Though cultivated sunflowers have been bred to self-pollinate, the crop still has substantial reliance on pollinators, especially for the production of hybrid seed. In North America, both managed (Apis mellifera) and wild bees pollinate sunflowers, but the sunflower leafcutting bee, Megachile pugnata, has been a species of focus for domestication as a sunflower pollinator. Research suggests M. pugnata is an efficient pollinator of sunflowers, accepts artificial nests, and can be stored and released as needed for sunflower bloom. It is unclear whether M. pugnata also could serve as a pollinator for other cultivated Asteraceae. Temperature management during adult emergence, nesting, overwintering, and post-diapause periods needs investigation, as high or low temperatures can result in significant M. pugnata population losses. The choice of nesting substrate and related handling of bees (cells) also are key concerns for efficiency; because M. pugnata in cells are only protected by a cocoon (i.e., without a leaf-lined envelope), it is unclear whether mechanical processing of nests is possible. Despite apparent challenges in managing a new crop pollinator, experience in research and management of other cavity-nesting bees (e.g., Megachile rotundata and Osmia spp.) can inform efforts to address knowledge gaps that could make large-scale use of M. pugnata more feasible.
Insect-borne plant pathogens pose a major threat to global agriculture and cause substantial economic losses. As natural vectors, insects display high tolerance to infection by plant pathogens, including viruses, bacteria, and phytoplasmas, while exhibiting no significant pathological effects. This suggests that they have evolved effective strategies to maintain immune homeostasis, thereby restricting pathogen infection to non-pathogenic levels. In this review, we summarize recent advances in understanding these immune mechanisms, including Toll, JAK-STAT, RNA interference, autophagy, apoptosis, and melanization. Future research may focus on identifying key pattern recognition receptors and developing innovative control strategies based on these immune mechanisms.
MicroRNAs (miRNAs) play important roles in diverse aspects of insect biology, and some have been explored as potential tools for insect pest management. In this review, we focus on recent advances in cross-species miRNA regulation in insect interactions with microbes, plant or animal hosts. We first provide a brief overview of the general functions of miRNAs in insects. We then summarize current studies on cross-species miRNA regulation in insect interactions with associated organisms, across trophic levels, with particular emphasis on recent studies that functionally characterize translocated miRNAs. In addition, we review current efforts that exploit miRNA translocation for insect pest control. Finally, we highlight major unanswered questions and key challenges in the field of cross-species miRNA regulation. Overall, we argue that research on cross-species miRNA regulation in insect systems is rapidly expanding, although still in its infancy in insect-bacterial symbioses, holds significant potential for advancing our understanding of insect associated interactions and for developing innovative and sustainable pest control strategies.
Mosquito-borne illnesses have shaped human history and continue to impose significant global public health burdens, with particularly devastating effects in socioeconomically disadvantaged areas. Blood feeding is essential for mosquito reproduction, as blood provides nutrients for egg development, and vector species are strongly driven to find and bite humans for this blood meal. These maternally-driven behaviors not only expose humans to pathogens but also promote mosquito population growth. Recent advances have deepened our understanding of the sensory systems and internal state regulation behind host seeking and biting. Here, we examine the behavioral and neurobiological mechanisms underlying mosquito-human interactions and their role in pathogen transmission and disease. We also highlight how these insights can inform emerging behavioral control strategies.
The economic injury level is a well-established paradigm in pest management. The concept states that there is a pest density where the cost of damage equals the cost of the insecticide treatment, and this density is used to trigger control actions. The economic injury level thus informs decisions about the need for insecticides based on pest sampling data. However, we argue that the concept often overlooks key biological assumptions about herbivory and typically fails to incorporate the role of crop and pest phenology in optimizing pest sampling and insecticide timing. In this review, we first overview the economic injury level concept and highlight the consequences of these limiting assumptions. We then propose that phenology models that incorporate crop susceptibility and pest life stages, combined with insecticide efficacy data, can allow for better timing of pest management actions. We also suggest that pest monitoring and management decisions should focus on minimizing pest damage accumulation, rather than limiting control actions to predefined thresholds. Future research should focus on effectively leveraging crop and pest phenology models along with field sampling to guide control actions only during the most key management times. While the economic injury level has been a historically important concept guiding pest management theory and practice, adapting the concept to specific crop-pest relationships can ensure more efficient use of pest control inputs.
Transposable elements (TEs) are mobile, repeated DNA sequences whose evolutionary relationships with host genomes span the full spectrum from parasitism to mutualism. Within Insecta, one of the most species-rich animal groups, TE content and family richness vary dramatically, yet annotation efforts have historically concentrated on Drosophila, leaving roughly half of non-drosophilid insect TEs classified as unknown. Insect genomes thus represent a vast, largely untapped reservoir of TE diversity. This review guides newcomers through the annotation of TEs in insect genomes, clarifying what can and cannot be achieved with automatic versus manually curated TE libraries. We outline the two core stages of modern annotation: de novo discovery of a representative repeat library, comparing the strategies of popular and emerging tools, followed by genome-wide annotation. We critically examine TE classification, including the promise and current limitations of machine-learning classifiers, and detail best practices for quality control and redundancy reduction. We argue that annotation depth should be dictated by the biological question rather than pursued exhaustively, and we survey both manual curation tools and recent automated curation pipelines. Finally, we address the shift toward pangenomic approaches and the evolving TE database landscape, along with the importance of depositing libraries in versioned, open repositories.
Species largely evolve in isolation, with little exchange of genetic material between them. Occasionally, however, mechanism like horizontal transfer disrupt this isolation and transfers genetic information between species. Transposable elements (TEs), short DNA sequences that can multiply within genomes, are frequently involved in such exchanges. The frequency of horizontal transposon transfer (HTT) between species remains a fundamental open question in biology, as classical sequence comparison approaches may substantially underestimate the true extent of HTT. In this review, we highlight that genomic time-series (GTS), i.e., genomes of specimens sampled across different years in the past, enable an alternative approach that may provide a more unbiased estimate of the true magnitude of HTT between species. Analysis of GTS in fruit flies suggests that HTT may be rampant, with 12 events found over the past 200 years. Species may thus exchange genetic material far more frequently than previously thought. We discuss the pros and cons of different approaches for detecting HTT, show how GTS can be generated for diverse species, and highlight various strategies for identifying HTT events. GTS may generally constitute a valuable resource for addressing a broad range of evolutionary questions.
Ant-plant mutualisms are typically framed as two-species exchanges in which plants provide food and shelter in return for herbivore defense. Yet ants are themselves valuable prey, potentially attracting vertebrate predators that impose hidden structural costs on host plants. Here, I argue that such interactions incur partner-associated indirect costs: plants may suffer damage not from their partners directly, but because those partners attract vertebrate predators. Using the Azteca-Cecropia mutualism as a focal example, I synthesize evidence that anteaters and woodpeckers excavate ant-occupied stems and internodes, producing mechanical damage while targeting the ants. I then develop a framework for understanding how ant-plant systems respond to recurrent predator disturbance through resistance (traits that reduce attack success) and recovery (traits that restore function after damage). Resistance traits include aggressive colony defense and protective architecture, whereas recovery traits include plant regrowth, ant-mediated wound repair, and microbial reinforcement of nest structures. Integrating these responses across ecological and evolutionary timescales generates predictions linking individual attack outcomes to population dynamics, ecosystem processes, and the diversification of convergent ant-plant lineages.
The establishment of mutualistic symbiosis with microorganisms has contributed to the ecological success and diversification of a wide range of insect lineages. In such systems, microbial partners are often stably inherited across generations and have co-evolved with their hosts over long evolutionary timescales. These intimate associations are often supported by specialized symbiotic organs that intracellularly or extracellularly harbor beneficial microorganisms. As an interface between hosts and symbionts, these symbiotic organs play a pivotal role in harnessing diverse symbiont functions, as represented by nutritional supplementation. However, what constitutes an optimal symbiotic state can vary across life stages, infection status, or environmental conditions. Recent studies have revealed that symbiotic organs undergo dynamic, life-stage-specific remodeling during the lifetime of a single insect, highlighting the remarkable flexibility and sophistication of insect-microbe interactions. This review synthesizes recent advances in our understanding of such dynamic regulation, with particular emphasis on the midgut symbiotic organ in stinkbugs. It illustrates how regional differentiation within the midgut enables diverse functions, including symbiont sorting, population control, and vertical transmission, beyond its primary role in nutritional interactions. Moreover, life stage-specific adjustments and remodeling of the symbiotic midgut flexibly accommodate potentially incompatible constraints arising from varying food sources, symbiont status, and host metabolic demands. Elucidating the dynamic nature of insect-microbe interactions across the entire life cycle will shed light on previously unexplored aspects of the evolutionary trajectories and adaptive mechanisms underlying mutualistic symbiosis.
The gut microbiota forms a competitive biological barrier against enteric pathogens and may also modulate antiviral immunity and disease prevention. This review presents recent advances demonstrating the tripartite model of the gut microbiome-immunity-virus axis in lepidopteran insects. Emerging evidence indicates that their gut microbiota regulates antiviral immunity through context-dependent mechanisms shaped by host species identity, microbial community composition, and strain-specific differences in viral resistance. Rather than acting as a uniformly protective factor, gut microbes fine-tune the local immune environment chiefly through antimicrobial peptide induction, modulation of prophenoloxidase/melanization, Duox/reactive oxygen species regulation, and maintenance of epithelial homeostasis. Although RNA interference, stimulator of interferon gene-related, and Janus kinase/signal transducer and activator of transcription signaling are established antiviral pathways in Lepidoptera, their direct regulation by gut microorganisms during viral infection remains elusive. These microbiota-conditioned immune states can either restrict viral replication and maintain gut barrier integrity or, conversely, favor virus pathogenesis when infection disrupts gut homeostasis, drives dysbiosis, or suppresses key antiviral effectors. Furthermore, strain-specific microbiome signatures correlate with differential viral resistance in susceptible and resistant hosts. By positioning the gut microbiome as a crucial immunological interface, this review integrates symbiosis biology into insect antiviral immunity and highlights microbiome-informed opportunities for sustainable pest management and the protection of beneficial insects.
Ant colonies are superorganisms containing a wingless, nonreproductive worker caste. The suppression (loss or reduction) of worker organs involved in mating and reproduction is a feature of many ant superorganisms. It is largely assumed that these worker organs, where present, are functionless and in the process of being eliminated through neutral degeneration or selection. Here, we argue that an underappreciated dimension of social evolution involves the co-option of worker organs to serve superorganism-level functions. We draw on two examples: the wings and ovaries. In some ant species, transiently appearing wing rudiments have been co-opted to regulate worker differentiation into soldiers. Likewise, in many ant species, the ovaries in adult workers have been co-opted to produce trophic eggs. We propose that the degree of organ co-option may itself be an indicator of superorganismal complexity. We discuss the broader implications of this idea and suggest novel avenues for future work.
While insect symbionts are known for their roles in nutrient supplementation and toxin detoxification, their potential roles in modulating plant immunity remain incompletely understood. Here, we synthesize how symbionts shape plant defenses against insects across three levels - physical barriers, immune signaling, and defensive chemistry. These effects arise through both host-mediated modifications - such as altered salivary composition - and direct microbial inputs, including symbiont-derived molecules and effectors. Symbionts can either inhibit or stimulate plant defenses, with outcomes that are highly context-dependent and shaped by host genotype, symbiont diversity, and the plant's background. Notably, the molecular patterns that plants perceive from symbionts remain largely unidentified, representing a research gap in the field. We argue that integrating multi-omics approaches with functional genetics and mechanistic validation will be essential to advance a predictive framework for plant-insect-symbiont interactions.
Anthropogenic climate change has a major impact on herbivorous insect outbreaks. Altered temperature regimes can directly affect insect population demography by altering insect traits through both ecological and evolutionary mechanisms, as well as indirectly affecting population dynamics through biotic interactions. However, the eco-evolutionary processes in insect population-level dynamics that regulate outbreaks are not well understood, and how climate change alters these processes has remained poorly explored. In this review, we summarize how climate change affects the outbreaks of herbivorous insects through ecological and evolutionary effects on insect traits and trophic interactions among herbivorous insects, their host plants, and their natural enemies. We propose that climate-driven changes in insect traits increase outbreak frequency and magnitude, thereby generating eco-evolutionary feedback. Specifically, outbreaks themselves may shift the mode of outbreaks rather than simply increasing their frequency. Recognizing this process is essential for forecasting future outbreaks and developing management strategies that consider changes in the evolutionary potential of outbreak populations.
With the advance of metatranscriptomic sequencing, an increasing number of symbiotic viruses have been recognized in insects. These insect symbiotic viruses not only modulate key aspects of insect biology, including physiology, fecundity, development, and behavior, but also influence the vector competence of arthropods for transmitting arboviruses. The majority of such vectors belong to the orders Hemiptera and Diptera, which transmit a wide spectrum of plant and animal arboviruses. Although insect symbiotic viruses usually replicate exclusively within insect cells, several symbiotic viruses have also been detected in insect secretions and even in host plants, indicating they may have more profound functions than we originally thought. In this review, we synthesize current knowledges on the hidden roles of insect symbiotic viruses across three key dimensions: their impact on insect adaptation to host plants, as reflected in fitness, feeding behavior, dispersal capacity, and resistance traits; their regulation of vector competence for the transmission of both plant and animal arboviruses; and their emerging application as biotechnological tools for the delivery of double-stranded RNA, small-interfering RNA, or recombinant proteins to control viral diseases in agriculture and public health.
Reliable prediction of weed biocontrol outcomes is desirable because developing new programmes can be costly and success is not guaranteed. In this review, we outline how advances in both agent and weed-target selection are improving programme efficiency without compromising environmental safety. Better prediction of candidate-agent impact and host specificity, aided by advances in molecular and modelling approaches, including plant-insect genotype and climate matching, has advanced agent selection. There has also been renewed interest in predicting biocontrol outcomes following recognition that the Enemy Release Hypothesis does not explain all plant invasions. Because classical weed biocontrol is expected to be most effective where enemy release contributes substantially to invasion success, identifying invasions facilitated by enemy release should improve the prediction of weed biocontrol outcomes and inform prioritisation systems that rank weed targets. Although studies of ecosystem recovery following successful weed suppression remain limited, there is growing recognition that weed suppression alone does not always restore heavily degraded ecosystems without additional interventions, some of which may be impractical or prohibitively expensive at large scales. Nevertheless, biocontrol benefits are likely to be greater in less heavily invaded areas, where restoration outcomes are typically better. Consequently, more proactive use of biocontrol, targeting weeds earlier in the invasion curve, should deliver more ecological and economic benefits.
Development, physiology, and reproduction in insects require juvenile hormones (JHs). Given such essential functions, the availability of these potent small molecules is tightly controlled by synthesis, transportation, and degradation. Insects possess two classes of enzymes to degrade JHs: the canonically extracellular JH esterases (JHEs) and intracellular JH epoxide hydrolases (JHEHs). While the biochemical activities of JHEs and JHEHs have been investigated in over sixty insect species in the last 50 years, functional studies have been hindered, until recently, by extensive genetic redundancies. This review highlights how increased availability of 'omics datasets and advances in genetic manipulation have revealed novel and sometimes unexpected insights into the functions of each class of JH degradation enzyme during development and beyond. These studies provide the tools and framework to not only answer many longstanding questions regarding where, when, and how each JH degradation enzyme regulates JH availability, but also hold promise to reveal the molecular mechanisms by which JHs impart diverse functions across development.
Ecdysone, the major steroid hormone in insects, coordinates developmental progression by coupling systemic hormonal pulses to tissue-specific cellular responses. In this review, we explore its multifaceted roles in regulating organ growth and patterning, highlighting how a single hormone can elicit diverse - and sometimes opposing - outcomes depending on cell type, developmental stage, and hormone concentration. These context-dependent responses are shaped by cell-specific chromatin landscapes, stage-specific transcription factors, and dynamic changes in cellular competence over time, ensuring that successive ecdysone pulses trigger appropriate developmental programs across tissues and life stages. Understanding how such precise spatial and temporal control is achieved remains a central and fascinating question, providing key insight into how a single hormonal signal can orchestrate the remarkable complexity of animal development.
In herbivorous insects, symbiotic microorganisms provide advantages through digestion, detoxification, and essential nutrient supplementation, thereby influencing the internal physiology of insect hosts. These symbiont-mediated changes can subsequently modulate host decision-making processes and manifest as measurable behavioral traits. Across insect-microbe interactions, many symbiotic bacteria occupy a distinct niche, colonizing the gut region. In this review, we summarize the current understanding of symbiont-mediated behavioral modifications related to foraging, chemical communication, and decision-making processes regarding learning and memory, particularly in insects and their gut symbionts. Understanding microbe-mediated behavioral modulation in insects will clarify how microbes function as internal regulators of host responses to external stimuli, ultimately affecting insect behavioral ecology.
