Local chemical eradication of the Argentine ant: A statistical model for estimating the time of eradication based on analyses of trapping data and pesticide applications

  The Argentine ant, Linepithema humile, a native of South America, has now spread to all continents except Antarctica, as well as a number of oceanic islands. This species was first detected in Japan in 1993 and has since become established in 12 prefectures. A test program of chemical eradication at two sites in Tokyo (Tokai and Jonan) was apparently successful, because the ant population decreased to undetectable levels within a short time; however, if individual ants were overlooked, the population could rebound and even expand its habitat. To estimate the time when the population is completely eradicated, a criterion with a statistical basis has therefore been needed: we developed such a statistical model for chemical eradication based on monthly trapping data and the history of pesticide applications. Application of this model using the Tokai and Jonan datasets indicated that the probability that ants were still present had declined to 1% in month 38 at the Tokai site and in month 42 at the Jonan site after the start of the pesticide application program. Based on the 1% probability level, we retroactively declared that eradication of Argentine ants had occurred at the Tokai site in May 2014 (17 months after the last sighting) and at the Jonan site in August 2015 (16 months after the last sighting).  This research will be published on 13th June 2017 (18:00 Japan time) in Scientific Reports.


Sakamoto, Y., Kumagai, N. H., and Goka, K. (2017) Declaration of local chemical eradication of the Argentine ant: Bayesian estimation with a multinomial-mixture model. Scientific Reports. DOI: 10.1038/s41598-017-03516-z
equal contribution


Yoshiko Sakamoto
National Institute for Environmental Studies
16-2 Onogawa, Tsukuba, Ibaraki 305-8506 Japan
sakamoto.yoshiko (please append ‘@nies.go.jp’ to complete the email address)