title: Scheloribatid mites as the source of pumiliotoxins in dendrobatid frogs.
abstract: The strawberry poison frog Dendrobates pumilio (Anura: Dendrobatidae) and related poison frogs contain a variety of dendrobatid alkaloids that are considered to be sequestered through the consumption of alkaloid-containing arthropods microsympatrically distributed in the habitat. In addition to ants, beetles, and millipedes, we found that adults of two species of oribatid mites belonging to the cohort Brachypylina, trophically a lower level of animal than ants and beetles, contain dendrobatid alkaloids. Gas chromatography/mass spectrometry (GC/MS) of hexane extracts of adult Scheloribates azumaensis (Oribatida: Acari) revealed the presence of not only pumiliotoxin 251D (8-hydroxy-8-methyl-6-(2'-methylhexylidene)-1-azabicyclo[4.3.0]nonane), but also precoccinelline 193C and another coccinelline-type alkaloid. From the corresponding extracts of an unidentified Scheloribates sp., pumiliotoxin 237A (8-hydroxy-8-methyl-6-(2'-methylpentylidene)-1-azabicyclo[4.3.0]nonane) was detected as a minor component, and identified by synthesis. The presence of related alkaloids, namely deoxypumiliotoxin 193H, a 6,8-diethyl-5-propenylindolizidine, and tentatively, a 1-ethyl-4-pentenynylquinolizidine, were indicated by the GC/MS fragmentation patterns, along with at least another six unidentified alkaloid components. Thus, one possible origin of pumiliotoxins, coccinellid alkaloids, and certain izidines found in poison frogs may be mites of the genus Scheloribates and perhaps related genera in the suborder Oribatida.
authors.affiliation: Department of Applied Life Sciences, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Takada
authors.forename: Tomoyo
authors.initials: T
authors.lastname: Sakata
authors.forename: Satoshi
authors.initials: S
authors.lastname: Shimano
authors.forename: Yoshinari
authors.initials: Y
authors.lastname: Enami
authors.forename: Naoki
authors.initials: N
authors.lastname: Mori
authors.forename: Ritsuo
authors.initials: R
authors.lastname: Nishida
authors.forename: Yasumasa
authors.initials: Y
authors.lastname: Kuwahara
mesh_terms: D000470:Alkaloids / Q000737:chemistry / Q000302:isolation & purification* / Q000633:toxicity; D000818:Animals; D001001:Anura / Q000378:metabolism*; D003497:Cyclic N-Oxides / Q000302:isolation & purification / Q000633:toxicity; D004032:Diet; D008401:Gas Chromatography-Mass Spectrometry; D006575:Heterocyclic Compounds, 3-Ring / Q000302:isolation & purification / Q000633:toxicity; D007212:Indolizines / Q000302:isolation & purification / Q000633:toxicity; D008925:Mites / Q000737:chemistry*; D010880:Piperidines / Q000302:isolation & purification / Q000633:toxicity
chemical_list: D000470:Alkaloids; D003497:Cyclic N-Oxides; D006575:Heterocyclic Compounds, 3-Ring; D007212:Indolizines; D010880:Piperidines; C467904:coccinelline; C035482:pumiliotoxin A