Optimizing pitfall sampling for the detection of argentine ants, Linepithema humile (Hymenoptera: Formicidae)

Effective sampling devices and optimized sampling strategies play an important role in the detection of invasive species and monitoring outcomes of pest management. Many ant species, such as the globally invasive Argentine ant, Linepithma humile (Mayr), are transported by human trade activity and establish in new regions. Because of their small size and their cryptic nature, they often go unnoticed upon arrival and survivors are hard to detect when controlled. This study compared the effectiveness of different pitfall trap designs (use of fish oil, Teflon coating on the trap) and trapping durations for the detection of Argentine ants in two urban reserves in Auckland, New Zealand. Detectability differences between pitfall traps and monitoringbaits were also evaluated. The probability of detecting the presence of Argentine ants increased sixteenfold with the addition offish oil. There was no significant change in detection if Teflon was used. The probability of detecting Argentine ants also increased with increasing duration of pitfall trapping. Pitfall trapping, particularly over 4-weeks duration, was consistently better at detecting the presence of Argentine ants than baiting. Optimizing sampling devices can play an important role in the detection of invasive species.