Fire Ant- Hemipteran Mutualisms: Comparison of Ant Preference for Honeydew Excreted by an Invasive Mealybug and a Native Aphid

Interaction between ants and honeydew-producing hemipterans is defined as mutualism which is beneficial for both species. Red imported fire ants, Solenopsis invicta, who tend the honeydew-producing hemipteran insects, can help reduce their predators and parasites. In return, ants receive honeydew as an important food resource. In this study, we tested the foraging intensity (FI), weight change and honeydew consumption (HC) of S. invicta on Phenacoccus solenopsis, Myzus persicae and infested plants by mixed-colony (both P. solenopsis and M. persicae) . Our results showed that FI of S. invicta was gradually increasing with time on the plants infested by aphids and the mixed-colony, while inverse situation was found on mealybug- infested plants. Within 10 and 15 days, FI on aphid and the mixed-species infested plant was significantly more than that on the mealybug infested plant. We compared the ant weight between the two moving directions, and the result showed that the weight of downward ants was significantly heavier than upward ants except that on the mealybug infested plant after 15 days. The study also indicated that there was no observable difference of HC among the three kinds of honeydew resource in one day and five days, while HC on aphid and the mixed colony infested plant in 10 and 15 days was significantly more than that on mealybug-infested plants.