{"id":14484,"date":"2026-04-28T07:57:23","date_gmt":"2026-04-28T07:57:23","guid":{"rendered":"https:\/\/www.proefschriftmaken.nl\/portfolio\/mengxiao-sun\/"},"modified":"2026-04-28T07:57:41","modified_gmt":"2026-04-28T07:57:41","slug":"mengxiao-sun","status":"publish","type":"us_portfolio","link":"https:\/\/www.proefschriftmaken.nl\/en\/portfolio\/mengxiao-sun\/","title":{"rendered":"Mengxiao Sun"},"content":{"rendered":"","protected":true},"excerpt":{"rendered":"","protected":true},"author":7,"featured_media":14485,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"footnotes":""},"us_portfolio_category":[45],"class_list":["post-14484","us_portfolio","type-us_portfolio","status-publish","post-password-required","hentry","us_portfolio_category-new-template"],"acf":{"naam_van_het_proefschift":"The role of service plants in promoting biological pest control and pollination in Xinjiang pear","samenvatting":"De moderne landbouw staat voor de uitdaging om de productiviteit op peil te houden en tegelijkertijd de negatieve milieueffecten van intensieve landbouw te verminderen, met name die welke gepaard gaan met een hoog gebruik van pesticiden en kunstmest. Het gebruik en de versterking van ecosysteemdiensten zoals biologische plaagbestrijding en bestuiving, geleverd door natuurlijke vijanden en bestuivers, wordt in toenemende mate erkend als een sleutelelement in duurzame landbouw. Het gebruik van 'service plants' (dienstverlenende planten) die hulpbronnen bieden zoals prooi, nectar, stuifmeel of beschutting, is naar voren gekomen als een veelbelovende strategie om nuttige insecten te stimuleren. Het blijft echter onduidelijk hoe plantkenmerken en de beschikbaarheid van prooien de aantrekkelijkheid van deze planten bepalen, en in hoeverre dit zich vertaalt naar verbeterde plaagbestrijding en bestuiving op gewasniveau, met name in conventioneel beheerde boomgaardsystemen zoals in Xinjiang, China. Dit proefschrift behandelt dit hiaat.\n\nIn Hoofdstuk 2 werden gemeenschappen van natuurlijke vijanden van bladluizen ge\u00ebvalueerd op 39 inheemse en uitheemse plantensoorten in een veldexperiment in Korla, Xinjiang, in 2020 en 2021. Alle groepen natuurlijke vijanden reageerden positief op hogere bladluisdichtheden. Volwassen lieveheersbeestjes vertoonden over beide jaren een consistente positieve associatie met planten met extraflorale nectar en open bloemkronen. Deze bevindingen tonen aan dat prooibeschikbaarheid en specifieke plantkenmerken de aanwezigheid van natuurlijke vijanden kunnen versterken, maar dat reacties groepsspecifiek en tijdsafhankelijk zijn.\n\nIn Hoofdstuk 3 werden zweefvlieg- en bijengemeenschappen onderzocht op 38 bloeiende plantensoorten. Plantensoorten met ondiepe bloemkronen en een langere bloeiperiode trokken grotere aantallen zweefvliegen, honingbijen en wilde bijen aan. Er werden geen verbanden gevonden tussen de lichaamslengte van bestuivers en plantkenmerken. Deze resultaten tonen aan dat de toegankelijkheid van bloemen en de bloeiduur belangrijke voorspellers zijn voor bestuiversbezoek.\n\nIn Hoofdstuk 4 werden plaag-, natuurlijke vijand- en bestuivergemeenschappen bestudeerd in conventionele perenboomgaarden met en zonder luzerne (alfalfa) als bodembedekker. De bladluispopulatie was in \u00e9\u00e9n van de twee jaar lager in boomgaarden met luzerne. Luzerne had echter geen significant effect op de overvloed aan natuurlijke vijanden of predatieactiviteit in de perenbomen zelf. Evenzo had luzerne geen meetbare invloed op het bezoek aan perenbloesems of de vruchtzetting. Het gebrek aan effect kan te wijten zijn aan de late opkomst van luzerne na de winter, waardoor er tijdens de bloei van de peer nog geen dekking was. Er was geen bewijs dat nuttige insecten vanuit de luzerne in relevante aantallen overstapten naar de perenbomen.\n\nIn Hoofdstuk 5 zijn de bevindingen gesynthetiseerd. Dit proefschrift laat zien dat hoewel service plants nuttige insecten kunnen ondersteunen, hun effectiviteit afhangt van plantkenmerken, de timing van de beschikbaarheid van hulpbronnen en de context van het gewassysteem. De resultaten onderstrepen het belang van lokaal aangepaste selectie en beheer van planten voor integratie in duurzame boomgaardsystemen zonder de productie in gevaar te brengen.","summary":"Modern agriculture faces a challenge to maintain productivity while reducing negative environmental impacts of high intensity agriculture, particularly those associated with a high use of pesticides and fertilizer. The use and augmentation of ecosystem services such as biological pest control and pollination, delivered by natural enemies and pollinators, is increasingly recognized as a key element in sustainable agriculture. The use of service plants that provide resources such as prey, nectar, pollen or shelter, has emerged as a promising strategy to augment beneficial insects, such as natural enemies and pollinators. However, it remains unclear how plant traits and prey availability determine the attractiveness of service plants to beneficial insects, and to what extent the use of service plants translates into improved pest control and pollination at the crop level, particularly in conventionally managed orchard systems such as those in Xinjiang, China. This thesis addresses this gap by evaluating how service plant traits, insect responses, and crop-system context jointly shape ecosystem service delivery.\n\nIn Chapter 2, aphid natural enemy communities were evaluated on 39 native and non-native service plant species in a replicated field experiment conducted in Korla, Xinjiang, China, in 2020 and 2021. Natural enemy communities and aphid abundance were assessed using visual counts and sweep netting. Plant traits, including flowering period, corolla type, and the presence of extrafloral nectar, were measured to determine whether these explained variation in natural enemy abundance among plant species. All natural enemy groups (including ladybeetles, parasitoids, and predatory bugs) responded positively to higher aphid densities. Ladybeetle adults consistently showed positive associations with plants that have extrafloral nectar and flowers with open corollas across both years. In contrast, positive associations between plant traits and other natural enemy groups were detected in only one of the two years. These findings demonstrate that prey availability and specific plant traits can enhance natural enemy presence, but that responses are natural enemy group-specific and temporally variable, underscoring the importance of multi-year evaluations when selecting service plants.\n\nIn Chapter 3, hoverfly and bee communities were examined on 38 flowering plant species in the same experimental setting. Pollinators were sampled using visual counts and sweep netting over 13 sampling rounds in 2020 and 15 rounds in 2021. Individuals collected by sweep netting were identified to species, and body size was recorded. Plant traits, including flower cover, corolla depth and width, plant height, and flowering duration, were assessed as potential predictors of pollinator attractiveness. Plant species with shallow corollas and longer flowering durations attracted higher numbers of hoverflies, honeybees, and wild bees than plants with deeper corollas or shorter flowering periods. No associations were found between pollinator body length and flowering plant traits. These results demonstrate that floral accessibility and flowering duration are key predictors of pollinator visitation, providing practical criteria for selecting service plants that support diverse pollinator communities. However, year-to-year variation in trait-pollinator relationships highlights the need for continued empirical testing when using trait-based approaches to select plants that support pollinator communities.\n\nIn Chapter 4, pest, natural enemy, and pollinator communities were studied in conventionally managed Korla fragrant pear orchards with and without alfalfa ground cover. Insect communities were assessed using sweep netting in alfalfa and visual counts in pear trees, while predation activity was measured using Helicoverpa armigera egg cards. Pollinators were sampled with pan traps, fruit yield was assessed by interviews with orchard owners, and fruit quality was assessed by measuring fruit set, seed set, fruit weight and sugar content of pears. In the study region, alfalfa is already used as an understory in pear orchards because the foliage can be used as animal fodder, making it a relevant and logistically feasible system for evaluating service plant effects under real farming conditions. Aphid abundance in pear was lower in orchards with alfalfa in one out of two years studied. However, alfalfa did not significantly affect the abundance of natural enemies or predation activity in pear trees. Similarly, alfalfa had no measurable impact on pollinator visitation to pear flowers, fruit and seed set or the sugar content of pears. The lack of effect may be due to the late emergence of alfalfa after winter, such that there was no alfalfa cover at the moment of pear flowering. Although alfalfa supported a relatively abundant natural enemy from May onwards, there was no evidence that the beneficial insects in alfalfa spilled over in relevant numbers to the pear trees. These findings indicate that the presence of a service plant alone does not guarantee spill-over or ecosystem service delivery, and that temporal and spatial mismatches between service plants and crops can limit their effectiveness.\n\nIn Chapter 5, I synthesized the findings from the three experimental chapters, discussed its relationships with current agroecological theory, addressed the limitations of the study, and proposed future directions for integrating service plants into sustainable orchard management. Overall, this thesis shows that while service plants can support beneficial insects, their effectiveness depends on plant traits, timing of resource availability, and crop-system context. These results underline the importance of locally tailored service plant selection and management, and provide empirical guidance for integrating service plants into sustainable orchard systems without compromising production.","auteur":"Mengxiao Sun","auteur_slug":"mengxiao-sun","publicatiedatum":"3 juni 2026","taal":"EN","url_flipbook":"https:\/\/ebook.proefschriftmaken.nl\/ebook\/mengxiaosun?iframe=true","url_download_pdf":"https:\/\/ebook.proefschriftmaken.nl\/download\/905fc3d5-8160-4d38-a803-f25d5154e42b\/optimized","url_epub":"","ordernummer":"18782","isbn":"978-94-6534-361-7","doi_nummer":"","naam_universiteit":"Wageningen University","afbeeldingen":14486,"naam_student:":"","binnenwerk":"","universiteit":"Wageningen University","cover":"","afwerking":"","cover_afwerking":"","design":""},"_links":{"self":[{"href":"https:\/\/www.proefschriftmaken.nl\/en\/wp-json\/wp\/v2\/us_portfolio\/14484","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.proefschriftmaken.nl\/en\/wp-json\/wp\/v2\/us_portfolio"}],"about":[{"href":"https:\/\/www.proefschriftmaken.nl\/en\/wp-json\/wp\/v2\/types\/us_portfolio"}],"author":[{"embeddable":true,"href":"https:\/\/www.proefschriftmaken.nl\/en\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"https:\/\/www.proefschriftmaken.nl\/en\/wp-json\/wp\/v2\/comments?post=14484"}],"version-history":[{"count":1,"href":"https:\/\/www.proefschriftmaken.nl\/en\/wp-json\/wp\/v2\/us_portfolio\/14484\/revisions"}],"predecessor-version":[{"id":14487,"href":"https:\/\/www.proefschriftmaken.nl\/en\/wp-json\/wp\/v2\/us_portfolio\/14484\/revisions\/14487"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.proefschriftmaken.nl\/en\/wp-json\/wp\/v2\/media\/14485"}],"wp:attachment":[{"href":"https:\/\/www.proefschriftmaken.nl\/en\/wp-json\/wp\/v2\/media?parent=14484"}],"wp:term":[{"taxonomy":"us_portfolio_category","embeddable":true,"href":"https:\/\/www.proefschriftmaken.nl\/en\/wp-json\/wp\/v2\/us_portfolio_category?post=14484"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}