Efficacy of Bacillus thuringiensis israelensis (Bti) and four plant extracts on the mortality and development of Culex quinquefasciatus Say (Diptera: Cullicidae)

Abstract

Abstract The efficacy of the bio-insecticide, Bacillus thuringiensis var. israelensis (Bti), and four plant-ethanol extracts Cinnamomum osmophloeum, Matricaria chamomilla, Seasamum indicum, and Nigella sativa was tested against larvae of filarial vector, Culex quinquefasciatus, under laboratory conditions. The Bti and extracts of N. sativa and C. osmophloeum showed the highest insecticidal activity, with LC50 values of 7.18, 14.59, and 28.87 mg/l 24 and 48 h post treatments, respectively. The extracts of M. chamomilla and S. indicum were effective. The tested extracts altered some biological aspects of Cx. quinquefasciatus, i.e., developmental periods, pupation rate, and adult emergence. Pupation rate was suppressed by Bti at 7.5 mg/l and by C. osmophloeum at 75 mg/l. In addition, the tested plant extracts exhibited various morphological abnormalities of larvae, pupae, and adults.

Keywords

• Culex quinquefasciatus
• Bacillus thuringiensis var. israelensis
• Plant extracts