Larvicidal efficacies and chemical composition of essential oils of Pinus sylvestris and Syzygium aromaticum against mosquitoes

Objective:To assess the chemical composition and mosquito larvicidal potentials of essential oils of locally sourced Pinus sylvestris(P.sylvestris)and Syzygium aromatkum(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 GCMS 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 within24 h.The larvae of A.aegypti were more susceptible to the oils[LC_(50)(S.aromaticum)=92.56 mg/L,LC_(50)(P.sylvestris)=100.39 mg/L]than C.quinquefasciatus[LC_(50)(S.aromaticum)=124.42 mg/L;LC_(50)(P.sylvestris)=128.00 mg/L].S.aromaticum oil was more toxic to the mosquito larvae than oil of P.sylvatris but the difference in lethal concentrations was insignificant(P>0.05).Condusioii:The results justify the larvicidal potentials of both essential oils and the need to incorporate them in vector management and control.

Larval habitats of mosquito fauna in Osogbo metropolis,Southwestern Nigeria

Objective:To determine the larval habitats of mosquito fauna and possible impact of land use/land cover changes on the epidemiology of mosquito-bome diseases in Osogbo metropolis,Southwestern,Nigeria.Methods:All accessible larval habitats were surveyed between May and September,2011in Osogbo metropolis while Land Use/Land cover of the city was analyzed using 2 Lansat Multispectral Scanner satellite imagery of SPOT 1986 and T.ANDSAT TM 2009.Results:A total of six species namely,Aedes aegypti,Aedes albopictus,Aedes vittatus,Anopheles gambiae complex,Culex quinquefascialus and Erelmapodite chrysogaster were encountered during the study.The occurrence and contribution of disused tyres was significantly higher(P<0.05)than the other habitats encountered,while there were no significant differences in the contribution of gutters/run-offs.septic tanks/drums,ground pools/open drains and discarded containers lo the breeding of mosquitoes(P>0.05).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 lo 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 rale of flooded environment which could provide ample breeding sites for mosquitoes call for sustained environmental sanitation and management in Osogbo metropolis.

尼日利亚西南部奥孙河沿线黑蝇Simulium damnosum Theobald complex的形态分类研究(双翅目：蚋科)(英文)

黑蝇Simulium damnosumsensu lato是由多个姊妹种组成的复合体,这些种在生态学和盘尾丝虫病的传播方面各不相同。本文对奥孙河沿线的尼日利亚西南部森林区域的黑蝇S. damnosum s.l.复合体的组成以及成虫的形态学特征进行了研究。本研究所用的黑蝇S. damnosum s.l.成虫标本来源于奥孙河沿线的3个区,分别是Osun Eleja,Osun Ogbere和Osun Budepo。标本采集通过人体诱捕的方式,采集时间从2008年2月至2009年6月上午7:00到下午6:00,每两周采集1次。通过观察成虫的翅毛簇(wing tufts)和其他形态特征,对其进行分类研究。结果表明:存在同域分布的森林种和稀树草原种。在奥孙河沿线3个区内,森林种为优势种,占总捕获量的99.18%,而稀树草原种仅占0.82%;森林种和稀树草原种在多度上存在显著差异(P<0.05)。所捕获的所有稀树草原种的翅毛簇均为灰白色,而捕获的森林种的翅毛簇颜色存在显著差异(P<0.05)。为了更清楚地揭示该地区黑蝇S. damnosum s.l.的物种组成,建议进行更深入的研究。

尼日利亚南部阿贝奥库塔地区冈比亚按蚊复合体的形态特征研究(双翅目：蚊科)

对采自尼日利亚南部城市阿贝奥库塔冈比亚按蚊复合体Anopheles gambiae complex的形态特征进行了研究。依据2005年8月至2006年7月灯诱捕获的364个冈比亚按蚊复合体标本,分别对它们的触角、翅、喙、前足、中足和后足6个部位的长度进行了测量,对月平均值进行回归分析,同时利用差异系数(coefficient of difference,CD)进行近缘分析。分析显示,各特征的长度平均值雨季大于旱季,但是回归分析表明长度变化与季节不显著相关(P>0.05)。差异系数分析结果表明,仅触角长度和翅长显示此复合体为两个不同的种群(CD>1.28),而其他特征值表明为同一种群。因此,该研究结果提示触角长度及翅长对冈比亚按蚊复合体近缘种的区分有重要参考价值。