Assessment of Toxicity of Parthenium hysterophorus L. Extract against Larvae of Trogoderma granarium

The leaves of parthenium (Parthenium hysterophorus L.) were extracted in ethanol and toxicity of the extract was examined on khapra beetle (Trogoderma granarium Everts) larvae. Four concentrations (2, 4, 6 and 8 µL mL-1 acetone) were applied directly on the larvae in Petri dishes. Toxicity was recorded after 12, 24 and 36 h. All the concentrations had considerable effect on the mortality of larvae. At the highest concentration (8 µL mL-1), the mortality observed was 57%, 72% and 78% after 12, 24 and 36 h, respectively. The minimum mortality was observed to be 43% at the concentration of 2 µL mL-1 acetone after 12 h. GC-MS analysis of the parthenium leaves showed 7 compounds in the extract including phytol (38.68%), β-cubebene (11.98%), hexadecanoic acid, methyl ester (11.22%), caryophyllene (10.37%), 9,12,15-octadecatrienoic acid, ethyl ester, (Z,Z,Z)- (9.98%), methyl stearate (9.01%), and hexadecanoic acid, ethyl ester (8.74%). The study concluded that an extract of 8 µL mL-1 acetone concentration is highly effective against larvae of khapra beetles that can cause 78% mortality after 36 h of direct exposure to the larvae.