Search bioRxiv⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.64898/2026.03.13.711545

Ethyl-iophenoxic acid as a serum biomarker for marsupial species in oral bait trials

Nofs, S. A.·Pye, R. J.·Nichols, D. S.·Johnson, S. R.·Gilbert, A. T.·Lazenby, B.·Flies, A. S.
View original source ↗Export metadata ↓

Abstract

Ethyl-iophenoxic acid (Et-IPA) is widely recognized as a useful biomarker to confirm oral bait consumption in eutherian species. In historical studies on marsupials, Et-IPA was rapidly eliminated from brushtail possums (Trichosurus vulpecula) and swamp wallabies (Wallabia bicolor) suggesting limited use for marsupial species. However, a 1 mg oral dose of Et-IPA was detectable in the marsupial Tasmanian devils (Sarcophilus harrisii) for [≥] 56 days suggesting the biomarker can be used in a devil bait vaccine program. To assess Et-IPA marking in off-target marsupials that may consume baits, we administered 1 mg oral doses of Et-IPA to brushtail possums, forester kangaroos (Macropus giganteus tasmaniensis), spotted-tailed quolls (Dasyurus maculatus) and eastern quolls (Dasyurus viverrinus). Liquid chromatography with tandem mass spectrometry was used to detect and quantify serum Et-IPA. Et-IPA was detected in the serum on day 2 but was not detected by day 14 in any of the species tested, including the two quoll species which are in the same carnivorous Dasyuridae family as the devils. The rapid elimination of Et-IPA in the marsupials included in this study suggests it is not useful as a biomarker for these species. Furthermore, rapid elimination in the kangaroos and possums suggests that Et-IPA is unlikely to accumulate in the food chain following distribution of Et-IPA-marked oral bait vaccines for Tasmanian devils. Short summary for non-expertsA recent study in Tasmanian devils (Sarcophilus harrisii) challenged the concept that ethyl iophenoxic acid (Et-IPA) is not a useful serum biomarker for marsupials. Using the same sensitive liquid chromatography-tandem mass spectrometry method we detected serum Et-IPA in four marsupial species on day two post-ingestion but by day 14, serum Et-IPA was undetectable. These findings indicate that Et-IPA is an unsuitable biomarker for these species and suggest that Et-IPA from devil bait vaccines is unlikely to bioaccumulate in the Tasmanian environment.

Explore related subjects

zoologyPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Nofs, S. A., Pye, R. J., Nichols, D. S., Johnson, S. R., Gilbert, A. T., Lazenby, B., Flies, A. S.. 2026-03-16. Ethyl-iophenoxic acid as a serum biomarker for marsupial species in oral bait trials. https://doi.org/10.64898/2026.03.13.711545

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Sea slugs unplugged: Review of subpopulation sampling in phylogeographic studies of nudibranchs and their allies

Nudibranchs and other sea slugs include many cryptic species groups with unknown phenotypic and ecological diversity. How broadly and deeply should researchers sample those cryptic species pairs to capture the genetic variation within each species and potential adaptive differences between species? Fast and inexpensive surveys of genetic diversity that sample a single well-known locus across the geographical range ("phylogeography unplugged") have long been used to identify structured populations and guide choice of sampling localities for subsequent comparative genomic or phenotypic studies of the same species. Results from such studies might also be used to better understand the expected relationships between sampling and population structure in future comparative studies in other species (including many marine gastropods) for which an unplugged phylogeographic survey is not available or impractical. We reviewed analyses of molecular variance that used mitochondrial barcode sequences from marine sea slugs, and we asked whether there are characteristic patterns of subpopulation sampling that are associated with the magnitude and geographical scale of differentiation. We found wide variation in sampling designs: studies with both many and few samples discovered significant population differentiation or broadly similar distribution of haplotypes on both large and small spatial scales, in species from different higher taxonomic groups and oceans. We found two significant associations between sampling variables and population genetic variables, and we suggest using those associations to help guide (or understand the consequences of) sampling design in future studies.

zoology↗
bioRxiv2026

A novel methodology for assessing reinforcement choice in primates under human care

Positive Reinforcement Training is a technique commonly employed in zoological collections to elicit a desired behaviour from an animal under human care. Typically, a food item is offered as a reward for performing that behaviour. Three non-human primate species (Mandrillus sphinx, Pan troglodytes, and Hylobates lar) were offered four different foods (banana, grape, apple, and sweet potato) in a series of choice experiments. Latent variable models were employed to investigate which foods were the best selection to use as reinforcement items. Results show that food preference varies between the three primate species. Pan troglodytes and H. lar showed strong preferences for grape and banana, whereas M. sphinx showed a very strong preference for sweet potato. This study indicates that foraging ecology might play an important part in fruit selection and preference in primates. The findings highlight that understanding a species' natural behaviour and dietary preferences is key to informing reinforcement and training decisions.

zoology↗
bioRxiv2026

A comprehensive identification protocol for postcranial bones of Southeast Asian Ruminantia. Part 2: Morphological criteria for small and medium-sized species

The taxonomic identification of postcranial elements from small and medium-sized ruminants represents a significant challenge in zooarchaeological and Late Quaternary paleontological studies, particularly in biodiversity-rich regions such as continental Southeast Asia. This study presents a comprehensive osteological reference framework for the small and medium-sized Ruminantia of this region, based on a comparative sample of 228 specimens representing 14 species across three families (Bovidae, Cervidae, and Moschidae). Osteological characters were first described on a small initial specimen set and subsequently scored across the full sample. Although a small number of character states were found to be unique to specific taxa, most proved highly variable, limiting their individual identification potential. To address this, a Random Forest and a Naive Bayes classifier were applied to assess the discriminatory power of character combinations across four taxonomic ranks (Family, Subfamily, Genus, and Species) on independent bones. Both approaches performed similarly, achieving mean identification accuracies of 87-86% at the family level, 69% at the subfamily level, 50% at the genus level, and 35-33% at the species level. The Naive Bayes models were further deployed as an interactive web application, allowing users to perform bone identification based on any combination of observable character states from a single anatomical element. Our results highlight the limits of morphological identification of postcranial elements in this taxonomic and biogeographic context, while demonstrating that a transparent, reproducible, and statistically grounded approach can still represent a significant step forward for zooarchaeological and Late Quaternary paleontological studies in Southeast Asia and beyond.

zoology↗