Rajan Maheswaran

Bioefficacy of essential oil from Polygonum hydropiper L. against mosquitoes, Anopheles stephensi and Culex quinquefasciatus.

The biological activity of essential oil extracted from the leaves of Polygonum hydropiper and a compound, confertifolin, isolated from this plant was bioassayed against larva of mosquitoes, Anopheles stephensi and Culex quinquefasciatus. The essential oil showed the LC50 values of 189 and 243ppm; 217 and 242ppm, confertifolin (6,6,9a-trimethyl-4,5,5a,6,7,8,9,9a-octahydronaphtho[1,2-c]furan-3(1H)-one) showed the LC50 values of 2.40 and 3.09ppm; 4.07 and 4.18ppm against the second and fourth instar larvae of An. stephensi and Cx. quinquefasciatus, respectively. At 10ppm confertifolin showed ovicidal activity of 100, 98.6 and 86.4% against An. stephensi and 100, 100 and 75.2% against Cx. quinquefasciatus on 0-6, 6-12 and 12-18h old eggs; the repellent activity persisted for 314.6 and 319.0min; oviposition deterrent activity was 97.2 and 99% and adulticidal activity was 100 and 100% against An. stephensi and Cx. quinquefasciatus, respectively. The results were statistically significant. Confertifolin could be considered for use in the control of human vector mosquitoes.

Bioefficacy of Ceasalpinea bonduc (L.) Roxb. against Spodoptera litura Fab. (Lepidoptera: Noctuidae)

Bioefficacy of hexane, chloroform and ethyl acetate extracts of the seeds of Ceasalpinea bonduc (L.) Roxb. was studied against third instar larvae of Spodoptera litura at 0.25, 0.5, 1, 2.5 and 5.0% concentrations. Significant antifeedant, larvicidal and pupicidal activities and least LC50 values were observed in chloroform extract. The chloroform extract was subjected to fractionation using silica gel column chromatography. Six fractions were obtained; among these, the third fraction showed high antifeedant, larvicidal and pupicidal activities at 1000 ppm concentration. Abnormalities in adults were also observed. All the activities were concentration dependent. C. bonduc could be useful in integrated pest management programme.

Meliaceae Plant Extracts as Potential Mosquitocides-A Review

Mosquitoes are responsible for the transmission of dreadful diseases such as Malaria, Dengue, Chikungunya, Lymphatic filariasis. An ecofriendly approaches made to control mosquito larvae by using plant extracts is alternative to synthetic pesticides for avoid the environmental hazards. In order to achieve control, knowledge about the interactions between the pest population and plant products is very much important. Many plant species exhibited mosquitocidal activity, among them meliaceae having potential activity against mosquitoes. For example Azadirachta indica, Dysoxylum malabaricum, Khaya senegalensis, Lansium domesticum, Melia volkensii Melia azedarach, Turraea abyssinica, Turraea wakefeldii, Turraea mombassana and Trichilia roka, were showed potential larvicidal activity against vector mosquitoes. Hence, there is a need to know the feasibility of using these plant extracts for the control of mosquito larva in the field condition. Since this plant is readily available and widely distributed, can be used as a cheap alternative to the conventional larvicides.

Evaluation of Larval Toxicity of Lantana Camara L. and Catharanthus Roseus L. against Culex Quinquefasciatus say and Aedes Aegypti L

The present study aimed to evaluate the aqueous extracts from the leaves of Catharanthus roseus L. and Lantana camara L. against filarial vector mosquito Culex quinquefasciatus Say and dengue vector Aedes aegypti L. The plant material was macerated and extracted with distilled water. The aqueous extract was tested at different concentrations of 1000, 500, 250, 125 and 62.5 ppm concentrations against I, II, III and IV instar larvae of C. quinquefasciatus and A. aegypti. The LC50 values of C. roseus against I, II, III and IV instar larvae of C. quinquefasciatus were 30.28, 38.01, 59.12 and 71.81 and against A. aegypti 26.64, 34.64, 53.10 and 72.89 ppm. The LC50 values of L. camara against I, II, III and IV instar larvae of C. quinquefasciatus were 35.48, 46.74, 67.64 and 95.51 and against A. aegypti 35.19, 38.26, 65.98 and 91.90 ppm. No mortality of was observed in control. Our results suggest that the aqueous extract of C. roseus have the potential to be used as an ecofriendly approach for the control larvae of vector mosquito C. quinquefasciatus and A. aegypti.