Elimination of a Tapinoma Melanocephalum (Hymenoptera: Formicidae) Infestation Using Imidacloprid Bait

Abstract:
Tapinoma melanocephalum F. (Ghost Ant) infestations have increased in Western Europe. Generally, Ghost Ant infestations resemble those of Monomorium pharaonis (Pharaoh’s Ant) with a focus to older, multi-unit apartment blocks which offer a multitude of nesting opportunities and easy migration of ants within the building. Control of these infestations is often regarded as difficult. Laboratory trials of a novel semi-liquid broad-spectrum ant bait product containing 0.03% imidacloprid against nest cells of Ghost ants demonstrated complete destruction of workers, queens and brood by week 6. The same ant bait product was tested in a field trial in Groningen, Netherlands. An apartment block containing 108 apartments had a seven year history of failing Ghost ant control. Using a conventional bait gun, one bait spot of 200 mg per m² treated area was applied. An area of 10 m² was treated; the average amount of product dispensed was 2 g per apartment. Several apartments were chosen as indicator sites and were closely followed. The remaining apartments were treated by a local pest control company using the same product with identical use pattern. Decline of ant numbers in the indicator flats was rapid (86 % reduction in 3 days) and total absence of ants was demonstrated from week eight after treatment. Similarly, all flats treated by the pest control company were shown to be free of ants at the last monitoring time point 5 months after initial treatment.