Molecular Entomology 2024, Vol.15 http://emtoscipublisher.com/index.php/me © 2024 EmtoSci Publisher, registered at the publishing platform that is operated by Sophia Publishing Group, founded in British Columbia of Canada. All Rights Reserved.
Molecular Entomology 2024, Vol.15 http://emtoscipublisher.com/index.php/me © 2024 EmtoSci Publisher, registered at the publishing platform that is operated by Sophia Publishing Group, founded in British Columbia of Canada. All Rights Reserved. Publisher EmtoSci Publisher Editedby Editorial Team of Molecular Entomology Email: edit@me.emtoscipublisher.com Website: http://emtoscipublisher.com/index.php/me Address: 11388 Stevenston Hwy, PO Box 96016, Richmond, V7A 5J5, British Columbia Canada Molecular Entomology (ISSN 1925-198X) is an open access, peer reviewed journal published online by EmtoSci Publisher. The journal is committed to publishing and disseminating all the latest and outstanding research articles, letters and reviews in all areas of molecular entomology. The range of topics including genome structure of insects, gene expression and their function analysis, molecular evolution, molecular ecology, molecular genetics, insect physiology and biochemistry and other topical advisory subjects. Meanwhile we also publish the articles related to basic research, such as anatomy, morphology and taxonomy, which are fundamental to molecular technique’s innovation and development. All the articles published in Molecular Entomology are Open Access, and are distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. EmtoSci Publisher uses CrossCheck service to identify academic plagiarism through the world’s leading plagiarism prevention tool, iParadigms, and to protect the original authors’ copyrights. EmtoSci Publisher is an international Open Access publisher specializing in insect science, and entomology-related research registered at the publishing platform that is operated by Sophia Publishing Group (SPG), founded in British Columbia of Canada.
Molecular Entomology (online), 2024, Vol.15, No.2 ISSN 1925-198X http://emtoscipublisher.com/index.php/me © 2024 EmtoSci Publisher, registered at the publishing platform that is operated by Sophia Publishing Group, founded in British Columbia of Canada. All Rights Reserved. Latest Content Developmental Biology and Morphological Evolution in Coleoptera Yunping Huang, Jia Xuan Molecular Entomology, 2024, Vol. 15, No. 2, 43-51 The Role of Genetic Engineering in Enhancing Sugarcane Resistance to Insect Pests ZhenLi Molecular Entomology, 2024, Vol. 15, No. 2, 52-60 Utilization of Natural Plant Volatiles for Pest Control in Maize Xiaojing Yang, Baixin Song Molecular Entomology, 2024, Vol. 15, No. 2, 61-68 Herbivorous Insects in Barley Cultivation: Impact and Control Methods Renxiang Cai Molecular Entomology, 2024, Vol. 15, No. 2, 69-77 Preventing the Spread of Colorado Potato Beetle: Strategies and Technologies Sibin Wang, Jia Xing, Xian He Molecular Entomology, 2024, Vol. 15, No. 2, 78-86
Molecular Entomology 2024, Vol.15, No.2, 43-51 http://emtoscipublisher.com/index.php/me 43 Review Article Open Access Developmental Biology and Morphological Evolution in Coleoptera Yunping Huang, Jia Xuan Institute of Life Science, Jiyang College of Zhejiang A&F University, Zhuji, 311800, Zhejiang, China Corresponding email: jia.xuan@jicat.org Molecular Entomology, 2024, Vol.15, No.2 doi: 10.5376/me.2024.15.0006 Received: 03 Mar., 2024 Accepted: 05 Apr., 2024 Published: 16 Apr., 2024 Copyright © 2024 Huang and Xuan, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Huang Y.P., and Xuan J., 2024, Developmental biology and morphological evolution in coleoptera, Molecular Entomology, 15(2): 43-51 (doi: 10.5376/me.2024.15.0006) Abstract This study explores the complex relationship between developmental biology and morphological evolution in Coleoptera (beetles). By investigating developmental pathways, allometric growth, modularity, and the role of homeotic genes, it reveals how Coleoptera drive morphological diversification through developmental processes, thereby adapting to different ecological environments. The research aims to enhance the understanding of the origin of existing morphological diversity and provide important insights into evolutionary mechanisms, thus laying a solid theoretical foundation for further exploration of insect morphological evolution. Keywords Coleoptera; Developmental biology; Morphological evolution; Allometry 1 Introduction Coleoptera, commonly known as beetles, represent one of the most diverse and ecologically significant orders of insects, with over 360 000 described species across four suborders: Adephaga, Archostemata, Myxophaga, and Polyphaga. This vast diversity is reflected not only in their morphology and behavior but also in their adaptation to a wide range of ecological niches, from aquatic environments to terrestrial habitats (Sheffield et al., 2008). The success of Coleoptera is largely attributed to their evolutionary adaptations, including the development of hardened forewings (elytra) and diverse feeding strategies that range from herbivory to predation (Ferns and Jervis, 2016). Understanding the developmental biology of Coleoptera is crucial for several reasons. Firstly, it provides insights into the mechanisms that drive their extraordinary morphological diversity, which in turn can reveal broader patterns in evolutionary biology. Developmental biology, particularly through the lens of evolutionary developmental biology (evo-devo), has shown how changes in developmental pathways can lead to significant morphological innovations, such as the diverse wing structures and feeding apparatus seen in beetles (Heffer and Pick, 2013). Additionally, studying the developmental stages of beetles, from larvae to adults, helps in understanding the ecological roles they play at different life stages, which is vital for conservation and pest management strategies (Polilov and Beutel, 2010). This study explores the developmental biology and morphological evolution of Coleoptera, including comparative analyses of various species within the order to identify key developmental genes and pathways that drive their morphological diversity. By utilizing morphological and molecular data, the research examines the phylogenetic relationships among different beetle families to understand the evolutionary history of these insects, with the aim of gaining a comprehensive understanding of how developmental processes shape the evolution of Coleoptera. 2 Developmental Biology in Coleoptera 2.1 Key stages of coleopteran development Coleopteran development is a complex process involving several distinct stages, each crucial for the survival and adaptation of the species. The life cycle of beetles typically includes the egg, larval, pupal, and adult stages. Each stage is marked by significant morphological and physiological transformations. For instance, in the hooded beetle Sericoderus lateralis, there are three larval stages, each with unique morphological traits that play a critical role in the insect's adaptation to its environment.
Molecular Entomology 2024, Vol.15, No.2, 43-51 http://emtoscipublisher.com/index.php/me 44 These larval stages are characterized by significant changes in body size, organ development, and behavior, which are essential for the beetle's ability to exploit different ecological niches. The transition from one stage to another is regulated by both genetic and environmental factors, ensuring that the insect develops in a manner best suited to its surroundings. In particular, environmental conditions such as temperature and humidity can significantly influence the duration of each developmental stage, thereby affecting the overall life cycle of the beetle. Understanding these stages is crucial for developing effective pest control strategies and for conservation efforts aimed at protecting endangered beetle species (Polilov and Beutel, 2010). 2.2 Genetic and molecular mechanisms The genetic and molecular mechanisms underlying coleopteran development are complex and involve a multitude of genes that regulate key developmental processes. Studies have shown that mitochondrial genomes play a critical role in the development of various beetle species. For instance, specific genetic sequences in the mitochondrial DNA are conserved across different beetle species, indicating their essential role in maintaining the integrity of developmental processes (Mckenna et al., 2019; Pandit et al., 2019). Moreover, the expression of certain genes is crucial for the development of morphological traits such as wings and antennae, which are vital for the survival and reproductive success of beetles. Research has also highlighted the phenomenon of phenotypic plasticity, where the same genotype can result in different phenotypes depending on environmental conditions. This adaptability is particularly evident in traits such as wing morphology, where environmental factors such as temperature and food availability can influence gene expression, leading to different developmental outcomes. Understanding these genetic and molecular mechanisms is not only important for comprehending the evolutionary success of beetles but also for identifying potential targets for genetic manipulation in pest control strategies (Wang et al., 2015; Benton et al., 2016). 2.3 Environmental influences on development Environmental factors play a critical role in shaping the development of Coleoptera, influencing everything from the timing of developmental stages to the expression of specific traits. Temperature is one of the most significant environmental factors affecting coleopteran development. For instance, in the beetle Zygogramma bicolorata, different temperature regimes can lead to the emergence of fast or slow developers within a population, demonstrating a clear case of developmental polymorphism. This polymorphism is not only a result of genetic factors but is also heavily influenced by environmental conditions, with higher temperatures generally favoring faster development. Additionally, environmental factors such as humidity, light, and diet also significantly impact the development of beetles. For example, variations in diet and moisture levels can influence the duration of larval development, with optimal conditions leading to faster development and higher survival rates. These environmental influences are crucial for the adaptability of beetles to different habitats and play a significant role in their evolutionary success. Understanding these factors is essential for developing effective strategies for managing beetle populations, particularly in the context of climate change and habitat destruction (Xu et al., 2020; Afaq et al., 2021). 3 Morphological Evolution in Coleoptera 3.1 Evolutionary adaptations in beetle morphology Beetles, or Coleoptera, are renowned for their extraordinary morphological diversity, which has enabled them to adapt to a vast array of ecological niches. One of the most remarkable examples of morphological adaptation in beetles is the evolution of their forewings, known as elytra. These hardened structures serve as protective shields for the delicate hindwings and abdomen, allowing beetles to survive in harsh environments. The evolution of elytra represents a significant morphological innovation that has contributed to the evolutionary success of Coleoptera. Research has shown that the molecular mechanisms underlying this adaptation involve the co-option and modification of existing genetic pathways. For instance, a comparative study of wing transcriptomes in beetles revealed that several genes are uniquely expressed in the elytra, including those involved in pigmentation, hardening, and sensory development (Linz et al., 2023).
Molecular Entomology 2024, Vol.15, No.2, 43-51 http://emtoscipublisher.com/index.php/me 45 Additionally, stag beetles exhibit significant morphological adaptations in their mandibles, which are enlarged and used for combat during mating rituals. The development of these structures is regulated by a suite of appendage-patterning genes, with specific genes such as dac playing a crucial role in the size and shape of male mandibles (Gotoh et al., 2017). These examples highlight the intricate genetic and developmental processes that drive morphological evolution in beetles, enabling them to adapt to a wide range of environments and ecological challenges. 3.2 Comparative morphology across coleopteran families The vast diversity of beetles is reflected in the wide range of morphological traits observed across different Coleopteran families. Comparative studies have revealed that these morphological differences are often linked to adaptations to specific ecological niches. For example, the evolution of aquatic adaptations in fireflies (Lampyridae) has led to significant changes in larval morphology. Aquatic firefly larvae exhibit morphological features such as modified tracheal systems and cuticles adapted to an underwater environment. Transcriptomic analysis has shown that these morphological adaptations are associated with the evolution of genes involved in metabolic efficiency and hypoxia response, which are essential for survival in freshwater habitats (Zhang et al., 2020). Similarly, comparative studies of stag beetles (Lucanidae) have demonstrated that the evolution of their characteristic large mandibles is closely tied to developmental plasticity, which allows these beetles to develop different morphologies in response to environmental conditions. This plasticity not only contributes to the intraspecific variation seen within populations but also plays a critical role in interspecific diversification (Kawano, 2020). By studying the comparative morphology of beetles across different families, researchers can gain insights into the evolutionary processes that have shaped the incredible diversity of this order, revealing how different lineages have adapted to their unique ecological contexts. 3.3 Role of developmental genes in morphological diversification The diversification of beetle morphology is deeply rooted in the complex interplay of developmental genes that regulate the growth and differentiation of various body parts. Developmental genes, particularly those involved in the formation of appendages and other key structures, have been shown to play a pivotal role in the evolution of beetle morphology. One of the most well-studied examples is the role of Hox genes, which are critical for determining the identity of body segments and their associated appendages. In beetles, modifications in the expression of Hox genes have been linked to the evolution of novel morphological traits, such as the elongation of mandibles or the development of specialized hindwings (Ravisankar et al., 2016). Additionally, the evolution of the elytra in beetles has been associated with changes in the expression of wing-patterning genes, which have been co-opted and modified to produce this unique structure. RNA interference (RNAi) studies in species such as Tribolium castaneum have identified several genes, including Tc-cactus and members of the odd-skipped family, that are essential for the proper development of elytra and other wing structures (Linz et al., 2015). These findings underscore the importance of developmental genes in driving the morphological innovations that have enabled beetles to diversify and adapt to a wide range of ecological niches. 4 Developmental Pathways and Their Role in Evolution 4.1 Heterochrony and its impact on morphology Heterochrony, the change in the timing of developmental events, plays a significant role in the morphological evolution of Coleoptera. By altering the onset, rate, or duration of developmental processes, heterochrony can lead to significant morphological changes, often resulting in the evolution of novel traits. For instance, studies on the evolutionary development of pigmentation pathways in Lepidoptera suggest that heterochronic shifts in gene expression timing contribute to the diversification of wing patterns and body coloration. This is seen in the sexually dimorphic development of melanin pathway genes, where females and males exhibit different peak activities at various developmental stages (Kuwalekar et al., 2020).
Molecular Entomology 2024, Vol.15, No.2, 43-51 http://emtoscipublisher.com/index.php/me 46 Similarly, heterochrony is implicated in the evolution of predatory behavior in certain species, where shifts in gene expression timing have led to novel phenotypes that provide adaptive advantages in specific ecological contexts (Ledón-Rettig, 2021). In beetles, such heterochronic shifts can result in the prolongation or truncation of developmental stages, leading to diverse adult morphologies that are key to their adaptive success in varied environments. Thus, heterochrony is a crucial mechanism driving the morphological diversity observed in Coleoptera and other insect orders (Benton et al., 2016; Yuan et al., 2016; Linz et al., 2023). 4.2 Evolutionary role of homeotic genes Homeotic genes, particularly the Hox genes, are central to the regulation of body plan development in insects and play a pivotal role in the morphological diversification of Coleoptera. These genes determine the identity of body segments and their associated structures, such as limbs and wings, by regulating the expression of downstream genes involved in segment-specific development. In Coleoptera, the evolution of novel structures, such as the elytra (hardened forewings), has been closely linked to modifications in Hox gene expression. For example, the gene Ultrabithorax (Ubx) has been shown to play a critical role in determining the morphology of the third thoracic segment in beetles, including the differentiation of hindwings and the development of elytra (Fu et al., 2020). Studies using CRISPR/Cas9-mediated mutagenesis in other insects, such as the Asian corn borer, have further demonstrated the impact of disrupting Hox genes like Abd-A and Ubx, leading to severe morphological defects and homeotic transformations (Bi et al., 2022). These findings highlight the evolutionary significance of homeotic genes in shaping the diverse morphologies observed in beetles, making them a key focus in studies of insect evolutionary developmental biology. 4.3 Modularity and morphological innovation in beetles Modularity refers to the concept that certain traits or structures within an organism develop relatively independently from others, allowing for more flexible evolutionary changes. In beetles, modularity has facilitated the evolution of highly specialized structures, such as the mandibles of stag beetles, which are used in combat and mating rituals. This modular development allows specific traits to evolve rapidly in response to selective pressures without necessarily affecting other parts of the body. For example, the development of beetle mandibles involves the modular expression of appendage-patterning genes, which can be co-opted and modified to produce the exaggerated mandibles seen in some species (Figure 1) (Gotoh et al., 2017). The concept of modularity is also crucial in understanding how complex traits, such as the elytra, can evolve through the integration of multiple developmental pathways, leading to the innovation of entirely new structures that are critical for survival. The role of modularity in morphological innovation underscores the flexibility of developmental processes in Coleoptera, enabling these insects to adapt to a wide range of ecological niches and contributing to their remarkable evolutionary success. 5 Case Study 5.1 Overview of selected beetle species The Colorado potato beetle (Leptinotarsa decemlineata), one of the most notorious agricultural pests, has garnered significant attention due to its incredible adaptability and resistance to insecticides. Originally native to North America, this beetle has expanded its range globally, posing a severe threat to potato crops. Its evolutionary success can be attributed to its rapid adaptive responses, driven by genetic diversity and phenotypic plasticity. Recent genomic studies have provided insights into the beetle's ability to quickly evolve resistance to various insecticides, highlighting the role of standing genetic variation in these adaptive processes. The beetle's ability to survive in different climates and on various host plants underscores its status as a "super-pest," making it a prime model for studying evolutionary biology and pest management strategies (Schoville et al., 2017; Cohen et al., 2022).
Molecular Entomology 2024, Vol.15, No.2, 43-51 http://emtoscipublisher.com/index.php/me 47 Figure 1 Reconstructed phylogenetic tree of Coleoptera (beetles), including genomic data from 146 beetle species and their close relatives (Adopted from Mckenna et al., 2019) Image caption: Different superfamilies are color-coded, and the distribution of certain gene families (e.g., GH1, GH9) is shown. These gene families are associated with plant cell wall-degrading enzymes that help beetles break down lignocellulose in plants. The figure also indicates a link between the emergence of these enzyme genes and beetle diversification, particularly in the evolution of herbivorous beetles (Adopted from Mckenna et al., 2019)
Molecular Entomology 2024, Vol.15, No.2, 43-51 http://emtoscipublisher.com/index.php/me 48 Moreover, phylogenomic studies have placed the Colorado potato beetle within a broader evolutionary context, revealing how its diversification aligns with other beetle species. These studies suggest that the beetle's success is partly due to its ability to exploit a wide range of ecological niches, a trait that is common among many beetles. The integration of genetic and environmental data has allowed researchers to better understand the evolutionary pathways that have led to the beetle's current status as a dominant agricultural pest (Figure 1) (Mckenna et al., 2019; Weng et al., 2021). 5.2 Detailed analysis of developmental pathways The developmental pathways of the Colorado potato beetle are a critical aspect of its adaptability and resilience. These pathways are underpinned by a complex genetic architecture that allows the beetle to thrive under various environmental conditions. The beetle's genome contains a large number of detoxification genes, including cytochrome P450 enzymes, esterases, and glutathione S-transferases, which are crucial for metabolizing and resisting insecticides. These genes are not only numerous but also highly inducible, meaning they can be upregulated in response to chemical exposure, providing a rapid defense mechanism against insecticides (Schoville et al., 2017; Cohen et al., 2022). Additionally, the beetle's developmental plasticity is supported by its extensive genetic diversity, particularly in genes related to digestion and metabolism. This diversity enables the beetle to adapt to a variety of host plants, a trait that has facilitated its spread across different geographic regions. Furthermore, recent studies have shown that the beetle's developmental pathways are closely linked to its ability to undergo rapid evolutionary changes, with certain pathways being more prone to selection pressures, leading to the evolution of resistant populations (Weng et al., 2021; Linz et al., 2023). The beetle's ability to exploit standing genetic variation and its capacity for rapid evolutionary change make it an excellent model for studying the interplay between genetics, development, and adaptation in insects. 5.3 Morphological adaptations and evolutionary significance The Colorado potato beetle exhibits several morphological adaptations that have played a crucial role in its evolutionary success. One of the most prominent adaptations is the development of its elytra, the hardened forewings that protect the delicate hindwings and body. This adaptation not only provides physical protection against predators and environmental hazards but also plays a significant role in the beetle's dispersal capabilities, allowing it to colonize new areas rapidly. The evolutionary significance of these adaptations is reflected in the beetle's ability to thrive in a wide range of environments, from temperate regions to areas with more variable climates (Schoville et al., 2017; Asgari et al., 2020). Moreover, the beetle's robust exoskeleton and efficient digestive system, which includes specialized enzymes for processing a variety of plant materials, have enabled it to exploit diverse ecological niches. This flexibility in diet and habitat choice has been a key factor in the beetle's global spread and its ability to persist in agricultural settings despite intensive pest control efforts. Phylogenetic analyses have further supported the idea that these morphological traits have evolved in response to both natural and anthropogenic selection pressures, highlighting the beetle's capacity for rapid adaptation and evolutionary innovation (Mckenna et al., 2019; Cohen et al., 2022). The Colorado potato beetle thus serves as a prime example of how morphological and genetic adaptations can drive the success of a species in a changing world. 6 Implications of Developmental Biology for Understanding Coleopteran Evolution 6.1 Insights into evolutionary processes The study of developmental biology in Coleoptera provides crucial insights into the evolutionary processes that have shaped the immense diversity within this order. Developmental pathways, particularly those involving key regulatory genes, play a significant role in the evolution of novel traits. For instance, research on the evolution of wing structures in beetles has revealed how modifications in gene expression during development can lead to the emergence of unique morphological features, such as the elytra, which have been instrumental in the ecological success of beetles (Timmermans et al., 2015; Short, 2018).
Molecular Entomology 2024, Vol.15, No.2, 43-51 http://emtoscipublisher.com/index.php/me 49 These developmental processes are not only important for understanding how current morphological diversity arose but also provide insights into the broader mechanisms of evolutionary change, including the role of genetic variation and the impact of environmental pressures on development (Timmermans et al., 2015; Linz et al., 2023). Additionally, studies on the evolution of neuropeptide signaling in beetles highlight how changes in developmental processes can influence behavior and physiology, further driving evolutionary diversification (Pandit et al., 2019). 6.2 Developmental constraints and evolutionary outcomes Developmental constraints are limitations imposed by an organism's developmental biology that can restrict the range of potential evolutionary outcomes. In Coleoptera, these constraints are evident in the conservation of certain developmental pathways, despite the vast morphological diversity within the order. For example, studies on mitochondrial genomes and phylogenetic relationships among beetles have shown that despite the evolutionary plasticity in some traits, others are highly conserved due to developmental constraints. These constraints can lead to evolutionary trade-offs, where certain adaptations are favored over others, shaping the evolutionary trajectory of a species. Understanding these constraints is essential for predicting evolutionary outcomes, as they can limit the directions in which a lineage can evolve. This is particularly relevant in the context of beetle phylogeny, where the balance between conservation and innovation has resulted in a wide array of forms while maintaining core developmental mechanisms (Tammaru et al., 2015; Yuan et al., 2016). 6.3 Future directions for research Future research in the developmental biology and evolution of Coleoptera should focus on expanding our understanding of the genetic and molecular bases of key developmental processes. This includes the continued exploration of the roles of Hox genes, neuropeptide signaling pathways, and other regulatory networks in driving morphological diversification. Moreover, there is a need to integrate high-throughput genomic technologies, such as transcriptomics and epigenomics, to uncover how gene expression patterns during development influence evolutionary outcomes. Another promising area of research is the study of developmental plasticity and how environmental factors interact with genetic mechanisms to produce phenotypic variation. Understanding these interactions will be crucial for predicting how beetle species might respond to changing environments, such as those caused by climate change or habitat destruction. Finally, comparative studies across different beetle lineages and other insect orders will help to identify common developmental themes and unique adaptations, providing a more comprehensive picture of insect evolution (Laland et al., 2015; McKenna et al., 2019). Acknowledgments We would like to thank two anonymous peer reviewers for their suggestions on my manuscript. Conflict of Interest Disclosure The authors affirm that this research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest. References Afaq U., Kumar G., and Omkar, 2021, Is developmental rate polymorphism constant? Influence of temperature on the occurrence and constancy of slow and fast development in Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae), Journal of Thermal Biology, 100: 103043. https://doi.org/10.1016/j.jtherbio.2021.103043 Asgari M., Alderete N., Lin Z., Benavides R., and Espinosa H.D., 2020, A matter of size? Material, structural, and mechanical strategies for size adaptation in the elytra of Cetoniinae beetles, Acta Biomaterialia, 122: 236-248. https://doi.org/10.1016/j.actbio.2020.12.039 Benton M.A., Kenny N., Conrads K.H., Roth S., and Lynch J.A., 2016, Deep, staged transcriptomic resources for the novel coleopteran models Atrachya menetriesi and Callosobruchus maculatus, PLoS One, 11(12): e0167431. https://doi.org/10.1371/journal.pone.0167431 Bi H., Merchant A., Gu J., Li X., Zhou X., and Zhang Q., 2022, CRISPR/Cas9-mediated mutagenesis of abdominal-a and ultrabithorax in the asian corn borer, Ostrinia furnacalis, Insects, 13(4): 384. https://doi.org/10.3390/insects13040384
Molecular Entomology 2024, Vol.15, No.2, 43-51 http://emtoscipublisher.com/index.php/me 50 Cohen Z.P., François O., and Schoville S., 2022, Museum genomics of an agricultural super-pest, the Colorado potato beetle, Leptinotarsa decemlineata (Chrysomelidae), provides evidence of adaptation from standing variation, Integrative and Comparative Biology, 62(6): 1827-1837. https://doi.org/10.1093/icb/icac137 Ferns P., and Jervis M., 2016, Ordinal species richness in insects-a preliminary study of the influence of morphology, life history, and ecology, Entomologia Experimentalis et Applicata, 159(2): 270-284. https://doi.org/10.1111/eea.12417 Fu S.J., Zhang J.L., Chen S.J., Chen H.H., Liu Y.L., and Xu H.J., 2020, Functional analysis of Ultrabithorax in the wing-dimorphic planthopper Nilaparvata lugens, Gene, 737: 144446. https://doi.org/10.1016/j.gene.2020.144446 Gotoh H., Zinna R., Ishikawa Y., Miyakawa H., Ishikawa A., Sugime Y., Emlen D., Lavine L., and Miura T., 2017, The function of appendage patterning genes in mandible development of the sexually dimorphic stag beetle, Developmental Biology, 422(1): 24-32. https://doi.org/10.1016/j.ydbio.2016.12.011 Heffer A., and Pick L., 2013, Conservation and variation in Hox genes: how insect models pioneered the evo-devo field, Annual Review of Entomology, 58: 161-179. https://doi.org/10.1146/annurev-ento-120811-153601 Kawano K., 2020, Differentiation of developmental plasticity as a major cause of morphological evolution in stag beetles (Coleoptera: Lucanidae), Biological Journal of the Linnean Society, 129(4): 822-834. https://doi.org/10.1093/biolinnean/blaa004 Kuwalekar M., Deshmukh R., Padvi A., and Kunte K., 2020, Molecular evolution and developmental expression of melanin pathway genes in Lepidoptera, Frontiers in Ecology and Evolution, 8: 226. https://doi.org/10.3389/fevo.2020.00226 Laland K., Uller T., Feldman M., Sterelny K., Müller G., Moczek A., Jablonka E., and Odling-Smee J., 2015, The extended evolutionary synthesis: its structure, assumptions and predictions, Proceedings of the Royal Society, 282(1813): 20151019. https://doi.org/10.1098/rspb.2015.1019 Ledón-Rettig C., 2021, Novel brain gene-expression patterns are associated with a novel predaceous behavior in tadpoles, Proceedings of the Royal Society, 288(1947): 20210079. https://doi.org/10.1098/rspb.2021.0079 Linz D., and Tomoyasu Y., 2015, RNAi screening of developmental toolkit genes: a search for novel wing genes in the red flour beetle, Tribolium castaneum, Development Genes and Evolution, 225(11): 11-22. https://doi.org/10.1007/s00427-015-0488-1 Linz D., Hara Y., Deem K.D., Kuraku S., Hayashi S., and Tomoyasu Y., 2023, Transcriptomic exploration of the Coleopteran wings reveals insight into the evolution of novel structures associated with the beetle elytron, Journal of Experimental Zoology, 340(2): 197-213. https://doi.org/10.1002/jez.b.23188 Mckenna D.D., Shin S., Ahrens D., Balke M., Beza-Beza C., Clarke D.J., and Ślipiński A., 2019, The evolution and genomic basis of beetle diversity, Proceedings of the National Academy of Sciences of the United States of America, 116(24): 24729-24737. https://doi.org/10.1073/pnas.1909655116 Pandit A.A., Davies S., Smagghe G., and Dow J., 2019, Evolutionary trends of neuropeptide signaling in Beetles - a comparative analysis of Coleopteran transcriptomic and genomic data, Insect Biochemistry and Molecular Biology, 114: 103227. https://doi.org/10.1016/j.ibmb.2019.103227 Polilov A., and Beutel R., 2010, Developmental stages of the hooded beetle Sericoderus lateralis (Coleoptera: Corylophidae) with comments on the phylogenetic position and effects of miniaturization, Arthropod Structure and Development, 39(1): 52-69. https://doi.org/10.1016/j.asd.2009.08.005 Ravisankar P., Lai Y., Sambrani N., and Tomoyasu Y., 2016, Comparative developmental analysis of Drosophila and Tribolium reveals conserved and diverged roles of abrupt in insect wing evolution, Developmental Biology, 409(2): 518-529. https://doi.org/10.1016/j.ydbio.2015.12.006 Schoville S., Chen Y.H., Andersson M., Benoit J., Bhandari A., Bowsher, J., and Yoon J.S., 2017, A model species for agricultural pest genomics: the genome of the Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae), Scientific Reports, 8(1): 1931. https://doi.org/10.1038/s41598-018-20154-1 Sheffield N., Song H., Cameron S., and Whiting M., 2008, A comparative analysis of mitochondrial genomes in coleoptera (arthropoda: insecta) and genome descriptions of six new beetles, Molecular Biology and Evolution, 25: 2499-2509. https://doi.org/10.1093/molbev/msn198 Short A., 2018, Systematics of aquatic beetles (Coleoptera): current state and future directions, Systematic Entomology, 43(1): 1. https://doi.org/10.1111/syen.12270 Tammaru T., Vellau H., Esperk T., and Teder T., 2015, Searching for constraints by cross-species comparison: reaction norms for age and size at maturity in insects, Biological Journal of the Linnean Society, 114(2): 296-307. https://doi.org/10.1111/BIJ.12417
Molecular Entomology 2024, Vol.15, No.2, 43-51 http://emtoscipublisher.com/index.php/me 51 Timmermans M.J.T.N., Barton C., Haran J., Ahrens D., Culverwell C., Ollikainen A., and Vogler A.P., 2015, Family-level sampling of mitochondrial genomes in coleoptera: compositional heterogeneity and phylogenetics, Genome Biology and Evolution, 8(1): 161-175. https://doi.org/10.1093/gbe/evv241 Wang X., Yang Z., Wei K., and Tang Y., 2015, Mechanisms of phenotypic plasticity for wing morph differentiation in insects, Acta Ecologica Sinica, 35: 3988-3999. https://doi.org/10.5846/STXB201310302610 Weng Y.M., Francoeur C.B., Currie C.R., Kavanaugh D.H., and Schoville S.D., 2021, A high-quality carabid genome assembly provides insights into beetle genome evolution and cold adaptation, Molecular Ecology Resources, 21(6): 2145-2165. https://doi.org/10.1111/1755-0998.13409 Xu Y., Li Y., Wang Q., Zheng C., Zhao D., Shi F., Liu X., Tao J., and Zong S., 2020, Identification of key genes associated with overwintering in Anoplophora glabripennis larva using gene co-expression network analysis, Pest Management Science, 77(2): 805-816. https://doi.org/10.1002/ps.6082 Yuan M.L., Zhang Q.L., Zhang L., Guo Z.L., Liu Y.J., Shen Y.Y., and Shao R., 2016, High-level phylogeny of the Coleoptera inferred with mitochondrial genome sequences, Molecular Phylogenetics and Evolution, 104: 99-111. https://doi.org/10.1016/j.ympev.2016.08.002 Zhang Q.L., Li H.W., Dong Z.X., Yang X.J., Lin L.B., and Chen J.Y., 2020, Comparative transcriptomic analysis of fireflies (Coleoptera: Lampyridae) to explore the molecular adaptations to fresh water, Molecular Ecology, 29: 2676-2691. https://doi.org/10.1111/mec.15504
Molecular Entomology 2024, Vol.15, No.2, 52-60 http://emtoscipublisher.com/index.php/me 52 Research Insight Open Access The Role of Genetic Engineering in Enhancing Sugarcane Resistance to Insect Pests ZhenLi Hainan Institute of Biotechnology, Haikou, 570206, Hainan, China Corresponding email: zhen.li@hibio.org Molecular Entomology, 2024, Vol.15, No.2 doi: 10.5376/me.2024.15.0007 Received: 05 Mar., 2024 Accepted: 06 Apr., 2024 Published: 17 Apr., 2024 Copyright © 2024 Li, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Li Z., 2024, The role of genetic engineering in enhancing sugarcane resistance to insect pests, Molecular Entomology, 15(2): 52-60 (doi: 10.5376/me.2024.15.0007) Abstract Sugarcane (Saccharum officinarum) is a vital crop for sugar production globally, yet it faces significant yield losses due to insect pest attacks. Traditional breeding methods have struggled to enhance pest resistance due to the complex genetic makeup of sugarcane and the absence of inherent resistance genes. Genetic engineering has emerged as a promising alternative, enabling the introduction of genes that confer resistance to pests. This study explores various genetic engineering strategies employed to enhance sugarcane resistance to insect pests. Key approaches include the overexpression of cry proteins, Vegetative Insecticidal Proteins (VIP), lectins, and Proteinase Inhibitors (PI), as well as the application of advanced biotechnological tools such as Host-Induced Gene Silencing (HIGS) and CRISPR/Cas9. This study also discusses the integration of multiple resistance genes, such as Cry1Ab and EPSPS, and their impact on pest resistance and agronomic traits. The findings highlight the potential of genetic engineering to develop transgenic sugarcane lines with robust resistance to insect pests, thereby contributing to sustainable sugarcane production. Keywords Genetic engineering; Sugarcane; Insect pest resistance; transgenic plants; CRISPR/Cas9 1 Introduction Sugarcane (Saccharumspp.) is a vital crop globally, contributing approximately 80% of the world's sugar and a significant portion of biofuel production (Budeguer et al., 2021). It is cultivated extensively in tropical and subtropical regions, where it serves as a primary source of income for millions of farmers and plays a crucial role in the economies of many countries (Verma et al., 2022). The demand for sugar and its by-products continues to rise, necessitating sustainable improvements in sugarcane yield and quality (Narayan et al., 2020). Despite its economic importance, sugarcane cultivation faces significant challenges, particularly from insect pests. Insect attacks, such as those from stem borers (e.g., Diatraea saccharalis) and the fall armyworm (Spodoptera frugiperda), lead to substantial yield losses and reductions in sucrose content (Li et al., 2022). Traditional pest management strategies, including the use of insecticides and integrated Pest Management (IPM) techniques, have had limited success and often pose environmental and health risks (Narayan et al., 2020; Iqbal et al., 2021). The lack of naturally resistant germplasms further complicates efforts to mitigate these pest-related challenges (Zhou et al., 2018). Given the limitations of conventional breeding and pest management approaches, there is a pressing need for advanced resistance mechanisms to protect sugarcane crops. Genetic engineering offers a promising solution by enabling the introduction of specific resistance genes into sugarcane varieties. Techniques such as the overexpression of cry proteins, Vegetative Insecticidal Proteins (VIP), lectins, and Proteinase Inhibitors (PI) have shown potential in enhancing insect resistance (Wang et al., 2017; Iqbal et al., 2021). Additionally, modern biotechnological tools like host-induced gene silencing (HIGS) and CRISPR/Cas9 provide innovative avenues for developing sustainable pest-resistant sugarcane cultivars. This study explores the role of genetic engineering in enhancing insect resistance in sugarcane by examining various gene modification strategies and their effectiveness, while providing a comprehensive understanding of the current progress and future prospects in this field. The study also delves into the integration of exogenous genes (such as cry1Ac) and their synergistic effects with endogenous stress-related genes, as well as the practical
Molecular Entomology 2024, Vol.15, No.2, 52-60 http://emtoscipublisher.com/index.php/me 53 applications and challenges associated with developing transgenic sugarcane varieties. The aim is to highlight the potential of genetic engineering to revolutionize pest management in sugarcane cultivation, thereby contributing to increased productivity and sustainability in the industry. 2 Traditional Methods of Insect Pest Control in Sugarcane 2.1 Chemical control: pesticides and their limitations Chemical control through the use of pesticides has been a common method for managing insect pests in sugarcane. Pesticides can provide immediate and effective control of pest populations, reducing the damage caused by insects such as cane borers and grasshoppers. However, the use of chemical pesticides presents several limitations. Firstly, many pesticides are relatively short-lived after application, necessitating frequent reapplication to maintain their effectiveness (Boulter, 1989). Additionally, pesticides can harm non-target organisms, including beneficial insects, humans, and other animals, leading to broader ecological and health concerns. The environmental impact of pesticide use, including contamination of soil and water, further complicates their application in sustainable agriculture (Iqbal et al., 2021). 2.2 Biological control: natural predators and parasitoids Biological control involves the use of natural predators and parasitoids to manage insect pest populations. This method leverages the natural ecological relationships between pests and their natural enemies. For example, certain species of wasps and beetles are known to parasitize or prey on sugarcane pests, thereby reducing their numbers. Biological control is considered environmentally friendly and sustainable as it minimizes the need for chemical interventions and reduces the risk of pest resistance development (Verma et al., 2018). However, the effectiveness of biological control can be inconsistent due to factors such as environmental conditions and the availability of natural predators (Srikanth et al., 2011). Additionally, the introduction of non-native biological control agents must be carefully managed to avoid unintended ecological consequences. 2.3 Breeding for resistance: conventional approaches Conventional breeding for resistance involves selecting and cross-breeding sugarcane varieties that exhibit natural resistance to insect pests. This method aims to develop cultivars that possess traits such as physical barriers (e.g., thicker stalks) or biochemical defenses (e.g., production of deterrent compounds) that reduce pest damage (Verma et al., 2018). However, the genetic complexity of sugarcane, coupled with the lack of naturally occurring resistance genes in its germplasm, makes conventional breeding a challenging and time-consuming process (Srikanth et al., 2011; Iqbal et al., 2021). Despite these challenges, conventional breeding remains a valuable tool in integrated pest management strategies, contributing to the development of more resilient sugarcane varieties over time. In summary, while traditional methods of insect pest control in sugarcane, including chemical control, biological control, and conventional breeding, have their respective advantages, they also present significant limitations. These challenges highlight the need for innovative approaches, such as genetic engineering, to enhance sugarcane resistance to insect pests and ensure sustainable crop production. 3 Genetic Engineering: A Modern Approach to Pest Resistance 3.1 Introduction to genetic engineering techniques Genetic engineering involves the direct manipulation of an organism's genome using biotechnology. This modern approach allows for the introduction of new traits and the enhancement of existing ones, which is particularly useful in agriculture for developing pest-resistant crops. Techniques such as Agrobacterium-mediated transformation, CRISPR/Cas9, and RNA interference (RNAi) are commonly employed to insert or modify genes that confer resistance to pests and diseases (Birch, 1996; Talakayala et al., 2020; Iqbal et al., 2021). These methods have revolutionized the way we approach crop improvement, offering precise and efficient solutions compared to traditional breeding methods. 3.2 Overview of genetic modifications in sugarcane Sugarcane, a vital crop for sugar production, has been a significant focus of genetic engineering efforts due to its susceptibility to various insect pests and environmental stresses. Researchers have successfully introduced genes
Molecular Entomology 2024, Vol.15, No.2, 52-60 http://emtoscipublisher.com/index.php/me 54 such as Cry1Ac, Cry2A, and EPSPS into sugarcane to confer resistance to cane borers and tolerance to glyphosate herbicide (Figure 1) (Qamar et al., 2015; Wang et al., 2017; Qamar et al., 2021). These transgenic sugarcane varieties have shown remarkable resistance to pests like Chilo infuscatellus, with up to 100% mortality of the pest larvae in some cases. Additionally, these genetically modified plants have demonstrated high tolerance to glyphosate, ensuring effective weed control without damaging the crop (Wang et al., 2017; Qamar et al., 2021). Figure 1 Schematic presentation of all the steps involved in genetic modification of sugarcane (Adopted from Qamar et al., 2021) Image caption: (A) Callus for Bombardment. (B) Homemade Biolistic machine. (C) Bombarded Callus after bombardment with DNA-coated tungsten particles. (D) Bombarded callus shifted on selection media with Kanamycime (50 mg/L) after 2 days. (E,F) Transformed callus regenerated on double selection (Kanamycine 50 mg/L + Glyphosate 40 mM) media, (G,H) Regenerated sugarcane plantlets on glyphosate selection media (45 mM), shifting on shoot multiplication media with Kanamycime (50 mg/L) and glyphosate (50 mM) selections. (I) Gus Assay for transgenic plant screening (abcd). (J) Transgenic plants for rooting. (K) Shifting on rooting media without any selection drug. (L, M) Acclimatization: Transgenic sugarcane plantlets in soil pots under green house conditions (Adopted from Qamar et al., 2021) 3.3 Benefits of genetic engineering over traditional methods Genetic engineering offers several advantages over traditional breeding methods. Firstly, it allows for the precise introduction of specific traits, such as pest resistance, without the need for extensive cross-breeding and selection processes (Qamar et al., 2015). This precision reduces the time required to develop new crop varieties. Secondly, genetically engineered crops can incorporate traits that are not naturally present in the species' gene pool, such as the Cry proteins from Bacillus thuringiensis, which provide effective pest resistance (Talakayala et al., 2020; Iqbal et al., 2021). Moreover, these crops often require fewer chemical inputs, such as pesticides and herbicides, leading to reduced environmental impact and lower production costs (Birch, 1996; Verma et al., 2022). The development of transgenic sugarcane with enhanced resistance to pests and herbicides exemplifies the potential of genetic engineering to improve crop resilience and productivity, ultimately benefiting both farmers and the environment (Hilder et al., 1987; Wang et al., 2017; Qamar et al., 2021). 4 Mechanisms of Genetic Engineering for Insect Pest Resistance 4.1 Bt toxin production in sugarcane The production of Bacillus thuringiensis (Bt) toxins in genetically engineered sugarcane has been a significant advancement in pest resistance. Bt toxins, such as Cry proteins, have been successfully expressed in transgenic sugarcane to combat various insect pests. These proteins act by binding to specific receptors in the insect gut, causing cell lysis and death. The introduction of Bt genes into sugarcane has shown promising results in both
Molecular Entomology 2024, Vol.15, No.2, 52-60 http://emtoscipublisher.com/index.php/me 55 laboratory and field conditions, significantly reducing pest populations and damage (Iqbal et al., 2021). However, the evolution of resistance in some pest species remains a challenge, necessitating the development of strategies to manage and mitigate resistance (Tabashnik et al., 2023). 4.2 RNA interference (RNAi) for targeted pest control RNA interference (RNAi) is another powerful tool for enhancing insect pest resistance in sugarcane. This technique involves the expression of double-stranded RNA (dsRNA) that targets and silences specific genes essential for pest survival. RNAi offers high target specificity and minimal environmental impact compared to traditional chemical insecticides. Studies have demonstrated the effectiveness of RNAi in downregulating detoxification genes in pests, leading to reduced pest viability and increased susceptibility to plant defenses (Price and Gatehouse, 2008; Eakteiman et al., 2018; Chung et al., 2021). Despite its potential, the commercial application of RNAi in transgenic plants is still limited, and further research is needed to optimize gene targets and delivery methods (Chung et al., 2021; Halder et al., 2022). 4.3 CRISPR-Cas9 and its potential in developing resistant varieties The CRISPR-Cas9 genome editing system has emerged as a revolutionary tool for developing insect-resistant sugarcane varieties. By precisely targeting and modifying specific genes, CRISPR-Cas9 can create mutations that confer resistance to insect pests. For instance, CRISPR-mediated knockout of ABC transporter genes in pests has been shown to confer high levels of resistance to Bt toxins (Guo et al., 2019; Fabrick et al., 2021). This technology allows for the rapid development of resistant strains and provides insights into the genetic mechanisms underlying pest resistance. The potential of CRISPR-Cas9 in sugarcane genetic engineering is vast, offering a flexible and efficient approach to enhance pest resistance. 4.4 Stacked traits for enhanced resistance Combining multiple resistance traits, or "stacking," is a strategy to enhance the durability and effectiveness of pest-resistant sugarcane. Stacked traits can include the expression of multiple Bt toxins, RNAi constructs, and other resistance genes within a single plant. This approach aims to provide broad-spectrum resistance and reduce the likelihood of pests developing resistance to any single trait. For example, transgenic sugarcane lines expressing both Bt toxins and herbicide tolerance genes have shown strong resistance to pests and improved agronomic performance under field conditions (Wang et al., 2017; Iqbal et al., 2021). The integration of stacked traits represents a comprehensive strategy to achieve sustainable pest management in sugarcane cultivation. By leveraging these genetic engineering mechanisms, researchers aim to develop sugarcane varieties with robust and long-lasting resistance to insect pests, thereby improving crop yield and reducing reliance on chemical pesticides. 5 Case Study 5.1 Overview of a specific genetic engineering initiative in sugarcane One notable genetic engineering initiative aimed at enhancing sugarcane resistance to insect pests involved the introduction of the cry1Ac gene, which encodes an insecticidal protein from Bacillus thuringiensis (Bt). This initiative was undertaken to address the significant yield losses caused by the sugarcane stem borer (Diatraea saccharalis), a prevalent pest in sugarcane cultivation. The cry1Ac gene was selected due to its proven efficacy in other crops and its ability to produce a protein that is toxic to certain insect pests but safe for humans and other non-target organisms (Weng et al., 2006; Zhou et al., 2018; Qamar et al., 2021). 5.2 Implementation and outcomes of the case study The implementation of this genetic engineering initiative involved several key steps. First, the cry1Ac gene was synthetically optimized to match the codon usage of sugarcane, enhancing its expression in the plant. This synthetic gene was then introduced into sugarcane varieties using Agrobacterium-mediated transformation and microprojectile bombardment techniques (Weng et al., 2006; Dessoky et al., 2020). The transformed sugarcane lines were subjected to rigorous testing to confirm the integration and expression of the cry1Ac gene. Molecular analyses, including PCR and Southern blotting, verified the presence of the gene,
RkJQdWJsaXNoZXIy MjQ4ODYzNA==