The Effects of Temperature on the Foraging Activity of Red Imported Fire Ant Workers (Hymenoptera: Formicidae) in South China

In this study, we investigated the effects of temperature of the ambient air, ground surface, and the soil at 5-cm deep on the foraging activity of the workers of red imported fire ant, Solenopsis invicta Buren, in South China with the method of bait traps. Significant correlations were observed between the temperature and the foraging activity of fire ants. Specifically, when the ambient temperature was above 20 °C, the fire ants foraged actively, and the activity reached a maximum when the ambient temperature was between 25 to 33 °C. But the foraging activity decreased as the ambient temperature rose higher than 34 °C. Moreover, fire ants were found to forage at maximal rates with the soil surface temperature between 27 to 40 °C. The ants started foraging when the soil temperature at 5-cm deep was between 16 to 48 °C, while 28~37 °C was the optimal temperature for the foraging activity. The extreme temperature thresholds for foraging of the ambient air, soil-surface, and soil at 5-cm deep were 11 °C/44 °C, 10 °C/57 °C, and 12 °C/48 °C respectively.