Larvicidal efficacy of three sustained insecticides against Culex pipiens larvae (original) (raw)
Related papers
Journal of entomology and zoology studies, 2016
Current researches for mosquito control have focused on insect specific insecticides without environmental concerns. The present study was conducted to evaluate the Ovicidal activity of an ecdysone agonist (methoxyfenozide) on Culex pipiens L. (Culicidae: Diptera) under laboratory conditions using standard WHO protocol. Lethal concentrations (LC50= 24.54 μg/L and LC90= 70.79 μg/L) previously determined were tested against freshly laid eggs. The egg viability was examined and the deferred effects of treatment were also investigated on the development duration and the sex ratio. Data obtained show that egg hatching inhibition was dose dependent, with a reduction of 13.44% and 46.99% with LC50 and LC90, respectively. In treated groups, the total development duration was significantly longer as compared to controls. The adult sex ratio was significantly skewed in favor of males emerged from treated eggs with LC50 and LC90 of methoxyfenozide. Moreover, changes in the egg shell morphology...
Journal of the Egyptian Society of Parasitology
The present study was tested certain chemical insecticides (Propetamphos and Cypermethrin) and a Bioinsecticide (Baciloid 5000: Bacillus thuringiensis) against Culex pippins, the dominant mosquito species in Abha City. LC 50 value of Propetamphos was 0.0162 ppm against the 3 rd instar larvae of laboratory strain compared with field strain which was 0.0442 ppm, and LC 90 of Propetamphos was 0.8109 ppm against the 3rd instar larvae of laboratory strain, comparing to field strain (3.31ppm). Cypermethrin was also very effective where LC50 was 0.0132 ppm against the adult females of laboratory strain, comparing to (0.1192 ppm) of laboratory strain. On the other hand, residual activity of Bacillus thuringiensis var. israelensis reached from 4 to 20 days of concentrations ranged between 0.001 to 100 ppm (lethality was 11.7 to 96.8%) in laboratory strain in the 1 st week, whereas ranged between 0.0 to 70.8% in the 2 nd week with same concentrations finally ranged between 0.0 to 12.7% in the 3 rd week. While reached 6-23 days at concentrations 0.001 to 100ppm in field strain in the 1 st week, whereas ranged between 0.0 to 70.8% in the 2n d week with the same concentrations and ranged between 0.0 to 12.7% in the 3 rd week. So, the field collected larvae of Cx. pipens were more susceptible and have prolonged residual effect as compared to laboratory reared larvae.
Annual Research & Review in Biology, 2014
Aims: In the present study, the objective was to estimate the toxicity of an insect growth regulator with juvenile hormone-like activity, kinoprene, on Culex pipiens, the most abundant and investigated mosquito species. Effects of this compound on growth and development were also evaluated. Methodology: A commercial formulation (Enstar 65% EC) was tested at different concentrations ranging between 162.5 and 650µg/L on newly molted fourth-instar larvae that were exposed for 24 h under standard laboratory conditions according to World Health Organization recommendations. Results: Kinoprene exhibited insecticidal activity by direct action on the treated fourthinstar larvae but also by differed action on the other following stages of development. Mortality occurred after earlier inhibition of their development or by their inability to complete their ecdysis. The LC 50 values were 1287.4µg/L for the direct action on fourth instar larvae, and 246.8µg/L for the differed action until adult emergence. Moreover, the compound disturbed growth and development since several morphological types and an increase in the duration of larval and pupal stages were recorded. In a second series of experiments, the effects of kinoprene were examined on morphometric measurements of Original Research Article
Toxicity and Joint Toxic Action of Some Control Agents on Culex pipiens L. Larvae
Alexandria Science Exchange Journal: An International Quarterly Journal of Science Agricultural Environments, 2010
The present study aimed to assess and to evaluate some of the sustainable and safe measures against Culex pipiens mosquito larva that can be implemented in areas at risk of contacting elephantiasis. The joint toxic action of these control measures was also studied. Data showed that Deltamethrin (LC 50 =0.021ppm) was more toxic than Bacillus thurengiensis var. israelensis, diflubenzuron, emamectin benzoate and azadiractin by 2.0, 491.42, 59.0 and 143.8 fold, respectively, after 24hr. Also, after 48hr Deltamethrin (LC 50 = 0.004 ppm) was 4.0, 1102.5, 25 and 232.5 times more toxic than Vectobac G, diflubenzuron, emamectin benzoate and azadiractin, respectively, after 48hr. After 72hr the toxicity of Deltamethrin (LC 50 =0.003 ppm) was 3.0, 206.66, 23.33, 246.66 fold more toxic than B.t.i., diflubenzuron, emamectin benzoate and azadiractin, respectively. Toxicity of Beauveria bassiana was very low compared with all the tested control measures with LC 50 value 1.85ml/L after 72hr of exposure. Data of joint toxic action revealed that, all mixtures of Beauveria bassiana with diflubenzuron and all mixtures of diflubenzuron with azadiractin resulted in antagonistic effects. Approximately, all other binary mixtures resulted in potentiating effects. The highest potentiating effect was obtained when the mixture of LC 12.5 B.t.i. + LC 12.5 Deltamethrin was used. Finally, the use of some binary mixtures of the tested control measures can achieve better control, reduce control cost and induce lesser environmental pollution.
The Journal "Agriculture and Forestry"
The present study was conducted to evaluate the larvicidal and pupacidal efficacy of Spinosad on Culex species in their breeding habitats in village of Saft, Beni Suef Governorate, Egypt. The results showed that Spinosad caused a pronounced toxicity against C. pipiens. The total mortality of second and fourth larval instars was achieved by lower concentrations of Spinosad. While the highest pupal morality of C. pipiens was obtained by concentration of 5000 ppm (93.3%), after 168 h under laboratory conditions. Spinosad was applied with concentration of 5000 ppm at semi-field experiments and resulted total mortality of larval instars of C. pipiens, C. theileri and C. perexiguus after 24 and 48 h of exposure. The same concentration induced strong pupal mortalities of C. pipiens, C. theileri and C. perexiguus (90, 60 and 70%), respectively after 48 h. The field experiments, Spinosad (5000 ppm) induced total mortality of larval instars of Culex species and the pupal mortality was higher in breeding habitat, cement irrigation tank (77.8 %) and decreased to 36.4% in agriculture canal. The present study concluded that Spinosad is a promising larvicide that can be used in treatment of mosquito breeding habitat sites with low efficacy on pupae at some habitat sites such as agricultural canals.
Evaluation of some insecticides against Culex pipiens, the dominant mosquito species in Abha city
— The present study was planned to test on certain chemical insecticides from different groups such as organophosphates, pyrethroids and Bioinsecticide. Among these compounds two were chemical insecticides (Propetamphos and Cypermethrin), while the third one is Bioinsecticide (Baciloid 5000: Bacillus thuringiensis) against Culex pipiens, the dominant mosquito species in Abha city. Taking LC50 values (concentration which to kill 50% of mosquito larvae) into consideration, mosquito larvae of CX. Pipes against Propetamphos was effective (LC50 0.0162 ppm) against the 3rd instar of the laboratory strain comparing with a field strain which was 0.0442 ppm. At LC90 level, data indicated that Propetamphos (LC90 0.8109 ppm) was effective insecticide against the 3rd instar larvae of laboratory strain, while against field strain gave (LC90 3.31 ppm). Similarly, the results clearly showed that Cypermethrin was also very effective insecticide (LC50 0.0132 ppm) against the adult females against laboratory strain, while against field strain Cypermethrin gave (LC50 0.1192 ppm). On the other hand, the residual activity of Bacillus thuringiensis var. israelensis reached from 4 to 20 days of concentrations ranged between 0.001 to 100 p.m. in case laboratory strain, while reaching between 6-23 days of concentrations ranged between 0.001 to 100 p.m. in case field strain. Mortality percent was also found between 11.7 to 96.8% of concentrations ranged between 0.001 to 100 p.m. against laboratory strain in the 1st week, whereas ranged between 0.0 to 70.8% in the 2nd week against the same concentrations finally ranged between 0.0 to 12.7% in the 3rd week. Hence, the field collected larvae of Culex pipens were more susceptible and have prolonged residual effect as compared to laboratory reared. Keywords— Evaluation of insecticides against Culex pipiens, in Abha city.
Conventional pesticides are the focal and mainstay tools being used in the control of mosquitoes. However, some of these pesticides are known to cause acute and long term health problems in man. Moreso that they constitute to the existing environmental pollution, there is therefore an urgent need to explore the effectiveness of biolarvicides which is usually considered as a safe alternative to these conventional pesticides. A thorough understanding of the fate and efficacy of biolarvicide formulations in mosquito breeding sites open to water fluctuations is required for effective implementation of larval source management programmes. This study investigated the colony progression and impact of Bacillus sp on the larval gut of Culex quinquefasciatus. rd Twenty 3 instar larvae of C. quinquefasciatus mosquitoes were introduced into each of the three replicates of-6-7-8-9 ® plastic beakers containing one litre of serial dilutions (1x10 , 1x10 , 1x 10 and 1 x10) of VectoMax CG concentrations. Mean larval mortality of mosquitoes in each concentration was calculated hourly over a 24-hour period. The concentration that induced 100% mortality under the shortest exposure period was chosen as the dosage to be evaluated for its colony forming units in the larval gut exposed. Surface sterilization of mosquito larvae and work space was carried out following standard techniques after which the mosquito guts were dissected and plated on nutrient agar. Discrete colonies on each of the replicated plates were counted using colony counter. The time taken to achieve 100% mortality of Culex quinquefasciatus after exposure to-6-7-8 10 , 10 and 10 serial dilutions of the larvicides increased from 6-10 hours with an increasing dilution ratio.-9 The least concentration of the microbial larvicide (10) induced 96 % mortality in the Culex population at 16 hours of exposure. The significant mean count of Bacillus sp found in the gut of Culex quinquefasciatus and ® the lethal impact at reduced concentrations have shown that VectoMax CG could be a useful Larval Source Management tool in habitat settings open to water fluctuations.
Controlling Culex pipiens: antagonists are more efficient than a neonicotinoid insecticide
Journal of vector ecology : journal of the Society for Vector Ecology, 2018
Species vulnerability to pesticides depends on physiological sensitivity, the potential to recover, and the ecological context. We assessed the vulnerability of the mosquito Culex pipiens to a repeated treatment with thiacloprid in outdoor microcosms with and without antagonists (competitive and predatory invertebrates). Microcosms were treated repeatedly (three times) with thiacloprid at a concentration of 0.1, 1, or 10 µg/liter. In microcosms without antagonists, the abundance of Cx. pipiens larvae decreased moderately after the second and the third exposures to 10 µg/liter thiacloprid. In microcosms with antagonists, the abundance of Cx. pipiens larvae declined to approximately zero in the control group and the low concentration treatments during the five weeks of observation. By contrast, the abundance of Cx. pipiens larvae temporarily increased at 10 µg/liter thiacloprid after the second and third contamination. We explained this positive effect on the development of Cx. pipien...
2018
Two organophosphate (OP) insecticides (Chlorpyrifos and Fenitrothion) and one synthetic pyrethroid insecticide (Deltamethrin) were evaluated against 4 instar larvae of Culex quinquefasciatus (Diptera: Culicidae) under laboratory condition. The larvae were collected from nearby area of Bangladesh Agricultural University, Mymensingh 2202 campus and reared at the Insect Biotechnology and Biopesticide Laboratory of Department of Entomology. For bioassay, five concentrations (viz. 10, 30, 50, 70 and 90ppm) of each of the insecticide were prepared. Ten actively swimming 4 instar larvae of C. quinquefasciatus were added into respective concentration. Mortality was recorded and the LC50 and LC90 values were determined by probit analysis. The LC50 values for Fenitrothion, Deltramethrin Chlorpyrifos, and were found to be 8.88, 26.73 and 71.14ppm, respectively. Thus, the Fenitrothion exhibited comparatively higher toxicity about 3 and 8 times more toxic compared to deltamthrin and chlorpyrifos...