Original Articles
Normah Awang, Nur Syuhada Isma
Abstract
The uncontrolled use of insecticides has caused major problems including resistance of mosquito towards the insecticides, environmental pollution, and effects on non-target organisms. Therefore, the potential of bismuth(III) dithiocarbamate compounds to be developed as insecticides to overcome these problem was explored in this study. The aim of this study was to examine the larvicidal effects of bismuth(III) dithiocarbamate compounds against Aedes aegypti (Linn.). The larvicidal bioassay test of a series of three bismuth(III) dithiocarbamate compounds was carried out on third instar larvae of A. aegypti in the laboratory. Bismuth(III) chloroethylaminoethanoldithiocarbamate showed the highest larvicidal effect with the LC50 and LC90 values of 7.53 ppm and 14.43 ppm, respectively. Bismuth(III) chloro-metylcyclohexyldithiocarbamate also displayed a good larvicidal effect with the LC50 and LC90 values of 14.29 ppm and 23.11 ppm, respectively. On the other hand, bismuth(III) chloro-butylmethyldithiocarbamate showed the lowest larvicidal effect with the LC50 and LC90 values of 28.30 ppm and 49.75 ppm, respectively. Morphological changes on the larvae were observed and recorded during the larvicidal bioassay test, for instances destructed digestive tract, shortened length, and elongated neck region. The order of larvicidal activity was based on the group attached to the dithiocarbamate compounds. Bismuth(III) chloro-ethylaminoethanoldithiocarbamate is the most effective compound among the seven bismuth(III) dithiocarbamate compounds tested against the dengue vector A. aegypti and has potential to be explored as a larvicide to control the spread of dengue fever.