text{a}\text{l} \text{n}\text{u}\text{m}\text{b}\text{e}\text{r} \text{o}\text{f} \text{e}\text{x}\text{p}\text{o}\text{s}\text{e}\text{d} \text{m}\text{o}\text{s}\text{q}\text{u}\text{i}\text{t}\text{o}\text{e}\text{s}}$ X 100.

$$\text{%} \text{M}\text{o}\text{r}\text{t}\text{a}\text{l}\text{i}\text{t}\text{y}= \frac{\text{T}\text{o}\text{t}\text{a}\text{l} \text{n}\text{u}\text{m}\text{b}\text{e}\text{r} \text{o}\text{f} \text{d}\text{e}\text{a}\text{d} \text{m}\text{o}\text{s}\text{q}\text{u}\text{i}\text{t}\text{o}\text{e}\text{s} \text{a}\text{f}\text{t}\text{e}\text{r} 24 \text{h}\text{r}\text{s}}{\text{T}\text{o}\text{t}\text{a}\text{l} \text{n}\text{u}\text{m}\text{b}\text{e}\text{r} \text{o}\text{f} \text{e}\text{x}\text{p}\text{o}\text{s}\text{e}\text{d} \text{m}\text{o}\text{s}\text{q}\text{u}\text{i}\text{t}\text{o}\text{e}\text{s}} \times 100$$

One-way Analysis of Variance (ANOVA) was used to assess larval and adult mortalities after varying ranges of exposures and Tukey’s HSD post hoc test was used to separate the means (P < 0.05). Statistical differences between plant oil, varying concentrations and exposure times were determined using Two-way ANOVA. Based on mortality data, the KdT₅₀ and KdT₉₅ as well as LT₅₀ values for successive plant oil concentrations were determined using probit analysis (Finney 1971). Probit regression analysis (Finney 1971) was also utilised to calculate the LC₅₀ and LC₉₀ values based on mortality data. All statistical analyses were performed with the aid of GraphPad Prism 8 software.

Larvicidal Activity

The mean larval mortality rates of A. gambiae exposed to various concentrations of each of the extracted plant oils and their LC₅₀. and LC₉₀ values are shown in Table 1. All plant oils were distinctly potent as toxicants against the third instar larvae with statistically different mortality rates (P < 0.05) even at the lowest plant oil application concentration of 0.05mg/ml. It was also observed that toxicity intensity was concentration dependent meaning as concentration increased, mortality rates increased.

After a 24-hour exposure period, there was no significant difference (P > 0.05) in the mean larval mortalities of the A. gambiae mosquitoes exposed to H. suaveolens (100%, 100%, 100%) and C. sinensis (94.7%, 100%, 100%), and also between N. tabacum (78.7%, 89.3%, 100%) and A. conyzoides (81.3%, 90.7%, 100%) at 0.30, 0.40 and 0.50 mg/ml respectively. However, the mean larval mortalities in A. gambiae mosquitoes exposed to these two groups of plant oils were significantly higher (P < 0.05) when compared to mortalities (58.7%, 60.0% and 65.3%) observed in A. gambiae mosquitoes exposed to O. gratissimum at the three concentrations. (Table 1).

After the 48-hour exposure period, mean larval mortality was 100% in A. gambiae exposed to 0.20 mg/ml of H. suaveolens, 0.30 mg/ml of C. sinensis, N. tabacum and A. conyzoides. The highest mortality (84.0%) in A. gambiae mosquitoes exposed to O. gratissimum occurred at 0.50 mg/ml. The percentage mortality observed in A. gambiae mosquitoes exposed to H. suaveolens at 0.20 mg/ml was significantly higher (P < 0.05) when compared to mortalities observed in A. gambiae mosquitoes exposed to C. sinensis, N. tabacum and A. conyzoides (85.3%, 69.3%, 78.7% respectively) at the same concentration. The mean larval mortalities of A. gambiae mosquitoes exposed to O. gratissimum were significantly lower (P < 0.05) than that of other plant oils at all concentrations (Table 1).

The LC₅₀ measurements indicated that C. sinensis (0.14 mg/ml) was more toxic at 24 hours of exposure compared to O. gratissimum (0.22 mg/ml), H. suaveolens (0.24 mg/ml) and N. tabacum (0.26 mg/ml). However, at both 24- and 48-hours exposure, H. suaveolens showed lower LC₉₀ (0.32 mg/ml, 0.22 mg/ml) larval toxicity when compared with oils of C. sinensis (0.37 mg/ml, 0.29 mg/ml), N. tabacum (0.76 mg/ml, 0.31mg/ml), A. conyzoides (NA, 0.42 mg/ml) and O. gratissimum (0.32 mg/ml, 0.51 mg/ml) (Table 1).

The lethal median time (LT₅₀) values of varying concentrations of the plant oils evaluated are shown in Table 2. The LT₅₀ values ranged from 17.1 to 6.7 h for Hyptis suaveolens, 24.7 to 6.7 h for Citrus sinensis, 22.6 to 7.4 h for Ocimum gratissimum, 15.6 to 8.5 h for Nicotiana tabacum and 17.5 to 8.5 h for Ageratum conyzoides. The lowest LT₅₀ values recorded for all the plant oils were in the highest concentration (0.5 mg.ml). Meanwhile, the highest LT₅₀ was recorded in 0.15 mg/ml for Hyptis suaveolens (17.1 h) and Ocimum gratissimum (22.6 h), 0.1 mg/ml for Nicotiana tabacum (15.6 h) and 0.05 mg/ml for Citrus sinensis (24.7 h) and Ageratum conyzoides (17.5 h).

Adulticidal Activity

Figure 1 shows the adulticidal activity of various concentrations of the extracted plant oils against A. gambiae after 24 hrs exposure and Table 3 shows the percentage knockdown after one hour and their LC₅₀. and LC₉₀ values. All plant oils were distinctly potent as toxicants against the female adult A. gambiae with statistically different mortality rates (P < 0.05) even at the lowest plant oil application concentration of 0.05 mg/ml. It was also observed that toxicity intensity was concentration dependent meaning as concentration increased, mortality rates increased also (Fig. 1).

N. tabacum at 0.50 mg/ml induced the highest percentage mortality (100%) on A. gambiae which was compared favourably with Deltamethrin (0.05%), a positive experimental control insecticide. Also, exposure of A. gambiae to O. gratissimum at 0.40 and 0.50 mg/ml and N. tabacum at 0.40 mg/ml) resulted in a minimum of 75%, 85% and 80% mortalities, respectively. The lowest percentage of mortality was recorded at 0.05 mg/ml of A. conyzoides (3.3%) (Fig. 1).

The lowest KdT₅₀ was recorded with N. tabacum at 0.25 mg/ml (20.3 mins) followed by O. gratissimum at 0.30 mg/ml (22.93 mins), while the highest KdT₅₀ was recorded with C. sinensis at 0.05 mg/ml (75.56 mins) followed by H. suaveolens at 0.30 mg/ml (73.25 mins). Meanwhile, the lowest KdT₉₅ was recorded with A. conyzoides at 0.10 mg/ml (35.97 mins) and 0.05 mg/ml (45.27 mins) followed by O. gratissimum at 0.30 mg/ml (48.11 mins) while the highest was recorded with N. tabacum at 0.20 mg/ml (313.1 mins) followed by C. sinensis at 0.05 mg/ml (288.9 mins) and 0.30 mg/ml (267.5 mins) (Table 3).

Mosquito larvicidal efficacy of plant oils and extracts varies according to plant species, the part of the plant, the geographical location where the plant is grown and application methods (Ghosh and Chowdhury 2012; Adelaja et al. 2021). The current study investigated the toxicity potentials of the following shortlisted plants: H. suaveolens, C. sinensis, O. gratissimum, N. tabacum and A. conyzoides against a major malaria vector, A. gambiae.

The 100% A. gambiae larvae mortally recorded with 0.30 mg/ml concentration of H. suaveolens, 0.40 mg/ml concentration of C. sinensis and 0.50 mg/ml concentrations of N. tabacum and A. conyzoides after 24 hours as well as 0.20 mg/ml concentration of H. suaveolens and 0.30 mg/ml concentrations of C. sinensis, N. tabacum and A. conyzoides after 48 hours compared favourably with Kavendan et al. (2014) and Bobbo et al. (2016) where H. suaveolens caused high mortalities against A. gambiae mosquito larvae after 24 hours post-exposure. Similarly, Musa et al. (2015) reported that A. conyzoides evoked 92.0% and 87.5% mortality respectively against A. gambiae after 24hrs of exposure while Ileke et al. (2015) reported that N. tabacum elicited high mortality to the larvae of A. gambiae. Hence, oils from H. suaveolens, C. sinensis, N. tabacum and A. conyzoides could be considered and adopted as natural larvicides for the management of Anopheles mosquitoes in malarious areas where breeding sites can easily be identified and accessed. However, it was observed that all the concentrations of O. gratissimum oils tested elicited lower larvicidal activities against A. gambiae larvae and may therefore not be a promising larvicidal agent. Meanwhile, the lowest LC₅₀ and LC₉₀ (after 24- and 48-hours exposure) against A. gambiae larvae were recorded in oil from C. sinensis and H. suaveolens. Oils from C. sinensis and H. suaveolens displayed the highest mortality at the lowest concentrations echoing their potential as good larvicides that should be considered for the management of Anopheles mosquitoes locally.

In this study, N. tabacum at 0.50 mg/ml recorded a hundred percent mortality within a one-hour test period on adult A. gambiae comparing favourably with the Deltamethrin positive control. Similarly, Owoeye et al. (2016) and Ileke et al. (2015) have reported the toxicity of N. tabacum against adult A. gambiae within a one-hour test period. The lowest KdT₅₀ against A. gambiae was recorded in 0.25 mg/ml of N. tabacum while the lowest KdT₉₅ was recorded in 0.30 mg/ml of O. gratissimum. Therefore, the active ingredients in oil from N. tabacum can further be investigated and developed as alternatives to the use of pyrethroids for vector control purposes. Also, the high mortalities recorded in A. gambiae mosquitoes exposed to 0.50 mg/ml of O. gratissimum demonstrated its potential as an alternative for Anopheles mosquito control in places where they naturally grow. This suggests that N. tabacum and O. gratissimum plant oils have the potential to be used as rapid knockdown agents to be incorporated into aerosols used indoors for personal protection against adult endophagic and anthropogenic malaria vectors.

Plant oils should be seen as supplements to the current vector control intervention in play in developing countries in other to achieve proposed vector control targets. This study was able to establish the bioactivity and efficacy of the evaluated plants exhibiting, varying knockdown, larvicidal and adulticidal potentials. This can be researched further which can be maximized for vector control purposes.

Acknowledgements

Gratitude goes to the Chief S.L. Edu Research Grant through the Nigerian Conservation Foundation to be able to carry out a part of this work and the Department of Pharmacology Therapeutics, University of Ibadan for space to carry out plant extractions.

Funding

Funding for this work was provided by the Chief S.L. Edu Research Grant through the Nigerian Conservation Foundation.

Conflict of interest

The authors declare no competing interests.

Availability of data and material

All relevant data are within the paper and its supporting files.

Authors’ contributions

Olukayode James Adelaja: Conceptualization, Data Curation, Writing Original Draft preparation, Methodology, Visualization.

Adedayo Olatubosun Oduola: Conceptualization, Supervision, Writing – Review & Editing.

Adeolu Taiwo Ande: Supervision, Writing – Review & Editing.

Oyindamola Olajumoke Abiodun: Methodology, Writing – Review & Editing

Abisayo Ruth Adelaja: Methodology, Writing – Review & Editing.

Ethical approval

Not applicable

Consent to participate

Not applicable

Consent to publication

Not applicable

Abbott WS. A method of computing the effectiveness of an insecticide. J Econ Entom. 1925; 18: 265–267.
Adelaja OJ, Oduola AO, Abiodun OO, Adeneye AK, Obembe A. Plants with insecticidal potential used by ethnic groups in North-Central Nigeria for the management of hematophagous insects. Asian J Ethnobio. 2021;4: 65–75.
Ande AT, Adelaja OJ, Agada AV, Akanni OI, Omotayo AI. Biological Fitness Costs Associated with the Various Permethrin Resistance Development Statuses in Anopheles gambiae in Nigeria. Sri Lanka J Bio. 2022; 7(1): 1–11. http://doi.org/10.4038/sljb.v7i1.73
Ayange-kaa AB, Hemen TJ, Onyezili N. The effect of dried leaves extract of Hyptis suaveolens on various stages of mosquito development in Benue State, Nigeria. IOSR-JPBS. 2015; 10(6 II): 28–32.
Bobbo AA, Pukuma MS, Qadeer MA. Assessment of Larvicidal Activity of Hyptis suaveolens and Balanites aegyptiaca Leaves and Root Extracts against Mosquito Species. IJSRP. 2016; 6(3):10–14
Dua VK, Alam MF, Pandey AC, Rai S, Chopra AK, Kaul VK, et al. Insecticidal activity of Valeriana jatamansi (Verbenaceae) against mosquitoes. J Am Mosq Control Assoc. 2008; 24: 315-8.
Finney DJ. “Probit Analysis,” Cambridge University Press, Cambridge, 1971.
Ghosh N, Chowdhury G. Plant extract as potential mosquito larvicide. Ind J Med Res. 2012; 135(5): 581–598.
Gillies MT, De Meillon, B. The Anophelinae of Africa South of the Sahara (Ethiopian Zoogeographical Region). Publication of South Africa Institute of Medical Research. 1968; 54: 203–207.
Ileke KD, Ogungbite OC. Alstonia boonei De Wild oil extract in the management of mosquito (Anopheles gambiae), a vector of malaria disease. J Coast Lif Med. 2015; 3(7): 557–563.
Ivoke N, Okafor FC, Owoicho LO. Evaluation of Ovicidal and Larvicidal effects of leaf extracts of Hyptis suaveolens (L) Poit (Lamiaceae) Against Anopheles gambiae (Diptera: Anophelidae) Complex. Ani Res Int. 2009; 6(3): 1072–1076.
Joshi RK. GC – MS Analysis of the Essential Oil of Ocimum gratissimum L. Growing Desolately in South India. Acta Chromatographica. 2017; 29: 111–119.
Kamaraj C, Rahuman AA, Bagavan A, Abduz ZA, Elango G, Kandan P, et al. Larvicidal efficacy of medicinal plant extract against Anopheles stephensi and Culex quinquefasciatus (Diptera: Culicidae). Trop Biomed. 2010; 27: 211–219.
Karunamoorthi K, Ilango K, Endale A. Ethnobotanical survey of knowledge and usage custom of traditional insect/mosquito repellent plants among the Ethiopian Oromo ethnic group. J Ethnopharm. 2009; 125: 224–229.
Kavendan K, Mahesh PK, Subramaniam J, Murugan K, William JS. Larvicidal activity of indigenous plant extracts on the rural malarial vector, Anopheles culicifacies Giles. J Entom Acar Res. 2014; 46:1747.
Mgbemena IC. Comparative Evaluation of Larvicidal Potentials of Three Plant Extracts on Aedes aegypti. J Amer Sci. 2010; 6(10): 435–440.
Musa AO, Sow GJ, Nasir IF, Shuaibu BU, Edogbanya PRO. Effects of aqueous and methanolic leaf extracts of Ageratum Conyzoides l. and Guiera senegalensis L. against mosquito larvae in Zaria. J Trop Biosci. 2015; 10: 38–44.
Nzelibe HC, Chintem DGW. Larvicidal Potential of Leaf Extracts and Purified Fraction Ocimum gratissimum against Culex quinquefasciatus Mosquito Larva. Int J Sci Res. 2015; 4(2): 2254–2258.
Obi OA, Nock IH, Adebote DA, Nwosu LC. Ecological and Molecular observations on Anopheles species (Diptera: Culicidae) breeding in rock pools on iselbergs within Kaduna State, Nigeria. Mol Ent. 2017; 8(01):1–10.
Oduola AO, Abba E, Adelaja OJ, Ande AT, Yoriyo KP, Awolola TS. Widespread Report of Multiple Resistance in Anopheles gambiae Mosquitoes in Eight Communities in Southern Gombe, North East Nigeria. J Arth Bor Dis. 2019.
Oduola AO, Adelaja OJ, Ayiegbusi ZO, Tola M, Obembe A, Ande AT, et al. Dynamics of Anopheline vector species composition and reported malaria cases during the rain and dry season in two selected communities in Kwara state. Nig J Paras. 2016;37(2): 158–164.
Ogban EI, Adelaja OJ, Ozovehe AS. Repellent potentials of Securidaca longepedunculata Fresen (Polygalaceae) crude extract and essential oil against mosquitoes. Int J Mosq Res. 2020; 7(5): 07–11.
Okigbo RN, Okeke JJ, Madu NC. Larvicidal effects of Azadirachta indica, Ocimum gratissimum and Hyptis suaveolens against mosquito larvae. J Agric Tech. 2010; 6(4): 703–719.
Okorie PN, McKenzie FE, Ademowo OG, Bockarie M. Nigeria Anopheles vector database: an overview of 100 years' research. PLoS One. 2011;6(12): e28347.
Olayemi IK, Ande AT, Chita S, Ibemesi G, Ayanwale VA, Odeyemi OM. Insecticide susceptibility profile of the principal malaria vector Anopheles gambiae s.l. (Diptera: Culicidae) in North-central Nigeria. J Vect bor Dis. 2011;48(2): 109–112.
Omotayo AI, Ande AT, Oduola AO, Adelaja OJ, Adesalu O, Jimoh TR, et al. Multiple insecticide resistance mechanisms in an urban population of Anopheles coluzzii (Diptera: Culicidae) from Lagos, South-West Nigeria. Acta Tropica. 2022;227: 10629. ISSN 0001-706X
Owoeye JO, Ibitoye OA. Analysis of Akure urban land use change detection from Remote Imagery Perspective. USR. 2016; 16: 1–9.
World Health Organization. Guidelines for laboratory and field testing of mosquito larvicides. 2005; 15–102.
World Health Organization. Susceptibility Test Manual Instructions for Determining the Susceptibility or Resistance of Mosquito Larvae to Insecticides. 2013; WHO/VBC/75.583.
World Health Organization. World malaria report. Global malaria programme World Health Organization, Geneva. 2019a; 1–284.
World Health Organization. World malaria report. Global malaria programme World Health Organization, Geneva. 2021; 1–254.
Youmsi RDF, Fokou PVT, Menkem EZ, Bakarnga-Via I, Keumoe R, Nana V, Boyom FF. Ethnobotanical survey of medicinal plants used as insects’ repellents in six malaria endemic localities of Cameroon. J Ethnobio & Ethnomed. 2017; 13(1): 33.

Table 1

Mean *An. gambiae* larval mortality (induced by) recorded at various plant oil concentrations and their lethal concentrations (LC₅₀ and LC₉₀) values
Plant oils			Mean Mortality (% ± SD)								Lethal Conc. (mg/ml)
Plant oils		Control	0.05	0.10	0.15	0.20	(mg/ml) 0.25	0.30	0.40	0.50	LC₅₀ (95% CL)	LC₉₀ (95% CL)
	24hrs Exposure
Hyptis suaveolens		0.0 ± 0.0	45.3 ± 1.5_a	60.0 ± 1.0_a	62.7 ± 0.6_a	65.3 ± 0.6_a	77.3 ± 1.5_a	100.0 ± 0.0_a	100.0 ± 0.0_a	100.0 ± 0.0_a	0.24 (2.22 to 2.64)	0.32 (2.63 to 3.87)
Citrus sinensis		0.0 ± 0.0	10.7 ± 0.6_b	40.0 ± 1.0_b	54.7 ± 0.6_b	80.0 ± 1.0_b	82.7 ± 0.6_a	94.7 ± 0.6_a	100.0 ± 0.0_a	100.0 ± 0.0_a	0.14 (1.19 to 1.54)	0.37 (2.74 to 4.95)
Ocimum gratissimum		0.0 ± 0.0	2.7 ± 0.6_c	6.7 ± 0.6_c	8.0 ± 0.0_c	29.3 ± 0.6_c	42.7 ± 0.6_b	58.7 ± 0.6_b	60.0 ± 0.0_b	65.3 ± 0.6_b	0.22 (2.08 to 2.26)	0.32 (2.90 to 3.53)
Nicotiana tabacum		0.0 ± 0.0	17.3 ± 0.6_b	29.3 ± 0.6_d	42.7 ± 0.6_d	48.0 ± 1.0_d	68.0 ± 1.0_c	78.7 ± 1.5_c	89.3 ± 2.5_c	100.0 ± 0.0_a	0.26 (1.94 to 3.53)	0.76 (3.40 to 16.77)
Ageratum conyzoides		0.0 ± 0.0	40.0 ± 1.0_a	61.3 ± 0.6_a	66.7 ± 0.6_a	70.7 ± 0.6_a	78.7 ± 0.6_a	81.3 ± 1.2_c	90.7 ± 0.6_c	100.0 ± 0.0_a	NA	NA
	48 hrs Exposure
Hyptis suaveolens		0.0 ± 0.0	65.3 ± 1.5_a	84.0 ± 1.7_a	86.7 ± 1.2_a	100.0 ± 0.0_a	100.0 ± 0.0_a	100.0 ± 0.0_a	100.0 ± 0.0_a	100.0 ± 0.0_a	0.09 (0.52 to 1.60)	0.22 (1.37 to 3.56)
Citrus sinensis		0.0 ± 0.0	65.3 ± 1.5_b	46.7 ± 1.5_b	61.3 ± 1.5_b	85.3 ± 1.5_b	89.3 ± 1.5_b	100.0 ± 0.0_a	100.0 ± 0.0_a	100.0 ± 0.0_a	0.15 (1.29 to 1.65)	0.29 (2.26 to 3.78)
Ocimum gratissimum		0.0 ± 0.0	6.7 ± 0.6_c	12.0 ± 1.0_c	17.3 ± 1.5_c	41.3 ± 0.6_c	48.0 ± 1.0_c	61.3 ± 0.6_b	77.3 ± 0.6_b	84.0 ± 1.0_b	0.25 (2.19 to 2.76)	0.51 (3.69 to 6.95)
Nicotiana tabacum		0.0 ± 0.0	24.0 ± 1.0_a	40.0 ± 1.0_a	48.0 ± 1.0_d	69.3 ± 1.2_d	86.7 ± 0.6_b	100.0 ± 0.0_a	100.0 ± 0.0_a	100.0 ± 0.0_a	0.19 (1.73 to 2.01)	0.31 (2.64 to 3.72)
Ageratum conyzoides		0.0 ± 0.0	54.7 ± 0.6_d	68.0 ± 1.0_d	72.0 ± 1.0_e	78.7 ± 0.6_b	90.7 ± 1.5_b	100.0 ± 0.0_a	100.0 ± 0.0_a	100.0 ± 0.0_a	0.19 (1.54 to 2.24)	0.42 (2.48 to 6.96)

NA = Not Applicable, SD = Standard Deviation, CL = Confidence Level, mean mortality values followed by different subscripts are significantly different (P < 0.05) between plant oils, n = 125.

Table 2

Lethal Median Time (LT₅₀) values of different Plant oil concentration
	LT₅₀ Values (95%CI) (h)
Concentration (mg/ml)	0.05	0.1	0.15	0.2	0.25	0.3	0.4	0.5
Hyptis suaveolens	15.9 (14.09–17.94)^a	13.6 (12.11–15.34)^a	17.1 (15.88–18.33)^b	15.6 (14.06–17.32)^c	17.0 (15.93–18.08)^c	9.0 (8.42–9.64)^d	7.5 (7.13–7.91)^e	6.7 (6.57–6.89)^e
Citrus sinensis	24.7 (19.62–29.84)^a	10.4 (9.06–11.92)^b	13.8 (12.46–15.20)^c	12.2 (11.42–13.01)^d	15.0 (13.86–16.12)^d	9.1 (8.62–9.59)^e	7.5 (7.13–7.91)^f	6.7 (6.57–6.89)^f
Ocimum gratissimum	20.7 (12.21–34.18)^a	18.1 (12.79–24.96)^a	22.6 (17.38–28.62)^a	12.9 (11.09–14.88)^b	12.1 (10.95–13.40)^c	7.6 (6.68–8.62)^d	9.4 (7.59–11.35)^e	7.4 (6.09–8.82)^f
Nicotiana tabacum	13.2 (11.11–15.72)^a	15.6 (14.22–17.13)^b	12.7 (11.36–14.19)^c	14.6 (12.72–16.60)^d	11.0 (10.19–11.93)^e	12.8 (11.26–14.50)^f	11.4 (9.23–13.71)^f	8.5 (6.79–10.38)^g
Ageratum conyzoides	17.5 (16.51–18.63)^a	15.7 (14.88–16.57)^b	14.6 (13.51–15.75)^c	13.8 (12.41–15.24)^d	11.0 (10.24–11.73)^e	12.6 (11.12–14.25) ^ef	11.3 (9.29–13.49)^f	8.5 (6.79–10.38)^g

LT₅₀ Values followed by different subscripts are significantly different (P < 0.05) across varying concentrations

Table 3

Knock-down Effect and Knockdown times ratings of plant oils against *Anopheles gambiae*
Plant oils	Conc. (mg/ml)	% Kd after 1hr	KdT₅₀ (95%CI)	KdT₉₅ (95%CI)
Hyptis suaveolens	0.05	6.67	31.05 (22.80 to 42.29)	53.88 (19.30 to 150.4)
	0.10	11.67	49.86 (24.19 to 102.8)	102.3 (19.65 to 532.4)
	0.15	13.33	NA	NA
	0.20	16.67	NA	NA
	0.25	18.33	NA	NA
	0.30	25.00	73.25 (NA)	NA
	0.40	30.00	NA	NA
	0.50	36.67	NA	NA
Citrus sinensis	0.05	8.33	75.56 (0.06 to 93831)	288.9 (NA)
	0.10	13.33	NA	NA
	0.15	20.00	NA	NA
	0.20	33.33	NA	NA
	0.25	41.67	NA	NA
	0.30	50.00	48.19 (0.9433 to 2462)	267.5 (NA)
	0.40	58.33	29.06 (25.49 to 33.13)	48.23 (32.33 to 71.93)
	0.50	70.00	36.21 (20.93 to 62.63)	84.95 (14.79 to 488.1)
Ocimum gratissimum	0.05	21.67	NA	NA
	0.10	36.67	NA	NA
	0.15	38.33	37.08 (23.97 to 37.22)	121 (15.01 to 975.0)
	0.20	55.00	40.1 (18.90 to 85.05)	144.5 (16.65 to 1254)
	0.25	51.67	34.19 (20.35 to 57.41)	152.5 (22.11 to 1053)
	0.30	53.33	22.93 (18.84 to 27.91)	48.11 (25.77 to 89.83)
	0.40	75.00	NA	NA
	0.50	85.00	NA	NA
Nicotiana tabacum	0.05	8.33	30.90 (20.51 to 46.56)	69.21 (16.84 to 284.5)
	0.10	18.33	NA	NA
	0.15	28.33	29.87 (19.01 to 72.31)	77.19 (34.32 to 173.6)
	0.20	43.33	60.4 (4.634 to 787.4)	313.1 (1.547 to 63336)
	0.25	45.00	20.3 (8.496 to 48.49)	98.22 (4.662 to 2069)
	0.30	48.33	32.96 (25.57 to 42.47)	78.26 (32.88 to 186.3)
	0.40	80.00	NA	NA
	0.50	100.00	27.89 (23.15 to 33.60)	69.74 (35.07 to 138.7)
Ageratum conyzoides	0.05	3.33	44.68 (NA)	45.27 (NA)
	0.10	8.33	26.29 (19.79 to 34.93)	35.97 (23.43 to 55.22)
	0.15	16.67	NA	NA
	0.20	26.67	NA	NA
	0.25	30.00	64.02 (13.25 to 309.4)	129.1 (9.150 to 1821)
	0.30	38.33	NA	NA
	0.40	43.33	30.25 (25.76 to 35.52)	69.59 (39.76 to 121.8)
	0.50	56.67	NA	NA

Conc. =Concentration, % Kd = Percentage KnockDown, NA = Not Applicable, KdT = Knock Down Time, CI = Confidence Interval, n = 100

No competing interests reported.

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Insecticidal plant oil’s toxicity activities on the larval and adult stages of a major malaria vector (Anopheles gambiae Giles 1920)

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Abstract

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Introduction

Materials And Methods

Plant Materials, Oil Extraction and Serial Dilution Procedures

Mosquito Collection And Rearing

Larvicidal Bioassay

Adulticidal Bioassay

Data Analysis

Results

Larvicidal Activity

Adulticidal Activity

Discussion

Conclusion

Declarations

References

Tables

Additional Declarations

Supplementary Files

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