Mahande Aneth M, Dusfour Isabelle, Matias Jonathan R, Kweka Eliningaya J
Tropical Pesticides Research Institute, Mabogini Field Station, Moshi, Tanzania.
J Glob Infect Dis. 2012 Apr;4(2):114-9. doi: 10.4103/0974-777X.96776.
Understanding vector behavioral response due to ecological factors is important in the control of disease vectors. This study was conducted to determine the knockdown resistance (kdr) alleles, dieldrin resistance alleles, and entomological inoculation rates (EIRs) of malaria vectors in lower Moshi irrigation schemes for the mitigation of disease transmission.
The study was longitudinal design conducted for 14 months. Mosquitoes were collected fortnightly by using a CDC miniature light trap in 20 houses. Mosquitoes were identified morphologically in the field, of which 10% of this population was identified to species level by using molecular techniques. Samples from this study population were taken for kdr and resistance to dieldrin (rdl) genes detection.
A total of 6220 mosquitoes were collected by using a light trap, of which 86.0% (n=5350) were Anopheles gambiae sensu lato and 14.0% (n=870) were Culex quinquefasciatus. Ten percent of the An. gambiae s.l. (n=535) collected were taken for species identification, of which 99.8% (n=534) were identified as An. arabiensis while 0.2% (n=1) were An. gambiae sensu stricto. Of the selected mosquitoes, 3.5% (n=19) were sporozoite positive. None of the mosquitoes tested had the kdr gene. The rdl resistant allele was detected at a frequency of 0.48 throughout the year. EIR was determined to be 0.54 ib/trap/year.
The findings of this study suggest that the homozygous and the heterozygous resistance present in rdl genes demonstrated the effect of pesticide residues on resistance selection pressure in mosquitoes. A better insecticide usage protocol needs to be developed for farmers to use in order to avoid excessive use of pesticides.
了解生态因素导致的病媒行为反应对于病媒控制至关重要。开展本研究以确定莫希下游灌溉区疟疾媒介的击倒抗性（kdr）等位基因、狄氏剂抗性等位基因和昆虫学接种率（EIRs），以减轻疾病传播。
本研究采用纵向设计，为期14个月。每两周在20所房屋中使用疾控中心微型诱蚊灯诱捕蚊子。在野外通过形态学鉴定蚊子，其中10%的蚊子种群通过分子技术鉴定到物种水平。从该研究种群中采集样本进行kdr和狄氏剂抗性（rdl）基因检测。
使用诱蚊灯共捕获6220只蚊子，其中86.0%（n = 5350）为冈比亚按蚊复合组，14.0%（n = 870）为致倦库蚊。采集的冈比亚按蚊复合组中10%（n = 535）用于物种鉴定，其中99.8%（n = 534）被鉴定为阿拉伯按蚊，0.2%（n = 1）为冈比亚按蚊指名亚种。在所选蚊子中，3.5%（n = 19）为子孢子阳性。所检测的蚊子均未携带kdr基因。全年检测到rdl抗性等位基因的频率为0.48。确定EIR为0.54只感染性按蚊/诱蚊灯/年。
本研究结果表明，rdl基因中存在的纯合抗性和杂合抗性证明了农药残留对蚊子抗性选择压力的影响。需要为农民制定更好的杀虫剂使用方案，以避免过度使用农药。
