Population dynamics of the Japanese beetle in the Azores: A 16-year long-term monitoring program

Abstract: We present an overview of the Japanese Beetle, Popillia japonica Newman, 1838,
density, over 16 years, from 2008 to 2023, in the Azores archipelago. This data resulted of a
Long-Term Ecological Research (LTER) program implemented by the operational official
services of the Secretaria Regional da Agricultura e Alimentação aiming to monitor Popillia
japonica population dynamics.
For this monitoring program, Ellisco traps with synthetic pheromones and floral lures were
installed on the 9 islands of the Azores. A total of 11897 unique traps were installed over 16
years which made it possible to determine adult peak flights, densities, and geographic
distribution of P. japonica in the Azores. The highest capture value occurred in 2019 with
approximately 7.67 million adults collected, followed by a decrease to 1.91 million, in 2022. In
contrast, the lowest capture rate was recorded in 2014, with approximately 460 thousand
beetles. In general, this data shows that P. japonica adults emerge in late June, peaking in early July, and persisting until October. The pest is currently confirmed on eight islands, being absent only on the island of Santa Maria.
This information is valuable for developing targeted intervention strategies and mitigating
economic losses caused by pest infestations. Establishing and maintaining long-term programs for monitoring P. japonica populations is essential for scientific understanding and practical pest management efforts in the Azores archipelago.