The impact of high and low toxicity insecticides on Formica exsectoides and Formica glacialis in Maine lowbush blueberry

Two species of Formica ants are common throughout Maine lowbush blueberry fields, Formica exsectoides and Formica glacialis. F. glacialis mounds are found throughout both conventionally and organically farmed fields, while the majority of F. exsectoides mounds are located in organic fields. To determine how insecticide treatment impacts workers of each species, laboratory studies exposing ants to high and low toxicity insecticides were conducted in 2007 and 2008. Worker ants were exposed to insecticide treated foliage. In 2007, 5 insecticides were applied to foliage: Imidan, Spintor, Intrepid, Provado, and Botanigard. A water control was also included. In 2008, Assail was also included. Treated foliage was collected at 0,1,2,4,8, and 16 days after treatment. Cups were assessed for mortality at daily intervals for 10 days. The experiment was conducted in 2007 with F. exsectoides workers and in 2008 with F. glacialis workers. In 2008, survival varied significantly between insecticide treatments at 0, 1, 2, 4, and 8 days after spray. Imidan-treated foliage killed workers 0, 1, 2, 4, 8 days after foliar application. Spintor, Intrepid, Provado and Botanigard treated foliage killed 30% or less of workers when exposed to foliage 2 days after application. Data from the 2008 assay is still being collected and will be reported during my presentation. In addition, field studies evaluating the presence and absence of Formica species in conventional, reduced input and organic fields will also be completed during the 2008 field season and presented at the meeting.