Larval susceptibility of Aloe barbadensis and Cannabis sativa against Culex quinquefasciatus, the filariasis vector.

Larvicidal potential of petroleum ether, carbon tetrachloride and methanol extracts of Aloe barbadensis and Cannabis sativa has been investigated against Culex quinquefasciatus. Among the extracts examined, Carbon tetrachloride extract (Cte) of Aloe barbadensis was the most effective with LC50 values of 15.31 and 11.01 ppm after 24 and 48 hr of exposure, respectively followed by pertoleum ether extract (Pee) of A barbadensis, Cte of C. sativa, methanol extract (Mee) of A. barbadensis, methanol and petroleum ether of C. saliva, LC, being 25.97, 88.51, 144.44, 160.78 and 294.42 ppm affer 24hr and 16.60, 68.69, 108.38, 71.71 and 73.32 ppm after 48 hr of post treatment, respectively. Cte of both the plants exhibits potential larvicidal activity and can be used as ecofriendly alternative in the management of the filariasis vector, Culex quinquefasciatus.

Comparative efficacy of Solanum xanthocarpum extracts alone and in combination with a synthetic pyrethroid, cypermethrin, against malaria vector, Anopheles stephensi.

With a goal of minimal application of environmentally hazardous chemical insecticides, the larvicidal activity of cypermethrin was studied alone and in combination with the root extract of Solanum xanthocarpum against anopheline larvae. Petroleum ether extract was observed to be the most toxic, with LC,, of 1.41 and 0.93 ppm and LC90 of 16.94 and 8.48 ppm at 24 and 48 hours after application, respectively, followed by carbon tetrachloride and methanol extracts. The values for cypermethrin were an LC50 of 0.0369 ppm after 24 hours and 0.0096 ppm after 48 hours and LC90 of 0.0142 and 0.0091 ppm after 24 and 48 hours, respectively. The ratios of cypermethrin and petroleum ether extracts tested were 1:1, 1:2 and 1:4. Of the various ratios tested, the cypermethrin and petroleum ether extract ratio of 1:1 was observed to be more efficient than the other combinations. From the individual efficacy of each constituent, synergism was noted. This is an ideal ecofriendly approach for the control of malaria vector, Anopheles stephensi.

Larvicidal potential of Nerium indicum and Thuja oriertelis extracts against malaria and Japanese encephalitis vector.

Ethanolic and acetone extracts of Nerium indicum and Thuja orientelis have been studied against III instar larvae of Anopheles stephensi and Culex quinquefasciatus. Ethanolic extract of N. indicum is found more effective than its acetone extract against anopheline larvae with LC50 values of 185.99 and 148.05 ppm for former and 229.28 and 149.43 ppm for the later after 24 and 48 hrs of exposure. The acetone extract with LC50 values of 209.00 and 155.97 ppm is more effective in case of culicine larvae than its ethanolic extract with LC50 494.07 and 194.49 ppm after 24 and 48 hours of treatment. Ethanolic extract of T. orientelis is more effective against both the larval species with LC50 values of 13.10 and 9.02 ppm after 24 and 48 hours for anopheline and 22.74 and 16.72 ppm against culicine larvae. The acetone extract showed LC50 values of 200.87 and 127.53 ppm against anopheline and 69.03 and 51.14 ppm against culicine larvae. Thus ethanolic extract of T. orientelis is an ideal potential larvicide for both types of mosquito larvae.

Evaluation of Solanum xanthocarpum extracts as mosquito larvicides.

Mosquito larvicidal activity of crude carbon-tetra-chloride, methanol and petroleum ether extracts of Solanum xanthocarpum fruits was examined against Anopheles stephensi and Culex quinquefasciatus. Among the extracts tested, carbon-tetra-chloride extract was the most effective with LC50 values of 5.11 ppm after 24 hours and 1.27 ppm after 48 hours of treatment against An. stephensi. In the case of Cx. quinquefasciatus the petroleum ether extract was observed as most toxic with LC50 values of 62.62 ppm after 24 hours and 59.45 ppm after 48 hours of exposure period respectively. It is, therefore, suggested that S. xanthocarpum can be applied as an ideal potential larvicide against An. stephensi and Cx. quinquefasciatus.

Larval susceptibility of Ajuga remota against anopheline and culicine mosquitos.

The objective of the present study is to determine the bioefficacy of different crude extracts of Ajuga remota against anopheline and culicine larvae. Larval susceptibility of crude carbon-tetrachloride, methanol and petroleum-ether extracts of Ajuga remota leaves was observed against the malaria vector, Anopheles stephensi and the filariasis vector, Culex quinquefasciatus. Among the extracts tested, petroleum-ether extract was the most effective with LC50 values of 0.033% after 24 hours and 0.029% after 48 hours of treatment against the larvae of Anopheles stephensi. In the case of the larvae of Culex quinquefasciatus, the carbon-tetra-chloride extract exhibited maximum efficacy with LC50 values of 0.043% after 24 hours and 0.026% after 48 hours of exposure, respectively. It is, therefore, concluded that Ajuga remota can be applied as an ideal larvicide against An. stephensi and Cx. quinquefasciatus.

Insecticidal activity of the plant Phyllanthus amarus against Tribolium castaneum.

The plant Phyllanthus amarus is used as folk medicine since the year 1800 and has been established for its important medicinal properties particularly for liver ailments. The present communication explores the insecticidal activity of ethanolic extract of aerial and root parts of this plant against stored grain pest Tribolium castaneum. LC 50 values of ethanolic aerial part were 895.77, 473.91, 279.89 and 260.85 microg/cm2, while 512.62, 376.96, 248.88 and 209.79 microg/cm2 for ethanolic root part at the exposure of 3, 5, 7, 9 and 11 days respectively. Ethanolic root extract possessed significant insecticidal activity against T. castaneum.