Control of mosquitoes with selective insecticides: efficacy of two birational products (kinoprene and methoxyfenozide) on reproduction of Culex pipiens (original) (raw)
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Physiological Entomology, 2018
Methoxyfenozide is an insect growth disruptor belonging to the class of nonsteroidal ecdysone agonists. In the present study, methoxyfenozide (23% emulsifiable concentrate) is evaluated against newly molted fourth-instar larvae of Culex pipiens L. and Culiseta longiareolata Macquart (Diptera: Culicidae), aiming to investigate its possible effects on growth and development. Larvae are exposed for 24 h under standard laboratory conditions in accordance with World Health Organization recommendations. The product is found to exhibit insecticidal activity against the two tested mosquito species with a concentration-response relationship. Moreover, based on the lethal concentrations determined, methoxyfenozide is slightly more toxic against C. pipiens than C. longiareolata. Furthermore, fourth-instar larva of the two mosquito species are treated using two lethal concentrations (LC 50 and LC 90) of methoxyfenozide, and then individual survivals (larvae, pupae and adults) from larval treatment are subjected to a biometrical and biochemical study. The compound is found to interfere with growth by reducing the larval and pupal development duration. Moreover, the body volume and the main biochemical contents (proteins, carbohydrates and lipids) from different stages are affected. The overall results suggest that the ecdysone agonist under investigation interferes with the development process and has potential for mosquito control.
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
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...
Ovicidal activity of three insect growth regulators against Aedes and Culex mosquitoes
Acta Tropica, 2013
Interspecific variations in the susceptibility of freshly and embryonated eggs of Aedes albopictus, Ae. aegypti, Ae. atropalpus and Culex pipiens were tested against three classes of insect growth regulators (IGRs) including ecdysone agonist (azadirachtin), chitin synthesis inhibitor (diflubenzuron) and juvenile hormone analog (pyriproxyfen) at 0.001, 0.01, 0.1 and 1.0 ppm concentrations. Egg hatching inhibition was dose dependent, the highest being at 1.0 ppm concentration for freshly laid eggs of Ae. albopictus (pyriproxyfen: 80.6%, azadirachtin: 42.9% and diflubenzuron: 35.8%). Aedes aegypti showed lower egg hatching inhibition when exposed to pyriproxyfen (47.3%), azadirachtin (15.7%) and diflubenzuron (25.5%). Freshly laid eggs of Cx. pipiens were most susceptible to diflubenzuron. Aedes atropalpus eggs were tolerant to all three classes of IGRs. Embryonated eggs of Ae. albopictus, Ae. aegypti, Ae. atropalpus and Cx. pipiens were resistant to pyriproxyfen, azadirachtin and diflubenzuron than freshly laid eggs. The median desiccation time (DT 50) of Ae. atropalpus eggs was maximum (5.1 h) as compared to Ae. aegypti (4.9 h), Ae. albopictus (3.9 h) or Cx. pipiens (1.7 h) eggs. Insignificant relationship between the rates of desiccation and egg hatching inhibition suggests other factors than physical providing eggs the ability to tolerate exposures to various IGRs. Egg hatching inhibition was due to the alteration in embryonic development caused by IGRs. Changes in the egg shell morphology and abnormal egg hatching from the side of the egg wall instead of operculum, was observed at higher concentrations of diflubenzuron. Morphological and physiological variations in eggs may be the key factor to influence the ovicidal efficacy of IGRs. The present data provide a base line for the improvement of the ovicidal efficacy of the insecticide and its formulation.
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...
Physiological Entomology, 2012
The effects of tebufenozide, a nonsteroidal agonist of ecdysone, on egg development and reproduction in the anautogenic mosquito Culex quinquefasciatus Say (Culicidae, Diptera) are examined. The study population originates from Hyderabad, India. A dose-dependent toxicity is observed when varying concentrations (10 μg L −1 to 10 pg L −1) of a flowable formulation of tebufenozide, known as Mimic 2F, are applied to first-instar larvae in water. The median lethal dose (LC 50) against larvae is very low at 1.29 ng L −1 H 2 O. Doses below the LC 50 induce vitellogenesis in the females that subsequently emerge, and these females lay eggs autogenically (without blood feeding). Autogenous egg clutches are laid through three ovarian cycles. The number of eggs laid in each clutch is lower compared with an anautogenous clutch. An autogenic population has been maintained for over 15 generations after the primary induction, during which time the females have not been allowed to feed on blood. By comparison, doses higher than the LC 50 inhibit ovarian development. There is a gradual degeneration of the ovaries, and the females die approximately 20 days after imaginal ecdysis without commencing vitellogenesis. The results are discussed in relation to the endocrine and nutritional regulation of vitellogenesis in C. quinquefasciatus, and the possibility of using tebufenozide to regulate populations of some species of mosquito .
Alexandria Science Exchange Journal: An International Quarterly Journal of Science Agricultural Environments, 2010
This study was carried out to evaluate the biological effects of two IGRs (Match ® and Baycidal ®) on Culex pipiens mosquitoes when fed the adults on sugar solution mixed with 0.1, 0.5 and 1 ppm of each compound. Some delayed effects of these treatments were also determined. The results indicated that the use of each of the tested IGRs caused a reduction in the blood-feeding activity of mosquito female when compared with the controls. The reductions were 18.2, 22.7 and 31.8% by using Match and 25, 27.3 and 36.3% by using Baycidal ® , respectively, at the tested concentrations. The reduction in biting activity of mosquito females may lead to a decrease in the number of fully engorged females and accordingly affect their reproductive capacity of mosquitoes. The use of Match ® and Baycidal ® at the tested concentrations caused a marked prolongation in the time needed for blood meal digestion by C. pipiens females. The prolongation percentages were 44.4, 48,8 and 55.5% by using Match and 51.1, 55.5 and 62.2% by using Baycidal ® , respectively. Also, treatments caused a reduction in the reproductive capacity. The maximum decreasing in egg production was 30.3% at concentration of 1 ppm of Match ®. The result showed that the treatment by Baycidal ® at 0.1, 0.5 and 1ppm led to a remarkable reduction in the egg production by 61.9, 66.1 and 69.2%, respectively and also the hatchability was reduced in the treated females. Subsequent study was carried out to investigate the delayed effect of IGRs Match ® and Baycidal ® on the hatched larvae. The result showed that the larval development was gradually inhibited by 17.8, 49.8 and 92.7% by using Match ® at 0.1, 0.5 and 1 ppm, respectively. On the other hand the larval development was completely inhibited after the treatment of adults fed by 0.5 and 1 ppm Baycidal ®. The larvae developed till the 2 nd instar but completely failed in molting to the 3 rd instar. Subsequent study was conduced on the effect of Match ® and Baycidal ® on the longevity of the survived mosquito adults that, the records showed that no significant differences in the mean of adult longevity between treatments and control.
2020
This study aimed to investigate the mosquito larvicidal efficacy of pyrethroids (deltamethrin, cypermethrin and lambda cyhalothrin), organophosphates (chloropyrifos and dichlorvos) and a neonicotinoid (acetamiprid) against Culex quinquefasciatus of Chakdara, Dir Lower, Khyber Pakhtunkhwa Pakistan. Fourth instar larvae of Culex quinquefasciatus were initially exposed to various concentrations (0.001 to 1.0 ppm) of these insecticides to determine the activity concentration ranges. The highest concentrations of deltamethrin, cypermethrin, lambda cyhalothrin, chloropyrifos, dichlorvos and acetamiprid that showed no insecticidal activity against Culex quinquefasciatus 4th instar larvae were 0.001, 0.0005, 0.000015, 0.001, 0.0005 and 0.001 ppm, respectively. The lowest concentration of these insecticides that were capable of insecticidal activity against mosquito larvae were 0.002, 0.001, 0.000031, 0.002, 0.001 and 0.002 ppm, respectively. The lowest concentrations of these insecticides t...
Effects of a brassinosteroid analogue to mosquito larvae
Ecotoxicology and Environmental Safety, 2003
Many plant compounds are able to modulate herbivore growth and reproduction by directly interacting with steroid hormones systems. In insects, several classes of phytochemicals, including brassinosteroids and related substances, interfere with molting and reproduction. The effects of the molting-hormone antagonist pesticide DI-31, a brassinosteroid analogue, on Aedes aegypti mosquito larvae were tested in two different exposure scenarios. After static exposure of first-instar larvae, the calculated NOEC, LOEC, and LC 50 values referenced to 19 d were 0.03, 0.036, and 0.04 mg/mL, respectively. Semistatic exposure of fourth-instar larvae revealed them to be slightly less susceptible than the younger larvae (NOEC 0.03 mg/mL, LOEC 0.036 mg/mL, LC 50 0.049 mg/mL referenced to 19 days). In both cases mortality was immediate and larval development was retarded. This study suggests that A. aegypti could be a useful model for the detection of hormonally active substances such as DI-31. r
Egyptian Journal of Zoology, 2021
Equal contribution Vector control is a serious concern in developing countries such as Egypt. The present study has been carried out to evaluate the larvicidal activities of 1,2,4-triazine derivatives against 3 rd larval instar of the mosquito "Culex pipiens" under laboratory conditions. To achieve this aim, the median lethal concentrations (LC 50) of the tested compounds and their effects on larval development and adult emergence were assessed. Adult females' fecundity and egg hatchability were estimated on the survivors of treatment. It was evident that 1,2,4-triazine compounds have a toxic effect on Cx. pipiens. The estimated LC 50 values of 1,2,4-triazine were 0.457, 0.333, and 2.047 mg/L for MSA 35, MSA 102, and the reference insecticide "pymetrozine", respectively. One week after treatment, both the compounds MSA 35 and MSA 102 were more effective (higher mortality rate and shorter lethal time) than the reference insecticide. The LC 50 of MSA 102 induced a significant prolongation in the development time and less adult emergence compared with the control. Moreover, adult females surviving the treatment of MSA 102 as larvae, laid no eggs, while those treated with MSA 35 showed reduced hatchability compared with the control. In conclusion, the larvicidal potency of the tested 1,2,4-triazine derivatives is suitable for application against Cx. pipiens mosquitoes and supposed to be a new alternative to other commercial insecticides like pymetrozine.