Entomocidal properties of Monodora myristica (Dunal, 1831) and Conyza sumatrensis (Retzius, 1742-1821) extracts: Studies on two dipterous insect pests Anopheles gambiae (Giles, 1902) and Culex quinquefasciatus (Say, 1823)

Kayode David Ileke

doi:10.21472/bjbs.051014

Abstract

Anopheles gambiae (Giles, 1902) and Culex quinquefasciatus (Say, 1832) mosquitoes are the main vectors of human malaria and lymphatic filariasis, respectively. This study aims to analyze the larvicidal, pupicidal and adulticidal properties of Monodora myristica (Dunal, 1831) and Conyza sumatrensis (Retzius, 1742-1821) extracts against An. gambiae and Cx. quinquefasciatus. The experiment was conducted in the laboratory at ambient temperature of 28 oC +/- 2 oC and 75% +/- 5% relative humidity. The results showed that M. myristica and C. sumatrensis extracts significantly affect all stages of An. gambiae and Cx. quinquefasciatus tested. The mosquitocidal toxicity of the two plant extracts is dosage dependent. Anti-larval activity of M. myristica at rate 500 mg/L and 1,000 mg/L caused 100% mortality of An. gambiae larvae while it evoked 80% and 100% mortality of Cx. quinquefasciatus larvae. The same trend of results were also obtained on the anti-pupal and adulticidal toxicity of M. myristica and C. sumatrensis extracts. As larvicides, pupicides and adulticides, the LC50s and LC90s, after 24 h varied across plant extracts and mosquito species. C. sumatrensis attained LC50 and LC90 at higher concentration than M. myristica. On An. gambiae larvae, the LC50s after 24 h, varied from 86.95 mg/L (M. myristica) to 131.73 mg/L (C. sumatrensis). Similarly, the LC90s after 24 h on An. gambiae larvae, varied from 278.39 mg/L (M. myristica) to 131.73 mg/L (C. sumatrensis). For Cx. quinquefasciatus larvae, the LC50s after 24 h, varied from 391.41 mg/L (M. myristica) to 898.20 mg/L (C. sumatrensis). The seed extract of M. myristica exerted the best pupicidal activity among the two tested extracts with LC50 and LC90 values of 140.61 mg/L and 520.35 mg/L on An. gambiae, respectively, followed by leaf of C. sumatrensis with LC50 and LC90 values of 157.59 mg/L and 781.86 mg/L on An. gambiae, respectively. More concentrations were require to achieve 50% and 90% death of Cx. quinquefasciatus pupae. On adulticidal activity, seed of M. myristica exerted LC50 and LC90 values of 122.79 mg/L and 502.99 mg/L on An. gambiae, respectively, followed by leaf of C. sumatrensis with LC50 and LC90 values of 215.05 mg/L and 981.25 mg/L on An. gambiae, respectively. More concentrations were require to achieve 50% and 90% death of Cx. quinquefasciatus adults. The two tested plants can be integrated into pest management programmes to combat human malaria and lymphatic filariasis vectors breeding site in Nigeria. I recommend formulation of M. myristica seeds which have the lowest LC50 and LC90 after 24 h of exposure for field evaluation.

Highlights

The dipterans are the most important orders of hexapods with veterinary and medical importance, which can transmit many pathogenic parasites causing diseases such as malaria and filariasis among the rural dwellers in the world (Sanei-Dehkordi et al, 2018)
The two tested plants can be integrated into pest management programmes to combat human malaria and lymphatic filariasis vectors breeding site in Nigeria
Despite the efforts made by World Health Organization and researchers over the past decades to decline the mortality rate of malaria and lymphatic filariasis all over the world, malaria disease are still household illness in the tropical regions of the world (Ileke et al, 2017; Vatandoost et al, 2018)

Summary

Introduction

The dipterans are the most important orders of hexapods with veterinary and medical importance, which can transmit many pathogenic parasites causing diseases such as malaria and filariasis among the rural dwellers in the world (Sanei-Dehkordi et al, 2018). Anopheles and Culex mosquitoes are most dangerous vectors commonly find in tropical region (Okorie et al, 2014). Human malaria is the most important vector-borne disease caused by Plasmodium species transmitted by anopheline mosquitoes. Culex species is the most medically important vectors of human pathogens causing etiologic agents of different forms of encephalitis, Rift valley fever and lymphatic filariasis that are still predominant in the tropical region (Vatandoost et al, 2018). Immediate intervention in the control of these vectors in the rural area where the breeding of mosquitoes appeared permanent or semi-permanent as a result of ignorance of the vectors on the part of rural dwellers

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