Journal of Environmental Biology

Laboratory observations on the larvicidal efficacy of three plant species

against mosquito vectors of malaria, Dengue/Dengue Hemorrhagic Fever

(DF/DHF) and lymphatic filariasis in the semi-arid desert

Author Details

S.K. Bansal

(Corresponding author)

Desert Medicine Research Centre (ICMR), New Pali Road, Jodhpur - 342 005, India

e-mail : bansalsk@dmrcjodhpur.org

Karam V. Singh

Desert Medicine Research Centre (ICMR), New Pali Road, Jodhpur - 342 005, India

Sapna Sharma

Desert Medicine Research Centre (ICMR), New Pali Road, Jodhpur - 342 005, India

M.R.K. Sherwani

Department of Chemistry, Jai Narayan Vyas University, Jodhpur - 342 005, India

Publication Data

Paper received:

03 November 2010

Revised received:

07 April 2011

Accepted:

23 April 2011

Abstract

Comparative larvicidal efficacy of aqueous and organic solvent extracts from seeds, leaves and flowers of three desert plants viz. Calotropis procera (Aiton), Tephrosia purpurea (L.) Pers. and Prosopis juliflora (Sw.) DC. was evaluated against Anopheles stephensi (Liston), Aedes aegypti (Linnaeus) and Culex quinquefasciatus (Say). For this purpose larvae of all the three mosquito species were reared in the laboratory and studies carried out on late 3^rd or early 4^th instars using standard WHO technique. Based on concentration mortality data 24 and 48 hr LC₅₀ and LC₉₀ values along with their 95% fiducial limits, regression equation, chi-square (c²)/ heterogeneity of the response were determined by log probit regression analysis. Experiments were carried out with different solvent extracts of seeds of C. procera which revealed that methanol (24 hr LC₅₀: 127.2, 194.8, 361.0) and acetone (229.9, 368.1, 193.0 mg l^-1) extracts were more effective with the three mosquito species, respectively. Petroleum ether extract was effective only on An. stephensi while aqueous extracts were not effective at all with any of the mosquito species (mortality <10-30%). Tests carried out with methanol extracts of fresh leaves (24 hr LC₅₀: 89.2, 171.2, 369.7) and flowers (24 hr LC₅₀: 94.7,617.3, 1384.0 mg l^-1) of Calotropis showed that preparations from fresh parts? were 2-3 times more effective as compared to the stored plant parts. Efficacy was less than 10-30% with both An. aegypti and Cx. quinquefasciatus while An. stephensi was still susceptible to extracts from both leaves and flowers even after two years of storage. The 24 hr LC₅₀ values as observed for methanol extracts of seeds of T. purpurea and leaves of P. juliflora were 74.9, 63.2 and 47.0 and 96.2, 128.1 and 118.8 mg l^-1 for the above three mosquito species, respectively. Experiments carried out up to 500 mg l^-1 with leaves (T. purpurea) and seeds (P. juliflora) extracts show only up to 10-30% mortality indicating that active larvicidal principle may be present only in the seeds of Tephrosia and leaves of Prosopis. In general, anophelines were found more susceptible than the culicines to the plant derived derivatives. More studies are being carried out on some other desert plants found in this arid region. The study would be of great importance while formulating vector control strategy based on alternative plant based insecticides in this semi-arid region. ?????????

Key words

Vector mosquitoes, Larvicidal, Desert plants, Semi-arid region ??

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