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)

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 °C ± 2 °C 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. Antilarval 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 Received August 11, 2018 Accepted August 30, 2018 Released August 31, 2018