ABSTRACT
Objective:To assess the chemical composition and mosquito larvicidal potentials of essential oils of locally sourced Pinus sylvestris (P. sylvestris) and Syzygium aromaticum (S. aromaticum) against Aedes aegypti (A. aegypti) and Culex quinquefasciatus (C. quinquefasciatus). Method:The chemical composition of the essential oils of both plants was determined using GC-MS while the larvicidal bioassay was carried out using different concentrations of the oils against the larvae of A. aegypti and C. quinquefasciatus in accordance with the standard protocol. Results:The results as determined by GC-MS showed that oil of S. aromaticum has eugenol (80.5%) as its principal constituent while P. sylvestris has 3-Cyclohexene-1-methanol, .alpha., .alpha.4-trimethyl (27.1%) as its dominant constituent. Both oils achieved over 85%larval mortality within 24 h. The larvae of A. aegypti were more susceptible to the oils [LC50 (S. aromaticum)=92.56 mg/L, LC50(P. sylvestris)=100.39 mg/L] than C. quinquefasciatus [LC50(S. aromaticum)=124.42 mg/L;LC50(P. sylvestris)=128.00 mg/L]. S. aromaticum oil was more toxic to the mosquito larvae than oil of P. sylvestris but the difference in lethal concentrations was insignificant (P>0.05). Conclusion: The results justify the larvicidal potentials of both essential oils and the need to incorporate them in vector management and control.
ABSTRACT
Objective:To determine the larval habitats of mosquito fauna and possible impact of land use/land cover changes on the epidemiology of mosquito-borne diseases in Osogbo metropolis, Southwestern, Nigeria. Methods: All accessible larval habitats were surveyed between May and September, 2011 in Osogbo metropolis while Land Use/ Land cover of the city was analyzed using 2 Lansat Multispectral Scanner satellite imagery of SPOT 1986 and LANDSAT TM 2009. Results:A total of six species namely, Aedes aegypti, Aedes albopictus, Aedes vittatus, Anopheles gambiae complex, Culex quinquefasciatus and Eretmapodite chrysogaster were encountered during the study. The occurrence and contribution of disused tyres was significantly higher (P0.05). The accessible land use/land covered of the study area between 1986 and 2009 showed that the wet land coverage and settlement area increased from 0.19 to 9.09 hectare and 1.00 to 2.01 hectare respectively while the forest area decreased from 60.18 to 50.14 hectare. Conclusion: The contribution of the habitats coupled with the increasing rate of flooded environment which could provide ample breeding sites for mosquitoes call for sustained environmental sanitation and management in Osogbo metropolis.