Location: Invasive Species and Pollinator HealthTitle: Foraging distance of the Argentine ant in California vineyards
|NELSON, ERIK - Dominican University Of California|
|DAANE, KENT - University Of California|
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/18/2017
Publication Date: 4/2/2018
Citation: Hogg, B.N., Nelson, E.H., Hagler, J.R., Daane, K.M. 2018. Foraging distance of the Argentine ant in California vineyards. Journal of Economic Entomology. 111:672-679.
Interpretive Summary: The invasive Argentine ant threatens native ecosystems on several continents, and can cause outbreaks of insect pests in crop systems. In California vineyards it feeds on the carbohydrate-rich honeydew produced by pests such as mealybugs and soft scales, which it tends and protects from natural enemies. Few methods for controlling Argentine ants are available. A particularly effective approach is to add small amounts of pesticide to feeding stations containing sugar water. The ants feed on the pesticide-treated sugar water and share it with other ants in their nests, maximizing the number of ants that are eventually killed. To estimate how many feeding stations to deploy in a given area, the foraging patterns and distances that ants move must be determined. We measured how far ants move in vineyards using feeding stations containing sugar water and a special protein that allowed us to identify ants that had fed on the sugar water. We then collected ants at different distances extending away from the feeding stations. Although ants that had fed on the sugar water were found up to 63 m from feeding stations, proportions of ants that had fed on the sugar water decreased drastically as the distance from feeding stations increased. Our results show that Argentine ants forage at distances of less than 70 m in California vineyards, and that pesticide-treated feeding stations must be deployed at intervals of less than 70 m to control ants.
Technical Abstract: Argentine ants, Linepithema humile (Mayr), form mutualisms with hemipteran pests in crop systems. In vineyards, they feed on honeydew produced by mealybugs and soft scales, which they tend and protect from natural enemies. Few options for controlling Argentine ants are available; one of the more effective approaches is to use liquid baits containing a low dose of an insecticide. Knowledge of ant foraging patterns is required to estimate how many bait stations to deploy per unit area. To measure how far ants move liquid bait in vineyards, we placed bait stations containing sugar water and a protein marker in plots for 6 d, and then collected ants along transects extending away from bait stations. Ants moved an average of 16.08 m and 12.21 m from bait stations in the first and second years of the study, respectively. Marked ants were found up to 63 m from bait stations; however, proportions of marked ants decreased exponentially as distance from the bait station increased. Results indicate that Argentine ants generally forage at distances <70 m in California vineyards, thus suggesting that insecticide bait stations must be deployed at intervals of <70 m to control ants. We found no effect of insecticide on distances that ants moved the liquid bait, but this may have been because bait station densities were too low to affect the high numbers of Argentine ants that were present at the study sites.