Aop: 360

Title

A descriptive phrase which references both the Molecular Initiating Event and Adverse Outcome.It should take the form “MIE leading to AO”. For example, “Aromatase inhibition leading to reproductive dysfunction” where Aromatase inhibition is the MIE and reproductive dysfunction the AO. In cases where the MIE is unknown or undefined, the earliest known KE in the chain (i.e., furthest upstream) should be used in lieu of the MIE and it should be made clear that the stated event is a KE and not the MIE. More help

Chitin synthase 1 inhibition leading to mortality

Short name
A name that succinctly summarises the information from the title. This name should not exceed 90 characters. More help
CHS-1 inhibition leading to mortality

Graphical Representation

A graphical representation of the AOP.This graphic should list all KEs in sequence, including the MIE (if known) and AO, and the pair-wise relationships (links or KERs) between those KEs. More help
Click to download graphical representation template Explore AOP in a Third Party Tool
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Authors

The names and affiliations of the individual(s)/organisation(s) that created/developed the AOP. More help

Simon Schmid 1,2, You Song 1, and Knut Erik Tollefsen 1,2,3

1 Norwegian Institute for Water Research (NIVA), Section of Ecotoxicology and Risk Assessment, Økernveien 94, N-0579, Oslo, Norway

2 Faculty of Environmental Science and Resource Management (MINA), Norwegian University of Life Sciences (NMBU), N-1432, Ås, Norway

3 Centre for Environmental Radioactivity (CERAD), Norwegian University of Life Sciences (NMBU), N-1432 Ås, Norway

Contact: Simon.Schmid@niva.no

Acknowledgements: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 859891 and was supported by NIVA’s Computational Toxicology Program, NCTP (www.niva.no/nctp).

Point of Contact

The user responsible for managing the AOP entry in the AOP-KB and controlling write access to the page by defining the contributors as described in the next section.   More help
Simon Schmid   (email point of contact)

Contributors

Users with write access to the AOP page.  Entries in this field are controlled by the Point of Contact. More help
  • Simon Schmid
  • You Song
  • Knut Erik Tollefsen

Status

Provides users with information concerning how actively the AOP page is being developed, what type of use or input the authors feel comfortable with given the current level of development, and whether it is part of the OECD AOP Development Workplan and has been reviewed and/or endorsed. OECD Status - Tracks the level of review/endorsement the AOP has been subjected to. OECD Project Number - Project number is designated and updated by the OECD. SAAOP Status - Status managed and updated by SAAOP curators. More help
Author status OECD status OECD project SAAOP status
Open for citation & comment WPHA/WNT Endorsed 1.94 Included in OECD Work Plan
This AOP was last modified on June 21, 2022 09:15

Revision dates for related pages

Page Revision Date/Time
Inhibition, Chitin synthase 1 February 24, 2021 04:41
Decrease, Cuticular chitin content February 17, 2021 05:37
Increase, Premature molting February 17, 2021 05:30
Increase, Mortality October 26, 2020 05:18
Inhibition, CHS-1 leads to Decrease, Cuticular chitin content February 17, 2021 07:50
Decrease, Cuticular chitin content leads to Increase, Premature molting February 17, 2021 08:20
Increase, Premature molting leads to Increase, Mortality February 17, 2021 08:47
Polyoxin B May 24, 2018 15:54
Polyoxin D October 23, 2020 06:20
Nikkomycins May 24, 2018 15:54
Captan October 23, 2020 06:50
Captafol October 23, 2020 06:52
Folpet October 23, 2020 06:53

Abstract

A concise and informative summation of the AOP under development that can stand-alone from the AOP page. The aim is to capture the highlights of the AOP and its potential scientific and regulatory relevance. More help

In order to grow and develop, arthropods need to shed their exoskeleton (or cuticle) periodically and replace it with a new one in a process called molting. Successful molting, and therefore a successful development necessitates stability and integrity of the cuticle to support muscular contractions involved in the shedding of the old cuticle. The integrity of the cuticle is largely dependent on the N-acetylglucosamine (GlcNAc) polymer chitin. Therefore, arthropods heavily rely on chitin synthesis as chitin is one of the main constituents of the cuticle. The cuticular chitin synthase (CHS-1) is the key enzyme in the biosynthetic pathway and arthropods are therefore especially dependent on its proper function. The present AOP describes the effects of chemical inhibition of the cuticular chitin synthase (CHS-1) on the molting process leading to increased mortality in arthropods. Inhibition of CHS-1 is the molecular initiating event and leads to a decreased chitin content in the arthropod cuticle which leaves the organism immature at the stage for ecdysis. This phenomenon can be described as premature molting. The organism eventually dies due to being stuck in the old cuticle or due to the consequences of a weak exoskeleton after ecdysis. The AOP is considered to be very consistent. Essentiality of key events was rated as high for every key event and the biological plausibility was rated as high for the whole AOP. However, there does not exist very much empirical evidence that allows to draw a representative conclusion on dose concordance along the AOP whereas time concordance can be supported by knockdown studies of CHS-1. Therefore, empirical evidence was considered to be moderate and the quantitative understanding was considered to be low. The overall confidence in the AOP was valued as moderate. The present AOP will guide assay development for further experimental studies by revealing data and knowledge gaps. One of its primary applications will also be providing guidance in screening strategies in order to identify chemicals directly interacting with CHS-1.

AOP Development Strategy

Context

Used to provide background information for AOP reviewers and users that is considered helpful in understanding the biology underlying the AOP and the motivation for its development.The background should NOT provide an overview of the AOP, its KEs or KERs, which are captured in more detail below. More help

Arthropods (including insects, crustaceans and arachnids) need to shed their exoskeleton in order to grow and reproduce. This process, also called molting or ecdysis, is mediated by behavioural mechanisms which involve the skeletal muscles (Ayali 2009; Song et al. 2017a). In order to properly shed its cuticle, the organism needs to possess a newly synthesized cuticle that possesses a certain integrity to support this process. Since chitin is a major constituent of the cuticle, it contributes substantially to its integrity (Cohen 2001; Vincent and Wegst 2004). Chitin is synthesized from uridine diphosphate-N-Acetylglucosamine (UDP-GlcNAc) in a polymerization reaction by the transmembrane enzyme chitin synthase isoform 1 (CHS-1). CHS-1 is localized on the apical side in the cuticular epithelium. Since chitin and the process of chitin synthesis does not occur in vertebrates, it can and has been exploited for the design of pest controlling agents. Inhibitors of chitin synthesis may not only be of use for the control of unwanted arthropods and fungi, they may also pose a risk for beneficial arthropods such as insects and crustaceans. Disruption of chitin synthesis or the endocrine mechanisms controlling molting generally lead to a disruption of ecdysis (Merzendorfer et al. 2012; Song et al. 2017a; Song et al. 2017b). If the amount of chitin in the cuticle decreases, the affected organism may not be able to molt properly and will most probably die of starvation or suffocation (Camp et al. 2014; Song et al. 2017a). Alternatively, if molting is completed despite an immature cuticle, the organism may be deformed and die as a consequence of a weak cuticle. Therefore, the present AOP should build the basis of a mechanistic approach for the systematic evaluation and the risk assessment of chemicals interfering with chitin synthesis by directly inhibiting CHS-1.

Strategy

Provides a description of the approaches to the identification, screening and quality assessment of the data relevant to identification of the key events and key event relationships included in the AOP or AOP network.This information is important as a basis to support the objective/envisaged application of the AOP by the regulatory community and to facilitate the reuse of its components.  Suggested content includes a rationale for and description of the scope and focus of the data search and identification strategy/ies including the nature of preliminary scoping and/or expert input, the overall literature screening strategy and more focused literature surveys to identify additional information (including e.g., key search terms, databases and time period searched, any tools used). More help

Summary of the AOP

This section is for information that describes the overall AOP. The information described in section 1 is entered on the upper portion of an AOP page within the AOP-Wiki. This is where some background information may be provided, the structure of the AOP is described, and the KEs and KERs are listed. More help

Events:

Molecular Initiating Events (MIE)
An MIE is a specialised KE that represents the beginning (point of interaction between a prototypical stressor and the biological system) of an AOP. More help
Key Events (KE)
A measurable event within a specific biological level of organisation. More help
Adverse Outcomes (AO)
An AO is a specialized KE that represents the end (an adverse outcome of regulatory significance) of an AOP. More help
Type Event ID Title Short name
MIE 1522 Inhibition, Chitin synthase 1 Inhibition, CHS-1
KE 1523 Decrease, Cuticular chitin content Decrease, Cuticular chitin content
KE 1524 Increase, Premature molting Increase, Premature molting
AO 350 Increase, Mortality Increase, Mortality

Relationships Between Two Key Events (Including MIEs and AOs)

This table summarizes all of the KERs of the AOP and is populated in the AOP-Wiki as KERs are added to the AOP.Each table entry acts as a link to the individual KER description page. More help

Network View

This network graphic is automatically generated based on the information provided in the MIE(s), KEs, AO(s), KERs and Weight of Evidence (WoE) summary tables. The width of the edges representing the KERs is determined by its WoE confidence level, with thicker lines representing higher degrees of confidence. This network view also shows which KEs are shared with other AOPs. More help

Prototypical Stressors

A structured data field that can be used to identify one or more “prototypical” stressors that act through this AOP. Prototypical stressors are stressors for which responses at multiple key events have been well documented. More help

Life Stage Applicability

The life stage for which the AOP is known to be applicable. More help
Life stage Evidence
Larvae High
Juvenile High
Adult Moderate

Taxonomic Applicability

Latin or common names of a species or broader taxonomic grouping (e.g., class, order, family) can be selected.In many cases, individual species identified in these structured fields will be those for which the strongest evidence used in constructing the AOP was available. More help
Term Scientific Term Evidence Link
Pieris brassicae Pieris brassicae High NCBI
Anopheles gambiae Anopheles gambiae High NCBI
Lucilia cuprina Lucilia cuprina High NCBI
Tribolium castaneum Tribolium castaneum High NCBI
Bombyx mori Bombyx mori High NCBI
Anopheles quadrimaculatus Anopheles quadrimaculatus High NCBI
Trichoplusia ni Trichoplusia ni High NCBI
Artemia salina Artemia salina High NCBI
Daphnia magna Daphnia magna High NCBI
Hyalophora cecropia Hyalophora cecropia High NCBI
Ostrinia nubilalis Ostrinia nubilalis High NCBI
Bradysia hygida Bradysia hygida Moderate NCBI
Mamestra brassicae Mamestra brassicae Moderate NCBI
Chilo suppressalis Chilo suppressalis Moderate NCBI
Locusta migratoria Locusta migratoria Moderate NCBI
Nilaparvata lugens Nilaparvata lugens Moderate NCBI
Aphis glycines Aphis glycines Moderate NCBI
Lepeophtheirus salmonis Lepeophtheirus salmonis Moderate NCBI
Panonychus citri Panonychus citri Moderate NCBI
Grapholita molesta Grapholita molesta Moderate NCBI
Ectropis obliqua Ectropis obliqua Moderate NCBI
Tigriopus japonicus Tigriopus japonicus Moderate NCBI

Sex Applicability

The sex for which the AOP is known to be applicable. More help
Sex Evidence
Unspecific Moderate

Overall Assessment of the AOP

Addressess the relevant biological domain of applicability (i.e., in terms of taxa, sex, life stage, etc.) and Weight of Evidence (WoE) for the overall AOP as a basis to consider appropriate regulatory application (e.g., priority setting, testing strategies or risk assessment). More help

Domain of Applicability

Addressess the relevant biological domain(s) of applicability in terms of sex, life-stage, taxa, and other aspects of biological context. More help

Taxonomic: Since the whole phylum of arthropods is dependent on the synthesis of chitin to molt successfully, it is extremely likely that the AOP is applicable to all arthropods. Effect data along the AOP exist from Dipteran, Lepidopteran and Coleopteran insect species as well as from Branchiopods and Anostracans of the crustacea. Although data is limited, KEs seem to be well conserved across taxa, as shown in available studies with specific stressors known to inhibit CHS and in studies where CHS-1 was knocked down by RNA interference. However, due to limited data availability, it was not possible to cover whole taxa but rather single species in the assessment of KEs. Alignment of amino acid residues in the catalytic center of CHS-1 using the Sequence Alignment to Predict Across Species Susceptibility tool (SeqAPASS, https://seqapass.epa.gov/seqapass, LaLone et al. 2016), confirmed structural and functional conservation in various insect, arachnid and crustacean species, strenghtening the evidence for the applicability domain to be the whole phylum of arthropods. However, taxonomic applicability may not only be defined by structural conservation of the protein sequence. So the evidence for the taxonomic applicability for species with support only from sequence alignment was judged as moderate, whereas evidence for species with support from sequence alignment and effect data was judged as high.

Life stage: The AOP is applicable for organisms undergoing continuous molt cycles. As insects do not molt in their adulthood, the AOP is only applicable for larval and pupal stages of insects. Crustaceans and arachnids grow and molt throughout their lifetime (Passano 1961; Uhl et al. 2015), which makes the AOP applicable to all life stages, where juvenile life stages might be more susceptible to chemical perturbations due to higher growth rate and therefore more frequent molting.

Sex: The AOP is applicable to all sexes.

Chemical: Substances known to trigger the MIE and leading to the AO are of the family of pyrimidine nucleosides (e.g. polyoxin D, polyoxin B and nikkomycin Z) (Osada 2019). There also exists evidence for phthalimides (captan, captafol and folpet) to inhibit CHS-1 activity and to decrease the cuticular chitin content in vitro (Cohen and Casida 1982; Gelman and Borkovec 1986). However, as these substances are known to covalently bind to thiol groups in proteins (Lukens and Sisler 1958), it is not clear if the inhibition is due to specific CHS-1 inhibition or due to unspecific protein binding.

Essentiality of the Key Events

The essentiality of KEs can only be assessed relative to the impact of manipulation of a given KE (e.g., experimentally blocking or exacerbating the event) on the downstream sequence of KEs defined for the AOP. Consequently, evidence supporting essentiality is assembled on the AOP page, rather than on the independent KE pages that are meant to stand-alone as modular units without reference to other KEs in the sequence. The nature of experimental evidence that is relevant to assessing essentiality relates to the impact on downstream KEs and the AO if upstream KEs are prevented or modified. This includes: Direct evidence: directly measured experimental support that blocking or preventing a KE prevents or impacts downstream KEs in the pathway in the expected fashion. Indirect evidence: evidence that modulation or attenuation in the magnitude of impact on a specific KE (increased effect or decreased effect) is associated with corresponding changes (increases or decreases) in the magnitude or frequency of one or more downstream KEs. More help

The essentiality of all key events was considered as high. Essentiality evaluations were mainly based on specifically designed studies demonstrating the expected effect pattern predicted by the AOP to occur after knockdown of CHS-1.

Inhibition, Chitin synthase 1 (High): Knockdown of the cuticular chitin synthase leads to the expected pattern of effects described in this AOP. It decreases the cuticular chitin content and leads to premature molting associated mortality in insects (Arakane et al. 2005; X. Zhang et al. 2010; Li et al. 2017; Zhai et al. 2017). If the cuticular chitin content was not directly measured as endpoint, knockdown of the CHS-1 led directly to the occurrence of premature molting associated increase of mortality (Chen et al. 2008; X. Zhang et al. 2010; Wang et al. 2012; Yang et al. 2013; Shang et al. 2016; Mohammed et al. 2017; Wang et al. 2019; Ye et al. 2019; Ullah et al. 2020)

Decrease, Cuticular chitin content (High): Abolishment of the cuticular chitin synthesis through knockdown of CHS-1 leads to premature molting associated mortality (Arakane et al. 2005; X. Zhang et al. 2010; Li et al. 2017; Zhai et al. 2017). By knocking down the UDP-GlcNAc pyrophosphorylase (UAP), which catalyzes the last sugar conversion before the polymerization to chitin, it was shown that reduced chitin content leads to the same outcome as the knockdown of CHS-1. Namely premature molting and increased mortality (Arakane et al. 2011; Liu et al. 2013). Knockdown of trehalase genes, which constitutes the start of the chitin synthetic pathway and convert trehalose to glucose, leads to a similar pattern of effects, namely decreased cuticular chitin content and premature molting associated mortality (Chen et al. 2010; Shi et al. 2016).

Increase, Premature molting (High): Several studies show that premature molting is a direct consequence of decreased chitin synthesis and leads to increased mortality. The KE is consistently listed as cause for mortality when CHS-1 is knocked down throughout a number of studies (Arakane et al. 2005; Chen et al. 2008; J. Zhang et al. 2010; X. Zhang et al. 2010; Wang et al. 2012; Yang et al. 2013; Shang et al. 2016; Li et al. 2017; Mohammed et al. 2017; Zhai et al. 2017; Wang et al. 2019; Ye et al. 2019).

Increase, Mortality (High): Increased mortality was observed in all of the abovementioned studies.

Evidence Assessment

Addressess the biological plausibility, empirical support, and quantitative understanding from each KER in an AOP. More help

Biological Plausibility: The biosynthesis of chitin is well characterized and is conserved among arthropods. Although the exact mode of action of chitin synthases remains elusive, it is widely accepted and well established that the chitin synthase is the key enzyme in the pathway, polymerizing chitin using UDP-N-Acetylglucosamine as substrate (Merzendorfer and Zimoch 2003). Arthropod cuticles mostly consist of chitin embedded into a matrix of cuticular proteins. It is therefore widely accepted that chitin contributes crucially to the quality and function of the cuticle (Reynolds 1987; Muthukrishnan et al. 2012). The molting process requires the new cuticle to be strong enough to withstand the stresses of ecdysis. During ecdysis, arthropods pause food intake and growth. If ecdysis is initiated before the new cuticle is strong enough, the organism likely dies of starvation or growth arrest (Song, Villeneuve, et al. 2017). It was also reported that certain arthropods pause respiration during ecdysis, which may lead to suffocation (Camp et al. 2014). Based on the well-established biological knowledge on the processes this AOP bases on, the biological plausibility for all KER was rated as high.

Empirical Evidence: Empirical evidence assessment was conducted on the basis of in vitro and in vivo experiments performed with stressors affecting key events throughout the AOP. Studies showed that the key events are affected by model stressors such as Polyoxin D and Nikkomycin Z, which are able to competitively inhibit CHS1 (Endo et al. 1970). Several studies provide evidence that polyoxin B, polyoxin D and nikkomycin Z trigger the MIE in cell free systems of coleopteran, lepidopteran and dipteran insect species (Cohen 1982; Turnbull and Howells 1982; Kuwano and Cohen 1984; Cohen and Casida 1990; Zhang and Yan Zhu 2013). Also the cuticular chitin content was shown to be decreased by polyoxin D and nikkomycin Z in lepidopteran and dipteran species as well as in the crustacean Artemia salina (Gijswijt et al. 1979; Calcott and Fatig 1984; Gelman and Borkovec 1986; Zhuo et al. 2014). The AO is supported by in vivo studies with polyoxin D and nikkomycin Z in dipteran insects and Daphnia magna (Tellam et al. 2000; Tellam and Eisemann 2000; Zhu et al. 2007; Zhang and Yan Zhu 2013; New Zealand Environmental Protection Authority 2015). A major data gap constitutes the absence of data covering the KE “Increase, premature molting”. This KE is mentioned in some studies but never assessed as an individual endpoint (Gijswijt et al. 1979; Tellam et al. 2000). Another major data gap is the lacking quantitative data for KERs. As endpoints were only measured as individual endpoints and not in sequence, it makes it nearly impossible to evaluate the dose for the KEs and KERs. However, data from studies where CHS-1 was knocked down are able to support temporal concordance for all KERs. Knockdown of CHS-1 led to decreased chitin content and subsequently to premature molting associated mortality (Arakane et al., 2005; Li et al., 2017). Based on the major data gaps and therefore the lacking information on dose concordance as well as the given time concordance, empirical evidence was evaluated to be moderate for the whole AOP.

Overall confidence in the AOP: Both, essentiality of KEs and the biological plausibility of the whole AOP were considered to be high. However, due to missing quantitative data and the lack of evidence for dose concordance, empirical evidence was judged to be moderate. Therefore the overall confidence in the AOP was evaluated as moderate.

Known Modulating Factors

Modulating factors (MFs) may alter the shape of the response-response function that describes the quantitative relationship between two KES, thus having an impact on the progression of the pathway or the severity of the AO.The evidence supporting the influence of various modulating factors is assembled within the individual KERs. More help

Quantitative Understanding

Optional field to provide quantitative weight of evidence descriptors.  More help

Quantitative data are limited for all KER and therefore the whole AOP. Therefore, predictions on the occurrence of downstream KE and the AO on the basis of the occurrence of upstream KEs is not readily feasible. Quantitative understanding of the AOP was therefore considered to be low.

Considerations for Potential Applications of the AOP (optional)

Addressess potential applications of an AOP to support regulatory decision-making.This may include, for example, possible utility for test guideline development or refinement, development of integrated testing and assessment approaches, development of (Q)SARs / or chemical profilers to facilitate the grouping of chemicals for subsequent read-across, screening level hazard assessments or even risk assessment. More help

Arthropods are responsible for many functions in terrestrial as well as aquatic ecosystems and are therefore jointly responsible for ecosystem health (Seastedt and Crossley 1984; Losey and Vaughan 2006; LeBlanc 2007). Therefore, it is important to develop AOPs which enhance the mechanistic knowledge on chemicals, such as chitin synthesis inhibitors, which may pose a risk to non-target arthropods. Those AOPs will contribute to the systematic use of mechanistic data to preserve beneficial arthropod populations and ecosystem health. The present AOP will help to guide future experimental studies by identifying data gaps. This will lead to the identification and development suitable bioassays in order to populate the AOP with (quantitative) experimental data which may allow for predictions of regulatory relevant endpoints on the basis of the occurrence of the MIE. The present AOP may also guide screening strategies in order to identify chemicals inhibiting CHS-1. The identified substances may then be prioritized and undergo a thorough hazard assessment. As there already exist approaches to assess mixture toxicity using the AOP framework (Altenburger et al. 2012; Beyer et al. 2014), the present AOP could be employed for the effect assessment  of mixtures of chemicals that share the same KEs (e.g. AOP #361, aopwiki.org/aops/361, AOP #358, aopwiki.org/aops/358, and AOP #359, aopwiki.org/aops/359).

References

List of the literature that was cited for this AOP. More help

Altenburger R, Scholz S, Schmitt-Jansen M, Busch W, Escher BI. 2012. Mixture toxicity revisited from a toxicogenomic perspective. Environ Sci Technol. 46(5):2508–2522. doi:10.1021/es2038036.

Arakane Y, Baguinon MC, Jasrapuria S, Chaudhari S, Doyungan A, Kramer KJ, Muthukrishnan S, Beeman RW. 2011. Both UDP N-acetylglucosamine pyrophosphorylases of Tribolium castaneum are critical for molting, survival and fecundity. Insect Biochem Mol Biol. 41(1):42–50. doi:10.1016/j.ibmb.2010.09.011. http://dx.doi.org/10.1016/j.ibmb.2010.09.011.

Arakane Y, Muthukrishnan S, Kramer KJ, Specht CA, Tomoyasu Y, Lorenzen MD, Kanost M, Beeman RW. 2005. The Tribolium  chitin synthase genes TcCHS1 and TcCHS2 are specialized for synthesis of epidermal cuticle and midgut peritrophic matrix. Insect Mol Biol. 14(5):453–463. doi:10.1111/j.1365-2583.2005.00576.x.

Ayali A. 2009. The role of the arthropod stomatogastric nervous system in moulting behaviour and ecdysis. J Exp Biol. 212(4):453–459. doi:10.1242/jeb.023879.

Beyer J, Petersen K, Song Y, Ruus A, Grung M, Bakke T, Tollefsen KE. 2014. Environmental risk assessment of combined effects in aquatic ecotoxicology: A discussion paper. Mar Environ Res. 96:81–91. doi:10.1016/j.marenvres.2013.10.008. http://dx.doi.org/10.1016/j.marenvres.2013.10.008.

Calcott PH, Fatig RO. 1984. Inhibition of Chitin metabolism by Avermectin in susceptible Organisms. J Antibiot (Tokyo). 37(3):253–259. doi:10.7164/antibiotics.37.253.

Camp AA, Funk DH, Buchwalter DB. 2014. A stressful shortness of breath: Molting disrupts breathing in the mayfly Cloeon dipterum. Freshw Sci. 33(3):695–699. doi:10.1086/677899.

Chen Jie, Tang B, Chen H, Yao Q, Huang X, Chen Jing, Zhang D, Zhang W. 2010. Different functions of the insect soluble and membrane-bound trehalase genes in chitin biosynthesis revealed by RNA interference. PLoS One. 5(4). doi:10.1371/journal.pone.0010133.

Chen X, Tian H, Zou L, Tang B, Hu J, Zhang W. 2008. Disruption of Spodoptera exigua larval development by silencing chitin synthase gene A with RNA interference. Bull Entomol Res. 98(6):613–619. doi:10.1017/S0007485308005932.

Cohen E. 1982. In vitro chitin synthesis in an insect: formation and structure of microfibrils. Eur J Cell Biol. 26(2):289–294.

Cohen E. 2001. Chitin synthesis and inhibition: A revisit. Pest Manag Sci. 57(10):946–950. doi:10.1002/ps.363.

Cohen E, Casida JE. 1982. Properties and inhibition of insect integumental chitin synthetase. Pestic Biochem Physiol. 17(3):301–306. doi:10.1016/0048-3575(82)90141-9.

Cohen E, Casida JE. 1990. Insect and Fungal Chitin Synthetase Activity: Specificity of Lectins as Enhancers and Nucleoside Peptides as Inhibitors. Pestic Biochem Physiol. 37(3):249–253. doi:10.1016/0048-3575(90)90131-K.

Endo A, Kakiki K, Misato T. 1970. Mechanism of action of the antifugal agent polyoxin D. J Bacteriol. 104(1):189–196. doi:10.1128/jb.104.1.189-196.1970.

Gelman DB, Borkovec AB. 1986. The pharate adult clasper as a tool for measuring chitin synthesis and for identifying new chitin synthesis inhibitors. Comp Biochem Physiol Part C, Comp. 85(1):193–197. doi:10.1016/0742-8413(86)90073-3.

Gijswijt MJ, Deul DH, de Jong BJ. 1979. Inhibition of chitin synthesis by benzoyl-phenylurea insecticides, III. Similarity in action in Pieris brassicae (L.) with Polyoxin D. Pestic Biochem Physiol. 12(1):87–94. doi:10.1016/0048-3575(79)90098-1.

Kuwano E, Cohen E. 1984. The use of a Tribolium chitin synthetase assay in studying the effects of benzimidazoles with a terpene moiety and related compounds. Agric Biol Chem. 48(6):1617–1620. doi:10.1080/00021369.1984.10866362.

LaLone, C.A., Villeneuve, D.L., Lyons, D., Helgen, H.W., Robinson, S.L., Swintek, J.A., Saari, T.W., Ankley, G.T., 2016. Sequence alignment to predict across species susceptibility (seqapass): A web-based tool for addressing the challenges of cross-species extrapolation of chemical toxicity. Toxicol. Sci. 153, 228–245. https://doi.org/10.1093/toxsci/kfw119

LeBlanc GA. 2007. Crustacean endocrine toxicology: A review. Ecotoxicology. 16(1):61–81. doi:10.1007/s10646-006-0115-z.

Li T, Chen J, Fan X, Chen W, Zhang W. 2017. MicroRNA and dsRNA targeting chitin synthase A reveal a great potential for pest management of the hemipteran insect Nilaparvata lugens. Pest Manag Sci. 73(7):1529–1537. doi:10.1002/ps.4492.

Liu X, Li F, Li D, Ma E, Zhang W, Zhu KY, Zhang J. 2013. Molecular and functional analysis of UDP-N-acetylglucosamine Pyrophosphorylases from the Migratory Locust, Locusta migratoria. PLoS One. 8(8). doi:10.1371/journal.pone.0071970.

Losey JE, Vaughan M. 2006. The economic value of ecological services provided by insects. Bioscience. 56(4):311–323. doi:10.1641/0006-3568(2006)56[311:TEVOES]2.0.CO;2.

Lukens RJ, Sisler HD. 1958. 2-Thiazolidinethione-4-carboxylic acid from the reaction of captan with cysteine. Science (80- ). 127(3299):650. doi:10.1126/science.127.3299.650.

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