Periodic Reporting for period 2 - PESTNET (Depicting the impact of an invasive alien crop pest on local ecological networks)
Okres sprawozdawczy: 2024-09-01 do 2025-08-31
Invasive alien herbivore species are a major threat to agriculture because they directly damage crops and induce severe yield losses, but also because they indirectly impact the structure, stability and functioning of native arthropod communities. Indirect facilitation mechanisms can cause unpredictable outbreaks of native pest species but, surprisingly, they have been rarely studied within arthropod communities. Within the framework of invasive species management (Regulation EU 1143/2014), understanding pest facilitation mechanisms is a research priority. This is also because invasive species negatively impact the reliability of agricultural Decision Support Systems, used in sustainable agriculture (Directive 2009/128/EC). PESTNET aims, as general objective, at developing a novel inter- multidisciplinary and intersectoral approach (field monitoring, dietary and landscape analysis, citizen science) to depict the basic and applied ecological consequences of a human-introduced alien crop pest on the invaded trophic network.
The main model system used for implementation is represented by the highly invasive Brown Marmorated Stink Bug, Halyomorpha halys (Hemiptera: Pentatomidae), native stink bug species and shared egg parasitoids. An original two-fold cutting-edge approach is proposed aiming at assessing the following specific objectives: Obj. 1) Evaluation of indirect pest facilitation mediated by top-down and bottom-up mechanisms in noninvaded vs. invaded networks; Obj. 2) Evaluation of stink bug community changes using a digital monitoring systems to estimate spatial trends instink bugs abundance. Through the involvement of academic and non academic (industry) partners, the project provided novel insights on how an invasive herbivore pest of worldwide economic importance is impacting sustainable agriculture by interference with the local arthropod community. Another model under investigation was represented by the Japanese beetle (Coleoptera: Scarabaeidae), indigenous populations of scarabeid beetles, and a parasitic fly (Diptera: Tachinidae).
The main model system used for implementation is represented by the highly invasive Brown Marmorated Stink Bug, Halyomorpha halys (Hemiptera: Pentatomidae), native stink bug species and shared egg parasitoids. An original two-fold cutting-edge approach is proposed aiming at assessing the following specific objectives: Obj. 1) Evaluation of indirect pest facilitation mediated by top-down and bottom-up mechanisms in noninvaded vs. invaded networks; Obj. 2) Evaluation of stink bug community changes using a digital monitoring systems to estimate spatial trends instink bugs abundance. Through the involvement of academic and non academic (industry) partners, the project provided novel insights on how an invasive herbivore pest of worldwide economic importance is impacting sustainable agriculture by interference with the local arthropod community. Another model under investigation was represented by the Japanese beetle (Coleoptera: Scarabaeidae), indigenous populations of scarabeid beetles, and a parasitic fly (Diptera: Tachinidae).
In 2023, a first season of field surveys was conducted together with morphological and distributional data analysis of the collected samples (stink bugs and parasitoids). Concerning the low amount of parasitised eggs retrieved in the field, this aspect suggested the low relevance of top-down mechanisms. Parallelly, our laboratory bioassays of host preference of the parasitoid Trissolcus japonicus revealed that possible indirect facilitations and interferences in the networks can be explained by the parasitoid differential ability to locate and develop on target and non-target individuals in real field situations (Arma custos slightly less preferred than H. halys) and on the poor ability of the parasitoid to forage in unfavourable agricultural sites, where neonicotinoid-based pesticides are commonly applied to tentatively control H. halys (see https://doi.org/10.1016/j.biocontrol.2024.105568(odnośnik otworzy się w nowym oknie)). More experiments were conducted later to explore pre-adult conditioning on rearing hosts and adult conditioning on plant-herbivore cues inducing phenotypic plasticity in Trissolcus japonicus (see full results at: https://doi.org/10.1016/j.biocontrol.2025.105796(odnośnik otworzy się w nowym oknie)).
The analysis of stink bug occurrence (about 2’500) suggests a significant effect of the invasive H. halys on native SB populations. More specifically, the invasive H. halys is negatively affecting some native species (e.g. Carpocoris spp.) in different habitats, but positively affecting others (e.g. Nezara viridula), although results changed depending on the timing and habitat. Inclusion of landscape analysis suggests a possible detrimental effect of the invasive species on native assemblage of stink bugs, calculated as Shannon Index. Citizen and farmers were involved from November 2023 to February 2024 to place overwintering traps for capturing stink bugs. This activity was paramount to evaluate the level of presence of the different species in the area, in particular of the BMSB.
In 2024 and 2025, overwintering diapause and post diapause stink bug physiology was conducted. We demonstrated the high overwintering resilience of H. halys relative to N. viridula. Within each species, individuals from different habitats showed distinct nutrient profiles and survival outcomes. Glycogen and lipid reserves emerged as the principal nutrients sustaining diapause, whereas protein content was a weak predictor of survival. These patterns indicate species-specific strategies of nutrient utilisation
Concerning the Japanese beetle multitrophic model system, using olfactometers and microcosm experiments we evaluated the long-range and close-range host location behaviour of I. aldrichi towards stimuli related to its target host, P. japonica, or of the alternative scarabid beetle, Exomala orientalis, highliting parasitoid specificity for target host cues.
The analysis of stink bug occurrence (about 2’500) suggests a significant effect of the invasive H. halys on native SB populations. More specifically, the invasive H. halys is negatively affecting some native species (e.g. Carpocoris spp.) in different habitats, but positively affecting others (e.g. Nezara viridula), although results changed depending on the timing and habitat. Inclusion of landscape analysis suggests a possible detrimental effect of the invasive species on native assemblage of stink bugs, calculated as Shannon Index. Citizen and farmers were involved from November 2023 to February 2024 to place overwintering traps for capturing stink bugs. This activity was paramount to evaluate the level of presence of the different species in the area, in particular of the BMSB.
In 2024 and 2025, overwintering diapause and post diapause stink bug physiology was conducted. We demonstrated the high overwintering resilience of H. halys relative to N. viridula. Within each species, individuals from different habitats showed distinct nutrient profiles and survival outcomes. Glycogen and lipid reserves emerged as the principal nutrients sustaining diapause, whereas protein content was a weak predictor of survival. These patterns indicate species-specific strategies of nutrient utilisation
Concerning the Japanese beetle multitrophic model system, using olfactometers and microcosm experiments we evaluated the long-range and close-range host location behaviour of I. aldrichi towards stimuli related to its target host, P. japonica, or of the alternative scarabid beetle, Exomala orientalis, highliting parasitoid specificity for target host cues.
Thanks to the outgoing period, the ER constructed a network of scientific contacts of about 50 scientists. In details, these were interested in IPM, stink bugs and other invasive species spanning several institutions Canada and Europe. By reinforcing public engagement with Citizen science, that would target the Commision’s goal of Responsible Research and Innovation (RRI), with easier access to scientific results and with the focus on invasive species issue of concerns to farmers. The impact on publication, so far, is high, with a first HQ paper and its inclusion in a special issue on the topic. The impact on employment has been high, as the ER was recruited by UNIPG as tenure track researcher, first, then Associate Professor after the end of the fellowship. Parallel work with the TEAMDEV industry has started remotely, with the ER learning how to cooperate with the industry; while the research output on SB data analysis will produce data and knowledge that will be used by TEAMDEV to improve DSS.
A knowledge-based economy and society, aware of organic management and IPM practices for IAS management was boosted, for example through webinars offered during 2023 and 2024 by the ER to farmers and practitioners on quarantine species, stink bugs monitoring and control, and organised by Technical associations and Phytosanitary services. Workshops were offered by the ER to students at UNIPG in 2024 and 2025. The various tuition workshop, seminars, meetings and outreach activities conducted enhanced the ER communication skills.
The internationalisation impact has been achieved, as the ER was able to disseminate the project activities at congresses, conferences and presentations. More dissemination envisaged newspaper communication on local journals and TV appearance.
Policy impact was ensured by establishing a network with phytosanitary services with decisional role. A sharp increase in policy impact is expected with deliverables D3.6 D3.10 on causes behind low efficacacy of biocontrol by T. japonicus, D3.11 an Editorial on Recent advances in characterizing trophic connections in biological control, D3.5 and D3.13 on ladscape effects and nutrient analysis of native vs. invasive stink bugs, and D3.7 and D3.8 on the hot-topic of Japanese beetle invasion to Europe and Canada.
A knowledge-based economy and society, aware of organic management and IPM practices for IAS management was boosted, for example through webinars offered during 2023 and 2024 by the ER to farmers and practitioners on quarantine species, stink bugs monitoring and control, and organised by Technical associations and Phytosanitary services. Workshops were offered by the ER to students at UNIPG in 2024 and 2025. The various tuition workshop, seminars, meetings and outreach activities conducted enhanced the ER communication skills.
The internationalisation impact has been achieved, as the ER was able to disseminate the project activities at congresses, conferences and presentations. More dissemination envisaged newspaper communication on local journals and TV appearance.
Policy impact was ensured by establishing a network with phytosanitary services with decisional role. A sharp increase in policy impact is expected with deliverables D3.6 D3.10 on causes behind low efficacacy of biocontrol by T. japonicus, D3.11 an Editorial on Recent advances in characterizing trophic connections in biological control, D3.5 and D3.13 on ladscape effects and nutrient analysis of native vs. invasive stink bugs, and D3.7 and D3.8 on the hot-topic of Japanese beetle invasion to Europe and Canada.