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Kitchen SA, Naragon TH, Brückner A, Ladinsky MS, Quinodoz SA, Badroos JM, Viliunas JW, Kishi Y, Wagner JM, Miller DR, Yousefelahiyeh M, Antoshechkin IA, Eldredge KT, Pirro S, Guttman M, Davis SR, Aardema ML, Parker J. The genomic and cellular basis of biosynthetic innovation in rove beetles. Cell 2024; 187:3563-3584.e26. [PMID: 38889727 PMCID: PMC11246231 DOI: 10.1016/j.cell.2024.05.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 02/29/2024] [Accepted: 05/06/2024] [Indexed: 06/20/2024]
Abstract
How evolution at the cellular level potentiates macroevolutionary change is central to understanding biological diversification. The >66,000 rove beetle species (Staphylinidae) form the largest metazoan family. Combining genomic and cell type transcriptomic insights spanning the largest clade, Aleocharinae, we retrace evolution of two cell types comprising a defensive gland-a putative catalyst behind staphylinid megadiversity. We identify molecular evolutionary steps leading to benzoquinone production by one cell type via a mechanism convergent with plant toxin release systems, and synthesis by the second cell type of a solvent that weaponizes the total secretion. This cooperative system has been conserved since the Early Cretaceous as Aleocharinae radiated into tens of thousands of lineages. Reprogramming each cell type yielded biochemical novelties enabling ecological specialization-most dramatically in symbionts that infiltrate social insect colonies via host-manipulating secretions. Our findings uncover cell type evolutionary processes underlying the origin and evolvability of a beetle chemical innovation.
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Affiliation(s)
- Sheila A Kitchen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Thomas H Naragon
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Adrian Brückner
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Mark S Ladinsky
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Sofia A Quinodoz
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Jean M Badroos
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Joani W Viliunas
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Yuriko Kishi
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Julian M Wagner
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - David R Miller
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Mina Yousefelahiyeh
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Igor A Antoshechkin
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - K Taro Eldredge
- Museum of Zoology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Stacy Pirro
- Iridian Genomes, 613 Quaint Acres Dr., Silver Spring, MD 20904, USA
| | - Mitchell Guttman
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Steven R Davis
- Division of Invertebrate Zoology, American Museum of Natural History, New York, NY 10024, USA
| | - Matthew L Aardema
- Department of Biology, Montclair State University, Montclair, NJ 07043, USA
| | - Joseph Parker
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
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2
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Kitchen SA, Naragon TH, Brückner A, Ladinsky MS, Quinodoz SA, Badroos JM, Viliunas JW, Wagner JM, Miller DR, Yousefelahiyeh M, Antoshechkin IA, Eldredge KT, Pirro S, Guttman M, Davis SR, Aardema ML, Parker J. The genomic and cellular basis of biosynthetic innovation in rove beetles. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.29.542378. [PMID: 37398185 PMCID: PMC10312436 DOI: 10.1101/2023.05.29.542378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
How evolution at the cellular level potentiates change at the macroevolutionary level is a major question in evolutionary biology. With >66,000 described species, rove beetles (Staphylinidae) comprise the largest metazoan family. Their exceptional radiation has been coupled to pervasive biosynthetic innovation whereby numerous lineages bear defensive glands with diverse chemistries. Here, we combine comparative genomic and single-cell transcriptomic data from across the largest rove beetle clade, Aleocharinae. We retrace the functional evolution of two novel secretory cell types that together comprise the tergal gland-a putative catalyst behind Aleocharinae's megadiversity. We identify key genomic contingencies that were critical to the assembly of each cell type and their organ-level partnership in manufacturing the beetle's defensive secretion. This process hinged on evolving a mechanism for regulated production of noxious benzoquinones that appears convergent with plant toxin release systems, and synthesis of an effective benzoquinone solvent that weaponized the total secretion. We show that this cooperative biosynthetic system arose at the Jurassic-Cretaceous boundary, and that following its establishment, both cell types underwent ∼150 million years of stasis, their chemistry and core molecular architecture maintained almost clade-wide as Aleocharinae radiated globally into tens of thousands of lineages. Despite this deep conservation, we show that the two cell types have acted as substrates for the emergence of adaptive, biochemical novelties-most dramatically in symbiotic lineages that have infiltrated social insect colonies and produce host behavior-manipulating secretions. Our findings uncover genomic and cell type evolutionary processes underlying the origin, functional conservation and evolvability of a chemical innovation in beetles.
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Mate attraction, chemical defense, and competition avoidance in the parasitoid wasp Leptopilina pacifica. CHEMOECOLOGY 2020. [DOI: 10.1007/s00049-020-00331-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
AbstractA major hypothesis for the evolution of chemical signals is that pheromones arise from non-communicative precursor compounds. However, data supporting this hypothesis are rare, primarily because the original functions of the antecedent compounds often have been lost. A notable exception, however, is the parasitoid wasp species Leptopilina heterotoma, whose compound (−)-iridomyrmecin is used as a defensive secretion, a cue for females to avoid competition with con- and hetero-specific females, and as the primary component of the females’ sex pheromone. To better understand the evolution of sex pheromones from defensive compounds, we examined the chemical ecology of L. pacifica, the sister species of L. heterotoma. Here, we show that L. pacifica also produces a defensive secretion containing a species-specific mixture of mostly iridoid compounds. However, the composition of the secretion is more complex than in L. heterotoma, and iridomyrmecin is only a minor component. Moreover, in contrast to L. heterotoma, conspecific female competitors were not avoided by female subjects, and a role of the iridoids in the female sex pheromone of L. pacifica can be excluded, as only the females’ cuticular hydrocarbons (CHCs) resulted in the elicitation of courtship by males. Although closely related, the two sister species show substantial differences in the use of the defensive secretion for communicative purposes. Variation in pheromone usage in this genus still presents a conundrum, highlighting the need for additional studies to understand the selective forces shaping the evolution of pheromone composition.
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Temperature Affects Chemical Defense in a Mite-Beetle Predator-Prey System. J Chem Ecol 2020; 46:947-955. [PMID: 32875537 DOI: 10.1007/s10886-020-01212-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 07/31/2020] [Accepted: 08/24/2020] [Indexed: 10/23/2022]
Abstract
Temperature influences all biochemical and biophysiological processes within an organism. By extension, it also affects those ecological interactions that are mediated by gland-produced chemical compounds, such as reservoir-based chemical defense. Herein, we investigate how environmental temperature affects the regeneration of defensive secretions and influences the efficacy of chemical defense in a model predator-prey system: the oribatid mite Archegozetes longisetosus and the predaceous rove beetle Stenus juno. Through a combination of chemical analyses, non-linear regression modeling and theoretical simulations we show that the amount of defensive secretion responded to temperature in a unimodal optimum curve: the regeneration rate followed a positive, linear relationship up to 35 °C, but rapidly broke down beyond this temperature ("tipping point" effect). Using functional response simulations, there is an initially positive dampening effect on the predation rate when regeneration is optimal, but at higher temperatures chemical defense does not counteract the previously described effects of elevated predatory pressure. In a larger context, our results demonstrate the need to integrate relevant environmental factors in predator-prey modeling approaches.
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Brückner A, Kaltenpoth M, Heethoff M. De novo biosynthesis of simple aromatic compounds by an arthropod ( Archegozetes longisetosus). Proc Biol Sci 2020; 287:20201429. [PMID: 32873199 PMCID: PMC7542773 DOI: 10.1098/rspb.2020.1429] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The ability to synthesize simple aromatic compounds is well known from bacteria, fungi and plants, which all share an exclusive biosynthetic route—the shikimic acid pathway. Some of these organisms further evolved the polyketide pathway to form core benzenoids via a head-to-tail condensation of polyketide precursors. Arthropods supposedly lack the ability to synthesize aromatics and instead rely on aromatic amino acids acquired from food, or from symbiotic microorganisms. The few studies purportedly showing de novo biosynthesis via the polyketide synthase (PKS) pathway failed to exclude endosymbiotic bacteria, so their results are inconclusive. We investigated the biosynthesis of aromatic compounds in defence secretions of the oribatid mite Archegozetes longisetosus. Exposing the mites to a diet containing high concentrations of antibiotics removed potential microbial partners but did not affect the production of defensive benzenoids. To gain insights into benzenoid biosynthesis, we fed mites with stable-isotope labelled precursors and monitored incorporation with mass spectrometry. Glucose, malonic acid and acetate, but not phenylalanine, were incorporated into the benzenoids, further evidencing autogenous biosynthesis. Whole-transcriptome sequencing with hidden Markov model profile search of protein domain families and subsequent phylogenetic analysis revealed a putative PKS domain similar to an actinobacterial PKS, possibly indicating a horizontal gene transfer.
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Affiliation(s)
- Adrian Brückner
- Technische Universität Darmstadt, Ecological Networks, Schnittspahnstraße 3, 64287 Darmstadt, Germany.,California Institute of Technology, Division of Biology and Biological Engineering, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Martin Kaltenpoth
- Evolutionary Ecology, Institute of Organismic and Molecular Evolution, Johannes Gutenberg University, Johann-Joachim-Becher-Weg 13, 55128 Mainz, Germany.,Department of Insect Symbiosis, Max Planck Institute for Chemical Ecology, Hans-Knöll-Strasse 8, 07745 Jena, Germany
| | - Michael Heethoff
- Technische Universität Darmstadt, Ecological Networks, Schnittspahnstraße 3, 64287 Darmstadt, Germany
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Schmelzle S, Blüthgen N. Under pressure: force resistance measurements in box mites (Actinotrichida, Oribatida). Front Zool 2019; 16:24. [PMID: 31312228 PMCID: PMC6611053 DOI: 10.1186/s12983-019-0325-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 06/12/2019] [Indexed: 11/10/2022] Open
Abstract
Background Mechanical defenses are very common and diverse in prey species, for example in oribatid mites. Here, the probably most complex form of morphological defense is known as ptychoidy, that enables the animals to completely retract the appendages into a secondary cavity and encapsulate themselves. The two groups of ptychoid mites constituting the Ptyctima, i.e. Euphthiracaroidea and Phthiracaroidea, have a hardened cuticle and are well protected against similar sized predators. Euphthiracaroidea additionally feature predator-repelling secretions. Since both taxa evolved within the glandulate group of Oribatida, the question remains why Phthiracaroidea lost this additional protection. In earlier predation bioassays, chemically disarmed specimens of Euphthiracaroidea were cracked by the staphylinid beetle Othius punctulatus, whereas equally sized specimens of Phthiracaroidea survived. We thus hypothesized that Phthiracaroidea can withstand significantly more force than Euphthiracaroidea and that the specific body form in each group is key in understanding the loss of chemical defense in Phthiracaroidea. To measure force resistance, we adapted the principle of machines applying compressive forces for very small animals and tested the two ptyctimous taxa as well as the soft-bodied mite Archegozetes longisetosus. Results Some Phthiracaroidea individuals sustained about 560,000 times their body weight. Their mean resistance was about three times higher, and their mean breaking point in relation to body weight nearly two times higher than Euphthiracaroidea individuals. The breaking point increased with body weight and differed significantly between the two taxa. Across taxa, the absolute force resistance increased sublinearly (with a 0.781 power term) with the animal's body weight. Force resistance of A. longisetosus was inferior in all tests (about half that of Euphthiracaroidea after accounting for body weight). As an important determinant of mechanical resistance in ptychoid mites, the individuals' cuticle thickness increased sublinearly with body diameter and body mass as well and did not differ significantly between the taxa. Conclusion We showed the feasibility of the force resistance measurement method, and our results were consistent with the hypothesis that Phthiracaroidea compensated its lack of chemical secretions by a heavier mechanical resistance based on a different body form and associated build-up of hemolymph pressure (defensive trade-off).
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Affiliation(s)
- Sebastian Schmelzle
- Department of Biology, Ecological Networks, Technische Universität Darmstadt, Schnittspahnstr. 3, 64287 Darmstadt, Germany
| | - Nico Blüthgen
- Department of Biology, Ecological Networks, Technische Universität Darmstadt, Schnittspahnstr. 3, 64287 Darmstadt, Germany
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Brückner A, Schuster R, Wehner K, Heethoff M. Nutritional quality modulates trait variability. Front Zool 2018; 15:50. [PMID: 30534185 PMCID: PMC6282258 DOI: 10.1186/s12983-018-0297-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 11/23/2018] [Indexed: 12/20/2022] Open
Abstract
Background Trait based functional and community ecology is en vogue. Most studies, however, ignore phenotypical diversity by characterizing entire species considering only trait means rather than their variability. Phenotypical variability may arise from genotypical differences or from ecological factors (e.g., nutritionally imbalanced diet), and these causes can usually not be separated in natural populations. We used a single genotype from a parthenogenetic model system (the oribatid mite Archegozetes longisetosus Aoki) to exclude genotypical differences. We investigated patterns of dietary (10 different food treatments) induced trait variation by measuring the response of nine different traits (relating to life history, morphology or exocrine gland chemistry). Results Nutritional quality (approximated by carbon-to-nitrogen ratios) influenced all trait means and their variation. Some traits were more prone to variation than others. Furthermore, the “threshold elemental ratio”- rule of element stoichiometry applied to phenotypic trait variation. Imbalanced food (i.e. food not able to fully meet the nutritional demands of an animal) led to lower trait mean values, but also to a higher variation of traits. Conclusion Imbalanced food led not only to lower trait value averages, but also to higher trait variability. There was a negative relationship between both parameters, indicating a direct link of both, average trait levels and trait variation to nutritional quality. Hence, variation of trait means may be a predictor for general food quality, and further indicate trade-offs in specific traits an animal must deal with while feeding on imbalanced diets. Electronic supplementary material The online version of this article (10.1186/s12983-018-0297-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Adrian Brückner
- 1Ecological Networks, Technische Universität Darmstadt, Schnittspahnstraße 3, 64287 Darmstadt, Germany.,2Division of Biology and Biological Engineering, California Institute of Technology, 1200 E California Boulevard, Pasadena, CA 91125 USA
| | - Romina Schuster
- 1Ecological Networks, Technische Universität Darmstadt, Schnittspahnstraße 3, 64287 Darmstadt, Germany
| | - Katja Wehner
- 1Ecological Networks, Technische Universität Darmstadt, Schnittspahnstraße 3, 64287 Darmstadt, Germany
| | - Michael Heethoff
- 1Ecological Networks, Technische Universität Darmstadt, Schnittspahnstraße 3, 64287 Darmstadt, Germany
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Heethoff M, Brückner A, Schmelzle S, Schubert M, Bräuer M, Meusinger R, Dötterl S, Norton RA, Raspotnig G. Life as a fortress – structure, function, and adaptive values of morphological and chemical defense in the oribatid mite Euphthiracarus reticulatus (Actinotrichida). BMC ZOOL 2018. [DOI: 10.1186/s40850-018-0031-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Nuylert A, Kuwahara Y, Hongpattarakere T, Asano Y. Identification of saturated and unsaturated 1-methoxyalkanes from the Thai millipede Orthomorpha communis as potential "Raincoat Compounds". Sci Rep 2018; 8:11730. [PMID: 30082895 PMCID: PMC6079017 DOI: 10.1038/s41598-018-30156-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 06/25/2018] [Indexed: 11/17/2022] Open
Abstract
Mixtures of saturated and unsaturated 1-methoxyalkanes (alkyl methyl ethers, representing more than 45.4% of the millipede hexane extracts) were newly identified from the Thai polydesmid millipede, Orthomorpha communis, in addition to well-known polydesmid defense allomones (benzaldehyde, benzoyl cyanide, benzoic acid, mandelonitrile, and mandelonitrile benzoate) and phenolics (phenol, o- and p-cresol, 2-methoxyphenol, 2-methoxy-5-methylphenol and 3-methoxy-4-methylphenol). The major compound was 1-methoxy-n-hexadecane (32.9%), and the mixture might function as “raincoat compounds” for the species to keep off water penetration and also to prevent desiccation.
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Affiliation(s)
- Aem Nuylert
- Asano Active Enzyme Molecular Project, JST, ERATO, 5180 Kurokawa, Imizu, Toyama, 939-0398, Japan.,Biotechnology Research Center and Department of Biotechnology, Toyama Prefectural University, 5180 Kurokawa, Imizu, Toyama, 939-0398, Japan
| | - Yasumasa Kuwahara
- Asano Active Enzyme Molecular Project, JST, ERATO, 5180 Kurokawa, Imizu, Toyama, 939-0398, Japan
| | - Tipparat Hongpattarakere
- Department of Industrial Biotechnology, Faculty of Agro-Industry, Prince of Songkla University, Hat Yai, Songkhla, 90112, Thailand
| | - Yasuhisa Asano
- Asano Active Enzyme Molecular Project, JST, ERATO, 5180 Kurokawa, Imizu, Toyama, 939-0398, Japan. .,Biotechnology Research Center and Department of Biotechnology, Toyama Prefectural University, 5180 Kurokawa, Imizu, Toyama, 939-0398, Japan.
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Nehring V, Steiger S. Sociality and communicative complexity: insights from the other insect societies. CURRENT OPINION IN INSECT SCIENCE 2018; 28:19-25. [PMID: 30551763 DOI: 10.1016/j.cois.2018.04.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 04/02/2018] [Accepted: 04/03/2018] [Indexed: 06/09/2023]
Abstract
Recognition and communication are essential processes when it comes to interaction of organisms with their biotic environment. As especially social interactions are coordinated by communication, it has been predicted that social evolution drives communicative complexity. However, studies comparing olfactory signals or receptor repertoires of solitary and eusocial insects found only mixed evidence for the social complexity hypothesis. We present some possible explanations and especially argue that our current knowledge of intermediate levels of sociality is insufficient to fully test the hypothesis, for which a more balanced comparative dataset would be required. We illustrate with chosen examples how complex communication within the other insect societies can be: Many messages are not unique to eusocial insects. Studying the other insect societies will provide us with a more detailed picture of the link between social and communicative complexity.
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Affiliation(s)
- Volker Nehring
- Department for Evolutionary Biology and Animal Ecology, University of Freiburg, 79104 Freiburg, Germany.
| | - Sandra Steiger
- Institute of Insect Biotechnology, University of Gießen, 35392 Gießen, Germany.
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12
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Bonte J, Van de Walle A, Conlong D, De Clercq P. Eggs of Ephestia kuehniella and Ceratitis capitata, and motile stages of the astigmatid mites Tyrophagus putrescentiae and Carpoglyphus lactis as factitious foods for Orius spp. INSECT SCIENCE 2017; 24:613-622. [PMID: 26573742 DOI: 10.1111/1744-7917.12293] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/19/2015] [Indexed: 06/05/2023]
Abstract
Several factitious foods were assessed for rearing the anthocorid predators Orius thripoborus (Hesse) and Orius naivashae (Poppius) (Hemiptera: Anthocoridae) in the laboratory. Developmental and reproductive traits of both Orius species were examined when offered frozen eggs of the Mediterranean flour moth, Ephestia kuehniella Zeller, frozen processed eggs of the medfly, Ceratitis capitata Wiedemann, or mixed motile stages of the astigmatid mites Tyrophagus putrescentiae (Schrank) or Carpoglyphus lactis (L). Whereas C. lactis and T. putresecentiae proved to be an inferior food for rearing O. thripoborus and O. naivashae, eggs of C. capitata fully supported development and reproduction of both predators. Results on medfly eggs were similar or slightly inferior to those on E. kuehniella eggs, which is the standard food for culturing these anthocorid bugs. O. thripoborus could be maintained for 4 consecutive generations on C. capitata eggs indicating that processed medfly eggs can be a suitable and cheaper alternative to E. kuehniella eggs for prolonged rearing of these Orius spp.
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Affiliation(s)
- Jochem Bonte
- Laboratory of Agrozoology, Department of Crop Protection, Ghent University, Coupure Links 653, B-9000, Ghent, Belgium
| | - Anaïs Van de Walle
- Laboratory of Agrozoology, Department of Crop Protection, Ghent University, Coupure Links 653, B-9000, Ghent, Belgium
| | - Des Conlong
- South African Sugarcane Research Institute, Private Bag X02, Mount Edgecombe, 4300, South Africa
- School of Biological and Conservation Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg, 3209, KwaZulu-Natal, South Africa
| | - Patrick De Clercq
- Laboratory of Agrozoology, Department of Crop Protection, Ghent University, Coupure Links 653, B-9000, Ghent, Belgium
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Storage and release of hydrogen cyanide in a chelicerate ( Oribatula tibialis). Proc Natl Acad Sci U S A 2017; 114:3469-3472. [PMID: 28289203 DOI: 10.1073/pnas.1618327114] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cyanogenesis denotes a chemical defensive strategy where hydrogen cyanide (HCN, hydrocyanic or prussic acid) is produced, stored, and released toward an attacking enemy. The high toxicity and volatility of HCN requires both chemical stabilization for storage and prevention of accidental self-poisoning. The few known cyanogenic animals are exclusively mandibulate arthropods (certain myriapods and insects) that store HCN as cyanogenic glycosides, lipids, or cyanohydrins. Here, we show that cyanogenesis has also evolved in the speciose Chelicerata. The oribatid mite Oribatula tibialis uses the cyanogenic aromatic ester mandelonitrile hexanoate (MNH) for HCN storage, which degrades via two different pathways, both of which release HCN. MNH is emitted from exocrine opisthonotal oil glands, which are potent organs for chemical defense in most oribatid mites.
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Saporito RA, Norton RA, Garraffo MH, Spande TF. Taxonomic distribution of defensive alkaloids in Nearctic oribatid mites (Acari, Oribatida). EXPERIMENTAL & APPLIED ACAROLOGY 2015; 67:317-333. [PMID: 26264156 DOI: 10.1007/s10493-015-9962-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 08/05/2015] [Indexed: 06/04/2023]
Abstract
The opisthonotal (oil) glands of oribatid mites are the source of a wide diversity of taxon-specific defensive chemicals, and are likely the location for the more than 90 alkaloids recently identified in oribatids. Although originally recognized in temperate oribatid species, alkaloids have also been detected in related lineages of tropical oribatids. Many of these alkaloids are also present in a worldwide radiation of poison frogs, which are known to sequester these defensive chemicals from dietary arthropods, including oribatid mites. To date, most alkaloid records involve members of the superfamily Oripodoidea (Brachypylina), although few species have been examined and sampling of other taxonomic groups has been highly limited. Herein, we examined adults of more than 60 species of Nearctic oribatid mites, representing 46 genera and 33 families, for the presence of alkaloids. GC-MS analyses of whole body extracts led to the detection of 15 alkaloids, but collectively they occur only in members of the genera Scheloribates (Scheloribatidae) and Protokalumma (Parakalummidae). Most of these alkaloids have also been detected previously in the skin of poison frogs. All examined members of the oripodoid families Haplozetidae and Oribatulidae were alkaloid-free, and no mites outside the Oripodoidea contained alkaloids. Including previous studies, all sampled species of the cosmopolitan oripodoid families Scheloribatidae and Parakalummidae, and the related, mostly tropical families Mochlozetidae and Drymobatidae contain alkaloids. Our findings are consistent with a generalization that alkaloid presence is widespread, but not universal in Oripodoidea. Alkaloid presence in tropical, but not temperate members of some non-oripodoid taxa (in particular Galumnidae) deserves further study.
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Affiliation(s)
- Ralph A Saporito
- Department of Biology, John Carroll University, University Heights, OH, 44118, USA.
| | - Roy A Norton
- College of Environmental Science and Forestry, State University of New York, Syracuse, NY, 13210, USA
| | - Martin H Garraffo
- Clinical Mass Spectrometry Core, NIDDK, NIH, DHHS, Bethesda, MD, 20892, USA
| | - Thomas F Spande
- Laboratory of Medicinal Chemistry, NIDA, NIH, DHHS, Bethesda, MD, 20892, USA
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Brückner A, Stabentheiner E, Leis HJ, Raspotnig G. Chemical basis of unwettability in Liacaridae (Acari, Oribatida): specific variations of a cuticular acid/ester-based system. EXPERIMENTAL & APPLIED ACAROLOGY 2015; 66:313-335. [PMID: 25913033 DOI: 10.1007/s10493-015-9914-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 04/09/2015] [Indexed: 06/04/2023]
Abstract
Oribatid mites of the family Liacaridae comprise a large number of species with smooth and shiny body surfaces that display extraordinary anti-wetting properties. The principle of liacarid unwettability is not related to micro-structured surfaces as present in many Oribatida ("Lotus effect") but the formation of raincoat-like lipid layers covering the epicuticle. We here conducted a comparative study on the chemistry of cuticular lipid layers in a selection of Liacaridae, including representatives of all major Central European genera, Liacarus, Dorycranosus, Adoristes, and Xenillus. Cuticular lipids of unwettable individuals were removed from mite bodies by hexane extraction, and were analyzed by GC-MS. Basically, two chemically distinguishable systems were found. Type I: cuticular lipids of Liacarus subterraneus, L. coracinus, L. nitens, Dorycranosus curtipilis, and Xenillus tegeocranus contained different carboxylic acids (C8-, C10-, C10:1-, C10:2-acids) and their corresponding di-glycerides in species-specific combinations. Type II: Adoristes ovatus exhibited a system of cuticular lipids composed of esters of pentanoic- and heptanoic acids with C14-, C15-, C16- and C17-alcohols. Interestingly, the chemistry of surface lipids did not reflect the morphology of the cuticle in the species investigated. Smooth and shiny cuticles, though exhibiting a specific pattern of round or slit-like pores, were found in representatives of Liacarus, Dorycranosus (all of which exhibiting cuticular chemistry of type I) and Adoristes (exhibiting cuticular chemistry of type II). Xenillus, possessing a rough, cerotegumental cement layer-covered surface, showed type I-chemistry. The acid-esters systems herein investigated are considered characteristic for the cuticular chemistry of Liacaridae or a lineage of these, and provide first insights into the comparative chemistry of the inner (=lipid) layer of the oribatid cerotegument.
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Affiliation(s)
- Adrian Brückner
- Institute of Zoology, University of Graz, Universitätsplatz 2, 8010, Graz, Austria
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Midthassel A, Leather SR, Baxter IH. Life table parameters and capture success ratio studies of Typhlodromips swirskii (Acari: Phytoseiidae) to the factitious prey Suidasia medanensis (Acari: Suidasidae). EXPERIMENTAL & APPLIED ACAROLOGY 2013; 61:69-78. [PMID: 23474738 DOI: 10.1007/s10493-013-9682-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Accepted: 02/26/2013] [Indexed: 06/01/2023]
Abstract
The predatory mite Typhlodromips swirskii (Athias-Henriot) is commonly used to suppress pest populations of thrips and whitefly in commercial greenhouses. Many generalist phytoseiid mites can be reared on astigmatid factitious prey. This study investigated the life table parameters of T. swirskii to the astigmatid mite Suidasia medanensis (Oudemans) and the capture success ratio of T. swirskii to different life stages of the prey. Juvenile development time and survival was 5.01 ± 0.10 days and 93 %, respectively. The intrinsic (r m ) and finite (λ) rates of increase were 0.222 and 1.249, respectively, with average oviposition rate of 1.71 ± 0.07 eggs/female/day. The capture success ratio of T. swirskii to S. medanensis was: eggs > freeze killed adults > nymphs > live adults. Typhlodromips swirskii was concluded to exhibit good population growth rates with S. medanensis as prey and, a prey population with predominance of eggs and nymphs to be advantageous to the predator due to an unidentified defence mechanism of adult prey.
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Affiliation(s)
- Audun Midthassel
- BCP Certis, Newbury House, Hinxhill, Ashford, Kent, TN25 5NR, UK.
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Heethoff M. Regeneration of complex oil-gland secretions and its importance for chemical defense in an oribatid mite. J Chem Ecol 2012; 38:1116-23. [PMID: 22836827 DOI: 10.1007/s10886-012-0169-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Revised: 04/19/2012] [Accepted: 06/24/2012] [Indexed: 10/28/2022]
Abstract
Most oribatid mites possess a pair of opisthonotal exocrine glands that produce mostly complex, species-specific secretions. Such blends may contain more than 10 different compounds, but hardly anything is known about their primary biosynthesis or regeneration. I analyzed recovery of the 6 main components from the 11-compound secretion of the oribatid mite Archegozetes longisetosus Aoki, including the main chemical classes hydrocarbons, aromatics, and terpenes, during a 20-day time course after complete gland depletion. About 10 % of the original total secretion amount was restored after 24 hr, and after 2-6 days, the amount had reached the range of total amount observed in the control group. Most compounds were recovered at similar rates within the first 48 hr. An important exception was pentadecane, which was predominantly produced in the first few hours, suggesting that this compound is the main solvent of the secretion. Although relative amounts of the main compounds differed significantly over time, the complex profile of the whole secretion was stable and not confidently distinguishable among the sampling dates. The general recovery rate was high during the first 48 hr, about 25 times higher than in the remaining 18 days. The biological importance of this high initial investment was supported by predation experiments: the predacious rove beetle Stenus juno was first repelled after 48 hr when at least 25 % of secretions was restored.
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Affiliation(s)
- Michael Heethoff
- Institute of Zoology, Karl-Franzens University, Universitätsplatz 2, 8010 Graz, Austria.
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Heethoff M, Raspotnig G. Triggering chemical defense in an oribatid mite using artificial stimuli. EXPERIMENTAL & APPLIED ACAROLOGY 2012; 56:287-295. [PMID: 22286143 DOI: 10.1007/s10493-012-9521-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Accepted: 01/18/2012] [Indexed: 05/31/2023]
Abstract
Most oribatid mites are well known for their exocrine oil gland secretions, from which more than a hundred different chemical components (hydrocarbons, terpenes, aromatics and alkaloids) have been described. The biological functions of these secretions have remained enigmatic for most species, but alarm-pheromonal and allomonal functions have been hypothesized, and demonstrated in some cases. Here, we tested different experimental stimuli to induce the release of defensive secretions in the model oribatid mite Archegozetes longisetosus Aoki. Whereas various mechanical stimuli did not result in a reproducible and complete expulsion of oil gland secretions, repeated treatments with hexane led to complete discharge. Life history parameters such as survival, development and reproduction were not influenced by the hexane treatment. Repeated hexane treatments also resulted in a complete depletion of oil glands in Euphthiracarus cribrarius Berlese.
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Affiliation(s)
- Michael Heethoff
- Institute of Zoology, Karl-Franzens University, Universitätsplatz 2, 8010 Graz, Austria.
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Heethoff M, Raspotnig G. Expanding the 'enemy-free space' for oribatid mites: evidence for chemical defense of juvenile Archegozetes longisetosus against the rove beetle Stenus juno. EXPERIMENTAL & APPLIED ACAROLOGY 2012; 56:93-97. [PMID: 22048786 DOI: 10.1007/s10493-011-9501-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Accepted: 10/24/2011] [Indexed: 05/31/2023]
Abstract
Adult oribatid mites are thought to live functionally in 'enemy-free space' due to numerous morphological and chemical defensive strategies. Most juvenile oribatid mites, however, lack hardened cuticles and are thus thought to be under stronger predation pressure. On the other hand, the majority of oribatids have exocrine oil glands in all developmental stages, possibly rendering chemical defense the crucial survival strategy in juvenile Oribatida. We manipulated tritonymphs of the model oribatid mite Archegozetes longisetosus to completely discharge their oil glands and offered these chemically disarmed specimens to the polyphagous rove beetle Stenus juno. Disarmed specimens were easily consumed. By contrast, specimens with filled oil glands were significantly protected, being rejected by the beetles. This is the first direct evidence that oil gland secretions provide soft-bodied juvenile oribatids with chemical protection against large arthropod predators.
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Affiliation(s)
- Michael Heethoff
- Institute of Zoology, Karl-Franzens University, Universitätsplatz 2, Graz, Austria.
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Snyder JC, Antonious GF, Thacker R. A sensitive bioassay for spider mite (Tetranychus urticae) repellency: a double bond makes a difference. EXPERIMENTAL & APPLIED ACAROLOGY 2011; 55:215-224. [PMID: 21761225 DOI: 10.1007/s10493-011-9472-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Accepted: 06/24/2011] [Indexed: 05/31/2023]
Abstract
Choice bioassays were used to determine repellency of homologous n-alkanes (C(8)H(18)-C(21)H(44)) to spider mites. When tested at 400 μg/cm(2), the C(15)-C(19) alkanes were highly repellent; the C(16) n-alkane, n-hexadecane, was most repellent. Subsequently the EC(50) values, the concentration at which 50% of the mites were repelled, were determined for the C(15)-C(19) n-alkanes and their analogous 1-n-alkenes (C(15)H(30)-C(19)H(38)). The EC(50) value for 1-heptadecene, the C(17) 1-n-alkene, was the lowest observed. Except for the 17-carbon hydrocarbons, the EC(50) values for the n-alkanes were less than those for their analogous 1-n-alkenes. Depending on the compounds evaluated, there was as much as a six-fold difference of repellency between an n-alkane its analogous 1-n-alkene. Thus, the bioassay has sufficient sensitivity to detect behavioral differences associated with the presence or absence of a single double bond. The EC(50) values for the most repellent hydrocarbons were similar to that reported for 2,3-dihydrofarnesoic acid, a naturally occurring repellent isolated from trichome secretions of a wild tomato, Solanum habrochaites, and also were similar to concentrations used to evaluate arthropod repellents. Consequently, this bioassay may be useful for providing a better understanding of the relationships between structures and activities of natural products that are repellent to spider mites.
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Affiliation(s)
- John C Snyder
- Department of Horticulture, N318 Ag. Sci. N., University of Kentucky, Lexington, KY 40546-0091, USA.
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Heethoff M, Koerner L, Norton RA, Raspotnig G. Tasty but Protected—First Evidence of Chemical Defense in Oribatid Mites. J Chem Ecol 2011; 37:1037-43. [DOI: 10.1007/s10886-011-0009-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 08/01/2011] [Accepted: 08/12/2011] [Indexed: 10/17/2022]
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Raspotnig G, Leutgeb V, Krisper G, Leis HJ. Discrimination of Oribotritia species by oil gland chemistry (Acari, Oribatida). EXPERIMENTAL & APPLIED ACAROLOGY 2011; 54:211-24. [PMID: 21350972 PMCID: PMC3105237 DOI: 10.1007/s10493-011-9434-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Accepted: 02/10/2011] [Indexed: 05/30/2023]
Abstract
The chemical composition of secretions from opisthonotal (oil) glands in four species of the oribatid mite genus Oribotritia (Mixonomata, Euphthiracaroidea, Oribotritiidae) was compared by means of gas chromatography--mass spectrometry. The secretions of all, O. banksi (from North America) and three Austrian oribotritiids (O. berlesei, O. hermanni, O. storkani), are shown to be based on certain unusual compounds, the iridoid monoterpenes chrysomelidial and epi-chrysomelidial and the diterpene β-springene. These components probably represent general chemical characteristics of oribotriid oil glands. Their relative abundance in the secretions along with further components (mainly saturated and unsaturated C(13)-, C(15)-, C(17)-hydrocarbons, and the tentatively identified octadecadienal) led to well-distinguishable, species-specific oil gland secretions profiles. In addition a reduced set of "Astigmata compounds" (sensu Sakata and Norton in Int J Acarol 27:281-291, 2001)--namely the two monoterpenes neral and geranial--could be detected in extracts of O. banksi nevertheless indicating the classification of euphthiracaroids within the (monophyletic) group of "Astigmata compounds-bearing"-Oribatida. These compounds are considered to be apomorphically reduced in all Austrian species. Our findings emphasize the potential of chemosystematics using oil gland secretion profiles in the discrimination of morphologically very similar, syntopically living or even cryptic oribatid species.
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Affiliation(s)
- Günther Raspotnig
- Institute of Zoology, Karl-Franzens-University, Universitätsplatz 2, 8010, Graz, Austria.
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Affiliation(s)
- Marianne Müller
- Department of Clinical Pharmacy & Diagnostics; Faculty of Life Sciences; University of Vienna; A-1090; Vienna; Althanstreet 14; Austria
| | - Gerhard Buchbauer
- Department of Clinical Pharmacy & Diagnostics; Faculty of Life Sciences; University of Vienna; A-1090; Vienna; Althanstreet 14; Austria
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Raspotnig G, Norton RA, Heethoff M. Oribatid mites and skin alkaloids in poison frogs. Biol Lett 2011; 7:555-6; discussion 557. [PMID: 21345855 DOI: 10.1098/rsbl.2010.1113] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Günther Raspotnig
- Institute of Zoology, Karl-Franzens-University, Universitätsplatz 2, A-8010 Graz, Austria
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Schmelzle S, Helfen L, Norton RA, Heethoff M. The ptychoid defensive mechanism in Euphthiracaroidea (Acari: Oribatida): a comparison of muscular elements with functional considerations. ARTHROPOD STRUCTURE & DEVELOPMENT 2009; 38:461-472. [PMID: 19595788 DOI: 10.1016/j.asd.2009.07.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Revised: 06/02/2009] [Accepted: 07/06/2009] [Indexed: 05/28/2023]
Abstract
Ptychoidy is a mechanical predator defence in some groups of Oribatida (Acari), where the animals can retract their legs into the idiosoma and encapsulate. This mechanism is enabled by a number of morphological adaptations. We used the non-invasive technique of synchrotron X-ray microtomography to compare muscular elements involved in ptychoidy of two species from the Euphthiracaroidea (Oribotritia banksi and Rhysotritia ardua) which differ in a number of cuticular elements involved in ptychoidy. We hypothesize that a strong functional correlation exists between these cuticular structures and their corresponding musculature. We found a number of distinct differences concerning quantitative and qualitative muscle morphology. For testing the functional impact of different muscle configurations we simulated two conditions in silico (encapsulated / opened) and analysed the spatial relative force vectors of the prodorsum lateral adjustor muscles (pla) which are responsible for retraction and adjustment of the prodorsum during encapsulation. We show that the functional morphology of these muscles strongly differs between the two species and that this can be explained by the structure of corresponding cuticular elements. Furthermore, the dynamics of pla, as measured by the extent of contraction during encapsulation, is more than two times higher in R. ardua than in O. banksi.
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Affiliation(s)
- Sebastian Schmelzle
- Universität Tübingen, Institut für Evolution und Okologie, Abteilung Evolutionsbiologie der Invertebraten, Auf der Morgenstelle 28E, D-72076 Tübingen, Germany.
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Raspotnig G, Leis HJ. Wearing a raincoat: exocrine secretions contain anti-wetting agents in the oribatid mite, Liacarus subterraneus (Acari: Oribatida). EXPERIMENTAL & APPLIED ACAROLOGY 2009; 47:179-190. [PMID: 19005767 DOI: 10.1007/s10493-008-9212-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2008] [Accepted: 10/27/2008] [Indexed: 05/27/2023]
Abstract
Liacarus subterraneus is a large, soil-dwelling oribatid mite species that possesses a conspicuously shiny, clean and not wettable cuticular surface. The exocrine cuticular chemistry of this species was investigated by means of gas chromatography-mass spectrometry. Besides a fraction of hydrocarbons and a terpene, hexane extracts of whole mite bodies exhibited free carboxylic acids and their glycerides as main components. The compounds were arranged in three distinct extract profiles. Based on data from individual extracts, (1) the majority (more than 3/4) of specimens showed large amounts of 1,2-dioctanoyl-glycerol (and three other related esters) but no (or only traces of) free carboxylic acids. (2) In about 1/8 of extracts, free acids (mainly octanoic (caprylic) acid) and glycerides were detected. This second type of profile highly varied with respect to the relative abundance of acids and esters. (3) The third profile (in about 7% of specimens) exclusively exhibited free acids and no (or only traces of) glycerides. In addition, a few extracts exhibited no components at all. The extract compounds most likely originate from the lipid layer of the cerotegument of L. subterraneus. The cuticle of individuals that possessed extractable cerotegumental compounds (profile I, II, III) exhibited strong water repellent properties, while the cuticle of individuals that possessed no components in their extract did not. After hexane extraction, water repellent properties got lost. The distinct extract profiles detected most likely portray the stepwise generation of an anti-wetting, exocrine surface lipid layer of glycerides: If this layer is lost, fatty acids may be discharged again (profile III) and may subsequently esterify (profile II) to larger and more stable esters (diacyl-glycerols), eventually building up the "raincoat" (mainly profile I) of L. subterraneus.
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Raspotnig G, Stabentheiner E, Föttinger P, Schaider M, Krisper G, Rechberger G, Leis HJ. Opisthonotal glands in the Camisiidae (Acari, Oribatida): evidence for a regressive evolutionary trend. J ZOOL SYST EVOL RES 2009. [DOI: 10.1111/j.1439-0469.2008.00486.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Domes K, Althammer M, Norton RA, Scheu S, Maraun M. The phylogenetic relationship between Astigmata and Oribatida (Acari) as indicated by molecular markers. EXPERIMENTAL & APPLIED ACAROLOGY 2007; 42:159-71. [PMID: 17611803 DOI: 10.1007/s10493-007-9088-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Accepted: 06/13/2007] [Indexed: 05/16/2023]
Abstract
Astigmata comprise a diverse group of acariform mite species with a remarkable range of life histories, most of which involve parasitic or commensal relationships with other organisms. Several authors have suggested that Astigmata evolved as a paedomorphic clade from within Oribatida, and both morphology and gland-chemistry strongly suggest that their sister-clade is within the oribatid subgroup Desmonomata. The biologies of these groups contrast greatly, since oribatid mites are mostly soil-living detritivores and fungivores, and have life cycles that are much longer than those in Astigmata. We tested the hypothesis that Astigmata evolved from within Desmonomata using two molecular markers, the ribosomal 18S region (18S) and the nuclear elongation factor 1 alpha (ef1alpha) gene. Representative acariform mites included 28 species of Oribatida, eight of Astigmata, two of Prostigmata and two of Endeostigmata; outgroups included members of Opilioacariformes, Parasitiformes and Ricinulei. To minimize the possibility of long-branch attraction artifacts, we limited highly variable sites by removing gaps (18S) and third codon positions (ef1alpha) from the sequences. Maximum parsimony, neighbor-joining and Bayesian algorithms formed trees that consistently placed Astigmata outside monophyletic Oribatida, usually as sister-group of the endeostigmatid mite Alicorhagia sp. Analyses with and without outgroups resulted in similar topologies, showing no evidence for long-branch artifacts and leaving the conflict with morphological and biochemical data unexplained.
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Affiliation(s)
- Katja Domes
- Technische Universität Darmstadt, Institut für Zoologie, Schnittspahnstr. 3, 64287 Darmstadt, Germany.
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