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The Anthropocene is posing extraordinary challenges for global agriculture. Agri-food production is increasingly impacted by concurrent biotic and abiotic stressors, climate-triggered pests or diseases, (pesticide) resistance breakdown and the unrelenting appearance of invasive biota. Farmers have relied upon simple, add-on constitutive crop defenses and synthetic pesticides for decades, but those tools prove ever more defunct. Here, we argue that dynamic, pluralistic and adaptable crop defenses can safeguard harvests in the face of erratic pest threats. When transitioning towards such nature-based crop defenses, plants prove an infinite source of inspiration. Inducible and/or indirect defenses that rely upon trichomes, sugar rewards, substrate-borne vibrations, plant volatiles, root exudates or allelochemicals have become the center of scientists’ attention. The ensuing plant health innovations regularly rely upon the action of resident beneficial organisms, are low-cost, practicable and environmentally sound, and custom-made for more resilient forms of agriculture. By thus harnessing on-farm biodiversity and agroecological processes, agri-food production can be intensified without disregard of human or environmental health, or ‘One Health’. [ABSTRACT FROM AUTHOR]

The fall armyworm [FAW, Spodoptera frugiperda (J. E. Smith)] is an important invasive pest of maize crops in Africa, Asia and the Middle East. To enable timely and effective pest management, accurate monitoring and forecasting of S. frugiperda populations is essential. In this study, we used food attractants to assess seasonal abundance of S. frugiperda in southern Yunnan (China) and determined adult age based upon ovarian development or testes size. During 2020–2021, the seasonal abundance of trapping S. frugiperda males with food attractants and sex pheromones were approximately the same at two field sites. Both trapping methods yielded S. frugiperda males of different ages—with an identical age structure for both trap types. The proportion of females trapped with food attractants was about 80%, which was significantly higher than that of males. S. frugiperda populations at two field sites were composed of immigrants that either originated in central Yunnan or in eastern Myanmar. Based upon field-level recordings of adult reproductive state, models reliably anticipated S. frugiperda fecundity dynamics. Next, drawing upon meteorological data and FAW adult age, migration trajectories were established for S. frugiperda immigrant populations. Overall, these novel (food-based) monitoring and forecasting tools can improve integrated pest management of S. frugiperda in China and abroad. [ABSTRACT FROM AUTHOR]

Globally, insect abundance and diversity are experiencing a rapid decline. Despite important inter-taxa and geographical variability, this can entail an extinction of ecological interactions and a decay of ecosystem functions. In this study, we compared the spatial distribution, abundance and species composition of Trichogramma spp. egg parasitoids (Hymenoptera: Trichogrammatidae) over a 30-year time period in China. During the 1980s and in 2016–2018, egg masses of the Asian corn borer (ACB), Ostrinia furnacalis, were systematically sampled from corn fields across the country. In 2018, five species were identified with Trichogramma ostriniae representing 90% of the species complex. Since the 1980s, two new species have made their appearance while nine (out of 12; i.e., 75%) species disappeared. These include comparative specialists but also generalists such as T. evanescens and T. exiguum. Across sites, species richness (R) and diversity (Shannon-Weiner index) have declined by a respective 25–86% and 56–100% (except for Heilongjiang province) over this time frame. We hypothesize that this is attributed to land use change, pesticide use and plant diversity decline in agro-landscapes. Conversely, no negative impacts were detected of augmentative biological control. Given the drastic reduction in ACB parasitoid richness, agro-ecological measures and diversification strategies should be deployed to restore the ecological resilience of local farming systems. Our work carries major implications for food security and helps to muster support for more nature-friendly, pest-resilient farming systems in China and abroad. [ABSTRACT FROM AUTHOR]

Soil invertebrates contribute to multiple ecosystem services, including pest control, nutrient cycling, and soil structural regulation, yet trophic interactions that determine their diversity and activity in soils remain critically understudied. Here, we systematically review literature (1966–2020) on feeding habits of soil arthropods and macrofauna and summarize empirically studied predator–prey linkages across ecosystem types, geographies and taxa. Out of 522 unique predators and 372 prey organisms (constituting 1947 predator–prey linkages), the vast majority (> 75%) are only covered in a single study. We report a mean of just 3.0 ± 4.7 documented linkages per organism, with pronounced taxonomic biases. In general, model organisms and crop pests (generally Insecta) are well-studied, while important soil-dwelling predators, fungivores and detritivores (e.g., Collembola, Chilopoda and Malacostraca) remain largely ignored. We argue that broader food-web based research approaches, considering multiple linkages per organism and targeting neglected taxa, are needed to inform science-driven management of soil communities and associated ecosystem services. [ABSTRACT FROM AUTHOR]

Interspecific interactions (e.g., competition, predation) are core determinants of insect population evolution, geographical distribution, trophic dynamics and ecosystem functioning. Following its recent invasion of eastern Asia, the fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) co-inhabits maize fields with native lepidopteran herbivores, such as the common cutworm, Spodoptera litura. Here, drawing upon laboratory and field studies, we demonstrate how late-instar S. frugiperda larvae directly prey upon S. litura immature stages and competitively displace them from the maize whorl. Individual maize plants did not mediate the above interactions, with herbivore-damaged leaves not affecting the development rate of either species. In the field, ecological niches of S. frugiperda and S. litura overlapped, with species-specific occupancy rates of whorl-stage leaves (vegetative phase) and ears or tassels (reproductive phase) exceeding 70% and 90%, respectively. Field cage trials showed that S. frugiperda larvae either preyed upon or repelled S. litura larvae from maize plants, routinely resulting in more than 90% mortality of the latter. Field visits and cage studies in Yunnan (SW China) also revealed how—within an approx. 1-year time period—S. frugiperda has become a dominant species in local maize fields and co-infestation of both herbivores on the same plant is rare. Overall, our work shows how the invasive S. frugiperda exhibits a clear competitive advantage over native lepidopterans and could replace certain species within local agroecosystems. This study not only unveils the mechanistic causes of rapid ecological shifts within S. frugiperda-invaded cropping systems, but may also guide subsequent monitoring and management interventions. [ABSTRACT FROM AUTHOR]

Land-use change and agricultural intensification concurrently impact natural enemy (e.g., parasitoid) communities and their associated ecosystem services (ESs), i.e., biological pest control. However, the extent to which (on-farm) parasitoid diversity and food webs mediate landscape-level influences on biological control remains poorly understood. Here, drawing upon a 3-year study of quantitative parasitoid-hyperparasitoid trophic networks from 25 different agro-landscapes, we assess the cascading effects of landscape composition, species diversity and trophic network structure on ecosystem functionality (i.e., parasitism, hyperparasitism). Path analysis further reveals cascaded effects leading to biological control of a resident crop pest, i.e., Aphis gossypii. Functionality is dictated by (hyper)parasitoid diversity, with its effects modulated by food web generality and vulnerability. Non-crop habitat cover directly benefits biological control, whereas secondary crop cover indirectly lowers hyperparasitism. Our work underscores a need to simultaneously account for on-farm biodiversity and trophic interactions when investigating ESs within dynamic agro-landscapes. Yang, Liu, Zhu et al. analyzed a dataset of 3-year parasitoid-hyperparasitoid trophic networks from 25 different agro-landscapes. Using path analysis, they uncover how species diversity and food web structure shape ecosystem functionality. [ABSTRACT FROM AUTHOR]

We present a synthetic review and expert consultation that assesses the actual risks posed by arthropod pests in four major crops, identifies targets for integrated pest management (IPM) in terms of cultivated land needing pest control and gauges the implementation "readiness" of non-chemical alternatives. Our assessment focuses on the world's primary target pests for neonicotinoid-based management: western corn rootworm (WCR, Diabrotica virgifera virgifera) in maize; wireworms (Agriotes spp.) in maize and winter wheat; bird cherry-oat aphid (Rhopalosiphum padi) in winter wheat; brown planthopper (BPH, Nilaparvata lugens) in rice; cotton aphid (Aphis gossypii) and silver-leaf whitefly (SLW, Bemisia tabaci) in cotton. First, we queried scientific literature databases and consulted experts from different countries in Europe, North America, and Asia about available IPM tools for each crop-pest system. Next, using an online survey, we quantitatively assessed the economic relevance of target pests by compiling country-level records of crop damage, yield impacts, extent of insecticide usage, and "readiness" status of various pest management alternatives (i.e., research, plot-scale validation, grower-uptake). Biological control received considerable scientific attention, while agronomic strategies (e.g., crop rotation), insurance schemes, decision support systems (DSS), and innovative pesticide application modes were listed as key alternatives. Our study identifies opportunities to advance applied research, IPM technology validation, and grower education to halt or drastically reduce our over-reliance on systemic insecticides globally. [ABSTRACT FROM AUTHOR]

Vast numbers of insects annually engage in trans-latitudinal migration and thereby impact structure and functioning of natural and man-made ecosystems. In eastern Asia, long-distance migration has historically been studied for single insect species rather than diverse species complexes. Here, we assessed migration dynamics of multiple economically important migratory species on an island in the Bohai Strait, China. Drawing upon 15-year trapping records of > 2.5 million specimens, we unveil inter- and intra-annual shifts in the species composition and abundance of migrant individuals. Migrants belonged to 9 orders and 36 families, primarily consisting of Lepidoptera (79% individuals), Odonata (8%), and Coleoptera (4%). Seven crop-feeding noctuids, e.g., Helicoverpa armigera (Hübner), Mythimna separata (Walker), represented 54% of the total trapping records. Trap catches exhibited marked seasonal variation, with the highest capture rate during early fall. Yearly abundance of migratory noctuids was coupled with that of their associated natural enemies. Although overall trap catches did not decrease over the monitoring period, the entire order of Odonata experienced a 14.1% annual rate of decline. Furthermore, 19 out of 108 species exhibited a progressively declining abundance over time, including the cosmopolitan cutworm Agrotis ipsilon (Hufnagel) and the insectivorous dragonfly Pantala flavescens Fabricius. Our work provides unprecedented insights into insect migration dynamics in eastern Asia, helps fine-tune forecasting and early-warning systems of crop pests, and thereby guides integrated pest management within local agro-landscapes. Also, a long-term tracking of migrant insect populations can shine light on the fate of (insect-mediated) ecosystem services and trophic dynamic processes at a macroscale. [ABSTRACT FROM AUTHOR]

Global warming has pronounced impacts on the physiology, development and behavior of multiple organisms and affects the geographical distribution of arthropods. Yet, little is known about how a heightened ambient temperature influences migratory insects that are globally relevant to agriculture. Here, we quantified the extent to which increases in surface temperature, over the span of 3 decades, impact long-distance migration processes of the globally important cutworm Agrotis ipsilon (Lepidoptera: Noctuidae). Multi-year monitoring in China indicated how high-altitude migrants of A. ipsilon annually attain two distinct seasonal peaks, i.e., during spring and summer. Stable isotope analyses of field-caught individuals further showed a gradually shifting origin of migrant populations, with ground-level A. ipsilon abundance partially reflecting population levels of high-altitude migrants. Over a 27-year time period, respective population peaks for overwintering and the first-generation A. ipsilon adults were reached 17 and 8 days earlier in the year. Also, the northern border of the A. ipsilon potential overwintering area progressed northward by 58–232 km, and its migration range expanded by 708 km. Our work reveals how a progressively increasing surface temperature affects long-distance migration of a cosmopolitan agricultural pest and alters the population phenology and geographical distribution of A. ipsilon in eastern Asia. Global warming thus influences ecological dynamics in temperate agro-ecosystems and can magnify the economic impacts of long-distance migratory pests. [ABSTRACT FROM AUTHOR]

Farmers' knowledge, attitudes, and beliefs are of paramount importance in shaping the on-farm adoption and diffusion of integrated pest management (IPM). In particular, for invasive pests, this (gendered) knowledge base can dictate how fast and effective farmers respond to emerging threats. In this study, we employ qualitative and quantitative methods to assess agro-ecological knowledge and pest management behavior of small-scale cassava growers in rural Vietnam and Laos, when faced with two new biotic threats, i.e., the invasive cassava mealybug Phenacoccus manihoti and cassava witches broom disease. Despite their pronounced impact on crop yields, farmers overall had limited knowledge of recent invaders and regularly ascribed their appearance to "climate change". Growers were largely unaware of preventative tactics for pest control, and resorted to curative measures (e.g., unguided pesticide sprays) at the P. manihoti invasion front. Farmers' attitudes toward invasive pests were highly context- and locality-dependent, and knowledge scores differed between households positioned along a gender continuum. Though women assumed a minor role in IPM decision-making and possessed comparatively deficient knowledge, they favored agro-ecological approaches and took on key tasks in the selection of propagation material. Gender roles in cassava crop protection are equally context-dependent, yet women may be well-positioned to promote IPM practices such as the use of disease-free planting material. Future extension should thus pay attention to (a) strengthening (women) farmers' knowledge base, to empower them as change agents and drive IPM adoption, and (b) transferring local innovations between sites, eventually through visual educational aids. Given the increasing importance of invasive pests in many developing countries, our work emphasizes how adult education and (adaptive) co-learning should become core components of mitigation programs. [ABSTRACT FROM AUTHOR]

Cropping system diversification, including the in-field establishment of strip crops can improve the effectiveness of natural enemies and enhance biological control of pestiferous herbivores. In China, habitat management such as the in-field establishment of alfalfa strips is used for pest control in cotton. However, their effect on other economically important pests, such as the mirid bug Apolygus lucorum (Meyer-Dür), has not been evaluated. In this study, we first assessed parasitism of A. lucorum within plots of 13 different host plant species. Next, we established strips of one suitable plant species within a commercial cotton field and evaluated its effect on A. lucorum parasitism level. The results showed that two A. lucorum parasitoids, i.e., Peristenus spretus Chen et van Achterberg and Peristenus relictus Ruthe, responded differently to host plant species. In 2014, the parasitism levels of P. spretus were highest on buckwheat Fagopyrum esculentum Moench, while parasitism levels of P. relictus were generally low and did not differ between the various plants. Furthermore, A. lucorum attained low population levels on buckwheat. In 2016, A. lucorum parasitism levels in buckwheat plots were higher than in cotton. When (2 m wide) buckwheat strips were established in cotton fields, P. spretus parasitism of A. lucorum on cotton plants increased 2.4-fold in 2016 and 8.5-fold in 2017 compared to cotton monocrops. In conclusion, the establishment of buckwheat strips in commercial cotton fields enhances A. lucorum parasitism. By deploying these habitat management tactics, parasitoid-mediated biological control may complement existing management schemes for the polyphagous mirid bug in China and abroad. [ABSTRACT FROM AUTHOR]

Insects provide critical ecosystem services to humanity, including biological control of pests. Particularly for invasive pests, biological control constitutes an environmentally sound and cost-effective management option. Following its 2008 invasion of Southeast Asia, biological control was implemented against the cassava mealybug Phenacoccus manihoti (Hemiptera: Pseudococcidae) through the introduction and subsequent release of the host-specific parasitoid Anagyrus lopezi (Hymenoptera: Encyrtidae) in Thailand. In this study, we quantify yield benefits of mealybug biological control in Thailand’s cassava crop by using two different types of manipulative field trials: i.e., ‘physical exclusion’ cage trials and field-level ‘chemical exclusion’ assays. In cage trials with two popular cassava varieties, root yield and total dry matter (or ‘biological yield’) were a respective 4.0-4.2 times and 3.5-3.9 times higher in the presence of biological control. Extrapolating results from cage trials, biological control thus ensured an approximate yield gain of 5.3-10.0 T/ha for either variety. Under chemical exclusion trials, P. manihoti populations attained levels of 3266 ± 1021 cumulative mealybug-days (CMD) over a 10-month time period, and no longer impact yields. Moreover, under effective P. manihoti control, both root yield and biological yield increased with season-long CMD measures, and pest management interventions-including insecticide sprays-led to notable reductions in yield. This study is the first to show how biological control effectively downgrades the globally invasive P. manihoti to non-economic status and restores yields in Thailand’s cassava crop. Our work emphasizes the economic value of biological control, reveals how current P. manihoti populations do not necessarily cause yield penalties, and underlines the central importance of nature-based approaches in intensifying global agricultural production. [ABSTRACT FROM AUTHOR]

In subsistence farming systems of the developing world, adoption of resource-conserving practices such as integrated pest management (IPM) is often strikingly low. This has partially been ascribed to researchers’ limited understanding of how technologies develop at the interface of the systems’ social and ecological components. In Honduras (Central America), there exists concern about limited adoption and diffusion of IPM technologies in certain smallholder production systems. In this study, we determine social and ecological drivers of IPM adoption in subsistence maize production in the country’s hillside environment. Honduran small-scale maize production is typified by a key insect pest (the fall armyworm, Spodoptera frugiperda) being partly kept at bay through action of a diverse natural enemy complex, including ants, social wasps, carabid beetles, and spiders. Local agricultural landscapes, primarily shaped through shifting cultivation, provide key resources to maintain this natural enemy diversity. These local ecological conditions and related natural enemy abundance strongly influence farmers’ agroecological knowledge and pest management practices. In the meantime, farmer practices are also affected by local communication networks, which help validate and spread IPM concepts and technologies. Based on our findings, we advocate a holistic approach to improve IPM extension through mapping of agroecological opportunities, visualization of regional patterns in farmer knowledge, and associated priority setting. Local IPM capacity could be built through institutional strengthening and adaptive comanagement, while IPM training should be linked with natural resource management initiatives. These approaches may eventually improve the way IPM is delivered to small-scale farmers who operate in the ecologically diverse environments of the tropics. [ABSTRACT FROM AUTHOR]

Integrated pest management (IPM) has been widely promoted in the developing world, but in many regions its adoption rates have been variable. Experience has shown that to ensure IPM adoption, the complexities of local agro-production systems and context-specific folk knowledge need to be appreciated. Our research explored the linkages between farmer knowledge, pest management decision making, and ecological attributes of subsistence maize agriculture. We report a case study from four rural communities in the highlands of southeast Honduras. Communities were typified by their agro-environments, IPM training history, and levels of infestation by a key maize pest, the fall armyworm ( Spodoptera frugiperda Smith). Although variable, infestation levels generally did not justify pest management intervention. Consequently, crop losses from this pest were considered of low importance and most farmers proceeded in a rational fashion by refraining from action in their fields. Farmers attributed the low degree of pest infestation predominantly to abiotic causal factors (rainfall, temperature). The role of natural enemies in controlling this pest (i.e., biological control) was deemed of low importance by farmers; nevertheless, a broad array of such organisms was mentioned by farmers as operating in their maize crop. Farmers’ knowledge of natural enemies only partially matched scientific knowledge and was associated with the ecological features of their respective field settings. Local knowledge about natural enemies was mainly restricted to abundant and easily observable predatory species. Farmers who were knowledgeable about biological control were also familiar with a larger variety of pest management alternatives than uninformed farmers. Management options covered a wide range of curative techniques, including conservation biological control. Farmers who relied on insecticides to manage pest outbreaks knew less about biological control and pesticide alternatives. In contrast, farmers who received IPM training mentioned more types of natural enemies and were familiar with a broader range of alternative pest management tactics. Our research suggests that IPM training modifies local knowledge to better fit its environmental context. This paper provides insights in the environmental context of local agro-ecological knowledge and its linkage with pest management decision making. It also constitutes a basis for modifying IPM extension programs to deliver locality-specific technologies while strengthening the local knowledge base. [ABSTRACT FROM AUTHOR]

Apolygus lucorum (Hemiptera: Miridae) is an important insect pest of cotton and fruit trees in China. The adults prefer host plants at the flowering stage, and their populations track flowering plants both spatially and temporally. In this study, we examine whether flower preference of its adults is mediated by plant volatiles, and which volatile compositions play an important role in attracting them. In olfactometer tests with 18 key host species, the adults preferred flowering plants over non-flowering plants of each species. Coupled gas chromatography-electroantennography revealed the presence of seven electrophysiologically active compounds from flowering plants. Although the adults responded to all seven synthetic plant volatiles in electroantennography tests, only four (m-xylene, butyl acrylate, butyl propionate and butyl butyrate) elicited positive behavioral responses in Y-tube olfactometer bioassays. The adults were strongly attracted to these four active volatiles in multi-year laboratory and field trials. Our results suggest that these four fragrant volatiles, which are emitted in greater amounts once plants begin to flower, mediate A. lucorum's preference to flowering host plants. We proved that the use of commonly occurring plant volatiles to recognize a large range of plant species can facilitate host selection and preference of polyphagous insect herbivore. [ABSTRACT FROM AUTHOR]