Inhibition Of Adult Emergence Research Articles

Bioactivity of Anacardium occidentale (L) and Allium sativum (L) Powders and Oils Extracts against Cowpea Bruchid, Callosobruchus maculatus (Fab.) [Coleoptera: Chrysomelidae

The powders and oils extracts of Anacardium occidentale (L.) seeds and Allium sativum (L.) bulbs were tested as contact insecticides against the cowpea bruchid, Callosobruchus maculatus (Fab.) in cowpea seeds. The powders were incorporated at rates 1, 2.5 and 5/20g of cowpea seeds and acetone extracts of the plants were also applied at 0.5, 1 and 1.5ml per 20g of cowpea seeds to assess contact mortality of adult insect, oviposition, adult emergence and damage assessment. The results obtained showed that at 72 hours; 1, 2.5 and 5/20g of cowpea seeds evoked 63.3, 80 and 100% adult mortality of the cowpea bruchid while the corresponding results for A. sativum were 60.7, 73.3 and 100% mortality respectively. All concentration of acetone extracts that were used evoked 100% mortality of C. maculatus after 72 hours of post treatment. Complete protection of seeds and complete inhibition of adult emergence in both powders and extracts of A. occidentale and A. sativum were achieved. The results obtained from this research revealed that powders and extracts of A. occidentale seeds and A. sativum bulbs were effective in controlling cowpea bruchid, C. maculatus in stored cowpea seeds.

Droplet size and efficacy of an adulticide–larvicide ultralow‐volume formulation on Aedes aegypti using different solvents and spray application methods

When cases of dengue are reported or the density of adult Aedes aegypti (L.) becomes too high, ultralow-volume (ULV) application of insecticides is the recommended control method. The droplet size of an aerosol insecticide influences its efficiency in killing adult mosquitoes. Many studies have been carried out to determine the optimum droplet size that maximises vector control efforts, but only a few have determined droplet-size spectra for specific equipment using different solvents and comparing thermal and non-thermal aerosols. The present study showed that the droplet size for a water-based adulticide-larvicide formulation was larger than for the same formulation diluted in gasoil or biodiesel. No significant differences in adult mortality were observed between sprayers and solvents, but efficacy decreased with distance from the sprayer nozzle. Adult emergence inhibition was more than 90% when using water as a solvent for both thermal and cold foggers, and the efficacy did not decrease with distance from the sprayer nozzle. On the other hand, oil-based solvents became less effective with distance. The use of water as a solvent with both thermal and cold foggers improves the efficacy of the studied formulation containing permethrin as adulticide and pyriproxyfen as larvicide in scaled-up assays. Moreover, it reduces the environmental impact and costs of spraying by comparison with formulations using oil solvents.

An autodissemination station for the transfer of an insect growth regulator to mosquito oviposition sites

A prototype autodissemination station to topically contaminate oviposition-seeking container-dwelling mosquitoes with the insect growth regulator, pyriproxyfen, was developed and tested in the laboratory. Our test subject was the Asian tiger mosquito, Aedes albopictus (Skuse) (Diptera: Culicidae), an urban species that colonizes small-volume cryptic larval habitats and is a skip ovipositor that visits multiple containers. The station consists of a water reservoir to attract gravid females, which is joined to a transfer chamber designed to contaminate visiting mosquitoes. The unit is easily constructed by moulding wet shredded cardboard using corn starch as a binder. The essential criteria that must be met to prove the efficacy of an autodissemination station require it to demonstrate effectiveness in attracting the target insect, in transferring the toxicant to the insect that will disperse the agent, and in facilitating the subsequent transfer of the toxicant from the insect to target habitats at a lethal concentration. Cage experiments demonstrated that the unit was readily accepted by gravid females as an oviposition site. A powder formulation of pyriproxyfen-impregnated silica particles adhered to visiting Ae. albopictus females (mean: 66 particles/female), although particles were lost over time. In cage (2.2 m(3) ) trials, pyriproxyfen-charged stations resulted in 100% inhibition of adult emergence, whereas in small-room (31.1 m(3) ) trials, 81% emergence inhibition was recorded. The venereal transfer of pyriproxyfen from contaminated males to virgin females was also observed, and pyriproxyfen was subsequently transferred to water-holding containers at concentrations that inhibited emergence. Key autodissemination station features include lack of maintenance requirements, biodegradable construction, low cost and low risk.

LARVICIDAL AND ADULT EMERGENCE INHIBITION ACTIVITY OF ABUTILON INDICUM (LINN.) (MALVACEAE) LEAF EXTRACTS AGAINST VECTOR MOSQUITOES (DIPTERA: CULICIDAE)

ABSTRACT The crude leaf extracts of Abutilon indicum were evaluated for larvicidal, pupal deformities and adult emergence inhibition activity against vector mosquitoes viz., Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus. Larvicidal activity was carried out using WHO protocol. Hexane extract with LC50 value of 261.31 ppm after a period of 24 hr was found to be effective against Aedes aegypti larvae. Larval and pupal development was arrested resulting in decreased pupal transformation and adult emergence. Larval and pupal periods were prolonged with appearance of larval–pupal and pupal–adult intermediates, with an overall increase in the developmental period. Hatching was delayed and its rate was reduced compared to control. Disrupted egg shells and dechitinized body walls were observed, indicating clearly the anti-juvenile potential of the extract. The growth index was considerably reduced. These results suggest the leaf extracts of Abutilon indicum as a promising adult emergence inhibitor against vector mosquitoes and might be used in small volume aquatic habitats or breeding sites of limited size in and around human dwellings.

A New Strategy for Aedes aegypti (Diptera: Culicidae) Control With Community Participation Using a New Fumigant Formulation

Dengue and dengue hemorrhagic fever are mosquito-borne viral diseases that coincide with the distribution of Aedes aegypti (L.), the primary vector in the tropical and semitropical world. With no available vaccine, controlling the dengue vector is essential to avoid epidemics. This study evaluates the efficacy of a new smoke-generating formulation containing pyriproxyfen and permethrin in Puerto Libertad, Misiones, Argentina. A fumigant tablet (FT) was applied inside the houses by the community members and compared with a professional application. A treatment combining the application of fumigant tablets indoors and ultralow volume fumigation outdoors was also assessed. The community perceptions and practices about dengue disease and the acceptance of this new nonprofessional FT were evaluated through surveys. Results show >90% adult emergence inhibition and 100% adult mortality with these treatments. More than 80% of the residents applied the FT and preferred participating in a vector control program by using a nonprofessional mosquito control tool, instead of attending meetings and workshops promoting cultural changes.

Diofenolan: a novel insect growth regulator in common citrus butterfly, Papilio demoleus

Penultimate and last instar larvae of the common citrus swallowtail butterfly, Papilio demoleus L. (Papilionidae: Lepidoptera), were treated with different doses of a novel juvenoid, diofenolan. Several deformities were observed as a result of topical administration of diofenolan which include delay in larval–larval and larval–pupal ecdysis, ecdysial failure, mortality, severe reduction in pupation, deformed pupae and complete inhibition of adult emergence. The juvenoid diofenolan severely hampers the normal growth, development and metamorphosis of P. demoleus and can be incorporated into integrated pest management programs for successful control of this important pest of citrus all over the world.

Efficacy of medicinal plant extracts against malarial vector, Anopheles subpictus Grassi

Insecticides of botanical origin may serve as suitable alternative biocontrol techniques in the future. The aim of this study was to evaluate the adulticidal activity and adult emergence inhibition (EI) of leaf hexane, chloroform, ethyl acetate, acetone, and methanol extracts of Aegle marmelos (Linn.) Correa ex Roxb, Andrographis lineata Wallich ex Nees., Andrographis paniculata (Burm.f.) Wall. ex Nees., Cocculus hirsutus L. Diels, Eclipta prostrata L., and Tagetes erecta L. tested against malarial vector, Anopheles subpictus Grassi (Diptera: Culicidae). All plant extracts showed moderate adulticidal activity and EI effects after 24 h of exposure at 1,000 ppm; however, the highest adulticidal activity was observed in ethyl acetate extract of A.lineata, chloroform extract of A. paniculata, acetone extract of C. hirsutus, and methanol extract of T. erecta (LD(50) = 126.92, 95.82, 109.40, and 89.83 ppm; LD(90) = 542.95, 720.82, 459.03, and 607.85 ppm); and effective EI was found in leaf acetone extract of the A. marmelos, ethyl acetate extract of A. lineata, methanol extracts of C. hirsutus, and T. erecta, (EI(50) = 128.14, 79.39, 143.97, and 92.82 ppm; EI(90) = 713.53, 293.70, 682.72, and 582.59 ppm), respectively, against A. subpictus. These results suggest that the leaf methanol extract of C. hirsutus and T. erecta have the potential to be used as an ideal eco-friendly approach for the control of A. subpictus. Therefore, this study provides first report on the mosquito adulticidal activity and EI of plant extracts against malaria vector.

Bioefficacy of Plumbago zeylanica (Plumbaginaceae) and Cestrum nocturnum (Solanaceae) plant extracts against Aedes aegypti (Diptera: Culicide) and nontarget fish Poecilia reticulata

In a search for natural products that could be used to control the vectors of tropical diseases, extracts of medicinal plants Plumbago zeylanica and Cestrum nocturnum have been tested for larvicidal activity against second, third, and fourth instar larvae of Aedes aegypti. The LC(50) values of all the extracts in different solvents of both the plants were less than 50 ppm (15.40-38.50 ppm) against all tested larval instars. Plant extracts also affected the life cycle of A. aegypti by inhibition of pupal development and adult emergence with increasing concentrations. The larvicidal stability of the extracts at five constant temperatures (19°C, 22°C, 25°C, 28°C, and 31°C) evaluated against fourth instar larvae revealed that toxicity of both plant extracts increases with increase in temperature. Toxicity studies carried out against fish species Poecilia reticulata, the most common nontarget organism in the habitats of A. aegypti, showed almost nil to meager toxicity at LC(50) and LC(90) doses of the plant extracts. The qualitative analysis of crude extracts of P. Zeylanica and C. nocturnum revealed the presence of bioactive phytochemicals with predominance of plumbagin in P. zeylanica and saponins in C. nocturnum. Partially purified plumbagin from P. zeylanica and saponins from C. nocturnum were obtained, and their presence was confirmed by thin-layer chromatography and biochemical tests. The bioassay experiment of partially purified secondary metabolites showed potent mosquito larvicidal activity against the fourth instar larval form. Therefore, this study explored the safer and effective potential of plant extracts against vector responsible for diseases of public health importance.

Adult emergence inhibition and adulticidal activities of medicinal plant extracts against Anopheles stephensi Liston

To determine the adult emergence inhibition (El) and adulticidal activities of hexane, chloroform, ethyl acetate, and acetone leaves extracts of Anisomeles malabarica (A. malabarica), Euphorbia hirta (E. hirta), Ocimum basilicum (0. basilicum), Ricinus communis (R. communis), Solanum trilobatum (S. trilobatum), Tridax procumbens (T. procumbens) and seeds of Gloriosa superba (G. superba) against Anopheles stephensi (An. stephensi). The El and adulticidal trials were carried out according to World Health Organization (WHO) procedures with slight modifications. The extracts were diluted in dimethyl sulphoxide in order to prepare a serial dilution of test dosages (15.625, 31.25, 62.5, 125, 250, 500 and 1 000 jU g/mL). Five duplicate trials were carried out for every sample concentration, and for each trial a negative control was included and the mortality was determined after 24 h of exposure. The highest El activity was found in ethyl acetate extracts of A. malabarica, chloroform extracts of 0. basilicum, S. trilobatum, acetone of extract of R. communis, T. procumbens, and seed extract of G. superba with EI50 values 143.12, 119.82, 157.87, 139.39, 111.19, and 134.85 fig/mL, and the effective adulticidal activity was observed in chloroform, acetone extracts of G. superba, T. procumbens, R. communis, S.trilobatum and ethyl acetate extract of 0. basilicum with LD50 values 120.17, 108.77, 127.22, 163.11, 118.27, and 93.02 l-i g/mL, respectively. Chi-square value was significant atP<0.05 level. These results should encourage further efforts to investigate the compounds that might possess good El and adulticidal properties when isolated in pure form.

Adult emergence inhibition and adulticidal activity of leaf crude extracts against Japanese encephalitis vector, Culex tritaeniorhynchus

Mosquitoes have developed resistance to various synthetic insecticides, making its control increasingly difficult. Insecticides of botanical origin may serve as suitable alternative biocontrol techniques in the future. The aim of this study was to evaluate the adult emergence inhibition (EI) and adulticidal activity of the leaf hexane, chloroform, ethyl acetate, acetone, and methanol extracts of Aegle marmelos (Linn.) Correa ex Roxb, Andrographis lineata Wallich ex Nees., Andrographis paniculata (Burm.f.) Wall. ex Nees., Cocculus hirsutus L. Diels, Eclipta prostrata L. and Tagetes erecta L. were tested against japanese encephalitis vector, Culex tritaeniorhynchus Giles (Diptera: Culicidae). All plant extracts showed moderate EI and adulticidal activity effects after 24h of exposure at 1,000ppm; however, the highest EI activity was found in leaf methanol extracts of A. marmelos, A. paniculata, T. erecta, and chloroform extract of E. prostrata (EI50=141.94, 214.17, 166.43, and 184.58ppm; EI90=590.26, 882.34, 532.00 and 571.81ppm); and the effective adulticidal activity was observed in acetone extract of A.marmelos, hexane of A.lineata, ethlyl acetate of A.paniculata, methanol extracts of C.hirsutus, E.prostrata, and T.erecta (LD50=139.05, 251.24, 205.06, 222.10, 166.73, and 232.74ppm; LD90=426.19, 837.09, 813.59, 794.42, 579.43 and 807.41ppm), respectively against C. tritaeniorhynchus. These results suggest that the leaf methanol extract of C. hirsutus, E. prostrata, and T. erecta have the potential to be used as an ideal eco-friendly approach for the control of the C. tritaeniorhynchus. Therefore, this study provides first report on the mosquito EI and adulticidal activity of plant extracts against a vector.

Exploration of larvicidal and adult emergence inhibition activities of Ricinus communis seed extract against three potential mosquito vectors in Kolkata, India

Objective To determine the larvicidal and adult emergence inhibition activities of castor ( Ricinus communis) seed extract against three potential mosquito vectors Anopheles stephensi (An. stephensi), Culex quinquefasciatus (Cx. quinquefasciatus) and Aedes albopictus (Ae. albopictus) in India. Methods The R. communis seed extract was tested, employing WHO procedure, against fourth larval instars of the three mosquito species for 24 h and larval mortalities were recorded at various concentrations (2-64 μg/mL); the 24 h LC 50 values of the R. communis seed extract were determined following Probit analysis. The larval killing, antipupation and adult emergence inhibition rates of the test extract, using a single concentration of 2 μ LC 50, were studied at different time periods (24-72 h); the extract toxicity was tested against a fish, Oreochromis niloticus (O. niloticus). Results The R. communis seed extract exhibited larvicidal effects with 100 % killing activities at concentrations 32-64 μg/mL, and with LC 50 values 7.10, 11.64 and 16.84 μg/mL for Cx. quinquefasciatus, An. stephensi and Ae. albopictus larvae, respectively. When the larvae were treated with the extract at a single concentration of 2×LC 50, significant differences were observed, compared to control groups, in rate of pupation (P<0.001) as well as in adult formation (P<0.001). Conclusions The present findings suggest that the R. communis seed extract provided an excellent potential for controlling An. stephensi, Cx. quinquefasciatus and Ae. albopictus mosquito vectors.

Efficacy of leaves extract of Calotropis procera Ait. (Asclepiadaceae) in controlling Anopheles arabiensis and Culex quinquefasciatus mosquitoes

The present study aimed to investigate, the larvicidal, adult emergence inhibition and oviposition deterrent activity of aqueous leaves extract of Calotropis procera against Anopheles arabiensis and Culex quinquefasciatus as natural mosquito larvicide. The larvicidal activity was monitored against 2nd, 3rd and 4th instar larvae of each mosquito species 24 h post-treatment. Adult emergence inhibition activity was tested by exposing 3rd instar larvae of each mosquito species to different concentrations of extracts (200, 400, 600, 800 and 1000 ppm for An. arabiensis and 100, 200, 300, 400, 500 and 600 ppm for Cx. quinquefasciatus). Probit analysis was used to analyze data from bioassay experiments. The oviposition deterrent activity was tested by using three different concentrations of extracts (1000, 500 and 200 for An. arabiensis, and 1000, 500 and 100 for Cx. quinquefasciatus) that caused high, moderate and low larval mortality in the larvicidal experiment against 3rd instar larvae. It was found that, LC50–LC90 values calculated were 273.53–783.43, 366.44–1018.59 and 454.99–1224.62 ppm for 2nd, 3rd and 4th larval instars, respectively, of An. arabiensis and 187.93–433.51, 218.27–538.27 and 264.85–769.13 ppm for 2nd, 3rd and 4th larval instars, respectively, of Cx. quinquefasciatus. Fifty percent of adult emergence inhibition (EI50) was shown at 277.90 and 183.65 ppm for An. arabiensis and Cx. quinquefasciatus, respectively. The pupal stage was not affected till a concentration of 5000 ppm. The extract showed oviposition deterrence and effective repellence against both mosquito species at different concentrations, with the observation on that maximal eggs were laid in low concentration of extract. These results suggest that the leaves extract of C. procera possess remarkable larvicidal, adult emergence inhibitor, repellent and oviposition deterrent effect against both An. arabiensis and Cx. quinquefasciatus, and might be used as natural biocides for mosquito control.

Efficacy of Novaluron Against Culex quinquefasciatus in Small- and Medium-scale Trials, India

Novaluron 10% emulsifiable concentrate (EC), an insect growth regulator (IGR), was tested against Culex quinquefasciatus immatures at 1, 5, and 10 mg active ingredient (AI)/m2 applied to cesspits, drains, and abandoned wells. The IGR produced 80-100% inhibition of adult emergence (IE) for > 1 week (10-14 days) in cesspits, 1-2 weeks in street drains, and 5-10 weeks in abandoned wells at the 3 application rates. The efficacy increased with the increasing dose in street drains and abandoned wells. The residual activity of the IGR was longer in abandoned wells compared to drains and cesspits. Based on the small-scale trial, doses of 1, 5, and 10 mg AI/m2 were used in the medium-scale trial for cesspits, abandoned wells, and street drains, respectively. The efficacy observed in medium-scale trial was similar to that in the small-scale trial. The results indicate that novaluron 10% EC can be used for larval control against Cx. quinquefisciatus at the application rate of 1 mg AI/m2 at 10-day intervals in cesspits, at 5 mg AI/m2 at 2-month intervals in abandoned wells, and at 10 mg AI/m2 applied at fortnightly intervals to drains. Even at the lowest rate of 1 mg AI/m2, the IGR prevented adult emergence for at least a week in cesspits and street drains and for a month in abandoned wells. Novaluron 10% EC could be one of the options for larval control operations in integrated vector management.

Thermal behaviour and biological activity against Aedes aegypti (Diptera: Culicidae) of permethrin and pyriproxyfen in a smoke‐generating formulation

The most common ways to control dengue vector Aedes aegypti (L.) are larval source reduction in domestic habitats and ground application of small quantities of aerosol insecticide (ultralow volume). Nevertheless, these actions have been shown repeatedly to be ineffective in controlling Ae. aegypti populations. The efficacy of a new smoke-generating formulation containing pyriproxyfen and permethrin was evaluated in the laboratory. Smoke-generating tablets containing each insecticide individually or combined were prepared, and the recovery of the insecticides from the smoke was determined. Recovery values of over 90% were obtained for pyriproxyfen, and around 50% for permethrin. The biological efficacy of pyriproxyfen released in the smoke was evaluated in the laboratory, on late third-instar or early fourth-instar Ae. aegypti larvae, using different concentrations of pyriproxyfen and exposure times. Adult emergence inhibition (EI) values of 100% were obtained at 30 min, and a dose-dependent effect was observed at 5 min. The effect of pyriproxyfen released in the smoke was due to direct contact with the larvicide in the water rather than by inhalation of the fumes. The efficacy of permethrin released in the fumes was also evaluated as knockdown effect (KT(50)) on adults for a tablet containing permethrin alone or permethrin plus pyriproxyfen. There was no significant difference in KT(50) values obtained for permethrin (KT(50) = 19.9 min) and permethrin plus pyriproxyfen (KT(50) = 19.4 min). The excellent laboratory performance of this new formulation on immature stages and adults indicates that a smoke-generating tablet containing pyriproxyfen and permethrin could be a new tool for controlling mosquitoes.

Laboratory Evaluation of the Aqueous Extract ofAzadirachta indica(Neem) Wood Chippings onAnopheles gambiaes.s. (Diptera: Culicidae) Mosquitoes

Azadirachta indica A. Juss (the neem tree), a source of limonoid insect growth regulatory (IGRs), grows well in many places in sub-Saharan Africa. We explored the potential of neem wood and bark chippings in malaria vector control by evaluating their aqueous extracts as a larvicide and growth disruptor of Anopheles gambiae s.s. (Diptera: Culicidae) under laboratory conditions. Immature stages of the mosquito were tested using WHO guidelines. Fifty percent inhibition of adult emergence (IE50) of all larval instars was obtained with <0.4 g of neem chippings in 1 liter of distilled water. For pupae, significant mortality occurred at 5 g/liter. Inhibition of pupation was seen with some larvae staying as LIVs for 9 d before dying. In addition to growth retardation, reduced reaction by larvae to visual and mechanical stimuli observed at higher neem concentrations may make them more susceptible to natural predators. There were no significant differences in the sex ratio of emerged adults or wing length of females compared with the controls. High-performance liquid chromatography of aqueous extracts showed a series of constituents of varying polarity, including the limonoids nimbin and salannin, which were quantified. Azadirachtin was not detected and the observed activities are attributed to other constituents of the chippings. Such larvicides can be particularly effective where larval habitats are relatively large and readily identifiable. Aqueous extracts of neem wood chippings can be produced locally and their use has the potential to be a low-tech component of integrated malaria vector control schemes in sub-Saharan Africa.

Efficacy of a new combined larvicidal–adulticidal ultralow volume formulation against Aedes aegypti (Diptera: Culicidae), vector of dengue

A new ultralow volume formulation (ULV) containing permethrin as an adulticidal active ingredient and the insect growth regulator (IGR) pyriproxyfen as a larvicide was developed and its efficacy evaluated in a field trial in Wanda, Misiones (Argentina). Two separate study areas were sprayed: one with a ULV formulation of permethrin 15% plus pyriproxyfen 3% and the other with permethrin 15% only. A third untreated area was kept as a control. Sentinel cages containing adult mosquitoes and jars containing Aedes aegypti larvae III/IV were placed in treated and control areas. The residual activity of the formulations was tested using 20 L water containers. The adulticide effect of permethrin 15% + pyriproxyfen 3% formulation was similar to the permethrin 15% formulation, however, the inhibition of adult emergence in the treatment with permethrin 15% never exceeded 20%, whereas the inhibition of adult emergence in the treatment with permethrin 15% plus pyriproxyfen 3% showed initial values of 96% maintaining this high level of inhibition up to 35 days after ULV spraying. Larval indexes (House and Breteau indexes) showed that a greater, long-lasting effect was obtained with the permethrin 15% plus pyriproxyfen 3% formulation.

Effectiveness of Pyriproxyfen and Diflubenzuron Formulations as Larvicides Against Aedes aegypti

The efficacy of technical pyriproxyfen and diflubenzuron was evaluated at the laboratory level against Aedes aegypti, where we achieved adult emergence inhibition (EI50) values of 0.048 and 1.59 ppb (microg/liter), respectively. We compared these data with values obtained for temephos. We prepared emulsifiable concentrate formulations of pyriproxyfen and diflubenzuron in the laboratory and obtained EI50 values of 0.01 and 0.02 ppb, respectively. We also obtained 100% adult emergence inhibition with 0.1% slow-release sand formulations of pyriproxyfen and diflubenzuron. In a simulated field study, the granular sand formulations of pyriproxyfen, diflubenzuron, and temephos remained active for over 4 mo. In a field study, a 0.2% granular formulation of diflubenzuron and 1% temephos showed a similar performance.

Laboratory Evaluation of Cyromazine Against Insecticide-Susceptible and -Resistant Mosquito Larvae

In this study, the activity of cyromazine was evaluated following WHO standard procedures against susceptible and resistant mosquito strains of Anopheles gambiae, Culex quinquefasciatus, and Aedes aegypti. The dose for 50% and 90% inhibition of adult emergence (IE50 and IE90) ranged from 0.028 mg/liter to 0.17 mg/liter and from 0.075 mg/liter to 0.42 mg/liter, respectively. The effects of cyromazine were closer to that of chitin synthesis inhibitors rather than that of juvenile hormone analogues, with only 10-20% pupal mortality. The toxicity of cyromazine was not strongly affected by the presence of common resistance mechanism, i.e., Kdr mutation and Ace.1(R) (resistance ratio from 0.5 to 2.3). The absence of cross resistance with common insecticides (pyrethroids, carbamates, organophosphates) makes cyromazine a potential candidate for disease vector control, especially for the management of insecticide resistance.

Larvicidal and adult emergence inhibition effect of &lt;I&gt;Centella asiatica&lt;/I&gt; Brahmi (Umbelliferae) against mosquito &lt;I&gt;Culex quinquefasciatus&lt;/I&gt; say (Diptera : Culicidae)

Ethanolic extract of Centella asiatica leaves were evaluated for the larvicidal and adult emergence inhibition activity against mosquito Culex quinquefasciatus under five constant temperatures 19, 22, 25, 28 and 31°C in the laboratory. Toxicity of this extract increased with temperature. The 50% medium lethal concentrations ranged between 6.84 ppm at 19°C and 1.12 ppm at 31°C. A similar trend was observed for the 90% lethal concentrations which varied from 9.12 to 3.63 ppm at the two temperatures, respectively. The adult emergence inhibition activity of this extract at LC50s of different temperatures was generally more pronounced in increased temperatures. These results suggest that the leaf extract of C. asiatica is promising as larvicide and adult emergence inhibitor against Culex quinquefasciatus and might be used directly in small volume aquatic habitats or breeding sites of limited size around human dwellings. African Journal of Biomedical Research Vol. 8(1) 2005: 31-33

Efficacy of Agnique® MMF Monomolecular Surface Film Against Anopheles stephensi Breeding in Urban Habitats in India1

Efficacy of Agnique MMF, a monomolecular film formulation, was tested against immatures of Anopheles stephensi, an urban malaria vector in India, in simulated and natural habitats. Simulated field trials carried out in cement tanks showed 100% inhibition of adult emergence for up to 1 wk at 0.4 ml/m2 and up to 3 wk at 1 ml/m2. A small-scale field trial in tanks and wells at 1 and 2 ml/m2 produced more than 75% reduction of late instars and 100% reduction of pupae on day 1. The reduction in pupae at 1 and 2 ml/m2 lasted up to 2 wk in tanks and 5 wk in wells. These results suggest that Agnique MMF could be used as one of the choices in an urban malaria control program.