1 Introduction

The Aphididae family, comprising approximately 5 200 species, represents a significant lineage of plant-feeding insects predominantly found in temperate regions (Owen and Miller, 2022). Aphids are known for their rapid diversification, which has been influenced by both abiotic and biotic factors, leading to complex morphological variations and taxonomic challenges. The family is divided into several subfamilies, with recent phylogenomic studies identifying three main clades (Ortiz-Rivas and Martínez-Torres, 2010). These insects exhibit a range of life cycles, including both asexual and sexual reproduction, and display notable intraspecific polyphenism.

Aphids play a crucial role in both agriculture and ecology. They are major pests of crops, vegetables, and fruit trees, causing significant economic damage through direct feeding and as vectors of plant viruses (Singh and Singh, 2017). Their interactions with host plants are highly specialized, and some species have evolved complex behaviors such as gall formation and sociality (Huang and Qiao, 2014). The ecological impact of aphids extends beyond agriculture, as they influence plant community dynamics and serve as prey for various predators, thus contributing to the broader ecosystem.

This study is to provide a comprehensive overview of the current taxonomic approaches used in the classification of the Aphididae family. By synthesizing recent molecular and morphological studies, it will clarify the phylogenetic relationships within the family and address the taxonomic inconsistencies that have arisen due to rapid adaptive radiation and gene tree discordance. The study expects to serve as a foundation for future research, facilitating more accurate identification and classification of aphid species, which is essential for effective pest management and ecological studies.

2 Historical Development of Aphid Taxonomy

2.1 Early classification attempts

The early classification of aphids (Hemiptera: Aphididae) was primarily based on morphological characteristics. Initial taxonomic efforts were often hampered by the high degree of morphological plasticity within aphid species, which led to significant challenges in distinguishing between closely related taxa. Early taxonomists relied heavily on observable traits such as body shape, coloration, and the structure of appendages to classify aphids. However, these morphological features were frequently influenced by environmental factors, leading to considerable taxonomic confusion and misclassification.

The first molecular studies aimed at resolving these taxonomic ambiguities encountered a lack of phylogenetic structure at higher taxonomic levels, likely due to the rapid adaptive radiation of aphids during the Late Cretaceous period (Ortiz-Rivas and Martínez-Torres, 2010). This rapid diversification resulted in a complex evolutionary history that was difficult to unravel using traditional morphological methods alone. Consequently, early attempts at aphid classification were often inconclusive and required the integration of additional data sources to improve taxonomic resolution.

2.2 Evolution of taxonomic concepts over time

As the field of taxonomy evolved, so did the approaches to classifying aphids. The advent of molecular techniques marked a significant turning point in aphid taxonomy. Researchers began to incorporate genetic data to complement morphological observations, leading to more robust phylogenetic frameworks. For instance, the use of genome and transcriptome data has provided deeper insights into the phylogenomic relationships among aphid subfamilies, revealing three main clades within the Aphididae family (Owen and Miller, 2022). These molecular approaches have helped to clarify previously incongruent phylogenies and have highlighted the impact of gene tree discordance and introgression events on aphid evolution.

Recent studies have further refined our understanding of aphid phylogeny by combining multiple molecular markers. For example, the analysis of nuclear and mitochondrial sequences has supported the existence of three main lineages within the Aphididae family and has suggested the basal position of the subfamily Lachninae (Ortiz-Rivas and Martínez-Torres, 2010). These findings underscore the importance of integrating diverse data types to achieve a comprehensive understanding of aphid taxonomy and evolution.

2.3 Contributions from notable taxonomists

Several notable taxonomists have made significant contributions to the field of aphid taxonomy. Their work has laid the foundation for our current understanding of aphid diversity and evolutionary relationships. Early pioneers in aphid taxonomy focused on detailed morphological descriptions and the establishment of classification schemes based on observable traits. However, the limitations of these early methods became apparent as more data accumulated.

In recent years, researchers such as those involved in the phylogenomic study of Aphididae subfamilies have advanced the field by leveraging modern molecular techniques. Their work has provided a more nuanced view of aphid phylogeny, revealing complex patterns of gene flow and introgression that were previously undetectable. Additionally, studies focusing on the phylogeny of the Aphidinae subfamily have challenged traditional views and suggested novel relationships based on molecular data (Dohlen et al., 2006). These contributions have been instrumental in refining aphid classification and enhancing our understanding of their evolutionary history.

3 Morphological Approaches to Aphid Classification

3.1 Key morphological traits used for identification

Morphological traits have long been the cornerstone of aphid classification. Key traits used for identification include the structure and segmentation of antennae, the presence and configuration of wing veins, and the morphology of the rostrum. For instance, the newly described genus and species Tanyaulus caudisetula from mid-Cretaceous Myanmar amber is characterized by unique morphological features such as stub-like hind wings, a 7-segmented antenna, and a long rostrum equal to body length (Poinar, 2018). These traits are critical for distinguishing between different aphid species and genera, especially in paleontological contexts where molecular data is unavailable.

Additionally, the external morphology of aphids can be highly variable and influenced by environmental factors. For example, the European species of the genus Eulachnus exhibit significant morphological differences in head, antennae, legs, and dorsal chaetotaxy, which have been used to propose three distinct species groups: “agilis”, “brevipilosus”, and “cembrae” (Kanturski et al., 2015). These morphological differences are essential for accurate species identification and understanding the evolutionary relationships within the genus.

3.2 Advances in microscopic techniques

Advances in microscopic techniques have significantly enhanced the resolution and accuracy of morphological studies in aphid taxonomy. Scanning electron microscopy (SEM) has been particularly valuable in revealing fine details of aphid morphology that are not visible with traditional light microscopy. For example, SEM methods were employed to study the external morphology of the European species of the genus Eulachnus, providing high-quality images that revealed detailed surface structures and morphological signs of cell deterioration (Kanturski et al., 2015). These high-resolution images allow for more precise comparisons between species and can uncover subtle morphological differences that are crucial for accurate classification.

Furthermore, the use of cryo-SEM and HMDS preparation techniques has improved image quality by reducing surface tension and minimizing artifacts such as depressions and membrane blebs. These advancements in microscopic techniques have not only facilitated more detailed morphological studies but also enabled the discovery of new species and genera, as demonstrated by the identification of Tanyaulus caudisetula in mid-Cretaceous amber (Poinar, 2018).

3.3 Limitations of morphological taxonomy

Despite the advancements in microscopic techniques, morphological taxonomy has its limitations. One major challenge is the phenotypic plasticity of aphids, where environmental factors can cause significant variations in morphology, leading to potential misidentifications. For instance, the rapid radiation and diversification of aphids, influenced by both abiotic and biotic factors, have resulted in incongruent molecular and morphological phylogenies (Owen and Miller, 2022). This discordance complicates the classification and understanding of evolutionary relationships among aphid species.

Moreover, morphological traits alone may not be sufficient to resolve complex taxonomic questions, especially in cases of cryptic species or recent divergences. The reliance on morphological characteristics can also be problematic when dealing with incomplete or damaged specimens, such as those found in fossil records. In such cases, integrating molecular data with morphological studies can provide a more comprehensive and accurate approach to aphid taxonomy. For example, the use of genome and transcriptome data has been shown to clarify phylogenomic relationships among aphid subfamilies, despite the presence of gene tree discordance and introgression events (Owen and Miller, 2022). Therefore, while morphological approaches remain fundamental, they are most effective when complemented by molecular techniques.

4 Molecular and Genetic Approaches

4.1 DNA barcoding and phylogenetic analysis

DNA barcoding has emerged as a powerful tool for the identification and classification of aphid species, leveraging the mitochondrial cytochrome c oxidase I (COI) gene as a standard marker. This method has proven effective in distinguishing between morphologically similar species and uncovering cryptic diversity. For instance, a comprehensive study on European aphids demonstrated that DNA barcoding could reliably identify 80% of species, even those difficult to distinguish morphologically (D’acier et al., 2014). Similarly, research on the subfamily Calaphidinae revealed significant cryptic diversity (Figure 1), with DNA barcoding identifying discrepancies between traditional taxonomy and genetic data in 21.7% of the species studied (Lee et al., 2017).

Phylogenetic analysis using DNA barcodes has also provided insights into the evolutionary relationships among aphid species. In the genus Toxoptera, COI barcoding successfully differentiated species and suggested the presence of cryptic species within the genus (Wang and Qiao, 2009). Additionally, studies on Chaitophorinae aphids employed multiple mitochondrial genes and endosymbiont genes to enhance species delimitation, demonstrating that COI and COII genes are particularly suitable for DNA barcoding in this group (Zhu et al., 2017). These findings underscore the utility of DNA barcoding not only for species identification but also for elucidating phylogenetic relationships and uncovering hidden biodiversity.

4.2 Genomic tools and molecular markers in aphid systematics

Beyond DNA barcoding, other genomic tools and molecular markers have been employed to advance aphid systematics. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) based on the COI gene has been used to identify aphid species in Kenya, providing a rapid and accurate method for distinguishing between morphologically similar species (Kinyanjui et al., 2016). This approach, combined with DNA barcoding, has proven effective in identifying economically important aphid species and aiding in pest management strategies.

The development of comprehensive DNA barcode libraries is crucial for the effective application of these genomic tools. For example, a study on subtropical aphids created a DNA barcode library encompassing 1 581 specimens from 143 morphospecies, facilitating species identification and population differentiation (Li et al., 2019). Similarly, efforts to build a reference library for pest aphids in Pakistan have highlighted the importance of well-parameterized libraries for accurate species identification and the detection of invasive species (Naseem et al., 2019). These libraries serve as valuable resources for future research and practical applications in aphid systematics and pest management.

4.3 Integration of genetic and morphological data

Integrating genetic and morphological data is essential for a comprehensive understanding of aphid taxonomy and systematics. DNA barcoding has been instrumental in resolving taxonomic ambiguities and linking different life stages of aphids that exhibit morphological plasticity. For instance, a study on Indian aphids demonstrated that DNA barcoding could accurately identify species and reveal the presence of cryptic species, which traditional morphological methods might overlook (Rebijith et al., 2013). This integration of genetic data with morphological observations enhances the accuracy and reliability of species identification.

Moreover, the combination of genetic and morphological data has facilitated the detection of cryptic species and the resolution of complex taxonomic issues. Research on aphids and adelgids has shown that DNA barcoding can uncover new taxa and assist in delineating species boundaries, which are often blurred by morphological variations due to environmental factors (Foottit et al., 2009). By providing a genetic framework to support morphological classifications, these studies contribute to a more robust and nuanced understanding of aphid diversity and evolution.

5 Biochemical and Ecological Taxonomy

5.1 Host plant specialization and ecology-based classification

Aphids exhibit a high degree of host plant specialization, which significantly influences their ecological classification. The intricate relationships between aphids and their host plants are pivotal in understanding their taxonomy. For instance, the study on the aphid Myzus persicae demonstrates how aphids acquire chloroplast DNA from their host plants during feeding, which can be used to identify recent host use patterns (Byrd et al., 2023). This host plant specialization is not only crucial for pest management but also provides insights into the ecological interactions and evolutionary adaptations of aphids.

Moreover, the host plant associations are often used to classify aphids into various subfamilies and tribes. The checklist of host plants for Calaphidinae in India highlights the importance of documenting host plant associations to understand the distribution and taxonomy of aphids (Singh and Singh, 2017). Similarly, the Australian National Insect Collection’s checklist provides a comprehensive catalog of aphid species and their host plants, emphasizing the role of host plant specialization in aphid classification (Brumley, 2020). These studies underscore the necessity of integrating ecological data into the taxonomic frameworks of aphids.

5.2 Chemical profiles of aphids as taxonomic indicators

Chemical profiles, including the composition of secondary metabolites and symbiotic bacteria, serve as valuable taxonomic indicators for aphids. The diversity of symbionts associated with aphids, such as those found in the genus Mollitrichosiphum, plays a crucial role in shaping their life history and ecological interactions (Qin et al., 2021). The study on Mollitrichosiphum aphids reveals that heritable symbionts dominate their microbiota, and the microbial community structure is significantly influenced by the host aphid species. This phylosymbiosis pattern suggests that chemical profiles, including symbiotic associations, can be used to delineate taxonomic boundaries within aphids.

Furthermore, the molecular phylogeny of Macrosiphini aphids indicates that host plant transitions and ecological adaptations are reflected in their chemical profiles (Choi et al., 2018). The study shows that host associations within the tribe Macrosiphini are consistent with the ecological habitats of the host plants, such as riparian versus drier forest habitats. These findings highlight the potential of using chemical profiles, including host plant-derived compounds and symbiotic bacteria, as taxonomic markers to classify aphids more accurately.

5.3 Environmental factors influencing aphid classification

Environmental factors, such as climate and geographical distribution, play a significant role in influencing aphid classification. The rapid adaptive radiation of aphids during the Late Cretaceous, driven by abiotic and biotic factors, has led to a complex phylogenetic structure that challenges traditional taxonomic approaches (Ortiz-Rivas and Martínez-Torres, 2010). The study on the phylogeny of aphids using molecular data reveals that environmental factors have contributed to the diversification and classification of aphids into three main lineages.

Additionally, the phylogenomic study of Aphididae subfamilies highlights the impact of gene tree discordance and introgression events on aphid classification (Owen and Miller, 2022). The research suggests that environmental factors, such as geographical barriers and ecological niches, have influenced the genetic makeup and evolutionary history of aphids. These factors must be considered when developing taxonomic frameworks to ensure they accurately reflect the evolutionary relationships and ecological adaptations of aphids.

6 Advances in Digital Taxonomy and Image-Based Tools

6.1 Use of artificial intelligence in aphid identification

The integration of artificial intelligence (AI) into aphid identification has revolutionized the field of entomology, particularly in the monitoring and management of aphid populations. AI techniques, such as machine learning and image recognition, have been employed to address the challenges associated with manual identification, which is often time-consuming and requires a high level of taxonomic expertise. For instance, the use of convolutional neural networks (CNNs) has shown significant promise in automating the identification process, thereby reducing the bottleneck in specimen processing (Júnior and Rieder, 2020). These AI-driven methods not only enhance the accuracy of identification but also allow for the processing of large datasets, which is crucial for long-term monitoring and forecasting of aphid populations (Batz et al., 2023).

Moreover, AI applications extend beyond mere identification. They are instrumental in developing predictive models that can forecast aphid abundance and the associated risks of plant virus transmission. This is particularly important in the context of climate change, which influences aphid population dynamics and peak occurrences. The potential of AI in aphid identification and monitoring underscores the need for continued research and development in this area, as it offers a scalable and efficient solution to the challenges posed by traditional taxonomic methods.

6.2 Development of digital databases and keys

The creation of digital databases and identification keys represents a significant advancement in the field of aphid taxonomy. These tools facilitate the accurate and efficient identification of aphid species, which is essential for effective pest management and biodiversity studies. One notable example is the development of a web-based digital key for the identification of Neuroptera in West Bengal, India. This digital key, accessible via the platform www.lacewingsofwestbengal.in, exemplifies how region-specific databases can be utilized to create user-friendly identification tools (Dutta et al., 2023).

Digital databases also play a crucial role in the global taxonomic community by providing centralized repositories of taxonomic information. The PhylAphidB@se website, for instance, offers a comprehensive database of DNA barcodes for European aphids, enabling researchers to identify species based on genetic data (D’acier et al., 2014). Such databases not only streamline the identification process but also support large-scale taxonomic projects by providing access to a wealth of information that can be used for comparative studies and biodiversity assessments.

6.3 Remote sensing and automated classification systems

Remote sensing and automated classification systems have emerged as powerful tools in the field of aphid taxonomy. These technologies enable the monitoring of aphid populations over large geographic areas and extended periods, providing valuable data for ecological and agricultural studies. Automated classification systems, which utilize computer vision and machine learning algorithms, have been developed to count and classify aphids from digital images. These systems offer a reliable and efficient alternative to manual counting, which is often labor-intensive and prone to errors (Lins et al., 2020).

The use of remote sensing technologies, such as suction traps combined with automated image analysis, allows for the continuous monitoring of aphid populations without the need for constant human intervention. This approach not only improves the accuracy of population estimates but also provides real-time data that can be used to inform pest management strategies (Batz et al., 2023). The integration of remote sensing and automated classification systems represents a significant advancement in the field, offering new opportunities for large-scale and long-term monitoring of aphid populations.

7 Case Study Analysis: A Comprehensive Taxonomic Revision of Aphis Species

7.1 Selection of the Aphis genus for case study

The genus Aphis was selected for this case study due to its significant taxonomic complexity and economic importance. Aphis is the largest aphid genus globally, encompassing numerous species that are major agricultural pests (D’acier et al., 2007). The genus is notorious for its taxonomic challenges, as many species within it are difficult to distinguish morphologically and often require molecular data for accurate identification. This complexity makes Aphis an ideal candidate for a comprehensive taxonomic revision, which can provide insights into broader taxonomic issues within the Aphididae family.

Moreover, recent studies have highlighted the need for a detailed taxonomic reassessment of Aphis species. For instance, the discovery of new species within the genus, such as Aphis (Toxoptera) fafuensis and Aphis (Toxoptera) sennae (Figure 2) in China, underscores the ongoing diversification and the necessity for updated classification keys (Cheng and Huang, 2023). These factors collectively justify the selection of Aphis for an in-depth case study aimed at refining its taxonomic framework.

7.2 Methodology for morphological and genetic reassessment

The methodology for reassessing the taxonomy of Aphis species involved a combination of morphological and genetic analyses. Morphological examination focused on detailed characterizations of physical traits, including body size, coloration, and specific anatomical features such as the siphunculi and cauda. These traits were compared across multiple specimens to identify consistent patterns and variations (Ciruelos et al., 2018; Cheng and Huang, 2023).

Genetic reassessment was conducted using mitochondrial DNA sequences, specifically targeting the COI/COII and CytB genes, which are commonly used in phylogenetic studies due to their high mutation rates and ability to resolve species-level relationships (D’acier et al., 2007). Additionally, other mitochondrial regions such as tRNA/COII and 12S/16S, along with nuclear genes like EF1α, were analyzed to construct a robust phylogeny of the genus. Bayesian phylogenetic analyses, maximum parsimony, and maximum likelihood methods were employed to ensure the accuracy and reliability of the phylogenetic trees generated (Kim and Lee, 2008).

7.3 Key findings and new species descriptions

The comprehensive taxonomic revision of Aphis species yielded several key findings. Firstly, the phylogenetic analyses confirmed the monophyly of certain subgenera and species groups within Aphis, such as the subgenus Bursaphis and the “Black” and “Black backed” species groups (D’acier et al., 2007). However, the nominal subgenus Aphis was found to be non-monophyletic, indicating the need for further taxonomic refinement.

New species were also described during this revision. For example, Aphis luzuriagae and Aphis gaultheriae were identified from specimens collected in Chile, expanding the known diversity of the genus (Ciruelos et al., 2018). These new species were distinguished based on unique morphological traits and supported by molecular data, which confirmed their distinct taxonomic positions within the genus (Ciruelos et al., 2018). Such discoveries highlight the ongoing diversification within Aphis and the importance of integrating morphological and genetic data in taxonomic studies.

7.4 Implications for broader aphid taxonomy

The findings from this case study have significant implications for broader aphid taxonomy. The challenges encountered in delineating species within Aphis, such as the difficulty in distinguishing morphologically similar species and the limitations of mitochondrial DNA in resolving certain taxonomic relationships, underscore the complexity of aphid taxonomy as a whole (D’acier et al., 2007). These issues suggest that a multi-faceted approach, combining morphological, molecular, and ecological data, is essential for accurate species identification and classification.

Furthermore, the discovery of new species and the identification of non-monophyletic groups within Aphis highlight the dynamic nature of aphid evolution and the need for continuous taxonomic updates (Ciruelos et al., 2018; Cheng and Huang, 2023). This case study serves as a model for revising other complex aphid genera, demonstrating the importance of comprehensive taxonomic revisions in improving our understanding of aphid diversity and evolution.

8 Challenges in Aphid Taxonomy

8.1 Taxonomic ambiguities and cryptic species complexes

One of the primary challenges in aphid taxonomy is the presence of taxonomic ambiguities and cryptic species complexes. Aphids exhibit significant morphological plasticity influenced by both abiotic and biotic factors, which complicates the accurate identification and classification of species. For instance, the rapid radiation of aphids has resulted in incongruent molecular and morphological phylogenies, making it difficult to resolve deep relationships between subfamilies (Owen and Miller, 2022). This issue is further exacerbated by the presence of cryptic species, which are morphologically indistinguishable but genetically distinct. Comprehensive DNA barcoding studies have revealed high levels of cryptic diversity within aphid subfamilies, such as Calaphidinae, where 21.7% of morphospecies showed discrepancies between DNA barcoding and traditional taxonomy, leading to the identification of multiple cryptic species (Lee et al., 2017).

The challenge of cryptic species is not limited to a single subfamily but is a widespread issue across the Aphididae family. For example, molecular phylogenetic analyses have shown that certain genera and species groups within the tribe Aphidini are not monophyletic, indicating the presence of cryptic species and necessitating taxonomic revisions (Kim and Lee, 2008). These findings underscore the need for integrative taxonomic approaches that combine molecular data with traditional morphological methods to accurately delineate species boundaries and resolve taxonomic ambiguities.

8.2 Sampling bias and geographic gaps

Another significant challenge in aphid taxonomy is the issue of sampling bias and geographic gaps. Many taxonomic studies are concentrated in specific regions, leading to an uneven representation of aphid diversity. This geographic bias can result in an incomplete understanding of aphid taxonomy and the potential overlooking of species that are endemic to under-sampled regions. For instance, the phylogenomic study of Aphididae subfamilies highlighted the need for more comprehensive sampling across different geographic regions to better understand the evolutionary relationships and diversity within the family (Owen and Miller, 2022).

Geographic gaps in sampling also hinder the detection of cryptic species and the accurate assessment of species distributions. The discovery of a new cryptic bamboo aphid species in Europe, which was previously unrecorded, illustrates the impact of geographic sampling gaps on aphid taxonomy (Wieczorek and Sawka-Gądek, 2023). Addressing these gaps requires coordinated efforts to conduct extensive field surveys and collect specimens from diverse and under-explored regions. This will not only enhance the taxonomic resolution of aphids but also contribute to a more complete understanding of their biogeography and ecological roles.

8.3 Funding and resource constraints in taxonomic studies

Funding and resource constraints pose a significant challenge to aphid taxonomy. Taxonomic research often requires substantial financial investment for fieldwork, specimen collection, and advanced molecular analyses. However, funding for taxonomic studies is frequently limited, leading to a shortage of resources and hindering the progress of taxonomic research. The “taxonomic impediment”, characterized by gaps in taxonomic knowledge, lack of infrastructure, and insufficient number of taxonomic experts, is a major roadblock in managing the current biodiversity crisis (Petrović, 2022).

The lack of funding and resources also affects the training and retention of taxonomic experts. The scientific community and society at large have become more aware of the crucial role of taxonomy in biodiversity conservation, yet the number of trained taxonomists is declining. This shortage of experts further exacerbates the challenges in aphid taxonomy, as there are fewer specialists available to conduct detailed taxonomic revisions and describe new species. To overcome these challenges, increased investment in taxonomic research and the development of collaborative networks are essential to support the training of new taxonomists and the advancement of aphid taxonomy.

9 Future Directions and Opportunities

The complexity of aphid taxonomy, influenced by rapid adaptive radiation and gene tree discordance, necessitates an interdisciplinary approach. Integrating molecular data with traditional morphological methods can provide a more comprehensive understanding of aphid phylogeny. For instance, the use of genome and transcriptome data has already shown promise in resolving phylogenetic relationships among aphid subfamilies, despite challenges such as gene tree discordance and introgression events (Owen and Miller, 2022). Combining these molecular techniques with ecological and behavioral studies could further elucidate the evolutionary pathways and adaptive strategies of aphids.

Citizen science can play a pivotal role in aphid taxonomy by expanding the scope of data collection and increasing public engagement in scientific research. With the advent of digital platforms and mobile applications, amateur naturalists can contribute valuable observations and specimens, which can be used to enhance taxonomic studies. This approach not only democratizes science but also helps in gathering large-scale data that might be otherwise inaccessible to researchers. Engaging the public in aphid monitoring can lead to the discovery of new species and provide insights into their distribution and ecology.

The integration of genomics and artificial intelligence (AI) holds significant potential for advancing aphid taxonomy. High-throughput sequencing technologies can generate extensive genomic data, which, when analyzed using AI algorithms, can uncover complex phylogenetic relationships and evolutionary histories. For example, phylogenomic studies have already identified three main clades of Aphididae subfamilies and highlighted the role of introgression in their evolution (Ortiz-Rivas and Martínez-Torres, 2010). AI can further enhance these studies by automating the identification of phylogenetically informative markers and predicting evolutionary trends. Additionally, machine learning models can be trained to recognize morphological traits from images, aiding in the rapid and accurate classification of aphid species.

Acknowledgments

The author sincerely thanks his colleague Kendra D.Y. Ding from the research group for the assistance provided during the literature and data collection process of this study.

Conflict of Interest Disclosure

The author affirms that this research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest.

References

Batz P., Will T., Thiel S., Ziesche T., and Joachim C., 2023, From identification to forecasting: the potential of image recognition and artificial intelligence for aphid pest monitoring, Frontiers in Plant Science, 14.

https://doi.org/10.3389/fpls.2023.1150748

Brumley C., 2020, A checklist and host catalogue of the aphids (Hemiptera: Aphididae) held in the Australian National Insect Collection, Zootaxa, 4728(4): 575-600.

https://doi.org/10.11646/zootaxa.4728.4.12

Byrd D., Tran M., Kenney J., Wilson-Rankin E., and Mauck K., 2023, The aphid Myzus persicae (Hemiptera: Aphididae) acquires chloroplast DNA during feeding on host plants, Environmental Entomology, 52: 900-906.

https://doi.org/10.1093/ee/nvad086

Cheng Z., and Huang X., 2023, Two new species of Aphis (Toxoptera) Koch (Hemiptera, Aphididae) from China. ZooKeys, 1172: 31-46.

https://doi.org/10.3897/zookeys.1172.106518

Choi H., Shin S., Jung S., Clarke D., and Lee S., 2018, Molecular phylogeny of Macrosiphini (Hemiptera: Aphididae): an evolutionary hypothesis for the Pterocomma-group habitat adaptation, Molecular Phylogenetics and Evolution, 121: 12-22.

https://doi.org/10.1016/j.ympev.2017.12.021

Ciruelos S., Brown P., and Nafría J., 2018, Two new species of the genus Aphis (Hemiptera, Aphididae) from Chile on host species of Alstroemeriaceae and Ericaceae, ZooKeys, 37-45.

https://doi.org/10.3897/zookeys.738.21966

D’acier A., Cruaud A., Artige E., Genson G., Clamens A., Pierre É., Hudaverdian S., Simon J., Jousselin E., and Rasplus J., 2014, DNA barcoding and the associated PhylAphidB@se website for the identification of European aphids (Insecta: Hemiptera: Aphididae), PLoS ONE, 9.

https://doi.org/10.1371/journal.pone.0097620

D’acier A., Jousselin E., Martin J., and Rasplus J., 2007, Phylogeny of the genus Aphis Linnaeus, 1758 (Homoptera: Aphididae) inferred from mitochondrial DNA sequences, Molecular Phylogenetics and Evolution, 42(3): 598-611.

https://doi.org/10.1016/j.ympev.2006.10.006

Dohlen C., Rowe C., and Heie O., 2006, A test of morphological hypotheses for tribal and subtribal relationships of Aphidinae (Insecta: Hemiptera: Aphididae) using DNA sequences, Molecular Phylogenetics and Evolution, 38(2): 316-329.

https://doi.org/10.1016/j.ympev.2005.04.035

Dutta S., Mondal R., Das R., Ganguli S., and Dey S., 2023, Development of web based digital key from dichotomous key through computer programming: model Aphid Predator Neuroptera (INSECTA), International Journal for Research in Applied Science and Engineering Technology.

https://doi.org/10.22214/ijraset.2023.50197

Foottit R., Maw H., and Pike K., 2009, DNA barcodes to explore diversity in aphids (Hemiptera: Aphididae and Adelgidae), Redia-Giornale Di Zoologia, 92: 87-91.

Huang X.L., and Qiao G.X., 2014, Aphids as models for ecological and evolutionary studies, Insect Science, 21(3): 247-250.

https://doi.org/10.1111/1744-7917.12130

Júnior T., and Rieder R., 2020, Automatic identification of insects from digital images: a survey, Comput. Electron. Agric., 178: 105784.

https://doi.org/10.1016/j.compag.2020.105784

Kanturski M., Karcz J., and Wieczorek K., 2015, Morphology of the European species of the aphid genus Eulachnus (Hemiptera: Aphididae: Lachninae) - a SEM comparative and integrative study, Micron, 76: 23-36.

https://doi.org/10.1016/j.micron.2015.05.004

Kim H., and Lee S., 2008, A molecular phylogeny of the tribe Aphidini (Insecta: Hemiptera: Aphididae) based on the mitochondrial tRNA/COII, 12S/16S and the nuclear EF1α genes, Systematic Entomology, 33.

https://doi.org/10.1111/j.1365-3113.2008.00440.x

Kinyanjui G., Khamis F., Mohamed S., Ombura L., Warigia M., and Ekesi S., 2016, Identification of aphid (Hemiptera: Aphididae) species of economic importance in Kenya using DNA barcodes and PCR-RFLP-based approach, Bulletin of Entomological Research, 106(1): 63-72.

https://doi.org/10.1017/S0007485315000796

Lee Y., Lee W., Kanturski M., Foottit R., Akimoto S., and Lee S., 2017, Cryptic diversity of the subfamily Calaphidinae (Hemiptera: Aphididae) revealed by comprehensive DNA barcoding, PLoS ONE, 12.

https://doi.org/10.1371/journal.pone.0176582

Li Q., Deng J., Chen C., Zeng L., Lin X., Cheng Z., Qiao G., and Huang X., 2019, DNA barcoding subtropical aphids and implications for population differentiation, Insects, 11.

https://doi.org/10.3390/insects11010011

Lins E., Rodriguez J., Scoloski S., Pivato J., Lima M., Fernandes J., Pereira P., Lau D., and Rieder R., 2020, A method for counting and classifying aphids using computer vision, Comput. Electron. Agric., 169: 105200.

https://doi.org/10.1016/j.compag.2019.105200

Naseem M., Ashfaq M., Khan A., Rasool A., Asif M., and Hebert P., 2019, BIN overlap confirms transcontinental distribution of pest aphids (Hemiptera: Aphididae), PLoS ONE, 14.

https://doi.org/10.1101/705889

Ortiz-Rivas B., and Martínez-Torres D., 2010, Combination of molecular data support the existence of three main lineages in the phylogeny of aphids (Hemiptera: Aphididae) and the basal position of the subfamily Lachninae, Molecular Phylogenetics and Evolution, 55(1): 305-317.

https://doi.org/10.1016/j.ympev.2009.12.005

Owen C., and Miller G., 2022, Phylogenomics of the Aphididae: deep relationships between subfamilies clouded by gene tree discordance, introgression and the gene tree anomaly zone, Systematic Entomology, 47: 470-486.

https://doi.org/10.1111/syen.12542

Petrović A., 2022, Sizing the knowledge gap in taxonomy: the last dozen years of Aphidiinae research, Insects, 13.

https://doi.org/10.3390/insects13020170

Poinar G., 2018, A new genus and species of aphids, Tanyaulus caudisetula gen. et sp. nov. (Hemiptera: Aphidoidea: Burmitaphidae) in mid-Cretaceous Myanmar amber, Cretaceous Research, 82: 36-39.

https://doi.org/10.1016/j.cretres.2017.10.025

Qin M., Chen J., Xu S., Jiang L., and Qiao G., 2021, Microbiota associated with Mollitrichosiphum aphids (Hemiptera: Aphididae: Greenideinae): diversity, host species specificity and phylosymbiosis, Environmental Microbiology, 23: 2184-2198.

https://doi.org/10.1111/1462-2920.15391

Rebijith K., Asokan R., Kumar N., Krishna V., Chaitanya B., and Ramamurthy V., 2013, DNA barcoding and elucidation of cryptic aphid species (Hemiptera: Aphididae) in India, Bulletin of Entomological Research, 103: 601-610.

https://doi.org/10.1017/S0007485313000278

Singh G., and Singh R., 2017, Updated checklist of host plants of Calaphidinae (Aphididae: Hemiptera) in India, International Journal of Contemporary Research and Review, 8(2): 20171-20190.

https://doi.org/10.15520/ijcrr/2017/8/02/111

Wang J., and Qiao G., 2009, DNA barcoding of genus Toxoptera Koch (Hemiptera: Aphididae): identification and molecular phylogeny inferred from mitochondrial COI sequences, Insect Science, 16.

https://doi.org/10.1111/j.1744-7917.2009.01270.x

Wieczorek K., and Sawka‐Gądek N., 2023, DNA barcoding and molecular phylogenetics revealed a new cryptic bamboo aphid species of the genus Takecallis (Hemiptera: Aphididae), Applied Sciences.

https://doi.org/10.3390/app13137798

Zhu X.C., Chen J., Chen R., Jiang L.Y., and Qiao G.X., 2017, DNA barcoding and species delimitation of Chaitophorinae (Hemiptera, Aphididae), ZooKeys, 656: 25-50.

https://doi.org/10.3897/zookeys.656.11440