Larvicidal and repellent activity of tetradecanoic acid against Aedes aegypti (Linn.) and Culex quinquefasciatus (Say.) (Diptera:Culicidae)

AbstractObjectiveTo investigate the larvicidal and repellent efficacy of tetradecanoic acid against Aedes aegypti (Ae. aegypti) L. and Culex quinquefasciatus (Cx. quinquefasciatus) Say (Diptera: Culicidae).MethodsLarvicidal efficacy of tetradecanoic acid was tested at various concentrations against the early third instar larvae of Ae. aegypti and Cx. quinquefasciatus. The repellent activity was determined against two mosquito species at three concentrations viz., 1.0,2.5 and 5.0 ppm under the laboratory conditions.ResultsThe tetradecanoic acid was found to be more effective against Cx. quinquefasciatus than Ae. aegypti larvae. The LC50 values were 14.08 ppm and 25.10 ppm, respectively. Tetradecanoic acid showed lesser repellency against Ae. aegypti and Cx. quinquefasciatus. The highest repellency was observed in higher concentration of 5.0 mg/cm2 provided 100% protection up to 60 and 90 min against Ae. aegypti and Cx. quinquefasciatus respectively.ConclusionsFrom the results it can be concluded the tetradecanoic acid is a potential for controlling Cx. quinquefasciatus and Ae. aegypti mosquitoes

AEROBIOLOGY OF MULBERRY FIELDS IN VELLORE DISTRICT

ABSTRACT Mulberry which forms the exclusive source of food for commercial silk producing silk worm (Bombyx mori L.) is affected by a number of diseases and pests. The aerobiology of crop field was very limited and much of the fields were to be opened for investigation. It affects the nutrition, growth and cocoon production of silkworm. Hence a detailed investigation was carried out on the aerobiology of mulberry fields in Vellore district. The Vellore district comprises of eight taluks, 14 ranges and 64 subdivisions. Much of the Vellore district land area is cultivated by Mulberry as a cottage industry. It is found that from October to January rainfall was maximum, Vaniyambadi, Tirupattur and Gudiyattam receives maximum rain. The humidity is relatively maximum during the period of October to September 1999. The temperature was maximum from March to June. This helps for the spread and growth of various microflora and airspores in Vellore district environs. From these data, the causative organisms of various diseases of Mulberry were identified. This data will be helpful for the treatment, management of the much useful plant Mulberry in Vellore district

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Abstract. -Background: Plant based repellent against mosquito borne diseases are used recently because synthetic repellents cause side effects like breathing problem, eye irritation, head ache, cough, etc. The use of natural products for dengue control would protect the environment, reduce dependence on expensive synthetic repellents and also generate local employment. Material and Methods: Essential oil was isolated by steam distillation which was used against the bites of Aedes aegypti and duration of protection period was assessed. Skin-irritant potential test was also conducted on 25 healthy volunteers by using four-point scale. Results: The increase in the concentrations of essential oil increased the mean protection time against the bites of Aedes aegypti. The lowest mean protection time was 180.0 min for 2.5% and highest time of 255.0 min for 10%. The mean score of zero for skin-irritant potential test for all the concentrations indicated that the essential oil did not cause irritation to human skin. Conclusions: Results indicated that the use of plant based repellent for the control of dengue fever would replace the currently used synthetic repellents which causes many side effects

Full Length Research Article - Larvicidal and Adult Emergence Inhibition Effect of Centella asiatica Brahmi (Umbelliferae) against Mosquito Culex quinquefasciatus 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

OVIPOSITION AND OVICIDAL ACTIVITIES OF ALKALOIDAL EXTRACT FROM MURRAYA KOENIGII AGAINST VECTOR MOSQUITOES

Alkaloidal extract from Murraya koenigii have shown oviposition activity at 250-1000 ppm concentration and ovicidal activity at 25-100 ppm concentration against Culex quinquefasciatus and Culex tritaeniorhynchus. Water treated with alkaloidal extract at 1000ppm received significantly more egg rafts of vector mosquitoes than lesser concentrations of alkaloidal extract and filtered cesspit water (control). The maximum Oviposition Active Index of 0.93 was observed at 1000ppm in Cx.quinquefasciatus. Laboratory treatment of the eggs of various age groups in different concentration of alkaloidal extract caused only moderate ovicidal activity but inflict delayed effects such as high larval and low pupal and adult mortality. The eggs of Cx.quinquefasciatus were found to be more susceptible than Cx.tritaeniorhynchus. The age of the egg rafts, concentration of alkaloidal extract and the duration of treatment also influenced the ovicidal activity. Key Words: Murraya koenigii; Rutaceae; alkaloidal extract; oviposition; ovicidal; Culex quinquefasciatus; Culex tritaeniorhynchus. Nigerian Journal of Natural Products and Medicine Vol.7 2003: 16-1

Studies on potential breeding habitats of dengue and chickungunya vector mosquitoes in Ramanathapuram district, Tamil Nadu, India

In recent past, entomological survey has not been carried out in the rural villages of Ramanathapuram district, Tamil Nadu, India. Keeping this in view, larvae and pupae of Aedes mosquitoes from different artificial containers were collected from higher altitudes of the Ramanathapuram, viz. Paramakudi, Rameshwaram, Tiruvadanai, Kadaladi, and Ramanathapuram during pre (May-June) and post (November-December) monsoon seasons in 2015 to understand the seasonal distribution, so as to forecast the risk of dengue transmission. Collected immature were transported to laboratory and allowed to emerge as adult. The adults were identified up to the species level. Aedes aegypti mosquitoes were highest in water tanks followed by in discarded tyres and the maximum number of collection was made from Ramanathapuram followed by Rameshwaram. The Shannon-Weiner diversity index value of Aedes mosquitoes in the study areas recorded for Ae. aegypti, Ae. albopictus, and Ae. vittatus were 1.1571, 0.1105, and 0.0674, respectively. Presence of Ae. aegypti and Ae. albopictus in both seasons reveals re-emergence of vector borne diseases at higher altitudes

Studies on potential breeding habitats of dengue and chickungunya vector mosquitoes in Ramanathapuram district, Tamil Nadu, India

234-239In recent past, entomological survey has not been carried out in the rural villages of Ramanathapuram district, Tamil Nadu, India. Keeping this in view, larvae and pupae of Aedes mosquitoes from different artificial containers were collected from higher altitudes of the Ramanathapuram, viz. Paramakudi, Rameshwaram, Tiruvadanai, Kadaladi, and Ramanathapuram during pre (May-June) and post (November-December) monsoon seasons in 2015 to understand the seasonal distribution, so as to forecast the risk of dengue transmission. Collected immature were transported to laboratory and allowed to emerge as adult. The adults were identified up to the species level. Aedes aegypti mosquitoes were highest in water tanks followed by in discarded tyres and the maximum number of collection was made from Ramanathapuram followed by Rameshwaram. The Shannon-Weiner diversity index value of Aedes mosquitoes in the study areas recorded for Ae. aegypti, Ae. albopictus, and Ae. vittatus were 1.1571, 0.1105, and 0.0674, respectively. Presence of Ae. aegypti and Ae. albopictus in both seasons reveals re-emergence of vector borne diseases at higher altitudes

Ovicidal response effects of selected plant essential oils against Aedes aegypti

The  ovicidal response  of  selected plant essential  oils  was  evaluated  under  laboratory  conditions against  Aedes aegypti. Three plant oils viz., Abutilon indicum, Acacia nilotica and Acalypha indica were tested for ovicidal response assays at six different concentrations viz., 75, 125, 175, 225, 275 and 325 ppm concentrations. The ovicidal activity degreasing of essential oils against Aedes aegypti were Acacia nilotica > Acalypha indica and Abutilon indicum