Philip C Stevenson

• BSc, PhD, FRSC FRES
• Professor at University of Greenwich

A plant-herbivore information “arms race” The consumption of plants by herbivores has driven the evolution of many diverse plant defense chemicals to which herbivores have constantly adapted. The transmission of chemical information at the community level is less known but important given the plethora of plant and herbivore species, especially in t...

1. Trees are a foundation for biodiversity in urban ecosystems and therefore must be able to withstand global change and biological challenges over decades and even centuries to prevent urban ecosystems from deteriorating. Tree quality and diversity should be prioritised over simply numbers to optimise resilience to these challenges. Successful est...

Phytosterols are primary plant metabolites that have fundamental structural and regulatory functions. They are also essential nutrients for phytophagous insects, including pollinators, that cannot synthesize sterols. Despite the well‐described composition and diversity in vegetative plant tissues, few studies have examined phytosterol diversity in...

Caffeine is a widely occurring plant defense chemical¹,² that occurs in the nectar of some plants, e.g., Coffea or Citrus spp., where it may influence pollinator behavior to enhance pollination.³,⁴ Honey bees fed caffeine form longer lasting olfactory memory associations,⁵ which could give plants with caffeinated nectar an adaptive advantage by ind...

Antimicrobial nectar secondary metabolites can support pollinator health by preventing or reducing parasite infections. To better understand the outcome of nectar metabolite–parasite interactions in pollinators, we determined whether the antiparasitic activity was altered through chemical modification by the host or resident microbiome during gut p...

Pollen sterols are essential micronutrients for bees as membrane components, hormone precursors and gene regulation. Sterols vary among plant species; therefore, bee development may be influenced by or adapted to specific pollen diets. To better understand the roles of pollen diet and sterol provisioning, we investigated the effect of different pol...

Establishing how plants contribute food and refuge to insects can be challenging for small species that are difficult to observe in their natural habitat, such as disease vectoring mosquitoes. Currently indirect methods of plant-host identification rely on DNA sequencing of ingested plant material but are often unsuccessful for small insects that f...

Caffeine is a widely occurring plant defence chemical that occurs in the nectar of some plants, e.g. Coffea or Citrus spp., where it may influence pollinator behaviour to enhance pollination. Previous laboratory work found inexperienced bumblebees (Bombus terrestris) located new food sources emitting a learned floral odour more consistently if they...

Table S1: List of phenolic compounds identified in oak leaves using LC-MS.

Assisted migration is a tree-planting method where tree species or populations are translocated with the aim of establishing more climate-resilient forests. However, this might potentially increase the susceptibility of translocated trees to herbivory. Stand diversification through planting trees in species or genotypic mixtures may reduce the amou...

Honeybees, the world’s most important crop pollinators, are increasingly facing pollen starvation arising from agricultural intensification and climate change. Frequent flowering dearth periods and high-density rearing conditions weaken colonies, often leading to their demise. Beekeepers provide colonies with pollen substitutes, but these feeds can...

Environmental exposure to cold is increasingly being associated with changes in metabolism. We developed and tested the hypothesis that exposure to cold drives systemic effects in lipid metabolism. Specifically, (i) that energy storage and provision adapts to the cold by altering triglyceride distribution and (ii) that membranes adapt to cold condi...

The global biodiversity crisis in agriculture is overlooked compared with that in wild systems. This must change if we are to safeguard domesticated plant diversity and meet global sustainable development and biodiversity goals. In this Perspective, we review tools developed through decades of wild biodiversity conservation and provide a framework...

The global biodiversity crisis in agriculture is overlooked compared with that in wild systems. This must change if we are to safeguard domesticated plant diversity and meet global sustainable development and biodiversity goals. In this Perspective, we review tools developed through decades of wild biodiversity conservation and provide a framework...

Lipid metabolism is recognised as being central to growth, disease and health. Lipids, therefore, have an important place in current research on globally significant topics such as food security and biodiversity loss. However, answering questions in these important fields of research requires not only identification and measurement of lipids in a w...

Lablab ( Lablab purpureus L.) is an important food and livestock feed legume that can also enhance soil fertility. However, its production is limited by insect pests, notably the black bean aphid ( Aphis fabae ). The present field study was conducted to determine the difference in the contribution of lablab genotypes and natural field margin vegeta...

Common bean production is constrained by a multitude of biotic constraints including bean flies and Fusarium wilt in tropical and subtropical farming systems globally. As these pests and diseases attack the crop beneath the soil, excessive applications of synthetic pesticides are frequently used for their control. The use of plant-based pesticides...

On 27 April 2023 the scientific community lost an inspirational and influential biologist of rare quality following the death of Professor Sue Nicolson.

Main conclusion One of seven Solanum taxa studied displayed associations between pollen presence and floral scent composition and volume, suggesting buzz-pollinated plants rarely use scent as an honest cue for foraging pollinators. Abstract Floral scent influences the recruitment, learning, and behaviour of floral visitors. Variation in floral sce...

Beetles of the genus Antherophagus are phoretic organisms that inhabit the nests of Bombus species. They migrate and colonize new nests using the same bumblebees as carriers. Although Antherophagus beetles from temperate Europe and North America are known to use some plant species to move between bumblebees, it is unknown which plants are used as t...

Background: Exploring genetic variation and screening for disease resistance is an important step in crop breeding initiatives but is lacking for many bean varieties including mung bean. The present study evaluated the diversity of 42 morpho-agronomic traits and screened mung bean genotypes for resistance to powdery mildew disease. A total of 132 m...

Anthracnose caused by Colletotrichum spp. remains an intractable problem in the most common bean ( Phaseolus vulgaris ) production areas worldwide and can cause total yield loss. Many smallholder farmers are familiar with using botanical extracts to control insect pests; however, there is less familiarity with their use to control fungal diseases d...

Fall armyworm, Spodoptera frugiperda (FAW) is a cosmopolitan crop pest species that has recently become established in sub-Saharan Africa and Southeast Asia. Current FAW control is almost entirely dependent on synthetic pesticides. Biopesticides offer a more sustainable alternative but have limitations. For example, pyrethrum is an effective botani...

Introduction: Populations of natural enemies of insect pests are declining owing to agricultural intensification and indiscriminate use of pesticides, and this may be exacerbated in agricultural systems that clear all margin plants after the cropping season for other uses such as fodder. Retaining a diversity of non-crop flowering vegetation outsid...

Specialization in plant pollination systems can arise from traits that function as filters of flower visitors. This may involve chemical traits such as floral volatiles that selectively attract favoured visitors and non-volatile nectar constituents that selectively deter disfavoured visitors through taste or longer-term toxic effects or both. We ex...

Little is known concerning terpenoids produced by members of the fungal order Ophiostomales, with the member Harringtonia lauricola having the unique lifestyle of being a beetle symbiont but potentially devastating tree pathogen. Nine known terpenoids, including six labdane diterpenoids (1–6) and three hopane triterpenes (7–9), were isolated from H...

The insect pathogenic fungus, Ascosphaera apis, is the causative agent of honeybee chalk brood disease. Amylases are secreted by many plant pathogenic fungi to access host nutrients through the metabolism of starch, and the identification of new amylases can have important biotechnological applications. Production of amylase by A. apis in submerged...

Leaf traits often vary with plant neighbourhood composition, which in turn may mediate plant susceptibility to herbivory. However, it is unknown whether there are any common patterns of change in leaf trait expression in response to neighbourhood diversity, and whether these responses confer increased resistance or susceptibility to herbivores. We...

Background Bees provide essential pollination services for many food crops and are critical in supporting wild plant diversity. However, the dietary landscape of pollen food sources for social and solitary bees has changed because of agricultural intensification and habitat loss. For this reason, understanding the basic nutrient metabolism and meet...

Sterols have several roles in planta, including as membrane components. Sterols are also essential nutrients for insects. Based on this, and the different functions of leaves and pollen, we tested the hypotheses that (a) the sterolome is different in leaves and pollen from the same plant, (b) pollens from wind- and insect pollinated plants comprise...

Introduction Fall armyworm continues to disrupt smallholder farming systems across sub-Saharan Africa, with sporadic outbreaks and chronic cereal crop losses. Smallholders have been adapting to the pest by increasing crop surveillance for targeted control measures and developing low-cost solutions. For example, some report placing soil or ash in ma...

Field margin plants around crops are postulated to increase natural enemy abundance to enhance pest management. A trial was conducted to determine the contribution of field margin vegetation and cropping systems to natural enemies of bean aphids ( Aphis fabae ) on Lablab purpureus , an orphan crop legume. Natural enemy populations were surveyed in...

Grayanotoxin I (GTX I) is a major toxin in leaves of Rhododendron species, where it provides a defence against insect and vertebrate herbivores. Surprisingly, it is also present in R. ponticum nectar, and this can hold important implications for plant-pollinator mutualisms. However, knowledge of GTX I distributions across the genus Rhododendron and...

Plants have unique chemical and physical traits that can reduce infections in animals ranging from primates to caterpillars. Sunflowers (Helianthus annuus; Asteraceae) are one striking example, with pollen that suppresses infections by the trypanosomatid gut pathogen Crithidia bombi in the common eastern bumble bee (Bombus impatiens). However, the...

Introduction Pests and diseases limit common bean ( Phaseolus vulgaris ) production in intensifying smallholder farming systems of sub-Saharan Africa. Soil-borne pests and diseases (SPD) are particularly challenging for farmers to distinguish and manage in cropping systems that vary in terms of soils, farmer knowledge, and management factors. Few s...

The homoterpenes 4,8‐dimethyl‐1,3,7‐nonatriene (DMNT) and 4,8,12‐trimethyl‐1,3,7,11‐tridecatetraene (TMTT) are volatile products of plant metabolism reported from diverse plant taxa and multiple plant tissues. As such, they have a range of potential ecological functions. Here, we review the key literature to assess evidence for roles in contrasting...

This chapter introduces the background and theory underpinning use of odours by insects in pollination, discusses how flowers produce odours and highlights issues specific to crops such as selective breeding. It then explores current technologies and case studies in which natural or synthetic odours on or near the crop, and the interaction with ins...

Simple Summary Field margin plants are important in providing resources for natural enemies (NEs) and improving biological control of crop pests. However, the use of field margin plants for biological control particularly of important common bean pests is understudied in smallholder farming systems of sub-Saharan Africa (SSA). We evaluated the pote...

The development of large-scale monocropped agrisystems has facilitated increased problems with pests and diseases, perpetuating the reliance of farmers on synthetic pesticides. The economic success of synthetic inputs has, however, been achieved at a high cost to the environment through the loss of biodiversity, depletion of soil quality, greenhous...

Plant compounds associated with herbivore defence occur widely in floral nectar and can impact pollinator health. We showed previously that Rhododendron ponticum nectar contains grayanotoxin I (GTX I) at concentrations that are lethal or sublethal to honeybees and a solitary bee in the plant's non-native range in Ireland. Here we further examined t...

Evidence from the last few decades indicates that pollinator abundance and diversity are at risk, with many species in decline. Anthropogenic impacts have been the focus of much recent work on the causes of these declines. However, natural processes, from plant chemistry, nutrition and microbial associations to landscape and habitat change, can als...

Botanical insecticides offer an environmentally benign insect pest management option for field crops with reduced impacts on natural enemies of pests and pollinators while botanically rich field margins can augment their abundance. Here, we evaluated the non‐target effects on natural enemies and pest control efficacy on bean aphids in Lablab of thr...

Wild bee populations are declining due to human activities, such as land use, which strongly affect the composition and diversity of available plants and food sources. The chemical composition of food (i.e. nutrition), in turn, determines health, resilience and fitness of bees. However, for pollinators, the term health is recent and subject to deba...

There are several frameworks which have been developed to describe the Natural Capital assessment approach. However, some of these frameworks are not fully operational in practice, and there is no unified methodology. Furthermore, calls have been made to increase the public’s awareness and understanding of Natural Capital issues. To address some of...

Flower-rich field margins provide habitats and food resources for natural enemies of pests (NEs), but their potential, particularly in the tropics and on smallholder farms, is poorly understood. We surveyed field margins for plant-NE interactions in bean fields. NEs most often interacted with Bidens pilosa (15.4% of all interactions) and Euphorbia...

Floral nectar and pollen commonly contain diverse secondary metabolites. While these compounds are classically thought to play a role in plant defense, recent research indicates that they may also reduce disease in pollinators. Given that parasites have been implicated in ongoing bee declines, this discovery has spurred interest in the potential fo...

BACKGROUND: Hymenopteran parasitoids provide key natural pest regulation services and are reared commercially as biological control agents. Therefore, understanding parasitoid community composition in natural populations is important to enable better management for optimized natural pest regulation. We carried out a field study to understand the pa...

Objective Poly-unsaturated fatty acid (PUFA) supplements have been trialled as a treatment for a number of conditions, and produced a variety of results. This variety is ascribed to both the supplements, often comprising mixtures of fatty acids and to different effects in different organs. Here, we tested the hypothesis that supplementation of indi...

BACKGROUND Hymenopteran parasitoids provide key natural pest regulation services and are reared commercially as biological control agents. Therefore, understanding parasitoid community composition in natural populations is important to enable better management for optimized natural pest regulation. We carried out a field study to understand the par...

Assessing the potential drivers of farmers using pesticidal plants for crop protection is essential for wider adoption. However, few studies have focused on collaborative assessments of the underlying trade-offs when using pesticidal plant extracts for pest control. Smallholder farmers in northern Tanzania involved in farmer driven research assessi...

Dolichos (Lablab purpureus L.) is a drought tolerant legume used as food/feed and improvement of soil fertility. The production of dolichos in Kenya, Nakuru County is however limited by insect pests like bean aphids, pod borers and whiteflies. Field studies were conducted to determine the effect of cropping systems (dolichos monocrop and maize-doli...

Background Besides feeding on blood, females of the malaria vector Anopheles gambiae sensu lato readily feed on natural sources of plant sugars. The impact of toxic secondary phytochemicals contained in plant-derived sugars on mosquito physiology and the development of Plasmodium parasites remains elusive. The focus of this study was to explore the...

Cattle are a livelihood asset to smallholder farmers in Africa yet remain threatened by the effects of ticks and tick-borne diseases during production because they cause morbidity and premature death. The use of indigenous plants in tick control is a worldwide practice spanning thousands of years. Changes in the agricultural and socio-cultural land...

Simple Summary Bean production by smallholder farmers in sub-Saharan Africa is frequently constrained by insect pests, two of the most serious being Maruca vitrata and Aphis fabae. For many bean farmers, the options available to control these pests are limited. A few can access synthetic insecticides, but these have negative consequences for their...

Chemical insecticide application has been the most widely used form of insect pest management in last six decades and resulted in well-documented negative impacts. Habitat manipulation based on intercropping to exert direct effects on pests and promote biological control has been explored in various systems as a more sustainable option. A range of...

Beneficial insect communities on farms are influenced by site- and landscape-level factors, with pollinator and natural enemy populations often associated with semi-natural habitat remnants. They provide ecosystem services essential for all agroecosystems. For smallholders, natural pest regulation may be the only affordable and available option to...

Sweetpotato weevil (SPW) pest management is challenging because the pest target is sub-terranean, so the application of pesticides is impractical and usually ineffective. Host plant resistance and the genetic transformation of sweetpotatoes to produce entomotoxic Bt proteins offer potential for environmentally benign pest control. Resistance can be...

Emergent infectious diseases are one of the main drivers of species loss. Emergent infection with the microsporidian Nosema bombi has been implicated in the population and range declines of a suite of North American bumblebees, a group of important pollinators. Previous work has shown that phytochemicals found in pollen and nectar can negatively im...

Background: Besides feeding on blood, females of the malaria vector Anopheles gambiae s.l. readily feed on natural sources of plant sugars. The impact of toxic secondary phytochemicals contained in plant-derived sugars on mosquito physiology and on the development of Plasmodium parasites remains elusive. The focus of this study was to explore the i...

Emergent infectious diseases are a principal driver of biodiversity loss globally. The population and range declines of a suite of North American bumblebees, a group of important pollinators, have been linked to emergent infection with the microsporidian Nosema bombi. Previous work has shown that phytochemicals in pollen and nectar can negatively i...

Phytosterols are primary plant metabolites that have fundamental structural and regulatory functions. They are also essential nutrients for phytophagous insects, including pollinators, that cannot synthesize sterols. Despite the well-described composition and diversity in vegetative plant tissues, few studies have examined phytosterol diversity in...

Background Many crops are dependent on pollination by insects. Habitat management in agricultural landscapes can support pollinator services and even augment crop production. Common bean ( Phaseolus vulgaris L.) is an important legume for the livelihoods of smallholder farmers in many low-income countries, particularly so in East Africa. While this...

Herbivory can induce chemical changes throughout plant tissues including flowers, which could affect pollinator-pathogen interactions. Pollen is highly defended compared to nectar, but no study has examined whether herbivory affects pollen chemistry. We assessed the effects of leaf herbivory on nectar and pollen alkaloids in Nicotiana tabacum, and...

Never before has the biosphere, the thin layer of life we call home, been under such intensive and urgent threat. Deforestation rates have soared as we have cleared land to feed ever-more people, global emissions are disrupting the climate system, new pathogens threaten our crops and our health, illegal trade has eradicated entire plant populations...

Kew’s State of the World’s Plants and Fungi project provides assessments of our current knowledge of the diversity of plants and fungi on Earth, the global threats that they face, and the policies to safeguard them. Produced in conjunction with an international scientific symposium, Kew’s State of the World’s Plants and Fungi sets an important inte...

Many pollinator species are declining due to a variety of interacting stressors including pathogens, sparking interest in understanding factors that could mitigate these outcomes. Diet can affect host-pathogen interactions by changing nutritional reserves or providing bioactive secondary chemicals. Recent work found that sunflower pollen (Helianthu...

Global perceptions about pesticides are changing as a consequence of their environmental impacts, persistence, broad spectrum activities and non-target effects. As a result of this, pesticide regulations are changing in some regions. For example, Europe has limited the number of synthetic chemical products permitted for use in pest control. The inc...

The plant kingdom produces an extraordinary diversity of secondary metabolites and the majority of the literature supports a defensive ecological role for them, particularly against invertebrate herbivores (antagonists). Plants also produce secondary compounds in floral nectar and pollen and these are often similar to those produced for defense aga...

Besides providing food and shelter to natural enemies of crop pests, plants used in conservation biological control interventions potentially provide additional ecosystem services including providing botanical insecticides. Here we concurrently tested the strength of these two services from six non-crop plants in managing cabbage pests in Ghana ove...

Immune systems provide a key defence against diseases. However, they are not a panacea and so both vertebrates and invertebrates co-opt naturally occurring bioactive compounds to treat themselves against parasites and pathogens. In vertebrates this co-option is complex, with pharmacodynamics leading to differential effects of treatment at different...

Fall Armyworm (FAW) (Spodoptera frugiperda) is a polyphagous and highly destructive pest of many crops. It was recently introduced into Africa and now represents a serious threat to food security, particularly because of yield losses in maize, which is the staple food for the majority of small-scale farmers in Africa. The pest has also led to incre...

Sustainable agricultural intensification employs alternatives to synthetic insecticides for pest management, but these are not always a direct replacement. Botanical insecticides, for example, have rapid knockdown but are highly labile and while biological pesticides are more persistent, they are slow acting. To mitigate these shortcomings, we comb...

Common bean (Phaseolus vulgaris) is an important food and cash crop in many countries. Bean crop yields in sub-Saharan Africa are on average 50% lower than the global average, which is largely due to severe problems with pests and diseases as well as poor soil fertility exacerbated by low-input smallholder production systems. Recent on-farm researc...

The fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae) is a recent invasive pest species that has successfully established across sub-Saharan Africa where it continues to disrupt agriculture, particularly smallholder cereal production. Management of FAW in its native range in the Americas has led to the development of resistance to...

Conservation biological control uses habitat management to enhance the survival and impact of arthropod natural enemies for pest control. Its advantages are that it relies on native or established invertebrate populations that are adapted to local agricultural ecosystems and conditions. We surveyed 300 farmers in three agro-ecological zones of Kili...

Tephrosia vogelii is a plant species chemically characterized by the presence of entomotoxic rotenoids and used widely across Africa as a botanical pesticide. Phytochemical analysis was conducted to establish the presence and abundance of the bioactive principles in this species across three countries in East Africa: Tanzania, Kenya, and Malawi. An...

Background Field margin and non-crop vegetation in agricultural systems are potential ecosystem services providers because they offer semi-natural habitats for both below and above ground animal groups such as soil organisms, small mammals, birds and arthropods that are service supplying units. They are considered as a target area for enhancing far...

Non-crop vegetation around farmland can be valuable habitats for enhancing ecosystem services but little is known of the importance of field margins in supporting natural enemies of insect pests in tropical agriculture. This study was conducted in smallholder bean fields in three elevation zones to assess the importance of field margin vegetation t...