Strong larvicidal activity of three species of Spilanthes (Akarkara) against malaria (Anopheles stephensi Liston, Anopheles culicifacies, species C) and filaria vector (Culex quinquefasciatus Say)

Hexane extract of tuber of plantCyperus rotundus(Cyperaceae) was screened under laboratory conditions for repellent activity against mosquito vectorAnopheles culicifaciesGiles species A (Diptera: Culicidae),Anopheles stephensiListon (Diptera: Culicidae), andCulex quinquefasciatusSay (Diptera: Culicidae). TheCyperus rotundustuber extract was used to determine their effect on mosquito vector, and comparison with the DEET (NN Diethyl 1-3 methyl Benzamide, formerly known as diethyl 1-m-toluamide). The tuber extracts showed more effective at all the dose. Result obtained from the laboratory experiment showed that the tuber extracts are more effective for repellency of allthe mosquito vector even at low dose. Clear dose response relationships were established with the highest dose of 10% tuber extract evoking 100% repellency. Percent protection obtained againstAn. culicifaciesGiles species A 100% repellency in 4 hours, 6 hours,An. stephensi100% repellency in 6 hours andCx. quinquefasciatuswas 100% repellency in 6 hours at the 10% concentration. Against DEET- 2.5%An. culicifaciesA 100% repellency in 1 hour, 2 hours, 6 hours, An.stephensihave shown 100% repellency in 6 hours, andCulex quinquefasciatushave shown 100% repellency in 1 hour, 2 hours, 6 hours. The consolidated data of the repellency observed in different species is given and it is evident that the over all repellency rates varied between 80 and 100% for different repellents concentrations (2.5%, 5%, and 10%). The extract can be applied as an effective personal protective measure against mosquito bites.

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Larvicidal Activity of Inorganic Salts Against Anopheles Stephensi and Culex Quinquefasciatus

International Annals of Science ◽

10.21467/ias.10.1.45-51 ◽

2020 ◽

Vol 10 (1) ◽

pp. 45-51

Author(s):

Francis Zakanda Nsimba ◽

Thierry Lengu Bobanga ◽

Pius Zakayi Kabututu ◽

Jean-Marie Iyamba Liesse

Keyword(s):

Larvicidal Activity ◽

Culex Quinquefasciatus ◽

Anopheles Stephensi ◽

Weak Acid ◽

Inorganic Salts ◽

Disease Vectors ◽

Development Of Resistance ◽

Late Instar ◽

Dose Dependent Fashion ◽

Larvicidal Activities

Mosquitoes transmit serious human diseases, causing millions of deaths worldwide every year and the development of resistance to chemical insecticides resulting in rebounding vectorial capacity. In this study, the larvicidal bioassays for activities of aqueous solutions of weak acid [(NH4)2SO4 and NaH2PO4] and weak base (Na2CO3 and NaHCO3) inorganic salts against late instar larvae of disease vectors Anopheles stephensi and Culex quinquefasciatus were carried out under laboratory settings. The four inorganic salts showed varied levels of larvicidal activities after 24 h-exposure on Anopheles stephensi and Culex quinquefasciatus larvae in a dose-dependent fashion. However, the larvicidal activities were relatively higher in Na2CO3 (LC50 = 3162 and 447 ppm) and NaHCO3 (LC50 = 5623 and 398 ppm) solutions as compared to those in (NH4)2SO4 (LC50 = 7943 and 1995 ppm) and NaH2PO4 (LC50 = 7943 and 7120 ppm). The present study showed that the inorganic salts Na2CO3, NaHCO3, (NH4)2SO4 and NaH2PO4 could serve as potential larviciding agents considering their low toxicity. Therefore, this study provides a first report on the larvicidal activity of the inorganic salts on mosquito larvae of disease vectors.

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