Insecticidal effect of volatile compounds from fresh plant materials of Tephrosia vogelii against Solenopsis invicta workers

The effect of volatile compounds from the mashed fresh bean pods (B) as well as the branches and leaves (L) of Tephrosia vogelii on the behavior of Solenopsis invicta workers was investigated by fumigation toxicity bioassay. Gas chromatography–mass spectrometry analysis was used to identify and quantify the volatile compounds. α-pinene, thujene, caryophyllene, and d-limonene were identified as major components of the volatile compounds, which were found toxic to workers when applied by fumigation. Responses varied according to worker size, exposure time, and plant material. An increase in exposure time from 1h to 12h led to increases in mortality from 18.33% to 100.00% (B) and 13.33% to 100.00% (L) in minor workers as well as increases from 1.67% to 95.00% (B) and 15.00% to 98.33% (L) in major workers. The volatile compounds were also found to exert a behavioral effect against S. invicta in an A4 paper test. Walking and grasping abilities decreased at exposure times ranging from 40 min to 280 min. These findings suggest that the volatile compounds of T. vogelii can be used to control S. invicta.