Beauty and the pest: ornamental plant biomass valorization for the management of lepidopteran crop and storage pests

1 Introduction

The global population is estimated to reach 9.7 billion by 2050 (UN, 2019), with the annual demand for cereals alone projected to reach approximately 3 billion tonnes (FAO, 2017). Concurrently, climate change is putting severe pressure on agricultural systems, seriously threatening global food security (Bibi and Rahman, 2023). Consequently, humankind faces numerous challenges in balancing societal, environmental, and economic demands. The adoption of sustainable practices and responsible resource use has therefore become essential in modern agri-food systems, in line with the principles of green policies, such as the United Nations’ Sustainable Development Goals and the European Green Deal’s ‘Farm to Fork’ strategy (Prasad et al., 2023). Conventional plant protection based on the use of synthetic pesticides, although effective in controlling agricultural pests over extended periods, has detrimental impacts on the environment, non-target organisms, and human health (Araújo et al., 2023; Zhou et al., 2025). The emergence of resistance in target pests, coupled with the bioaccumulation of pesticide residues further question the justification for their widespread use (Chormare and Kumar, 2022; Sparks, 2025). However, the lack of adequate alternatives for pest control limits their complete elimination from protection programs. Integrated pest management considers all available pest control measures, such as physical, biological, chemical, and crop-specific (cultural) practices, relying on ecosystem monitoring and economic thresholds, thereby mitigating negative effects to the greatest extent possible (Sharma, 2023; FAO, 2026). To enable environmentally safe and cost-effective food production, pest management strategies are increasingly shifting toward the use of less harmful, nature-based solutions (Shang et al., 2024; Narandžić et al., 2025).

Insect pests cause substantial damage to agricultural crops and yields, both under field conditions and during storage. Global crop losses due to arthropod pests, including insects and mites, have varied across reports in the past and current century, with some estimates reaching up to 20% losses (Mateos Fernández et al., 2022). According to some newer projections, yield losses for major grain crops (wheat, rice, and maize) due to insects will increase by 10% to 25% per degree Celsius of warming (Deutsch et al., 2018). Culliney (2014) indicates that among the insect pests responsible for losses in agricultural production, a significant number belong precisely to the Lepidoptera order, estimating losses for over 20 species that cause damage in pre- and post-harvest, such as Plutella xylostella, Helicoverpa armigera, Lobesia botrana, Spodoptera frugiperda, Sitotroga cerealella, and others. In addition to locally established species, lepidopteran pests are increasingly invading new regions, leading to pest outbreaks and serious economic consequences for both growers and local communities (Kalleshwaraswamy et al., 2019). Driven by climate change and rising temperatures, altered biology and phenology of certain lepidopteran pests within agricultural landscapes have already been observed (Altermatt, 2010; Martín-Vertedor et al., 2010), potentially questioning the efficiency of currently applied control measures (Skendžić et al., 2021). Additional burdens on agri-food systems include the rapid development of resistance to applied products, multiple generations per year, and the high fecundity of lepidopterans (Le Goff and Nauen, 2021; Wei et al., 2025b).

To overcome issues related to currently employed plant protection strategies, the demand for sustainable pesticide alternatives is increasing. When developing pest control products, it is necessary to aim for formulations that ensure optimal efficacy with a minimal number of applications, while maintaining selectivity and safety for non-target organisms and remaining environmentally benign (Jeschke, 2021). While biopesticides—microbial, macrobial, and biochemical—demonstrate potential to meet established criteria as alternatives to chemical options, their practical integration faces notable constraints. Critical challenges include short shelf life, strict regulatory frameworks, and variable field efficacy. Furthermore, high production costs and quality control issues often limit their widespread application compared to conventional pesticides (Šunjka and Mechora, 2022). Having been used since ancient times before being replaced by synthetic agents, botanical preparations are once again gaining importance. In particular, a substantial number of studies demonstrates that plant extracts and essential oils exert diverse effects on various crop pests, including lepidopteran species, through adult and larval toxicity, ovicidal activity, repellency, antifeedant properties, and developmental inhibition (Acheuk et al., 2022; Šarac et al., 2024; Bošković et al., 2024). Many bioactive compounds, such as capsaicin from Capsicum spp., eugenol from Syzygium aromaticum, citronellal from Cymbopogon spp., azadirachtin from Azadirachta indica, 1,8-cineole from Salvia rosmarinus, and thymol from Thymus spp., are active ingredients in commercial botanical pesticides (Ngegba et al., 2022). With ongoing efforts to identify new sources of raw materials with biopesticidal potential, it is essential to address the challenges associated with plant material acquisition, including its selection and technical availability.

In this context, urban green spaces and managed landscapes represent an underexploited source of ornamental plant biomass for the development of plant-based pest management strategies within the circular bioeconomy framework (Tan and Lamers, 2021). The utilization of green waste generated during regular maintenance practices could add productive value to these landscapes, in addition to the myriad ecosystem services they continuously provide (Pušić et al., 2023). Improving urban green infrastructure is a key imperative in sustainable city planning, which is often achieved through increasing the extent of green spaces. However, with the expansion of green areas, the amount of generated biomass also increases, thereby intensifying the challenge of waste management (Cappucci et al., 2022). Given the diversity and abundance of ornamental species used in landscaping, various types of green waste are generated, further expanding the opportunities for biomass valorization. Previous research has documented the potential of ornamental species as valuable sources of active compounds for botanical insecticide development. Notable examples include pyrethrins from Chrysanthemum cinerariifolium flowers, alpha-terthienyl from Tagetes spp., and geraniol and linalool from Pelargonium spp (Shimira et al., 2021; Awasthi, 2025; Aboelhadid et al., 2024). Nevertheless, the development of novel formulations faces critical practical challenges, such as standardization issues driven by variable phytochemical stability across different spatial and temporal scales, as well as the need to screen for phytotoxic compounds that could threaten non-target organisms (Tangtrakulwanich and Reddy, 2014).

This review synthesizes recent evidence on the use of ornamental plant biomass as a source of extracts and essential oils for the management of lepidopteran crop pests, with emphasis on bioactivity, plant parts used, and opportunities for biomass valorization within a circular bioeconomy framework.

2 Literature search strategy

A systematic search within the Web of Science database, developed by Clarivate Analytics (Philadelphia, PA, USA; London, UK), was performed to identify ornamental plant species with insecticidal potential against lepidopteran pests,. Publications from the Web of Science Core Collection (all Editions) were searched within a ten-year timeframe (from 31 March 2016 to 28 February 2026). The search query was structured into four topic levels: (i) terms defining the insect order (e.g., Lepidoptera, moths and butterflies), (ii) terms related to plant-derived products (e.g., extracts and essential oils), (iii) terms describing insecticidal activity and pest control functions (e.g., insecticidal, antifeedant, repellent), and (iv) terms associated with bioassays and the assessment of biological effects (e.g., bioassay, larval mortality, feeding deterrence). Boolean operators (“AND” and “OR”) were used to combine and refine the search terms. The exact and reproducible search equation utilized in the Web of Science was: TS=(Lepidoptera* OR butterfl* OR moth) AND TS=(extract* OR “essential oil”) AND TS=(bioinsecticide OR insecticid* OR biopesticide* OR “botanical pesticide” OR pesticidal OR activity OR effect OR “biological control” OR biocontrol OR control OR “pest management” OR larvicidal OR adulticidal OR repellent OR antifeedant OR mortality OR toxic* OR larvae OR adult OR nymph) AND TS=(“bioassay” OR “larval mortality” OR “adult mortality” OR “antifeedant activity” OR “repellent activity” OR “feeding deterrence” OR “growth inhibition” OR “toxicity” OR “behavioral assay” OR “fumigation activity” OR “contact activity”). Figure 1 outlines the complete workflow of the study selection process.

Only peer-reviewed original research articles published in English were included in the analysis, leaving a total of 817 records to undergo title and abstract screening. During the subsequent second screening phase, plant species documented as sources of botanical preparations were evaluated based on predefined criteria, considering their regional and global distribution and use. To eliminate selection bias, this assessment was conducted cooperatively by all three authors, with the selection process strictly guided by the expertise of the author specializing in horticulture and landscape architecture. To guarantee taxonomic accuracy and verify ornamental status, the analysis relied on globally recognized publicly available databases, such as the Botanic Gardens Conservation International (BGCI, 2026) PlantSearch for validating nomenclature, and family classifications, and the Royal Horticultural Society (RHS, 2026) index for verifying commercial and public landscape value. To resolve ambiguity regarding multi-purpose and dual-use taxa, specifically those with overlapping medicinal, culinary, or industrial applications (e.g., Lavandula, Rosmarinus, Salvia, Tagetes, and Swietenia), inclusion was strictly contingent upon documented evidence of their active cultivation within the ornamental and landscaping sectors. These entries were cross-verified through professional horticultural and landscape architecture literature, as well as global urban forestry records. Specifically, taxa were selected if they possessed distinct ornamental attributes—such as highly aesthetic plant organs, sensory traits, or a compelling overall growth habit. These traits (e.g., foliage, flowers, bark, fruits, or fragrance) were subsequently detailed within the tabular overview of the results section “Ornamental plants as sources of extracts and essential oils with insecticidal potential”. Furthermore, taxa were retained only if they possessed structural, functional, or aesthetic roles within managed landscapes, such as serving as urban canopy trees, street avenue trees, or functional windbreaks, thereby ensuring an objective and reproducible screening process. A total of 63 studies met the final inclusion criteria and were comprehensively evaluated for qualitative synthesis. To avoid data redundancy and maintain a concise overview, the overview tables present only one representative reference demonstrating the maximum efficacy per specific plant-pest combination. This approach specifically aimed to comply with the study objective to identify potential ornamental species suitable for extract and essential oil production showcasing single or multiple insecticidal activities against lepidopteran pests, rather than providing an exhaustive meta-analysis of extraction variables.

Several methodological limitations should be acknowledged regarding the literature retrieval strategy. First, restricting the search query strictly to the Web of Science Core Collection introduces a potential selection bias and the risk of omitting relevant records; however, this reputable database provided a sufficiently robust and standardized dataset to thoroughly address the research objective. The authors are aware that some studies meeting the inclusion criteria may not have been retrieved due to potential mismatches with the applied search keywords. Further, the exclusion of non-English publications presents an additional limitation. Nevertheless, since non-English records constituted less than 1.5% of the initially retrieved results (11 records), this criterion is expected to have a minimal impact on the overall validity and robustness of the final conclusions. Additionally, the designated time frame for data collection inherently restricts the absolute comprehensiveness of the surveyed literature. Finally, the taxonomic focus was strictly limited to studies addressing preparations with insecticidal activity against Lepidoptera, thereby intentionally excluding otherwise relevant data regarding other insect pest orders.

3 Green biomass conversion into value-added products

In general, green waste represents heterogeneous lignocellulosic biomass that does not originate from purpose-grown biomass production, thereby excluding agricultural crops (Langsdorf et al., 2021). Therefore, the primary sources of green waste are public green spaces, particularly those in urban areas. Green waste consists of biomass generated through routine maintenance practices, such as pruning and lawn mowing. It includes various plant parts or entire plants, such as pruned branches, foliage, decayed and fallen flowers, cut grass, weeds, and other types of plant residues (Bhange et al., 2012). Consequently, green biomass is considered a biodegradable component of municipal solid waste, which in most cases is not adequately managed after collection (Zhang and Sun, 2016).

Pruning of urban vegetation is carried out for both aesthetic and safety reasons, aiming to remove dry and damaged plant parts, as well as plant residues generated during the growing season, thus representing an essential horticultural practice. However, pruning waste management practices raise certain environmental concerns, particularly considering that the level of greenhouse gas (GHG) emissions largely depends on how green biomass is handled and disposed of (Araujo et al., 2024). In addition, inadequate management of green waste may also create favorable conditions for the development of breeding sites for pathogenic microorganisms and pests (Amato et al., 2024). Municipal authorities worldwide often fail to implement measures that would assign added value to green waste, and in many cases, there is a lack of systematic data that could indicate the most sustainable use of collected biomass (de Meira et al., 2024). Instead of conventional disposal, these ornamental residues can serve as a valuable feedstock within a nature-based solutions framework. Transforming this green waste into biochemical pesticides, specifically plant extracts and essential oils with insecticidal properties, offers an innovative opportunity for sustainable agricultural practices, supporting safe food production from open fields to urban rooftops and vertical green walls.

The amount of green waste generated annually can reach considerable levels, and with each ton of unused raw material, both the environment and the economy are adversely affected. These quantities vary depending on the size and level of urbanization of a given area, as well as the plant species present. For instance, in Milan, Italy, the estimated amount of green waste reached 25,297 tonnes per year (Ferla et al., 2020). In Berlin, the biomass potential of leaves and grass cuttings originating from roadside vegetation, yards, and biotope areas was estimated at 120,609 tonnes annually, with an additional potential of more than 140,000 tonnes from areas outside the urban zone (Medick et al., 2017). In the city of Piracicaba, São Paulo State, Brazil, approximately 180 tonnes of afforestation waste were generated within a single month, resulting in an estimated total of around 2,160 tonnes annually (de Meira et al., 2024). Such substantial volumes demonstrate that urban centers generate a continuous and abundant supply of biomass, which could overcome one of the main limitations in botanical insecticide commercialization—the availability of raw materials.

The transformation of urban biomass into value-added products has been widely explored in the literature (Liu et al., 2022). In addition to composting, which represents one of the initial forms of green waste reuse, the production of bioenergy, biogas, briquettes, bioethanol, biohydrogen, and bioplastics has received considerable attention (Bhange et al., 2012; Sofokleous et al., 2022; McGookin et al., 2025). Urban pruning residues have also been identified as a potential source of soil amendments (Pavesi et al., 2024). In parellel, the diverse chemical composition of ornamental plants—which are often rich in secondary metabolites developed for stress resistance—makes this green waste highly suitable for the extraction of bioactive compounds. Consequently, grass clippings and pruning waste showed potential for the production of biostimulants and biopesticides (Ghoreishi et al., 2023).

Research on ornamental species commonly present in both urban and rural environments that exhibit potential for botanical insecticides development could contribute to the transformation of green spaces into productive and sustainable landscapes aligned with bioeconomy principles.

4 Lepidopteran pests in fruit and crop production and current control strategies

Lepidoptera, an order of insects encompassing both moths and butterflies, comprises more than 180,000 species classified into more than 40 superfamilies (Kereši et al., 2018; GBIF, 2026). Although many lepidopteran species are beneficial for their ecological roles, a large proportion are regarded as economically important pests, causing significant losses in crop, vegetable, and fruit production (Rajabpour and Zarahmadi, 2025).

The largest family within the Macrolepidoptera group, Noctuidae, comprises more than 35,000 species (Hussain et al., 2022), and is widely distributed worldwide. In addition to Noctuidae, several other lepidopteran families include species of major agricultural importance, such as Plutellidae, Gelechiidae, Pyralidae, Erebidae, Pieridae, Tortricidae, and Lyonetiidae. To evaluate their economic and ecological impact more effectively, these destructive lepidopterans can be categorized into distinct functional groups based on their feeding mechanisms and economic targets.

Broad-spectrum defoliators cause extensive canopy damage and impair photosynthetic capacity. Key examples include various Spodoptera species (e.g., S. frugiperda, S. exigua) and Helicoverpa armigera within Noctuidae (Awad et al., 2024), alongside Lymantria dispar and Hyphantria cunea from Erebidae (Nikolić et al., 2022; Xue et al., 2025), and Pieris brassicae from Pieridae (Hussain et al., 2026). Special attention is often directed at Plutella xylostella (Plutellidae), a highly destructive specialist defoliator of cruciferous crops (Muthomi et al., 2025).

Cryptic feeders, such as fruit and stem borers, tunnel directly into plant tissues, making them exceptionally difficult to manage. This functional group is heavily represented by tortricid leafroller moths, including Cydia pomonella and Grapholita molesta, which devastate pome and stone fruit production (Wang et al., 2026; Stupp et al., 2025). Similarly, Tuta absoluta (Gelechiidae) acts as a highly destructive borer in solanaceous vegetable crops (Rasouli et al., 2024).

Internal leaf tissue feeders, or miners, cause severe wilting and premature leaf drop in host plants. The family Lyonetiidae contains critical examples like Leucoptera coffeella and Lyonetia clerkella (Silva et al., 2025; An et al., 2024), whose larvae feed exclusively between the epidermal layers of host leaves.

Post-harvest losses are primarily driven by specialized pests that attack grains and dried goods under storage conditions. This group includes pyralid moths such as Cadra cautella and Plodia interpunctella (Lin et al., 2023; Jesser et al., 2017), as well as Sitotroga cerealella from Gelechiidae (Salman et al., 2025).

During the insect life cycle, the larval stage is responsible for the majority of damage, as caterpillars feed on host plant tissues, destroying leaves, stems, and fruits, as well as other plant parts, thereby impairing normal plant growth and leading to partial or complete yield loss (Dwisandi et al., 2024). According to estimates, herbivorous insects alone can contribute to the loss of up to one-fifth of global crop production annually, causing damage amounting to hundreds of billions of dollars (Shelton et al., 2020). A single species, such as Helicoverpa armigera, can cause annual losses exceeding 3 billion USD worldwide in vegetable and crop production (Riaz et al., 2021). In the case of the diamondback moth, Plutella xylostella, which in addition to cruciferous crops also attacks other vegetable species, the estimated damage reaches approximately 5 billion USD (Zalucki et al., 2012). To the authors’ knowledge, no updated global macroeconomic calculation has been conducted since that study; however, recent literature continues to confirm the ongoing scale of these estimated losses (e.g., Massarolli et al., 2024). In some cases, economic losses are even higher, as observed for the fall armyworm, Spodoptera frugiperda, which attacks dozens of host species, primarily maize and rice (Niassy et al., 2021).

Over the past decades, the global trade of plants and plant products has facilitated the spread of numerous alien lepidopteran pests. In addition, climate change has altered insect behavior and distribution patterns, making it increasingly difficult to predict their spread to new regions and the potential damage they may cause, particularly when combined with non-climatic factors (Kocsis and Hufnagel, 2011). For example, according to the analysis by Lopez-Vaamonde et al. (2010), more than 90 non-native Lepidoptera species have been introduced into Europe, of which more than 70% became established during the 20th century. The introduction of new pest species into a given region requires rapid and effective control measures, highlighting the importance of understanding the factors influencing their spatiotemporal distribution patterns (Hussain et al., 2022). With the advancement of technology, species monitoring has been supported by tools such as smart traps, remote sensing, UAVs, and AI-driven predictive modeling, which enable early detection and timely interventions as integral components of integrated pest management (Rajabpour and Zarahmadi, 2025).

Despite their toxic effects on non-target organisms and the environment, the control of lepidopteran pests still largely relies on the application of synthetic insecticides (Nauen et al., 2019). However, with the increasing occurrence of resistance, which reduces their effectiveness, and growing awareness of their environmental and health impacts, biological control has become an important alternative (Sharma et al., 2023). The use of biocontrol agents represents an effective approach for managing these pests, however, its success depends on numerous abiotic and biotic factors, such as climatic conditions, predation pressure, and the presence of pesticides in the environment (Thakur and Singh, 2025), as well as the potential risks associated with the introduced organisms themselves. Microbial pesticides, including bacteria, fungi, and viruses, are widely used, with ongoing efforts focused on developing more effective formulations (Wei et al., 2025b). Pheromone-based strategies, including mass trapping, lure-and-kill, and mating disruption, have also been widely applied in the management of lepidopteran pests. In addition, broader semiochemical approaches are increasingly being developed to enhance monitoring and control efficiency (Suckling et al., 2017). One of the promising control strategies is the sterile insect technique, which is used for population suppression, local eradication, or prevention of pest establishment (Wei et al., 2025a).

It is crucial to acknowledge that even the most widely used botanical insecticides globally, such as pyrethrum and neem (Isman, 2020), are not entirely immune to the development of resistance in target species (Siegwart et al., 2015). In the case of lepidopteran pests, in addition to heavily documented resistance to synthetic insecticides in species such as Helicoverpa armigera, Plutella xylostella, Spodoptera exigua, Spodoptera frugiperda, and Spodoptera litura (Junqueira et al., 2024), there is evidence of resistance to microbial agents (Afzal et al., 2024) and desensitization to active ingredients in botanical insecticides (Bomford and Isman, 1996). Generally, the risk of resistance emerging against botanical insecticides arises when isolated active compounds are used instead of the raw, complex natural mixtures. This risk escalates with high application frequencies and the exclusive reliance on a single bioinsecticide product (Feng and Isman, 1995). The true potential of botanical insecticides in resistance management lies precisely in their complex chemical composition and multiple modes of action, which significantly hinder the pest’s ability to rapidly evolve resistance mechanisms (Saxena, 2025). Furthermore, because these plant-derived compounds degrade significantly faster in the environment compared to synthetic alternatives, prolonged selective pressure—a key driver of resistance—is effectively prevented (Isman, 2023). Integrating botanical pesticides into Integrated Pest Management (IPM) strategies, alongside their synergistic rotation with other botanicals and conventional insecticides, offers a more effective and sustainable approach to crop protection (Saikumar et al., 2025). As noted by Suckling et al. (2017), each pest control strategy has its own advantages and limitations, whether related to effectiveness, cost, or applicability under specific environmental conditions, which highlights the need for continuous development of new and improved approaches. In this context, botanical insecticides have gained increasing attention in recent years as a sustainable alternative for the protection of crops against lepidopteran pests. Current research is primarily focused on identifying new plant-based raw materials rich in bioactive compounds, improving extraction methods, and developing more efficient application strategies, particularly through the use of nanotechnology (Ullah et al., 2025).

5 Ornamental plants as sources of extracts and essential oils with insecticidal potential

Following the search criteria and literature screening, a total of 63 research papers investigating ornamental plant species with reported insecticidal activity against lepidopteran pests were analyzed. A total of 72 plant species belonging to 32 families were identified and categorized based on growth form and type of botanical preparation, with species arranged alphabetically by family name. Among the identified plant species, approximately 80% of these taxa exhibited insecticidal activity, followed by antifeedant activity reported in extracts and essential oils derived from 54% of the evaluated species. The third most frequently reported activity was related to insect growth and developmental inhibition, including effects on physiological, biochemical and reproductive processes, with 47% of analyzed species showing such effects. Most extracts and essential oils were derived from leaves (approximately 70%), while flowers, bark, and seeds were each used as raw materials in approximately 10% of the studies. Although most reviewed studies focused on leaves as the source material for botanical preparation, this dominance is largely a reflection of experimental design choices, where researchers frequently evaluated leaves exclusively without screening other anatomical organs. Where multi-organ comparisons were available, the dataset clearly demonstrates that insecticidal efficacy is strictly species-specific, depending on the precise plant part utilized. Therefore, a general chemical superiority of one organ over another cannot be assumed across the board. For instance, in some taxa, a combination of different organs was utilized, as observed with the mixed flower and leaf extracts of Nerium oleander (Salman et al., 2025). In other cases, distinct plant parts from the same taxon yield highly contrasting bioactivity profiles; for instance, the bark, flowers, leaves, and seeds of Handroanthus impetiginosus exhibit significantly different levels of insecticidal activity – with seed and leaf ethanolic extracts demonstrating the highest efficacy (Silva et al., 2025). Furthermore, certain plant parts may completely lack toxic fractions for specific target pests, as demonstrated by Pistacia lentiscus, where fruit extracts show toxicity, but leaf and bark extracts exhibit no larvicidal effect against Lobesia botrana (Dasenaki et al., 2022). This organ-specific complexity is further highlighted in a study on invasive Triadica sebifera, where even fractions of bark and leaf extracts exhibit notably different effects on the target pest Plutella xylostella (Dolma and Reddy, 2022). A direct quantitative comparison of whether woody species are more effective than herbaceous ones remains highly constrained by the methodological heterogeneity of the reviewed studies, including extraction solvent and method, concentration, application dosage, exposure time, the developmental stage of the tested insect, as well as the bioassay method and environmental conditions (controlled vs. field trials). Furthermore, as a substantial number of studies in the available literature focus primarily on laboratory assays, it remains difficult to draw definitive conclusions regarding the practical applicability of the tested preparations under real-world field and greenhouse conditions. The profound impact of just one of these aforementioned factors on preparation efficacy is clearly illustrated by the study of Escobar-Garcia et al. (2024), which compared three extraction methods for testing aqueous botanical extracts from seven different plant species. Their experiment demonstrated that the exact same plant species evaluated against Plutella xylostella could induce a larvicidal effect that varied by up to 20% depending strictly on the extraction method utilized. Similarly, depending on the choice of solvent, extracts from the identical plant taxon can display highly contrasting bioactivity profiles. For instance, as documented by Shilaluke and Moteetee (2022) for specific Meliaceae species, varying the solvent polarity can fundamentally alter the behavioral response of target pests, shifting the phytopreparation’s profile from strong repellency to insect stimulation. Furthermore, a robust analytical comparison regarding the type of botanical preparation is severely restricted by the scarcity of studies that directly evaluate the comparative impact of crude extracts versus essential oils derived from the exact same plant species against the identical insect pest. The insect species tested for susceptibility to plant extracts and essential oils in the reviewed literature belonged to ten families, with the following pests being the most frequently investigated: Plutella xylostella (Plutellidae), Spodoptera frugiperda (Noctuidae), Spodoptera litura (Noctuidae), and Lymantria dispar (Erebidae). The high frequency of trials targeting these specific species underscores their immense economic significance in key agricultural regions and highlights the urgent need for innovative pest control strategies. Overall, the reviewed dataset clearly highlights which target pests are most sensitive to the tested botanical preparations; across all analyzed studies, the highest susceptibility was consistently demonstrated by species within the families Plutellidae and Noctuidae. However, a definitive conclusion regarding the absolute susceptibility of these families should not be drawn solely based on the literature reviewed in this study. When focusing strictly on peak biological performance (for example, treatments inducing 95–100% mortality), specific botanical families stood out across the reviewed literature. Within the woody species category, the family Fabaceae consistently excelled in extract applications, while the families Myrtaceae and Lamiaceae dominated the essential oil treatments. Conversely, for both extracts and essential oils within the herbaceous and semi-woody categories, the families Lamiaceae and Asteraceae were established as the predominant sources of high bioactivity.

The observed biological activities were often attributed to specific active compounds present in plant extracts and essential oils (Dhivya et al., 2024). However, a systematic evaluation of plant metabolites and their mechanisms of action in plant protection was beyond the scope of this study.

5.1 Woody species

A literature survey of extracts from woody ornamental species revealed considerable diversity of taxa exhibiting insecticidal activity against lepidopteran pests (Tables 1–3). Among the reviewed plant families, species within the Meliaceae family were the most numerous, followed by Fabaceae, Moraceae, and Oleaceae. Many studies reported both lethal and sublethal effects, demonstrating that the control of target insects can be achieved through both toxic and behavioral mechanisms. A substantial number of assessed species exhibited larvicidal activity, including species belonging to 15 plant families. Several species showed larval mortality above 95%, with notable variation depending on the plant part used for extraction, extract type, dosage, and exposure conditions (Shilaluke and Moteetee, 2022; Silva et al., 2025; Ammar et al., 2025).

Table 1. Extracts from ornamental woody plants with reported insecticidal activity against target insect pests (families Anacardiaceae – Lythraceae).

Table 2. Extracts from ornamental woody plants with reported insecticidal activity against target insect pests (families Malvaceae – Myrtaceae).

Table 3. Extracts from ornamental woody plants with reported insecticidal activity against target insect pests (families Oleaceae – Theaceae).

The highest mortality (98–100%) was reported for extracts derived from Handroanthus impetiginosus, Jatropha curcas, Delonix regia, Juglans mandshurica, and Ficus auriculata, tested against insects from the families Lyonetiidae, Noctuidae, Pieridae, and Plutellidae (Silva et al., 2025; Valdez-Ramírez et al., 2024; Ammar et al., 2025; Zhang et al., 2023; Vasantha‐Srinivasan et al., 2023). Strong antifeedant activity was also observed, particularly in Triadica sebifera tested against Plutella xylostella (up to 99.68%; Dolma and Reddy, 2022), with similarly high feeding inhibition recorded for Pongamia pinnata (94.6%), Ceiba pentandra (92.4%), Punica granatum (92.96%), and Murraya paniculata (98.90%) extracts (Lakshmanan et al., 2017; Amel et al., 2015; Mehboob et al., 2019). Repellent and oviposition deterrent effects were reported in approximately one-third of the reviewed studies. Species from the families Meliaceae and Euphorbiaceae showed high potential in repellency tests, while oviposition deterrence above 90% was recorded against Helicoverpa armigera following the application of Pongamia pinnata and Ceiba pentandra extracts, and against Spodoptera litura when Murraya paniculata extracts were applied (Lakshmanan et al., 2017; Mehboob et al., 2019).

In addition, numerous studies reported different growth and developmental alterations throughout the life cycle of target pests following the application of investigated extracts. Wagner et al. (2021) reported that Spodoptera frugiperda fed on a diet containing Ailanthus altissima extract exhibited prolonged larval stage and delayed pupation, reduced larval and pupal growth, as well as reduced adult emergence and decreased biomass and wing development in surviving individuals. Salman et al. (2025) recorded a reduction in Sitotroga cerealella adult emergence of up to 90% when Nerium oleander extract was applied, while anatomical and morphological changes were observed by many authors (Ponsankar et al., 2016). Other studies have also described changes following plant extract treatments, including inhibition of enzymatic activity and genetic alterations, resulting in growth abnormalities and reduced insect survival rates (Mishra et al., 2019; Ammar et al., 2025).

The reviewed research articles on essential oil activity against lepidopteran pests highlighted insecticidal potential of several woody ornamental species (Table 4). The selected bioassays included species from the plant families Anacardiaceae, Annonaceae, Cupressaceae, Lamiaceae, Lauraceae, Myrtaceae, Pinaceae, and Verbenaceae, while Cupressaceae and Myrtaceae species were the most represented. The effect of essential oils on survival and behavior of Plutella xylostella was predominantly investigated. Insecticidal activity against larval and adult stages was reported for 11 species, affecting pests from the families Erebidae, Gelechiidae, Noctuidae, Plutellidae, and Pyralidae families. The effectiveness of essential oils was influenced by the plant part from which the oil was derived, the geographical origin of the plant material, as well as the oil concentration and exposure time (Abada et al., 2020; de Paula Rosetti et al., 2023; Nazirzadeh et al., 2026).

Table 4. Essential oils from ornamental woody plants with reported insecticidal activity against target insect pests.

High levels of larvicidal activity were reported for several species, with mortality exceeding 90% in some cases, such as Duguetia lanceolata, where essential oils derived from different plant parts showed strong toxicity against Spodoptera frugiperda caterpillars (de Paula Rosetti et al., 2023). Essential oil obtained from aerial parts of Salvia rosmarinus plants showed high larvicidal mortality against Ectomyelois ceratoniae and Tuta absoluta (Abada et al., 2020; Cherif et al., 2025). Notably, Filomeno et al. (2017) reported 100% mortality of Plutella xylostella larvae within less than 3 min following essential oil application, while Callistemon speciosus essential oil induced total mortality of Anticarsia gemmatalis and Spodoptera frugiperda larvae (Silvestre et al., 2022). Cinnamomum camphora showed strong repellent effect (around 88%) against Plutella xylostella larvae (Koundal et al., 2018), as well as Eugenia uniflora against Diaphania hyalinata (Lobo et al., 2019) and Cedrus deodara against Plutella xylostella (Reddy et al., 2016). In addition to toxicity and repellency, several species exhibited antifeedant activity, including species belonging to Anacardiaceae, Cupressaceae, Lamiaceae and Lauraceae plant families. Some species exhibited growth and developmental inhibition against tested insects, as well as influence on reproductive efficiency.

5.2 Herbaceous and semi-woody species

The majority of the reviewed studies on herbaceous and semi-woody species (specifically subshrubs characterized by a perennial woody base and herbaceous upper growth, such as Lavandula and Salvia species) focused on aerial parts as the primary plant material (Table 5), with extracts predominantly prepared using ethanol and methanol. Ornamental species from eight plant families, valued for their attractive foliage and flowers, demonstrated promising activity against lepidopteran pests relevant to food production. Extracts from species belonging to the families Asteraceae, Commelinaceae, Crassulaceae, Lamiaceae, Ranunculaceae, and Solanaceae exhibited larvicidal activity, with mortality exceeding 90% in several cases. Notably, high larval mortality was observed in Malacosoma neustria testacea treated with Rudbeckia hirta extract (above 96%; Wang et al., 2025) and in Plutella xylostella treated with Perilla frutescens extract (up to 100%; Kim et al., 2019). In addition to toxicity, antifeedant activity was reported against insects from the families Lasiocampidae, Noctuidae, and Plutellidae. For example, Kalanchoe daigremontiana extract showed antifeedant capacity above 80% against Plutella xylostella (Hidayati et al., 2016), while extracts derived from Consolida ajacis seeds exceeded 90% (Peng et al., 2023). Species belonging to Asteraceae, Sapindaceae, and Solanaceae families showed repellent activity – for instance, regardless of extract dose and exposure time, Tagetes erecta caused 100% repellency against Spodoptera frugiperda larvae, followed by highly efficient Datura metel (Henagamage et al., 2023).

Table 5. Extracts from ornamental herbaceous and semi-woody plants with reported insecticidal activity against target insect pests.

Studies investigating essential oils derived from herbaceous and semi-woody ornamental species as potential botanical insecticides against lepidopteran pests primarily highlighted species from the Asteraceae and Lamiaceae families, followed by Geraniaceae and Zingiberaceae (Table 6). Lethal effects on larval and/or adult stages were observed across all assessed bioassays, with notable toxicity reported for Pelargonium graveolens essential oil against Plutella xylostella (Song et al., 2022), Lavandula dentata against Anticarsia gemmatalis (100% mortality; Vicenço et al., 2021), and Cymbopogon citratus leaf essential oil against Tuta absoluta (100% mortality; Cherif et al., 2025). In addition to lethal effects, sublethal responses were observed in insects belonging to the families Gelechiidae, Erebidae, Noctuidae, Plutellidae, and Pyralidae. Essential oils from Pelargonium graveolens and Hedychium spicatum applied to Plutella xylostella, as well as Lavandula angustifolia tested against Mythimna separata, notably affected feeding activity (Song et al., 2022; Koundal et al., 2018; Wang et al., 2022). Growth and developmental inhibition, along with physiological changes, were also reported in target pests treated with Achillea millefolium, Artemisia argyi, Tanacetum vulgare, Pelargonium graveolens, Lavandula multifida, Cymbopogon citratus, and Ruta graveolens. These effects included alterations in enzyme activity, reduced larval weight and growth rate, and changes in the duration of larval and pupal stages (Devrnja et al., 2020; Song et al., 2022; Awad et al., 2024; Górska-Drabik et al., 2025). Disruption of reproductive performance, reflected in changes in fecundity and fertility, was also observed following essential oil treatments and has likewise been documented in studies on plant extracts (Rocha et al., 2022).

Table 6. Essential oils from ornamental herbaceous and semi-woody plants with reported insecticidal activity against target insect pests.

6 Towards sustainable green waste management: opportunities, challenges, and future perspectives

6.1 Diversity of ornamental biomass and associated ecosystem services and disservices

Ornamental plant species considered as potential sources of raw material for the production of extracts and essential oils in lepidopteran pest management encompass a wide spectrum of woody and herbaceous taxa. Some species, such as the woody taxa Nerium oleander, Camellia japonica, and Fraxinus ornus, are attractive choices for landscaping purposes primarily due to their visual characteristics (Durak and Atik, 2023; Borden and Dale, 2020; Čukanović et al., 2024), while others, including Pistacia lentiscus, Punica granatum, and Morus alba, possess edible value in addition to notable ornamental attributes and are therefore cultivated beyond productive orchards (Öztürk and Ağırtaş, 2021; Abbasoğlu and Kahramanoğlu, 2025; Blitek et al., 2022). The assessed plant species are regarded as ornamental due to specific traits, such as an imposing canopy (Cedrus deodara), uniquely coloured foliage (Tradescantia pallida), or fragrant and morphologically distinctive flowers (Consolida ajacis) (Li et al., 2023; Khudhur et al., 2021; Zhang et al., 2020). Beyond their ornamental value, as integral components of green spaces in urban and rural environments, these species contribute to ecosystem functioning through a range of regulatory, provisioning, supporting, and cultural ecosystem services (Pušić et al., 2023; Despotović et al., 2025). Consequently, their role in landscapes is highly context-dependent and varies with design objectives and environmental settings.

Among species with confirmed insecticidal activity against key pests in grain, fruit, and vegetable production, some, after introduction into non-native regions for ornamental purposes, have exhibited invasive behaviour, thereby negatively affecting biodiversity in new habitats and outcompeting native species (Nickerson and Flory, 2015). Such species are often widely present in urban gardens and along roadsides, where they produce substantial amounts of vegetative biomass (Montagnani et al., 2026). Species such as Ailanthus altissima and Lantana camara, although widely distributed in public and private landscapes, have thus become problematic and require management interventions (Krzeptowska-Moszkowicz and Moszkowicz, 2014; Morka, 2025). The utilization of their pruning and residual biomass not only reduces the risk of further spread into surrounding green areas, but also represents a pragmatic solution where complete eradication is economically or logistically challenging (Pušić et al., 2024). In such cases, integrating biomass valorization into containment strategies helps offset high management costs without encouraging the deliberate cultivation of these invasive species. Due to their allelopathic effects, species such as Artemisia argyi and Thuja orientalis release strong bioactive compounds that may persist in plant residues and pruned biomass (Li et al., 2021; Begum et al., 2017). Consequently, composting, as one of the primary uses of green waste, may not be suitable for such materials without prior assessment (Medic et al., 2023). At the same time, these characteristics highlight their potential for the development of botanical insecticides targeting lepidopteran pests (Song et al., 2022; Hamza and Sayed, 2019).

Therefore, sustainable green waste management requires an integrated approach that respects existing ecosystem services while actively resolving these disservices through valorization. Although the valorization of green waste for the development of biopesticides directly represents a provisioning ecosystem service, the maintenance of green spaces must be carefully planned and balanced with other ecosystem services provided by urban greenery (Bonu, 2023). Inadequate pruning and failure to respect natural cycles within urban ecosystems may lead to habitat disturbance for wildlife species or even their complete loss. Branches in contact with the ground can create microhabitats for various animal species, as can veteran trees with cavities and broken branches that provide shelter (Bonu, 2023). Ecologically informed management of ornamental vegetation could reduce the risk of interference with wildlife population dynamics, thereby preserving “nature” within the urban environment (Luniak, 2018; Zevgolis et al., 2024).

6.2 Biomass yield quantification, phytochemical quality dynamics, and regulatory hurdles

An important advantage of using biomass from ornamental plant species is that such an approach does not require additional land for raw material production (Langsdorf et al., 2021). This “living” resource is already present within landscapes and is continuously renewed over time. The amount of biomass that can be collected through pruning varies considerably depending on the species, as each plant has a specific growth rate and distinct pruning requirements. Quantification of biomass potential for particular species, based on direct field measurements and dendrometric equations, provides a basis for estimating annual biomass yield (Ferla et al., 2020). For example, it has been estimated that a single Morus alba tree under urban conditions can produce between 30 and over 70 kg of dried pruned biomass, depending on location (Velázquez-Martí et al., 2013), while the estimated yield for Platanus hispanica is approximately 24 kg per tree (Sajdak et al., 2014). However, due to the numerous factors influencing biomass estimation (Sajdak et al., 2014), obtaining accurate predictions remains challenging. Therefore, systematic recording of pruned material represents the most reliable indicator of available biomass.

In addition to biomass quantity, raw material quality represents a major challenge. The composition of biomass varies both regionally and seasonally, while physicochemical characteristics differ among species, as well as with plant maturity and growing conditions (Langsdorf et al., 2021; Mohapatra et al., 2017). Therefore, the timing of biomass harvesting is of primary importance for the quality of botanical preparations, as it directly affects their performance against target organisms (Rathore et al., 2022). Standardization of such products remains one of the key challenges that must be addressed in order to ensure consistent and reproducible results in pest control applications (Ivase et al., 2021).

The high spatial and temporal plasticity of secondary metabolites introduces severe challenges for achieving a standardized median lethal concentration (LC50). To overcome these variation hurdles, implementing systematic chemical standardization before and during manufacturing is critical (Ivase et al., 2021). Ensuring a predictable LC50 depends on maintaining rigorous quality control to verify the uniformity, performance, and safety of the primary active components (Sarkar and Kshirsagar, 2014). Although fluctuating environmental factors frequently complicate biological reproducibility, a reliable formulation can be achieved by adhering to strict validation guidelines that mandate precise botanical verification alongside thorough physicochemical stability profiling, which encompasses both qualitative and quantitative assessments (Sharma et al., 2010). Furthermore, unlike targeted botanical production systems, green waste frequently consists of a highly heterogeneous mix of senesced foliage. Although senescence typically alters phytochemical profiles, evidence in the reviewed literature demonstrates that such materials can still maintain robust biological efficacy. Specifically, extracts derived from senescent leaves have been shown to exhibit significant antifeedant activity and high insecticidal mortality against lepidopteran pests, while also serving as potent natural synergists to enhance overall formulation performance (Bullangpoti et al., 2012). Moreover, the transition from fresh to senescent states due to environmental or storage stress can trigger mechanisms that actually elevate the accumulation of specific bioactive components, such as total phenolic compounds, thereby reinforcing or even enhancing the baseline bioactivity of the biomass (Chua and Hidayathulla, 2017). Consequently, the perceived dilution effect of green waste does not automatically negate its practical potency in pest management. Furthermore, urban-sourced ornamental biomass presents potential safety risks regarding environmental contaminants. However, to the authors’ knowledge, the reviewed literature regarding botanical insecticides currently offers no evidence, empirical data, or screening protocols to ensure that these localized contaminants are not co-extracted during processing – thus representing a critical knowledge gap that needs to be addressed in future studies. Finally, while secondary metabolites suffer from rapid enzymatic degradation post-pruning, the literature rarely accounts for this collection-to-processing efficacy loss, necessitating the use of rapid “green” extraction protocols to prevent bioactivity breakdown (Faraone et al., 2021). Although some of the assessed studies addressed the safety of preparations toward non-target insects and plants (Ponsankar et al., 2016; Wang et al., 2025; Górska-Drabik et al., 2025), further investigation of botanical products is essential, particularly regarding their effects on other non-target organisms, potential phytotoxicity, and broader environmental impacts. Long-term studies on the fate of active substances contained in biopesticides after field application are essential for their authorization and approval (Acheuk et al., 2022). The primary obstacles confronting biopesticide developers represent formidable commercialization barriers that are inherently financial and temporal, given that the development pipeline for these products is highly capital-intensive and prolonged. Although certain regions worldwide feature different regulatory schemes for recognizing plant extracts and essential oils, frameworks within the United States and the European Union remain highly demanding; the timeline spanning from initial submission to final approval ranges from over two years to more than seven years, respectively (Isman, 2023). Furthermore, registration and compliance costs can escalate dramatically, reaching up to five million pounds within the EU market, largely driven by the stringent data requirements for extensive toxicology packages and detailed residue studies necessary to ensure consumer safety (Ansari, 2021). Regulatory bodies also enforce strict efficacy requirements, including mandatory greenhouse and field validation trials conducted over a minimum of two consecutive seasons to verify consistent pest control. Meeting these criteria is exceptionally challenging for biomass valorization, as seasonal and regional variations cause fluctuations in bioactive metabolite concentrations, resulting in inconsistent field performance. Finally, the absence of standardized protocols for the extraction, formulation, and practical deployment of these complex mixtures significantly hinders systematic quality control and predictable commercial scaling (Saikumar et al., 2025).

6.3 Socio-economic and environmental benefits and alignment with sustainability goals

For such preparations to be truly sustainable, and not only environmentally sound, it is necessary to carefully consider the social and economic aspects of their production. Localizing the production of biomass-derived solutions, including the use of pruning biomass and plant residues for the development of biopesticides, could reduce the need for managing unused green waste, as well as associated logistical costs (Langsdorf et al., 2021). Waste segregation, even in the presence of high heterogeneity, would be more easily carried out within limited urban units, without combining waste from a large number of locations. The application of simple and cost-effective approaches, such as plant extract preparation, could enable on-site production, thereby fully supporting the principles of a circular bioeconomy (Tan and Lamers, 2021). This concept could further be extended to smaller private holdings and farms, supporting the integration of nature-based solutions as a natural component of food production systems.

The ambitious objectives set within the European Green Deal initiative, aimed at the circular management of resources and waste, the conservation of ecosystems and biodiversity, and the establishment of environmentally conscious agri-food systems, can be supported by the use of biopesticides derived from green waste of ornamental plants, provided that the solutions are demonstrated to be cost-effective (Prasad et al., 2023). Such a concept may contribute to the achievement of various Sustainable Development Goals (SDGs), including supporting food security based on sustainable agricultural practices (SDG 2), promoting healthier lives by reducing negative impacts on the environment and human health (SDG 3), and enhancing the sustainability of urban green spaces while enabling sustainable production through the development of value-added products (SDG 11, SDG 12) (UN General Assembly, 2015). Furthermore, reducing greenhouse gas emissions through adequate green waste management can contribute to climate change mitigation while also preventing further land and ecosystem degradation by utilizing existing biomass as a resource in production (SDG 13, SDG 15). However, alongside a number of limitations associated with the development of biopesticides and challenges related to their applicability across different agricultural systems, a key factor is the willingness of food producers to adopt such solutions in their production practices (Fenibo and Matambo, 2025; Kontogeorgos and Tsiamis, 2025). Continuous farmer education and collaboration among public, research, and private sectors can facilitate the transfer of plant-derived active substances from urban green spaces to field application.

Despite the defined methodological boundaries and the distinct regional distribution of the assessed species, the compiled list of ornamental plant taxa provides a valuable baseline to guide future research. Specifically, it highlights critical avenues for investigating the active compounds underlying botanical efficacy, evaluating their associated non-target effects, and driving the development of high-efficacy formulations capable of meeting stringent regulatory approval standards.

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Footnotes

Edited by: Jameel M. Al-Khayri, King Faisal University, Saudi Arabia

Reviewed by: Selvamuthukumaran Thirunavukkarasu, Annamalai University, India

Héctor Alonso Escobar-García, National University of Piura, Peru