Oluwole Akinola S, Ekpo Uwem F, Mafiana Chiedu F, Adeofun Clement O, Idowu Olufunmilayo A
Department of Biological Sciences, University of Agriculture, Abeokuta, Nigeria.
Parasit Vectors. 2009 Nov 16;2(1):55. doi: 10.1186/1756-3305-2-55.
Simulum damnosum Theobald sensu lato (s.l.) is the vector of the parasitic filarial worm Onchocerca volvulus Leuckart which causes onchocerciasis. In order to understand the vector population dynamics, a preliminary 12 months entomological evaluation was carried out at Abeokuta, the Southwest Zone of Nigeria, an onchocerciasis endemic area, where vector control has not been previously initiated. S.damnosum s.l. flies were caught on human attractants between 700 to1800 hours each day, for 4 days each month, from August 2007 to July 2008. The flies caught were classified as either forest-dwelling or savanna-dwelling groups based on the colour of certain morphological characters. Climatic data such as rainfall, humidity and temperature were also collected monthly during the period of survey.
A total of 1,139 flies were caught, 596 (52.33%) were forest-dwelling group while 543 (47.67%) were savanna-dwelling group of S. damnosum s.l. The highest percentage of forest-dwelling group was caught in the month of August 2007 (78.06%) and the least percentage of forest-dwelling groups was caught in November 2007 (8.14%). The highest percentage of savannah-dwelling group was caught in the month of November 2007 (91.86%) and the least percentage of savannah-dwelling group was caught in August 2007 (21.94%). There was no significant difference between the population of forest and savannah-dwelling groups of the fly when the means of the fly population were compared (P = 0.830). Spearman correlation analysis showed a significant relationship between monthly fly population with monthly average rainfall (r = 0.550, n = 12, P = 0.033), but no significant relationship with monthly average temperature (r = 0.291, n = 12, P = 0.179). There was also a significant relationship between monthly fly population and monthly average relative humidity (r = 0.783, n = 12 P = 0.001). There was no significant correlation between the population of forest-dwelling group of S. damnosum s.l. and monthly average rainfall (r = 0.466, n = 12, P = 0.064) and monthly average temperature (r = 0.375, n = 12, P = 0.115) but there was significant correlation with monthly average relative humidity (r = 0.69, n = 12, P = 0.006). There was significant correlation between savannah-dwelling group and monthly average rainfall (r = 0.547, n = 12, P = 0.033), and monthly average relative humidity (r = 0.504, n = 12, P = 0.047) but there was no significant correlation with monthly average temperature (r = 0.142, n = 12, P = 0.329)
The results from this study showed that both the forest and the savannah dwelling groups of S. damnosum s.l. were caught biting in the study area. This could have implications on the transmission and epidemiology of human onchocerciasis if not monitored.
恶蚋复合组（Simulum damnosum Theobald sensu lato，s.l.）是寄生丝虫盘尾丝虫（Onchocerca volvulus Leuckart）的传播媒介，盘尾丝虫可导致盘尾丝虫病。为了解该传播媒介的种群动态，在尼日利亚西南部地区阿贝奥库塔开展了为期12个月的初步昆虫学评估，该地区是盘尾丝虫病流行区，此前尚未开展过病媒控制工作。2007年8月至2008年7月期间，每月有4天在每天700至1800时用人体诱捕器捕捉恶蚋复合组的苍蝇。根据某些形态特征的颜色，将捕获的苍蝇分为森林型或稀树草原型两类。在调查期间，每月还收集降雨、湿度和温度等气候数据。
共捕获1139只苍蝇，其中596只（52.33%）为森林型恶蚋复合组，543只（47.67%）为稀树草原型恶蚋复合组。森林型组捕获比例最高的月份是2007年8月（78.06%），捕获比例最低的月份是2007年11月（8.14%）。稀树草原型组捕获比例最高的月份是2007年11月（91.86%），捕获比例最低的月份是2007年8月（21.94%）。比较苍蝇种群数量的均值时，森林型和稀树草原型苍蝇种群数量之间没有显著差异（P = 0.830）。Spearman相关性分析表明，每月苍蝇种群数量与月平均降雨量之间存在显著关系（r = 0.550，n = 12，P = 0.033），但与月平均温度之间没有显著关系（r = 0.291，n = 12，P = 0.179）。每月苍蝇种群数量与月平均相对湿度之间也存在显著关系（r = 0.783，n = 12，P = 0.001）。森林型恶蚋复合组的种群数量与月平均降雨量（r = 0.466，n = 12，P = 0.064）和月平均温度（r = 0.375，n = 12，P = 0.115）之间没有显著相关性，但与月平均相对湿度存在显著相关性（r = 0.69，n = 12，P = 0.006）。稀树草原型组与月平均降雨量（r = 0.547，n = 12，P = 0.033）和月平均相对湿度（r = 0.504，n = 12，P = 0.047）之间存在显著相关性，但与月平均温度没有显著相关性（r = 0.142，n = 12，P = 0.329）。
本研究结果表明，在研究区域捕获了森林型和稀树草原型的恶蚋复合组苍蝇。如果不进行监测，这可能会对人类盘尾丝虫病的传播和流行病学产生影响。
