We confirmed that Argentine ants are expanding their distribution along the coastal areas of Pacific Ocean side in Japan, though we succeeded in eradication of one small population in Yokohama using Z-(9)-Hexadecenal as well as a common myrmecocide. To prevent the invasion of RIFA into Japan, we developed methods for identification (using DNA bar coding) and detection (using the parasitoid wasp Microplitis croceipes) which can readily be used even by quarantine officers. In the surveys in Taiwan, USA and Argentina, we found that polyploid workers rapidly increased in the countries where RIRA had recently invaded. Using Diacamma sp. which is useful for molecular biology, we studied the sex determination mechanism in ants and found some intriguing expression patterns of genes such as feminizer.
