ARS | Publication request: Efficacy of larvividal and pupicidal properties of Acalypha alnifolia Klen ex Willd. (Euphorbiaceae) leaf extract and Metarhisium anisopilae (Metsch.) against Culex quinquefasciatus Say. (Diptera: Cuclicidae)

Submitted to: Journal of Biopesticides
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 3, 2012
Publication Date: July 9, 2012
Citation: Kovendan, K., Murugan, K., Vincent, S., Barnard, D.R. 2012. Efficacy of larvividal and pupicidal properties of Acalypha alnifolia Klen ex Willd. (Euphorbiaceae) leaf extract and Metarhisium anisopilae (Metsch.) against Culex quinquefasciatus Say. (Diptera: Cuclicidae). Journal of Biopesticides. 5 (supplementary):170-176.

Interpretive Summary: In India, Culex quinquefasciatus is one of the most important mosquito vectors of the pathogens that cause lymphatic filariasis and Japanese encephalitis in humans. The milkweed plant Acalypha alnifolia (Sirukurunjan in Tamil) occurs throughout southern India where it is known as Cattail or Copperleaf. Metarizhium anisopliae is an entomopathogenic (insect-infecting) fungus that occurs in many parts of the world. In this study, Indian and ARS scientists determined the effectiveness of milkweed leaf extracts combined with M. anisopliae for control of Culex quinquefasciatus larvae. Results showed that 1.8% leaf extract combined with 1x1010 M. annisopliae conidia killed 96% of the mosquito larvae within 24 h. The combination of botanical and microbial insecticides evaluated in this study, comprising readily available plant materials and an effective biocontrol agent, has excellent potential for filariasis vector control.

Technical Abstract: This study was made to determine the lethal effects of Acalypha alnifolia leaf extract and the microbial insecticide Metarizhium anisopliae against larvae and pupae of the filariasis vector Culex quinquefasciatus. Methanol extracts of A. alnifolia were most effective in this regard with LC50 values against 1st through 4th instars and pupae of 5.6% , 6.6%, 7.5%, 9.05%, and 10.2%, respectively. Corresponding LC50 values for M. anisopliae were 10.5%, 15.6%, 23.1%, 31.4%, and 42.5%, respectively. When treatment with leaf extract was combined with fungus treatment, LC50 values for 4th instars and pupae were 7.6%, and 9.2%, respectively. The results showed the combination of botanical and microbial insecticides used in the study to have excellent potential for controlling the mosquito vector of lymphatic filariasis.