Location: Integrated Cropping Systems ResearchTitle: Do additional sugar sources affect the degree of attendance of Dysmicoccus brevipes by the fire ant Solenopsis geminata? Author
Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/26/2012
Publication Date: 6/10/2013
Citation: Carabali, D., Wyckhuys, K., Montoya, J., Kondo, T., Lundgren, J.G. 2013. Do additional sugar sources affect the degree of attendance of Dysmicoccus brevipes by the fire ant Solenopsis geminata? Entomologia Experimentalis et Applicata. 148:65-73. Interpretive Summary: Ants occasionally care for and protect sap-sucking insects (insects like mealybugs and aphids) in exchange for sugary solutions that are produced by these herbivores (this secretion is called honeydew). Sometimes, these sap-sucking insects are pests of crops, and therefore ants can be viewed as pests in that they are the friend of our enemy. This research shows that this relationship between ants and mealybugs depends on the availability of other sugar sources; ants that have alternative sugars are less likely to care for mealybugs. Specifically, we found that ants spent less time tending mealybugs when the ants are provided a vial of sugar (sucrose) water. The worker ants also had more fructose in their stomachs when sucrose was provided versus when they only had access to honeydew. Although the ants were less likely to tend the mealybugs when alternative sugars were available, sugar availability did not increase ant predation on the mealybugs. This research suggests that one way to control mealybugs and other ant-tended pests in the tropics may be to provide adequate sugar resources in and near cropland.
Technical Abstract: Mutualistic interactions between ants and Hemiptera are mediated to large extent by the amount and quality of sugar-rich honeydew produced. Throughout the neotropics, the fire ant Solenopsis geminata (F.) (Hymenoptera: Formicidae) is found in association with colonies of the pineapple mealybug Dysmicoccus brevipes (Cockerell) (Hemiptera: Pseudococcidae), which they actively tend and protect from attack by natural enemies. In this study, we evaluate the effects of access to a sucrose solution on the mutualistic association between S. geminata and D. brevipes. A total of 10 colonies of either species were established, with D. brevipes maintained on pumpkin, Cucurbita maxima, in screen cages. Five of the S. geminata colonies were permitted access to vials with 20% sucrose solution and a pumpkin fruit with 20 adult mealybugs. The remaining ant colonies were only allowed access to mealybug-infested pumpkins. Ant colonies with access to the sucrose solution attended mealybugs significantly less than those without additional sugar sources. Mealybug survival rates were similar under both treatments. Total body sugars and fructose was nearly twice as high in the ants fed mealybugs + sucrose versus those offered mealybugs + water. Fructose accumulated on the pumpkins over time in both treatments, suggesting that honeydew was not fully exploited by the ants. In conclusion, mealybugs enjoy lesser degrees of ant attendance when ants have alternative sources of carbohydrates. We further discuss the significance of these findings for the conservation of predaceous ants and mealybug biological control.