Effects of different kinds of oils and antioxidants on the bait-transport behavior of Solenopsis invicta

The red imported fire ant, Solenopsis invicta, is a significant health, agricultural and forest pest. Baiting is one of the main methods to control S. invicta. The fire ant bait is usually composed of three compounds, which are active ingredient (pesticide), carrier and oil. Previous studies showed that the type and concentration of pesticides, as well as size and color of carrier, significantly affected bait transport by S. invicta. However, few studies focused on the potential impact of kinds of oil on the foraging behavior of S. invicta. In this study, we conducted field studies to evaluate the effect of different liposoluble antioxidants (butylated hydroxyanisole, butylated hydroxytoluene, tert-butylhydroquinone, or propyl gallate) and oil (soybean oil, corn oil, coconut oil, palm oil, peanut oil, butter, or lard) on bait transport under field conditions. Results showed that adding antioxidants did not significantly affect bait transport. In addition, S. invicta transported significantly more corn-oil bait (0.73 ± 0.16 g) than that of coconut-oil bait (0.08 ± 0.03 g). We then conducted a laboratory experiment to compare the searching and transport behavior of S. invicta in response to bait containing corn or coconut oil. There was no significant difference in search duration between the two kinds of oils. However, the first particle of corn-oil bait was transported earlier than that of coconut-oil bait. Also, the transport amount was larger and the transport speed was higher. Our study provides insight for improving S. invicta bait.