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Integrated Pest Management of the invasive Japanese Beetle, Popillia japonica

Periodic Reporting for period 1 - IPM-Popillia (Integrated Pest Management of the invasive Japanese Beetle, Popillia japonica)

Reporting period: 2020-09-01 to 2022-02-28

The invasion of the Japanese beetle, Popillia japonica, threatens the entire agricultural sector, as well as the biodiversity in the invaded area. The more than 300 host plants of Japanese beetles include many important crops, like wine, fruit trees, soft berries or maize and soybean. In addition, measures for containment of this regulated pest complicate trade of fruit crops, potted plants, or turf grass. IPM-Popillia aims at confining the spread of the new pest, and preventing the build-up of high population densities that cause economic loss to agricultural crops and increase migration pressure of the Japanese beetles. The overal objectives of the project IPM-Popillia are grouped in four overarching aims:

1. Identifying the Japanese beetles’ pathways of entry and spread.
This includes development of detection of fast and reliable monitoring tools, and the provision of an optimal surveillance strategy for Europe. Objectives also comprise support to EU policy in the management of high priority pests in general, and raising public awareness for invasive pest species.

2. Understanding the drivers of Japanese beetles’ population development
This includes our efforts to characterize abiotic factors and identify the most relevant groups of organisms associated with P. japonica in infested and non-infested areas of the same region, and to understand the underlying processes that lead to pest establishment or failure of establishment.

3. Providing an IPM Toolbox for Japanese beetle control
Here, the objectives are to develop a range of sustainable biocontrol options of larvae and of adults of the Japanese beetle. We include preventive treatments of potting substrates, attract-and kill and attract-and infest strategies, and low risk spray applications against adults, suitable for sites with low and high pest abundance, respectively.

4. Developing sustainable Japanese Beetle management in Europe
The economic and socioeconomic impacts of the P. japonica invasion, and the feasibility of the control measures against P. japonica are investigated. On the base of these analyses, we will design customized information and policy advice for sustainable Japanes beetle management in Europe.
Work within IPM-Popillia is organized in six work packages, which comprise R&D activities, dissemination activities and coordination activities. A graphical overview of how the WPs work together is shown in the graph below. The progress made in these work packages is described in detail in the technical report, only some selected highlights are given here:

Within WP1,
• An innovative, remotely controlled monitoring trap prototype was designed, and tested at several locations in the Piedmont and the Ticino.
• The first version of the IPM-Popilla Citizen Science App was developed and released for a testing phase in 2022.
• First risk maps for P. japonica spread in europe have been produced, based on P. japonica occurrence data and a large set of predictors (including climate, land uses, soil typology and topography, etc.).
• A first reconstruction of the worldwide colonization route of P. japonica based on microsatellites and mitochondrial haplotypes was obtained.

Within WP2,
• a preliminary assembly of the P. japonica genome was computed.
• Sites with heavy and with low population densities of P. japonica on the Azores islands and in Northern Italy have been deliminated. Preliminary results indicate that certain climatic and soil biotic factors seem to correlate with P. japonica population density.

Within WP3,
• Strains of entomopathogenic nematodes and fungi, which are natural antagonists of P. japonica, were isolated in the infested areas of northern Italy and the Azores and are meanwhile under extensive testing in lab, nurseries, and field.
• Attract-and-kill devices with LLINs (long-lasting insecticide-treated nets) have been designed and are tested in the field.
• Lab-tests have shown that horizontal and vertical transmission of spores of entomopathogenic fungi within P. japonica populations is possible. This is a pre-requisite for a novel biocontrol approach against P. japonica called "attract-and-infest" strategy.

Within WP4,
• The project’s website has been designed and launched in the internet. Furthermore, social media activities have been started.
• A survey on the economic losses of the P. japonica invasion, and the willingness to pay for biological control of the invasive pest was designed and will be carried out in the upcoming season.
The most important advance beyond the state-of-the-art is that our IPM-Toolbox for control of P. japonica relies exclusively on environmentally friendly control measures. These are either biocontrol methods or biotechnical approaches with low environmental impact. The ambition of IPM-Popillia is to show that successful control of the new pest, and meeting the requirements of quarantine regulations, must not contrast with respecting the environment and the principles of sustainability.

IPM-Popillia is also special because of its timeliness. Unlike other recent invasions in Europe (e.g. that of the corn rootworm Diabrotica virgifera, the brown marmorated stink bug Halyomorpha halys, or the spotted wing drosophila Drosophila suzukii), the invasion of the Japanese beetle has been detected at a very early time point. IPM-Popillia brings together all important stakeholders in a collaborative effort to impede the spread of the new pest at a time point where it is still confined to one single and comparatively small infested zone. This timeliness is exceptional for Europe, and significantly enhances the chances for successful containment of P. japonica.

A decisive factor in controlling a new pest is fast and reliable detection of its first incidence in so far pest-free areas. Such incidences will be inevitable in the upcoming years, and IPM-Popillia provides the necessary innovations to enhance reliability and responsiveness of monitoring.

IPM strategies are per se innovative as they take into consideration the complexity of biotic and environmental factors affecting a pest species. IPM-Popillia introduces a further layer of complexity in IPM studies, by performing in depth molecular genetic analyses of the interactions among the pest insect, applied biocontrol organisms, as well as soil microorganisms and arthropods. These interactions are decisive for success or failure of the establishment of the pest and biocontrol organisms. Furthermore, in IPM-Popillia, the new pest is not considered a mere passive object of control efforts, but a living organism, capable of reaction. We monitor this reaction to different treatment regimes in terms of modulation of gene expression as a source of adaptations of the new pest to control measures. Taken together this is a novel and powerful interdisciplinary approach in the development of sustainable pest control.
Project components and their interactions in IPM-Popillia