Analysis of the occurrence of the fall armyworm (Spodoptera frugiperda) in the winter season on the southwestern islands of Japan using the insect’s strontium radiogenic isotope ratio (87Sr/86Sr)

Spodoptera frugiperda, an invasive pest insect that targets maize and other crops, first arrived in Japan in the summer of 2019. This species occurs year-round in East Asian subtropical regions such as southern mainland China and the island of Taiwan, where the mean air temperature in the coldest month is above 10°C. Adults are similarly found throughout the year on the southwestern islands of Japan. Trap monitoring there showed continuous or intermittent S. frugiperda catches in the 3 winter seasons since 2019. However, it was difficult to distinguish between immigrants arriving from these neighboring areas and local individuals occurring on each Japanese island. In this study, the possible natal origin of captured insects on 5 small islands (Yonagunijima, Taramajima, Okinawajima, Amamioshima, and Tanegashima) was determined by investigating the strontium radiogenic isotope ratios (87Sr/86Sr) and comparing them with those of reference hosts and insects. Since trapping data and the 87Sr..., , , # Analysis of the occurrence of the fall armyworm, Spodoptera frugiperda, in the winter season on the southwestern islands of Japan using the insect’s strontium radiogenic isotope ratio (87Sr/86Sr)

[https://doi.org/10.5061/dryad.12jm63z50](https://doi.org/10.5061/dryad.12jm63z50)

## Author Information:

Naoya Hidaka1, Sachiyo Sanada-Morimura1, Gaku Akiduki1, Takashi Oyadomari2, Shinta Higa2, Kunio Kinjo2, Yuuki Ikenoue3, Ki-Cheol Shin4, Ichiro Tayasu4, Akira Otuka1

1\. Institute for Plant Protection, National Agriculture and Food Research Organization, Koshi, Kumamoto, 861-1192 Japan.

2\. Okinawa Prefectural Plant Protection Center, Naha, Okinawa, 902-0072 Japan.

3\. Kagoshima Prefectural Institute for Agricultural Development, Minami-Satsuma, Kagoshima, 899-3401 Japan.

4\. Research Institute for Humanity and Nature, Kyoto, Kyoto, 603-8047 Japan.

## Correspondence:

Naoya Hidaka, Institute for Plant Protection, National Agriculture and Food Research Organization, Kumamoto, Japan...