Larvicidal effects of a neem (Azadirachta indica) oil formulation on the malaria vector Anopheles gambiae (original) (raw)
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2018
s The study was carried out to investigate the larvicidal potential of seeds and leaf crude extract of A. indica as an environmentally safe measure to control malaria vector. The early fourth-instar larvae of anopheles were reared in the laboratory. At varying level of larvae exposure to the crude seeds extract of A. indica; 1ml, 5ml, 10ml, 15ml and 20ml. 30%, 55%, 73%, 92% and 100% mortality rate were recorded at interval of 72 hours with LC50 value (lethal concentration) of 4.4ml while the crude leaf extract presented 32%, 56.5% 76%, 86% and 100% mortality and LC50 4.5ml respectively. The result of the crude seed extracts of A. indica when compare to that of leaf extract were found to be an effective bioagent in controlling the propagation of anopheles larvae as there was no significant different (p < 0.05) in the level of their larvicidal activity and severity. The result therefore suggest A. indica as a sound candidate for the formulation of bioinsecticides to curb rising mal...
Despite increasing reports and concerns about resistance development to public-health insecticides in malaria vectors, significant steps have been put into the quest for novel strategies to disrupt the disease transmission cycle by targeting insect vectors hence sustaining vector management. This study evaluates the toxicity potential of oils of insecticidal plants shortlisted in an ethnobotanical survey on the larvae and adult stages ofAnopheles gambiae. Oils from leaves ofHyptis suaveolens, Ocimum gratissimum, Nicotiana tabacum, Ageratum conyzoidesand fruit-peel ofCitrus sinensiswere extracted by steam-distillation using a Clevenger apparatus. Larvae and female adults of deltamethrin-susceptibleAnopheles gambiaewere gotten from an already established colony in the Entomological Research Laboratory, University of Ilorin. Twenty-five third instar stage larvae were used for larvicidal assays while twenty 2-5 days old adults were used for the adulticidal assays in five replicates.A. g...
Mosquito transmits serious human diseases such as malaria, yellow fever elephantiasis, etc., which have been the cause of millions of deaths annually. The use of synthetic insecticides to control vector mosquitoes has developed physiological resistance in the mosquitoes and adverse environmental effect in addition to high operational cost. Insecticides of botanical origin have been reported as useful for the control of such mosquitoes. Azadirachta indica (Neem) and its derived products have shown a variety of insecticidal properties. This paper aims at the analysis of the efficacy on Larvicide activity of Neem bark (Azadirachta indica) extract pesticide on African malaria vector Anopheles gambiae (Diptera culicidae) for the control of such mosquitoes. 80 grams of Azadirachta indica powder was weighed and extracted with soxhlet using the standard WHO procedures (WHO, 2005). The result shows that the bark extract has a larvicidal activity against Anopheles. This might be due to the effect of phytochemical constituents in the extract such as flavonoid, alkaloid and tannin. Further investigation might be needed for the use of this extract to elucidate active ingredients responsible for larvicidal activity which could be identified and utilized in preparing a commercial product. Index terms: anopheles, Azadirachta indica bark extract, phytochemical screening, larcidal bioassay.
Larvicidal activity of neem oil (Azadirachta indica) formulation against mosquitoes
Malaria Journal, 2009
Background: Mosquitoes transmit serious human diseases, causing millions of deaths every year. Use of synthetic insecticides to control vector mosquitoes has caused physiological resistance and adverse environmental effects in addition to high operational cost. Insecticides of botanical origin have been reported as useful for control of mosquitoes. Azadirachta indica (Meliaceae) and its derived products have shown a variety of insecticidal properties. The present paper discusses the larvicidal activity of neem-based biopesticide for the control of mosquitoes.
The potency of aqueous and methanolic extracts of neem (Azadirachta indica A. Juss) seed kernel, in inhibiting and disrupting development of Anopheles mosquito was assessed in the laboratory. Different concentrations of aqueous and methanolic extracts were tested on eggs, larvae and pupae. Both extracts were found to cause mortality on the specimens used and the level of mortality was concentration dependent. Mortality increased as the concentration increased. Methanolic extract of the neem seed kernel caused significantly higher (P = 0.05) mortality than aqueous extract. Few adults emerged among those treated with lowest concentration of 1 %(wt./vol.) aqueous extract, whereas no larvae or pupae survived to next stage in methanolic extract of the same concentrations. At highest concentration of 5 % (wt/vol), both extracts caused 100% mortality of larvae although the methanolic extract gave a quicker kill (12 hours) than the aqueous extract (24 hours). No egg hatched in all concentrations of both extracts.
Hindawi, 2021
As one of the killer diseases in the world, malaria contributes to child mortality and global death annually. As a result, many reactive mechanisms have evolved to control and repel mosquitoes. e use of synthetic mosquito repellents with N,N-Diethylmeta-toluamide (DEET) is one of the popular interventions despite its dermatological limitations such as skin irritations. Ethnobotanical reviews have identified that the adoption of natural repellents promises high repellence on mosquitoes with minimal side effects compared with synthetic ones. However, this has received little attention in modern pharmaceutical literature. is research is focused on the formulation of a natural mosquito repellent from the oil extracted from Azadirachta indica (A. Juss). e oil cream was formulated in concentrations of 10% v/w, 12.5% v/w, 15% v/w, 17.5% v/w, and 20% v/w using an in vitro evaluation approach. Pharmacopoeia characteristics of the cream such as pH, viscosity, spreadability, and organoleptic properties were carried out to verify acidity, permeation, and flow properties of the formulated cream. e spreadability rate was inversely proportional to the concentration of the cream in terms of oil content falling from 1.24 gm/s to 0.84 gm/s from concentrations 10% v/w to 20% v/w correspondingly. Skin irritation tests, however, indicated traces of irritation at 20% v/w. Repellency properties of the cream revealed a lasting effect on the mosquitoes, although this was dependent on concentration levels. Formulations of 17.5% v/w and 20% v/w neem seed oil cream had an equal repellency effect of 87.5%, whereas the synthetic repellent had a repellency of 75% within a justifiable time frame for all the formulations. is work shows that plant-based mosquito repellents promise a healthier approach in controlling mosquito bites, protecting the skin, and preventing malaria.
Vector control plays a key role in prevention and control of major vector-borne diseases and often constitutes the first line of activity in case of epidemics of vector-borne diseases, and particularly, malaria. Chemical control (use of pesticides) is still the most important element in the integrated approach to vector control. But they are non-selective and harmful to other beneficial organisms. Some of the insecticides are carcinogenic agents and are positively dangerous and even carried through the food chain which in turn affects the non-target organism. In view of the above, the uses of biologically-active plant materials with anti-mosquitocidal properties and ecofriendly-biopesticides are attracted in recent years, because of their biodegradable nature and being relatively safer to human and other non-target organism in the environment. The present paper is to investigate on the larvicidal, pupicidal, smoke repellency effect of neem products against malarial vector, Anopheles stephensi. Six neem limonoids (purity>99%), namely azadiractin, salannin, deacetylgedunin, gedunin, 17-hydroxyazadiradione and deacetylnimbin were sent from Central Research Laboratories, Taiyo Kagaku Co Ltd., Japan. Larvicidal bioassays were conducted at the laboratory with neem limonoids the lethal concentrations (LC 50, LC 90) were worked out by Abottts' formula. Repellency bioassay was done by human volunteers by using neem oil which was procured from the Local Neem Oil Mill, Kalverrampalayam, Coimbatore-641 046, India. Smoke toxicity was performed on the adult female mosquitoes at the laboratory by using neem seed kernel power and it was collected from the Bharathiar University Campus, Coimbaotore-641 046, India. The neem products also had significant larvicidal activity. The larval mortality was dose dependant. The LC 50 and LC 90 values of Azadirachtin treatment at 0.50, 1.0 and 1.5 ppm concentrations was 0.299% and 1.061%, respectively. After treatment of neem oil at 0.50, 1.0 and 1.5 ppm concentrations were 0.503 and 1.324, respectively. After the treatment of salanin, 17-Hydroxyazadiradione, Deacetyl gedunin, Gedunin and Dacetyl nimbin the LC 50 and LC 90 values were increased when compare to Azadirachtin. There was significant repellent activity after the treatment of neem products at three different concentrations (0.2, 0.4, and 0.6). Neem oil had higher repellent activity (<300 minutes at 0.6 concentration), followed by Gedunin which showed less activity (<200 minutes at 0.6 concentration). However, the ethanol applied arm served as control which provided maximum 7.0 minutes repellency. The leaves and pods were also tested smoke repellency bioassay. Smoke Murugan et al.
Journal of Medicinal Plants Research, 2017
Larvicidal effects of plant extracts against larvae of Anopheles gambiae were studied in the malaria entomology laboratory at Mendefera. The aim of the study was to evaluate ethanol and hot water extracts from leaves of seven different plants, viz., Azadirachta indica, Eucalyptus globulus, Tagetes minuta, Datura stramonium, Lantana camara, Ricinus communis and Jatropha curcas, as natural larvicides against third instar larvae of An. gambiae. Insecticidal susceptibility tests were carried out using WHO standard method and the mortality was observed after 24 and 48 h (h) of exposure. The experiment was conducted in complete randomized design in three replications. Data were collected on mortality of mosquito larvae in all the treatments and then subjected to statistical analysis using oneway ANOVA. Most of the tested extracts showed more than 50% mortality. J. curcas (100±0.00%) and R. communis (99.44±0.56) gave significantly higher larval mortalities at 1000 ppm concentration after 48 h of exposure. The experiment also showed that ethanol extracts gave higher larval mortality than hot water extracts and the efficiency of the extracts increased with an increase in the exposure period of the larvae.
Repellent Action of Neem (Azadirachta indica) Seed Oil Cream against Anopheles Gambiae Mosquitoes
This paper conducted an evaluation of repellent effect of neem seed oil formulated in a vanishing type cream base against Anopheles gambiae mosquito under laboratory conditions using human volunteers. The seed oil was extracted and then prepared in five different concentrations of 0, 2.5, 5.0, 7.5 and 10.0% w / w respectively in a vanishing cream base. A commercially available repellent Deet was used as control. The result shows that concentrations 2.5, 5.0, 7.5, and 10.0% w / w and Deet (control) all repelled night-biting Anopheles gambiae mosquitoes at three consecutive 10mins interval for every 5-min exposure time. The duration of protection of various concentrations of neem seed oil cream and control (Deet) was of the order 10.0% > Deet> 7.5%> 5.0% >2.5%.The present study demonstrates potential of neem seed oil cream as mosquito repellent particularly at higher concentrations of 7.5 and 10.0% w / w respectively. This finding may lead to
Journal of Mosquito Research, 2015
Introduction: Plant extracts are an attractive target for search of effective malaria vector control agents. The reason for this is that they present a cost effective, target specific and biodegradable insecticides. The other reason is that they posses varied phytochemical contents that vectors are unlikely to develop resistance to very soon. In this study, we report on effectiveness of ethanol and water extracts of Phytolacca dodecandra (L' Herit) against Anopheles gambiae (Diptera: Culicidae) larvae. Methods: Crude ethanol and water extracts of leaves (shoot and midsection) and mature green fruits of P. dodecandra were scrutinized for larvicidal activity against 1 st to 4 th instar larvae of An. gambiae. Larvicidal bioassays were conducted and effectiveness evaluated using the >80% as per the WHO methods and threshold respectively. ANOVA analyses were performed for statistical justifications of the larvicidal property with P considered significant at p < 0.05. The effects of the extracts were evaluated under laboratory conditions. Result: Ethanol extracts were more potent than water extracts of P. dodecandra as larvicide. The highest mortality (56%) was recorded for L4s for ethanol extracts of mature green fruits of Endod sourced from Eldoret. Water extracts of Neem leaves killed 31% L3s while deltamethrin killed over 80% of all exposed larvae. Conclusion: Ethanol extracts P. dodecandra killed more of the exposed An. gambiae larvae than water extracts. Recorded mortalities due to exposure to the extracts were less than the WHO threshold of >80%. We recommend that additional refinement and tests need to be done before commercial exploitation as a malaria vector larvicide.