PRECISION TARGETING: REDUCED PESTICIDE USE STRATEGY FOR PHARAOH’S ANT (HYMENOPTERA: FORMICIDAE) CONTROL

Abstract:
Pharaoh’s ants, Monomorium pharaonis, are one of the more difficult indoor pest ants to control. We studied if routine exterior monitoring and initiating baiting when infestations are incipient, will prevent infestations inside a building. The study was conducted at a 7,841 m2 two-level building with 4 separate wings. Monitoring techniques to determine Pharaoh’s ant foraging distribution were conducted with attractant-baited index cards placed on the exterior ground floor window sills. All treatment were with Combat Superbaits® (Clorox Company, Pleasanton, CA, USA). Monitoring and treatments were performed on both the exterior and the interior floors to assess success of the exterior treatments on interior infestations. This was followed by exterior monitoring and baiting with assessments of only those interior locations corresponding to exterior sites positive for foraging ants. Numbers of foraging ants were lower 1 month post initial treatment, and continued to drop showing an 88% reduction in foraging ants by the second month. A survey at this time of the interior of the building showed only 3 locations positive for foraging ants. Monitoring showed that the exterior treatment of this location eliminated the interior population for the remainder of the study. Three months post initial survey there was a population increase of foraging ants on the exterior of the building with 14 positive sites. Of these 14 sites only 1 spatially correlated to an interior foraging population. Exterior treatments again eliminated this population. During the final survey of the exterior of the building, only 1 Pharaoh’s ant was found with no interior corresponding population. This study confirmed that the vast majority of populations present inside the structure could be eliminated with exterior bait treatments.