UC Riverside

Argentine ants are a majorly invasive tramp species in natural, urban, and agricultural settings all over the world. Practical and effective control strategies for their control in agricultural settings are still being sought out as the predominant form of control, chlorpyrifos, continues to be phased out in the United States. This research develops our understanding of boric acid hydrogel bait as a potential solution for Argentine ant, Linepithema humile (Mayr) control. Laboratory studies revealed 1) that this bait with a representative preservative, potassium sorbate, is effective in causing Argentine ant mortality 2) that bait is best used fresh and 3) that prior to mortality, Argentine ants exhibit a clumping behavior in response to bait consumption. A large-scale and continuous method of manufacture of the hydrogel beads was devised, allowing for large-scale field applications of the bait in a citrus grove operated by UCR Agricultural Operations. The bait proved effective in reducing ant numbers by up to 80%. If the levels of control prove to be sufficient, then boric acid hydrogel bait utilizing calcium alginate can be considered an effective, practical, sustainable, and environmentally friendly means of Argentine ant control in citrus groves.