Development On Attractant To Aedes Albopictus And Preliminary Research On Prewarning Indices Of Dengue

BackgroundDengue fever is an acute arthropod-borne infections disease, which is caused by dengue virus, and mainly transmitted by Aedes aegypti and Aedes albopictus. It mostly appears in tropical and subtropical areas. But as the economy globalization as well as global warming and increasingly abominable environment, dengue fever has been the most widespread and have the most people to attack one of the most imported which are arthropod-borne infectious diseases in the world. At the same time, it has spreading character of emergency quick transmission quickly and high incidence. And it has been a worldwide public health problem. In China, dengue fever mainly distributes in the provinces of Guangdong, Hainan, Guangxi, Fujian and Taiwan. Specifically, Guangdong is a high-risk area, and people here affected by this disease about 90% in China. In recent years, it trends to spread to the north area.Aedes albopictus, as the main transmitting medium, its distribution and density have very close relationship with dengue fever prevalence. As excellent vaccine has not been successfμlly developed, monitoring and controlling the density of Aedes albopictus is the main method to inhibit prevailing trend of dengue fever.For a long time, domestic and overseas countries take passive monitoring methods to acquire the density and distribution of mosquitoes, such as human-mosquito net—trapping method. However, in the point of view of ethics, the methods are threatering the health of monitors. Also, this traditional monitoring method has some shortcomings in the accuracy of acquiring the mosquito density. Recently, container monitoring method has been applied to the routine monitoring in world's public health departments, but its efficiency of trapping mosquitoes and their eggs is not good enough. In order to reflect the real situation of mosquito density more accurately, it is needed to find out effective mosquito attractant formula to improve the luring efficiency of monitoring container. Moreover, since it's difficult to apply these traditioned monitoring indices like breteau index (BI) and container index (CI) etc in the urban areas. Further improvement in monitoring indices is required amongst container monitoring method for more accurate and reasonable reflection of mosquito density.Objective1. Study the attractant of Aedes albopictus.2. Use outdoor mosquito vectors routine monitoring data to primarily disguise dengue fever container monitoring corresponding parameters.MethodsⅠ.Optimization of attractantAs is known, the strongest level of L-Lactic's attractive effect is 1mg/ml, Therefore, in order to 1mg/ml as the center,take the three levels, adding to the orthogonal experiment. Screen the Dimethyl disulfide,acetone and fish flour soak etc. And use orthogonal test to optimize it.1. Reparation of fish flour soaksPut different dose fish flour into 50ml water, and we can get 1mg/ml,2mg/ml,3mg/ml, 4mg/ml,5mg/ml,6mg/ml,7mg/ml,8mg/ml,9mg/ml,10mg/ml etc.10 concentration levels fish flour soak. Compare the number of mosquitoes which catches by the 10 concentration levels soak, we get the optimum concentration level is 2mg/ml.But in the above 10 levels, fish flour will cause water to be turbid, and it will decrease the attractive effects to adult mosquito. Therefore, we can separately take 25μl,50μl,75μl, 100μl,125μl,175μl,200μl from the fish flour soak of 2mg/ml level and put them into the attractant screening—optimizing test.Dimethyl disulfide,acetone,xylene, ammonia are chemical reagents, if the concentration is too high, it can erode monitoring container, which will increase the monitoring cost. But if too low, these reagents evaporate much faster, which will bad for the long time attractive effect. So the concentration range of each reagent is 0.5μl-4μl/ml,and divide reagent within this range into eight level:0.5μl/ml,1μl/ml,1.5μl/ml,2μl/ml,2.5μl/ml,3μl/ml,3.5μl/ml,4μl/ml. The lactic acid concentration fell too low, not lured into a mosquito, So, determine the concentration of lactate remains unchanged,still the original concentration of the experiment (0.5mg/ml, 1mg/ml,2mg/ml)2. The experiment of comparison between the simple composition of attractant and waterEach reagent is separately processed as following treatment. Take 25μl,50μl,75μl, 100μl,125μl,150μl,175μL 200μl reagent respectively into 8 monitoring containers with 50ml water,and they are experimental group, another 50ml water is control group. Then, let the containers in Mongolian—type mosquito nets which are 1.2cm long,0.8cm short, also, put about 110 adμlt Aedes albopictus that have sucked blood. After 4 days recover these containers and count the number of mosquitoes. The experiment repeats two times.(1) Comparison of Dimethyl disulfide and water(2) Comparison of acetone and water(3) Comparison of xylene disulfide and water(4) Comparison of ammonia water and water(5) Comparison of fish flour soak and water3. Carry on optimal to effective concentration of each reagent in order to seek the best concentration.(1) Comparison of different concentration of Dimethyl disulfide(2) Comparison of different concentration of acetone(3) Comparison of different concentration of xylene(4) Comparison of different concentration of fish flour soak4. Screening of the interactionStep one:Fixed the first reagent in the first concentration and change the concentration of the second reagent, then the groups were divided into A1 and A2.Fixed the first reagent in the second concentration and change the concentration of the second reagent, then the groups were divided into al and a2.Step two:Fixed the second reagent in the first concentration and change the concentration of the first reagent, then the groups were divided into B1 and B2.Fixed the second reagent in the second concentration and change the concentration of the first reagent, then the groups were divided into b1 and b2.Put in separately the bed nets experimental groups above.There were 110 Mosquitoes about in each bed net. Recover and observe the different tendency of inducing effect in two step experiment after four days.The experiment repeats two times.(1) Interaction between Dimethyl sulfide and acetone(2) Interaction between Dimethyl sulfide and xylene(3) Interaction between Dimethyl sulfide and fish flour soak(4) Interaction between acetone and xylene(5) Interaction between acetone and fish flour soak(6) Interaction between xylene and fish flour soak(7) Interaction between Dimethyl sulfide and L-lactic(8) Interaction between acetone and L-lactic(9) Interaction between xylene and L-lactic (10) Interaction between fish flour soak and L-lactic5. The orthogonal table was utilized to optimize the moity and concentration of the attractant, which purpose is getting the best arranges combination in groups.Ⅱ. Preliminary approach on supporting indices of vessel monitoring method1. Analysis of correlation between supporting indices of vessel monitoring method and traditional monitoring indices.2. The multiple regression analysis was utilized to get the prewarning equation.Results:Ⅰ.Optimization of screening in attractant of Aedes albopictus1. Preparation of fish flour soaksAccording to statistical analysis of the concentration of fish flour soak in ten, there was significant difference among ten kinds of concentration (F=12.428,P=0.000). Besides through the multiple comparisons, it was seen that the best concentration of fish flour soak was 2mg/ml.2. The experiment of comparison between the simple composition of attractant and water(1) The experiment of inducing effect in each concentration of Dimethyl sulfide The inducing effect of each concentration of Dimethyl sμlfide is high (P<0.05).(2) The experiment of inducing effect-in each concentration of acetone The inducing effect of each concentration of acetone is high (P<0.05).(3) The experiment of inducing effect in each concentration of xylene In addition to 1.5μl/ml (P>0.05),2.5μl/ml (P>0.05), the inducing effect of each concentration of xylene is high (P<0.05).(4) The experiment of inducing effect in each concentration of ammonia water There was no significant difference between ammonia water and water (P>0.05).(5) The experiment of inducing effect in each concentration of fish flour soak The inducing effects of each concentration of fish flour soak is high (P<0.05). 3. Carry on optimal to the concentration of each attractant in eight in order to seek the best concentration.(1) Comparison of the concentration of Dimethyl sulfide in eight There was significant difference in inducing effects of eight kinds of concentration of Dimethyl sulfide (F=290.914,P=0.000). Besides through the multiple comparisons and by comparison of mean, it was seen that there were 3 kinds of concentration of Dimethyl sulfide which has better effect.They were 4μl/ml,2μl/ml,1.5μl/ml.(2) Comparison of the concentration of acetone in eight There was significant difference in inducing effects of eight kinds of concentration of acetone (F=379.345, P=0.000). Besides through the multiple comparisons and by comparison of mean, it was seen that there were 3 kinds of concentration of acetone which has better effect.They were 4μl/ml,0.5μl/ml,1μl/ml.(3) Comparison of the concentration of xylene in eight There was significant difference in inducing effects of eight kinds of concentration of xylene (F=258.651,P=0.000). Besides through the multiple comparison and by comparison of mean, it was seen that there were 3 kinds of concentration of xylene which has better effect.They were 1μl/ml,0.5μl/ml,3μl/ml.(4) Comparison of the concentration of fish flour soak in eight There was significant difference in inducing effects of eight kinds of concentration of fish flour soak (F=127.580, P=0.000). Besides through the multiple comparison and by comparison of mean, it was seen that there were 3 kinds of concentration of fish flour soak which has better effect.They were0.5μl/ml,1μl/ml,2μl/ml.4. Screening of interaction(1) Interaction between Dimethyl sulfide and acetone When the concentration of Dimethyl sulfide is fixed in 4μl/ml,there was significant difference between A200 and A25(t=10.633,P=0.000).According to compare means, the trapping effect of A200 is better than that of A25(A200>A25).When the concentration of Dimethyl sulfide is fixed in 2μl/ml,there was significant difference between a200 and a25(t=16.058, P=0.000).According to compare means, the trapping effect of a25 is better than that of a200(a200B100).When the concentration of acetone is fixed in 0.5μl/ml,there was significant difference between b200 and b100(t=16.890, P=0.000).According to compare means, the trapping effect of b100 is better than that of b200 (b200< b100).According to the resμlt above, there was a interaction between Dimethyl sulfide and acetone.(2) Interaction between Dimethyl sulfide and xyleneWhen the concentration of Dimethyl sulfide is fixed in 2μl/ml,there was significant difference between A25 and A50(t=11.225, P=0.000).According to compare means, the trapping effect of A50 is better than that of A25(A50>A25).When the concentration of Dimethyl sulfide is fixed in 4μl/ml,there was significant difference between a25 and a50 (t=7.961, P=0.001).According to compare means, the trapping effect of a50 is better than that of a25(a50>a25).When the concentration of xylene is fixed in 0.5μl/ml,there was significant difference between B100 and B200 (t=15.200, P=0.000).According to compare means, the trapping effect of B200 is better than that of B100(B200>B100).When the concentration of xylene is fixed in 1μl/ml,there was significant difference between b100 and b200 (t=13.202, P=0.000).According to compare means, the trapping effect of b200 is better than that of b100(b200> b100).According to the resμlt above, there was no interaction between Dimethyl sulfide and xylene.(3) Interaction between Dimethyl sulfide and fish flour soak When the concentration of Dimethyl sulfide is fixed in 4μl/ml,there was significant difference between A50 and A25(t=10.094, P=0.001).According to compare means, the trapping effect of A25 is better than that of A50(A25>A50).When the concentration of Dimethyl sulfide is fixed in 2μl/ml,there was significant difference between a50 and a25 (t=8.500, P=0.001).According to compare means, the trapping effect of a25 is better than that of a50(a25>a50).When the concentration of fish flour soak is fixed in 1μl/ml,there was significant difference between B200 and B100 (t=6.425, P=0.003).According to compare means, the trapping effect of B200 is better than that of B100(B200>B 100). When the concentration of fish flour soak is fixed in 0.5μl/ml,there was significant difference between b200 and b100 (t=16.444, P=0.000).According to compare means, the trapping effect of b200 is better than that of b100(b200> b100).According to the resμlt above, there was no interaction between Dimethyl sulfide and fish flour soak.(4) Interaction between acetone and xyleneWhen the concentration of acetone is fixed in 4μl/ml,there was significant difference between A50 and A25 (t=16.570, P=0.000).According to compare means, the trapping effect of A50 is better than that of A25(A50> A25).When the concentration of acetone is fixed in 0.5μl/ml,there was significant difference between a50 and a25 (t=7.216, P=0.002).According to compare means, the trapping effect of a50 is better than that of a25(a50> a25).When the concentration of xylene is fixed in 0.5μl/ml,there was significant difference between B200 and B25 (t=16.760, P=0.000).According to compare means, the trapping effect of B200 is better than that of B25(B200>B25).When the concentration of xylene is fixed in 1μl/ml,there was significant difference between b200 and b25(t=19.454, P=0.000).According to compare means, the trapping effect of b200 is better than that of b25(b200> b25).According to the resμlt above, there was no interaction between acetone and xylene. (5) Interaction between acetone and fish flour soakWhen the concentration of acetone is fixed in 4μl/ml,there was significant difference between A50and A25 (t=10.076, P=0.001).According to compare means, the trapping effect of A25 is better than that of A50(A25>A50).When the concentration of acetone is fixed in 0.5μl/ml,there was significant difference between a50 and a25 (t=7.439, P=0.002).According to compare means, the trapping effect of a25 is better than that of a50(a25>a50).When the concentration of fish flour soak is fixed in 1μl/ml,there was significant difference between B25 and B200(t=9.621, P=0.001).According to compare means, the trapping effect of B200 is better than that of B25(B200>B25).When the concentration of fish flour soak is fixed in 0.5μl/ml,there was significant difference between b25 and b200 (t=6.957, P=0.002).According to compare means, the trapping effect of b200 is better than that of b25(b200>b25).According to the resμlt above, there was no interaction between acetone and fish flour soak.(6) Interaction between xylene and fish flour soakWhen the concentration of xylene is fixed in 1μl/ml,there was significant difference between A50 and A25 (t=20.813, P=0.000).According to compare means, the trapping effect of A25 is better than that of A50(A25>A50).When the concentration of xylene is fixed in 0.5μl/ml,there was significant difference between a50 and a25 (t=34.785, P=0.000).According to compare means, the trapping effect of a25 is better than that of a50(a25>a50).When the concentration of fish flour soak is fixed in1μl/ml,there was significant difference between B25 and B50 (t=9.354, P=0.001).According to compare means, the trapping effect of B50 is better than that of B25(B50>B25).When the concentration of fish flour soak is fixed in 0.5μl/ml,there was significant difference between b25 and b50 (1=10.070, P=0.001).According to compare means, the trapping effect of b50 is better than that of b25(b50> b25).According to the resμlt above, there was no interaction between xylene and fish flour soak. (7) Interaction between Dimethyl sulfide and L-lacticWhen the concentration of Dimethyl sulfide is fixed in 2μl/ml,there was significant difference between A50 and A100 (t=6.164, P=0.004).According to compare means, the trapping effect of A50 is better than that of A100(A50>A100).When the concentration of Dimethyl sμlfide is fixed in 4μl/ml,there was significant difference between a50 and a100 (t=6.472, P=0.003).According to compare means, the trapping effect of a50 is better than that of a100(a50>a100). When the concentration of L-lactic is fixed in lmg/ml,there was significant difference between B200 and B100 (t=-12.167, P=0.000).According to compare means, the trapping effect of B200 is better than that of B100(B200>B100).When the concentration of L-lactic is fixed in 2mg/ml,there was significant difference between b200 and b100 (t=-19.888, P=0.000).According to compare means, the trapping effect of b200 is better than that of b100(b200> b100).According to the resμlt above, there was no interaction between Dimethyl sulfide and L-lactic.(8) Interaction between acetone and L-lacticWhen the concentration of acetone is fixed in 4μl/ml,there was significant difference between A50 and A100 (t=10.956, P=0.000).According to compare means, the trapping effect of A50 is better than that of A100(A50>A100).When the concentration of acetone is fixed in 0.5μl/ml,there was significant difference between a50 and a100 (t=6.736, P=0.003).According to compare means, the trapping effect of a50 is better than that of a100(a50>a100). When the concentration of L-lactic is fixed in lmg/ml,there was significant difference between B200 and B25 (t=11.377, P=0.000).According to compare means, the trapping effect of B200 is better than that of B25(B200>B25).When the concentration of L-lactic is fixed in 2mg/ml,there was significant difference between b200 and b25 (t=7.546, P=0.002).According to compare means, the trapping effect of b200 is better than that of b25(b200>b25).According to the resμlt above, there was no interaction between acetone and L-lactic.(9) Interaction between xylene and L-lacticWhen the concentration of xylene is fixed in 0.5μl/ml,there was significant difference between A50 and A100 (t=16.292, P=0.000).According to compare means, the trapping effect of A50 is better than that of A100(A50>A100).When the concentration of xylene is fixed in 1μl/ml,there was significant difference between a50 and a100 (t=25.924, P=0.000).According to compare means, the trapping effect of a50 is better than that of a100(a50>a100). When the concentration of L-lactic is fixed in lmg/ml,there was significant difference between B25 and B50 (t=-4.118, P=0.015).According-to compare means, the trapping effect of B50 is better than that of B25(B50>B25).When the concentration of L-lactic is fixed in 2mg/ml,there was significant difference between b50 and b25 (t=-14.000, P=0.000).According to compare means, the trapping effect of b50 is better than that of b25(b50>b25).According to the resμlt above, there was no interaction between xylene and L-lactic.(10) Interaction between fish flour soak and L-lacticWhen the concentration of fish flour soak is fixed in 1μl/ml,there was significant difference between A50 and A100(t=11.939,P=0.000).According to compare means, the trapping effect of A50 is better than that of A100(A50>A100).When the concentration of fish flour soak is fixed in 0.5μl/ml,there was significant difference between a50 and a100 (t=8.222, P=0.001).According to compare means, the trapping effect of a50 is better than that of a100(a50>a100). When the concentration of L-lactic is fixed in lmg/ml,there was significant difference between B25 and B50 (t=-9.339, P=0.001).According to compare means, the trapping effect of B25 is better than that of B50(B25>B50).When the concentration of L-lactic is fixed in 2mg/ml,there was significant difference between b50 and b25 (t=-7.354, P=0.002).According to compare means, the trapping effect of b25 is better than that of b50(b25>b50). According to the resμlt above, there was no interaction between fish flour soak and L-lactic.5. The orthogonal table was utilized to optimize the moity and concentration of the attractant, which purpose is getting the best arrange combination in groups. The best magistral formμla of the attractant contained dimethyl disulfide 1.5μl/ml, acetone 1μl/ml, xylene 3μl/ml, fish flour soaking solution 1μl/ml, L-lactic lmg/ml. The regression equation: Y=66.778+2.889A+1.667A*B+1.667B+0.889C was obtained on the basis of resμlts, showing dimethyl disμlfide, acetone, and the interaction between them, xylene contributed greatest to the temptation efficiency of attractant in turn.Ⅱ.Preliminary approach on supporting indices of vessel monitoring method1. Analysis of correlation between supporting indices of vessel monitoring method and traditional monitoring indices.BI and MI (Mosquito-trap positive index), OI(Oviposition index), MOI(Mosquito and oviposition positive index) are relevant.. Beside, BI and MI(r=0.758,P=0.007),BI and OI (r=0.667,P=0.025),BI and MOI (r=0.758,P=0.007)2. Early warning equation was acquired from multiple regression analysis①Y=-702.837+47.035a Y:The total number of mosquito eggs, a:Temperature To test the equation, (F=22.213, P=0.001).R2=0.712, The equation fitted well.②Y=-18.358+1.297a Y:The total number of mosquitoes, a:Temperature To test the equation, (F=59.075, P=0.000).R2=0.868。The equation fitted well.③Y=1.045+0.677 a-0.590b. Y:Breteau index, a:mosquito temptation index, b:oviposition temptation index To test the equation, (F=13.580, P=0.003),.R2=0.772. The equation fitted well.Conclusions1, orthogonal design was utilized to optimize the attractant to Aedes albopictus, and a relatively good magistral formμla has been obtained. 2, Correlation analysis was done between routine monitoring index of the container and the traditional monitoring index using outdoor routine monitoring data, and the linear regression correlation between the two was proposed. At the same time, analysis of the impact of climatic factors on mosquito.