The tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is among the most destructive pests that attack tomato in many countries. In this study, the efficiency of three suspensions (106;105;104 cell/...The tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is among the most destructive pests that attack tomato in many countries. In this study, the efficiency of three suspensions (106;105;104 cell/ml) of Bacillus thuringiensis var. Kurstaki was tested on T. absoluta larvae 1st, 2nd, 3rd and 4th instar was assessed to study the effect of these suspensions on larval mortality. Results showed that the concentration 106 cell/ml resulted in the highest mortality of all instars larvae with an average mortality of 20%, 22.66%, 18.66% and 23.33% was recorded for the first, second, third and fourth instar, respectively. The greatest percentage of mortality occurred in the third day after the larvae fed with leaves treated with suspension B. thuringiensis.展开更多
Techniques of production of enthomopatogenic bacteria are developed aiming to increase the productivity and to reduce the costs of the fermentative process. Like this, it has been using agroindustrial wastes or by-pro...Techniques of production of enthomopatogenic bacteria are developed aiming to increase the productivity and to reduce the costs of the fermentative process. Like this, it has been using agroindustrial wastes or by-products as nutrient sources in culture medium, having been used, in this study, the manipueira, a by-product of the processing of the cassava flour. Fermentations were performed in flasks of Erlenmeyer of 500 mL containing 250 mL of culture media, conditioned in shaker at 180 r.p.m. and 28°C, and the media were composed by manipueira, in concentrations that varied between 400 and 1000 mL/L. The time of the process varied between 48 and 120 hours. They appraised the following parameters: cellular growth, the production of spores, the reduction of organic matter (COD analysis) and the variation of reduction sugar. Although there was a proportional cellular growth to the manipueira concentration, the production of spores was similar in all the cases, at the end of the process, in spite of the smallest speed of production of the same ones in the highest concentrations. In relation to the variation of COD, it has, also, a percentile minor of reduction in the highest concentrations. In the analysis of variation of reduction sugars, the higher concentrations are the ones that they present larger slowness in the reduction of this.展开更多
In the cities of Algeria, Culex pipiens L. (Diptera: Culicidae) is the mosquito which presents most interest because of its wide geographical distribution and of its abundance which engender a strong nuisance. Besides...In the cities of Algeria, Culex pipiens L. (Diptera: Culicidae) is the mosquito which presents most interest because of its wide geographical distribution and of its abundance which engender a strong nuisance. Besides, its role of vector of the virus West Nile arouses a particular interest in the Mediterranean Basin. These insects are generally controlled by conventional insecticides for the greater part, chemicals which cause in the long term side effects (effects on the not aimed bodies and the resistance of the aimed species). A research for the effect of the bioinsecticide Bacillus thuringiensis (granulated commercial shape in 200 IUT1/mg) was realized on préimaginales populations of the artificial deposits sites (taken directly of them natural the deposits sites) and cleansed populations (stemming from a breeding) having never been handled previously, taking into account local weather and physico-chemical conditions. Analyses of variance, allowed to determine the combined effect of the factor measure and of the factor time which by increasing, increase the efficiency of the product. The results of the rates of mortalities registered after treatment allowed to loosen the DL50 and the DL90 for every embryonic stage. From the results, we estimated the degree of sensibility of the larva populations of Culex pipiens which have proved heterogeneous in partial tolerance in Bacillus thuringiensis for the populations of the sensitive artificial and homogeneous the deposits sites for those stemming from the breeding.展开更多
初步研究了苏云金杆菌以色列变种(Bacillus thuringiensis var.israelensis de Barjac,以下均用B.t.i简称)对水环境中出现的摇蚊幼虫的毒杀效果,并采用聚乙烯醇(PVA)加少量海藻酸钠及活性炭的方法固定B.t.i.结果表明,控制质量百分比分别...初步研究了苏云金杆菌以色列变种(Bacillus thuringiensis var.israelensis de Barjac,以下均用B.t.i简称)对水环境中出现的摇蚊幼虫的毒杀效果,并采用聚乙烯醇(PVA)加少量海藻酸钠及活性炭的方法固定B.t.i.结果表明,控制质量百分比分别为10%PVA、1%海藻酸钠和20%活性炭,采用4%CaCl2的饱和硼酸溶液(pH为6.7)作为交联剂且交联时间为24 h时,制得的凝胶颗粒机械强度好,操作简单.B.t.i以及固定化微球对摇蚊幼虫具有很高的毒力作用,微球缓慢释放B.t.i.展开更多
文摘The tomato leaf miner, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is among the most destructive pests that attack tomato in many countries. In this study, the efficiency of three suspensions (106;105;104 cell/ml) of Bacillus thuringiensis var. Kurstaki was tested on T. absoluta larvae 1st, 2nd, 3rd and 4th instar was assessed to study the effect of these suspensions on larval mortality. Results showed that the concentration 106 cell/ml resulted in the highest mortality of all instars larvae with an average mortality of 20%, 22.66%, 18.66% and 23.33% was recorded for the first, second, third and fourth instar, respectively. The greatest percentage of mortality occurred in the third day after the larvae fed with leaves treated with suspension B. thuringiensis.
文摘Techniques of production of enthomopatogenic bacteria are developed aiming to increase the productivity and to reduce the costs of the fermentative process. Like this, it has been using agroindustrial wastes or by-products as nutrient sources in culture medium, having been used, in this study, the manipueira, a by-product of the processing of the cassava flour. Fermentations were performed in flasks of Erlenmeyer of 500 mL containing 250 mL of culture media, conditioned in shaker at 180 r.p.m. and 28°C, and the media were composed by manipueira, in concentrations that varied between 400 and 1000 mL/L. The time of the process varied between 48 and 120 hours. They appraised the following parameters: cellular growth, the production of spores, the reduction of organic matter (COD analysis) and the variation of reduction sugar. Although there was a proportional cellular growth to the manipueira concentration, the production of spores was similar in all the cases, at the end of the process, in spite of the smallest speed of production of the same ones in the highest concentrations. In relation to the variation of COD, it has, also, a percentile minor of reduction in the highest concentrations. In the analysis of variation of reduction sugars, the higher concentrations are the ones that they present larger slowness in the reduction of this.
文摘In the cities of Algeria, Culex pipiens L. (Diptera: Culicidae) is the mosquito which presents most interest because of its wide geographical distribution and of its abundance which engender a strong nuisance. Besides, its role of vector of the virus West Nile arouses a particular interest in the Mediterranean Basin. These insects are generally controlled by conventional insecticides for the greater part, chemicals which cause in the long term side effects (effects on the not aimed bodies and the resistance of the aimed species). A research for the effect of the bioinsecticide Bacillus thuringiensis (granulated commercial shape in 200 IUT1/mg) was realized on préimaginales populations of the artificial deposits sites (taken directly of them natural the deposits sites) and cleansed populations (stemming from a breeding) having never been handled previously, taking into account local weather and physico-chemical conditions. Analyses of variance, allowed to determine the combined effect of the factor measure and of the factor time which by increasing, increase the efficiency of the product. The results of the rates of mortalities registered after treatment allowed to loosen the DL50 and the DL90 for every embryonic stage. From the results, we estimated the degree of sensibility of the larva populations of Culex pipiens which have proved heterogeneous in partial tolerance in Bacillus thuringiensis for the populations of the sensitive artificial and homogeneous the deposits sites for those stemming from the breeding.
