Insect Pigments Research Articles

From genes to color: Evolutionary insights and mechanistic pathways of the yellow gene in insect pigmentation

Insect pigmentation plays a vital role in ecology and evolution, influencing survival, mate attraction, and communication. This review examines the complex mechanisms governing insect coloration, focusing on the roles of pigments (melanins and carotenoids) and structural colors. Specifically, the yellow gene in Drosophila is highlighted for its critical function in melanin biosynthesis and its evolutionary implications. Variations in the yellow gene's expression and regulation, influenced by both cis- and trans-regulatory elements, contribute to the phenotypic diversity of pigmentation patterns across insect species. The interplay between developmental genes and the yellow gene further illustrates how subtle genetic changes drive morphological diversity. While advances in CRISPR and other genetic tools have enhanced our understanding of pigmentation, challenges remain in deciphering the gene’s complex interactions and the influence of environmental factors. Future research should focus on refining genomic techniques, exploring environmental impacts on pigmentation, and utilizing single-cell omics to gain deeper insights into the regulatory networks governing the yellow gene. This comprehensive understanding of insect pigmentation will not only enrich our knowledge of biodiversity but also inform conservation and biotechnological innovations.

The Use of Insect Pigment in Art Works.

In this compilation, the focus is on the Cochineal insect (Dactylopius coccus Costa, 1835 (Hemiptera: Dactylopiidae)), a creature native to South America that produces a potent natural red pigment known as "carmine". This pigment, utilized for obtaining the color red, has been an integral part of the art world for thousands of years. Indigenous cultures, in particular, have employed the dye extracted from this insect in the creation of textile dyes and paintings. Moreover, the Cochineal insect and its unique pigments have not only supported artistic expression but also captivated and inspired artists. During the Renaissance period, artists preferred the carmine pigment produced by the females of the Cochineal insect for obtaining bright and vivid red tones. This study delves into the history of the Cochineal insect, its role in art, and its perception in the modern world. Famous paintings created with dyes obtained from the Cochineal insect are discussed, exploring how pigments have found a place in the art world and how artists have utilized this extraordinary source to create distinctive works.

Genome-wide identification of yellow gene family in Hermetia illucens and functional analysis of yellow-y by CRISPR/Cas9.

The yellow gene family plays a crucial role in insect pigmentation. It has potential for use as a visible marker gene in genetic manipulation and transgenic engineering in several model and non-model insects. Sadly, yellow genes have rarely been identified in Stratiomyidae species and the functions of yellow genes are relatively unknown. In the present study, we first manually annotated and curated 10 yellow genes in the black soldier fly (BSF), Hermetia illucens (Stratiomyidae). Then, the conserved amino acids in the major royal jelly proteins (MRJPs) domain, structural architecture and phylogenetic relationship of yellow genes in BSF were analyzed. We found that the BSF yellow-y, yellow-c and yellow-f genes are expressed at all developmental stages, especially in the prepupal stage. Using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein9 (Cas9) system, we successfully disrupted yellow-y, yellow-c and yellow-f in the BSF. Consequently, the mutation of yellow-y clearly resulted in a pale-yellow body color in prepupae, pupae and adults, instead of the typical black body color of the wild type. However, the mutation of yellow-c or yellow-f genes did not result in any change in color of the insects, when compared with the wild type. Our study indicates that the BSF yellow-y gene plays a role in body pigmentation, providing an optimal marker gene for the genetic manipulation of BSF.

The melanin pigment gene black mediates body pigmentation and courtship behaviour in the German cockroach Blattella germanica.

Genes involved in melanin production directly impact insect pigmentation and can affect diverse physiology and behaviours. The role these genes have on sex behaviour, however, is unclear. In the present study, the crucial melanin pigment gene black was functionally characterised in an urban pest, the German cockroach, Blattella germanica. RNAi knockdown of B. germanica black (Bgblack) had no effect on survival, but did result in black pigmentation of the thoraxes, abdomens, heads, wings, legs, antennae, and cerci due to cuticular accumulation of melanin. Sex-specific variation in the pigmentation pattern was apparent, with females exhibiting darker coloration on the abdomen and thorax than males. Bgblack knockdown also resulted in wing deformation and negatively impacted the contact sex pheromone-based courtship behaviour of males. This study provides evidence for black function in multiple aspects of B. germanica biology and opens new avenues of exploration for novel pest control strategies.

Whole-Genome Resequencing-Based Qualitative Trait Locus Mapping Correlated yellow with the Mutant Color in Honeybees, Apis cerana cerana.

The honeybee, Apis cerana cerana (Ac), is an important pollinator and has adapted to the local ecological environment with relevant coloration. The cuticle coloration of the brown (br) mutant is brown instead of black in wild-type individuals. Therefore, this study aimed to identify and characterize the gene responsible for the br mutation. Genome resequencing with allele segregation measurement using Euclidean distance followed by Lowess regression analysis revealed that the color locus linked to the mutation was located on chromosome 11. A 2-base deletion on exon 4 was identified in the g7628 (yellow) gene after genome assembly and sequence cloning. In addition, the cuticle color of the abdomen of worker bees changed from black to brown when a defect was induced in the yellow gene using short interfering RNA (siRNA); however, the survival rate did not decrease significantly. These results indicate that the yellow gene participated in the body pigmentation, and its defect was responsible for the br mutation. This study promotes the understanding of the molecular basis of body coloration in honeybees, enriching the molecular mechanisms underlying insect pigmentation.

Genetic basis of variation in thermal developmental plasticity for Drosophila melanogaster body pigmentation.

Seasonal differences in insect pigmentation are attributed to the influence of ambient temperature on pigmentation development. This thermal plasticity is adaptive and heritable, and thereby capable of evolving. However, the specific genes contributing to the variation in plasticity that can drive its evolution remain largely unknown. To address this, we analysed pigmentation and pigmentation plasticity in Drosophila melanogaster. We measured two components of pigmentation in the thorax and abdomen: overall darkness and the proportion of length covered by darker pattern elements (a trident in the thorax and bands in the abdomen) in females from two developmental temperatures (17 or 28°C) and 191 genotypes. Using a GWAS approach to identify the genetic basis of variation in pigmentation and its response to temperature, we identified numerous dispersed QTLs, including some mapping to melanogenesis genes (yellow, ebony, and tan). Remarkably, we observed limited overlap between QTLs for variation within specific temperatures and those influencing thermal plasticity, as well as minimal overlap between plasticity QTLs across pigmentation components and across body parts. For most traits, consistent with selection favouring the retention of plasticity, we found that lower plasticity alleles were often at lower frequencies. The functional analysis of selected candidate QTLs and pigmentation genes largely confirmed their contributions to variation in pigmentation and/or pigmentation plasticity. Overall, our study reveals the existence and underlying basis of extensive and trait-specific genetic variation for pigmentation and pigmentation plasticity, offering a rich reservoir of raw material for natural selection to shape the evolution of these traits independently.

Characterization and RNA interference-mediated silencing of tryptophan 2,3-dioxygenase gene in Carpophilus hemipterus (L.) (Coleoptera: Nitidulidae).

Dried fruit beetle, Carpophilus hemipterus(Linnaeus, 1758) (Coleoptera: Nitidulidae), is a serious pest of ripened fresh fruit in the orchard and dried fruit in postprocessing storage. Despite the economic impact and widespread distribution of C. hemipterus, there is a lack of functional genomics research seeking to elucidate features of molecular physiology for improved pest management. Here, we report the characterization of the gene named Vermilion in C. hemipterus (ChVer) that encodes for tryptophan 2,3-dioxygenase. The Vermilion is frequently used as a visual marker for genomics approaches as tryptophan 2,3-dioxygenase is involved in the biosynthesis of eye coloration pigments in insects. We identified 1628 bp long full-length transcript of ChVer from transcriptomic database of C. hemipterus. The expression analysis among adult body parts revealed peak ChVer expression in head compared to thorax and abdomen, which is consistent with its role. Among the C. hemipterus developmental stages, peak ChVer expression was observed in first instar larva, second instar larva, and adult male stages, whereas the lowest levels of expression were seen in third instar larva, prepupa, and pupa. The nanoinjection of ChVer double-stranded RNAin larval C. hemipterus resulted in a significant reduction in ChVer transcript levels as well as caused a loss of eye color, that is, the white-eyed phenotype in adults. Characterization of visually traceable marker gene and robust RNA interferenceresponse seen in this study will enable genomics research is this important pest.

Exploring the attractiveness of combinations of natural colors and contemporary shapes in fashion design

In this research, the attractiveness of combinations of natural colors and contemporary shapes in fashion design is explored. This was done by means of a questionnaire survey. Four shapes of clothing and ten colors obtained from plant and insect pigments are proposed. The research was conducted in two phases – qualitative and quantitative analysis. The quantitative study confirmed the results of the qualitative study and using an appropriate data reduction method, the study results were analyzed graphically. The results showed that users rated designs with high-contrast color and shape combinations as more attractive than those with low-contrast combinations. The study also showed that in addition to the shape of the garment, the choice of natural color sources can also influence consumer preferences. This study aims to overcome the shortcomings of previous studies that only examined color without investigating its relationship to garment shape. The knowledge gained from this study can help fashion designers create garments that are both aesthetically pleasing and environmentally friendly. However, further research is needed to determine the relationship between natural colors, contemporary shapes and consumer behavior in selecting them.

Temperature-dependent melanism and phenoloxidase activity in the dimorphic sepsid fly Sepsis thoracica

Climate is changing towards both higher average temperatures and more frequent and severe heat waves. Whereas numerous studies have investigated temperature effects on animal life histories, assessments of their immune function are limited. In the size- and colour-dimorphic black scavenger (or dung) fly Sepsis thoracica (Diptera: Sepsidae), we experimentally studied how developmental temperature and larval density influence phenoloxidase (PO) activity, a key enzyme in insect pigmentation, thermoregulation, and immunity. Flies from five latitudinal European populations were raised at three developmental temperatures (18, 24, 30 °C). PO activity increased with developmental temperature differently in the sexes and the two male morphs (black and orange), altering the sigmoid relationship between melanism, i.e. colouration and fly size. PO activity further positively correlated with larval rearing density, potentially because of higher risks of pathogen infection or greater developmental stress following stronger resource competition. Populations varied somewhat in PO activity, body size and colouration, however with no clear latitudinal pattern. Overall our results indicate that morph- and sex-specific PO activity, and thus likely immune function, in S. thoracica depends on temperature and larval density, modifying the underlying putative trade-off between immunity and body size. The strong dampening of the immune system of all morphs at cool temperatures suggests low-temperature stress in this warm-adapted species common in southern Europe. Our results also support the population density dependent prophylaxis hypothesis, which predicts higher investment in immunity when facing limited resource availability and increased pathogen infection probability.

Common Themes and Future Challenges in Understanding Gene Regulatory Network Evolution.

A major driving force behind the evolution of species-specific traits and novel structures is alterations in gene regulatory networks (GRNs). Comprehending evolution therefore requires an understanding of the nature of changes in GRN structure and the responsible mechanisms. Here, we review two insect pigmentation GRNs in order to examine common themes in GRN evolution and to reveal some of the challenges associated with investigating changes in GRNs across different evolutionary distances at the molecular level. The pigmentation GRN in Drosophila melanogaster and other drosophilids is a well-defined network for which studies from closely related species illuminate the different ways co-option of regulators can occur. The pigmentation GRN for butterflies of the Heliconius species group is less fully detailed but it is emerging as a useful model for exploring important questions about redundancy and modularity in cis-regulatory systems. Both GRNs serve to highlight the ways in which redeployment of trans-acting factors can lead to GRN rewiring and network co-option. To gain insight into GRN evolution, we discuss the importance of defining GRN architecture at multiple levels both within and between species and of utilizing a range of complementary approaches.

Melanic pigmentation and light preference within and between two Drosophila species.

Environmental adaptation and species divergence often involve suites of co‐evolving traits. Pigmentation in insects presents a variable, adaptive, and well‐characterized class of phenotypes for which correlations with multiple other traits have been demonstrated. In Drosophila, the pigmentation genes ebony and tan have pleiotropic effects on flies' response to light, creating the potential for correlated evolution of pigmentation and vision. Here, we investigate differences in light preference within and between two sister species, Drosophila americana and D. novamexicana, which differ in pigmentation in part because of evolution at ebony and tan and occupy environments that differ in many variables including solar radiation. We hypothesized that lighter pigmentation would be correlated with a greater preference for environmental light and tested this hypothesis using a habitat choice experiment. In a first set of experiments, using males of D. novamexicana line N14 and D. americana line A00, the light‐bodied D. novamexicana was found slightly but significantly more often than D. americana in the light habitat. A second experiment, which included additional lines and females as well as males, failed to find any significant difference between D. novamexicana‐N14 and D. americana‐A00. Additionally, the other dark line of D. americana (A04) was found in the light habitat more often than the light‐bodied D. novamexicana‐N14, in contrast to our predictions. However, the lightest line of D. americana, A01, was found substantially and significantly more often in the light habitat than the two darker lines of D. americana, thus providing partial support for our hypothesis. Finally, across all four lines, females were found more often in the light habitat than their more darkly pigmented male counterparts. Additional replication is needed to corroborate these findings and evaluate conflicting results, with the consistent effect of sex within and between species providing an especially intriguing avenue for further research.

Many ways to make darker flies: Intra- and interspecific variation in Drosophila body pigmentation components.

Body pigmentation is an evolutionarily diversified and ecologically relevant trait with substantial variation within and between species, and important roles in animal survival and reproduction. Insect pigmentation, in particular, provides some of the most compelling examples of adaptive evolution, including its ecological significance and genetic bases. Pigmentation includes multiple aspects of color and color pattern that may vary more or less independently, and can be under different selective pressures. We decompose Drosophila thorax and abdominal pigmentation, a valuable eco‐evo‐devo model, into distinct measurable traits related to color and color pattern. We investigate intra‐ and interspecific variation for those traits and assess its different sources. For each body part, we measured overall darkness, as well as four other pigmentation properties distinguishing between background color and color of the darker pattern elements that decorate each body part. By focusing on two standard D. melanogaster laboratory populations, we show that pigmentation components vary and covary in distinct manners depending on sex, genetic background, and temperature during development. Studying three natural populations of D. melanogaster along a latitudinal cline and five other Drosophila species, we then show that evolution of lighter or darker bodies can be achieved by changing distinct component traits. Our results paint a much more complex picture of body pigmentation variation than previous studies could uncover, including patterns of sexual dimorphism, thermal plasticity, and interspecific diversity. These findings underscore the value of detailed quantitative phenotyping and analysis of different sources of variation for a better understanding of phenotypic variation and diversification, and the ecological pressures and genetic mechanisms underlying them.

Diversity of Pigments in Insects, Their Synthesis and Economic Value for Various Industries

Pigments play an essential role in imparting colors to the various organs of invertebrates particularly, insects. Genetic evolution and adaptive pigmentation of invertebrates have been studied which depicted that insect colors respond to the climatic changes. The physical, chemical and structural properties of insect pigments are being studied by researchers for years to elucidate their evolutionary aspects of physiology, metabolism, and economic importance for human welfare. Color development in insects varies within the species of different genera. In this state-of-the-art literature review, we discuss the variety of pigments other than visual ones found in different species of insects. The review also highlights the potential benefits or functions of pigments to insects.

Immune function differences between two color morphs of the red palm weevil Rhynchophorus ferrugineus (Coleoptera: Curculionidae) at different life stages.

Several studies demonstrated that in insects cuticle melanism is interrelated with pathogen resistance, as melanin‐based coloration and innate immunity possess similar physiological pathways. For some insects, higher pathogen resistance was observed in darker individuals than in individuals with lighter cuticular coloration. Here, we investigated the difference in immune response between two color morphs (black and red) and between the life stages (pupa and adult) of the red palm weevil Rhynchophorus ferrugineus (Coleoptera: Curculionidae). Here in this study, cuticle thickness, microbial test (antimicrobial activity, phenoloxidase activity, and hemocyte density), and immune‐related gene expression were evaluated at different stages of RPW. Study results revealed that cuticle thickness of black phenotype was thicker than red phenotype at old‐pupa stage, while no significant difference found at adult stage. These results may relate to the development processes of epidermis in different stages of RPW. The results of antimicrobial activity, phenoloxidase (PO) activity, and hemocyte density analyses showed that adults with a red phenotype had stronger pathogen resistance than those with a black phenotype. In addition to antimicrobial activity and PO activity, we tested relative gene expression in the fat body of old pupae. The results of hemolymph antimicrobial analysis showed that old pupae with a red phenotype were significantly different from those with a black phenotype at 12 hr after Staphylococcus aureus injection, suggesting that red phenotype pupae were more sensitive to S. aureus. Examination of gene expression in the fat body also revealed that the red phenotype had a higher immune response than the black phenotype. Our results were inconsistent with the previous conclusion that dark insects had increased immune function, suggesting that the relationship between cuticle pigmentation and immune function in insects was not a direct link. Additional possible factors that are associated with the immune response, such as life‐history, developmental, physiological factors also need to be considered.

Genome-wide identification and gene-editing of pigment transporter genes in the swallowtail butterfly Papilio xuthus

BackgroundInsect body coloration often functions as camouflage to survive from predators or mate selection. Transportation of pigment precursors or related metabolites from cytoplasm to subcellular pigment granules is one of the key steps in insect pigmentation and usually executed via such transporter proteins as the ATP-binding cassette (ABC) transmembrane transporters and small G-proteins (e.g. Rab protein). However, little is known about the copy numbers of pigment transporter genes in the butterfly genomes and about the roles of pigment transporters in the development of swallowtail butterflies.ResultsHere, we have identified 56 ABC transporters and 58 Rab members in the genome of swallowtail butterfly Papilio xuthus. This is the first case of genome-wide gene copy number identification of ABC transporters in swallowtail butterflies and Rab family in lepidopteran insects. Aiming to investigate the contribution of the five genes which are orthologous to well-studied pigment transporters (ABCG: white, scarlet, brown and ok; Rab: lightoid) of fruit fly or silkworm during the development of swallowtail butterflies, we performed CRISPR/Cas9 gene-editing of these genes using P. xuthus as a model and sequenced the transcriptomes of their morphological mutants. Our results indicate that the disruption of each gene produced mutated phenotypes in the colors of larvae (cuticle, testis) and/or adult eyes in G0 individuals but have no effect on wing color. The transcriptomic data demonstrated that mutations induced by CRISPR/Cas9 can lead to the accumulation of abnormal transcripts and the decrease or dosage compensation of normal transcripts at gene expression level. Comparative transcriptomes revealed 606 ~ 772 differentially expressed genes (DEGs) in the mutants of four ABCG transporters and 1443 DEGs in the mutants of lightoid. GO and KEGG enrichment analysis showed that DEGs in ABCG transporter mutants enriched to the oxidoreductase activity, heme binding, iron ion binding process possibly related to the color display, and DEGs in lightoid mutants are enriched in glycoprotein binding and protein kinases.ConclusionsOur data indicated these transporter proteins play an important role in body color of P. xuthus. Our study provides new insights into the function of ABC transporters and small G-proteins in the morphological development of butterflies.

My 60-Year Love Affair with Natural Products.

The author describes his 60-year career in studying the chemistry of natural products, which includes structural, synthetic, and biosynthetic studies of natural products ranging from insect pigments, antibiotics, and fecal mutagens to taxol and other anticancer natural products as well as antimalarial natural products. One of the compounds discussed, napabucasin, is now an anticancer drug in phase III clinical trials.

Imaginal disc growth factor maintains cuticle structure and controls melanization in the spot pattern formation of Bombyx mori.

The complex stripes and patterns of insects play key roles in behavior and ecology. However, the fine-scale regulation mechanisms underlying pigment formation and morphological divergence remain largely unelucidated. Here we demonstrated that imaginal disc growth factor (IDGF) maintains cuticle structure and controls melanization in spot pattern formation of Bombyx mori. Moreover, our knockout experiments showed that IDGF is suggested to impact the expression levels of the ecdysone inducible transcription factor E75A and pleiotropic factors apt-like and Toll8/spz3, to further control the melanin metabolism. Furthermore, the untargeted metabolomics analyses revealed that BmIDGF significantly affected critical metabolites involved in phenylalanine, beta-alanine, purine, and tyrosine metabolism pathways. Our findings highlighted not only the universal function of IDGF to the maintenance of normal cuticle structure but also an underexplored space in the gene function affecting melanin formation. Therefore, this study furthers our understanding of insect pigment metabolism and melanin pattern polymorphisms.

Molecular and Potential Regulatory Mechanisms of Melanin Synthesis in Harmonia axyridis.

Melanization is a common phenomenon in insects, and melanin synthesis is a conserved physiological process that occurs in epidermal cells. Moreover, a comprehensive understanding of the mechanisms of melanin synthesis influencing insect pigmentation are well-suited for investigating phenotype variation. The Asian multi-colored (Harlequin) ladybird beetle, Harmonia axyridis, exhibits intraspecific polymorphism based on relative levels of melanization. However, the specific characteristics of melanin synthesis in H. axyridis remains elusive. In this study, we performed gene-silencing analysis of the pivotal inverting enzyme, tyrosine hydroxylase (TH), and DOPA decarboxylase (DDC) in the tyrosine metabolism pathway to investigate the molecular and regulatory mechanism of melanin synthesis in H. axyridis. Using RNAi of TH and DDC genes in fourth instar larvae, we demonstrated that dopamine melanin was the primary contributor to the overall body melanization of H. axyridis. Furthermore, our study provides the first conclusive evidence that dopamine serves as a melanin precursor for synthesis in the early pupal stage. According to transcription factor Pannier, which is essential for the formation of melanic color on the elytra in H. axyridis, we further demonstrated that suppression of HaPnr can significantly decrease expression levels of HaTH and HaDDC. These results in their entirety lead to the conclusion that transcription factor Pannier can regulate dopamine melanin synthesis in the dorsal elytral epidermis of H. axyridis.

Comparative analysis of integument transcriptomes identifies genes that participate in marking pattern formation in three allelic mutants of silkworm, Bombyx mori

The diversity markings and pigment patterns in insects are outcomes of adaptive evolution. The elucidation of the molecular mechanism underlying variations in pigment patterns may improve our understanding of the origin and evolution of these spectacular diverse phenotypes. Melanin, ommochrome, and pteridine are the three main types of insect pigments, and the genes that directly participate in pigment biosynthesis have been extensively studied. However, available information on gene interactions and the whole pigment regulatory network is limited. In this study, we performed integument transcriptome sequencing to analyze three larval marking allelic mutants, namely, multi lunar (L), LC, and LCa, which have similar twin-spot markings on the dorsal side of multiple segments. Further analysis identified 336 differentially expressed genes (DEGs) between L and Dazao (wild type which exhibits normal markings), 68 DEGs between LC/+ and +LC/+LC, and 188 DEGs between LCa/+ and +LCa/+LCa. Gene Ontology (GO) analysis indicated a significant DEG enrichment of the functional terms catalytic activity, binding, metabolic process, and cellular process. Furthermore, three mutants share six common enriched KEGG pathways. We finally identified eight common DEGs among three pairwise comparisons, including Krueppel-like factor, TATA-binding protein, protein patched, UDP-glycosyltransferase, an unknown secreted protein, and three cuticular proteins. Microarray-based gene expression analysis revealed that the eight genes are upregulated during molting, which coincides with marking formation, and are significantly differentially expressed between marking and non-marking regions. The results suggest that the eight common genes are involved in the construction of the multiple twin-spot marking patterns in the three mutants.

Tyrosine hydroxylase coordinates larval-pupal tanning and immunity in oriental fruit fly (Bactrocera dorsalis).

The oriental fruit fly Bactrocera dorsalis (Hendel), a notorious world pest infesting fruits and vegetables, has evolved a high level of resistance to many commonly used insecticides. In this study, we investigate whether tyrosine hydroxylase (TH) that is required for cuticle tanning (sclerotization and pigmentation) in many insects, could be a potential target in controlling B. dorsalis. We cloned TH cDNA (BdTH) of B. dorsalis. The complete open reading frame of BdTH (KY911196) was 1737 bp in length, encoding a protein of 578 amino acids. Quantitative real-time PCR confirmed that BdTH was highly expressed in the epidermis of 3rd instar larvae, and its expression increased prior to pupation, suggesting a role in larval-pupal cuticle tanning. When we injected dsBdTH or 3-iodo-tyrosine (3-IT) as a TH inhibitor or fed insect diet supplemented with 3-IT, there was significant impairment of larval-pupal cuticle tanning and a severe obstacle to eclosion in adults followed by death in most. Furthermore, injection of Escherichia coli into larvae fed 3-IT resulted in 92% mortality and the expressions of four antimicrobial peptide genes were significantly downregulated. These results suggest that BdTH might play a critical role in larval-pupal tanning and immunity of B. dorsalis, and could be used as a potential novel target for pest control. © 2017 Society of Chemical Industry.