Marking through molts: An evaluation of visible implant elastomer to permanently mark individuals in a lower termite species.

Rebecca F B Padget,Faye J Thompson

doi:10.1002/ece3.8030

Abstract

Advances in individual marking methods have facilitated detailed studies of animal populations and behavior as they allow tracking of individuals through time and space. Hemimetabolous insects, representing a wide range of commonly used model organisms, present a unique challenge to individual marking as they are not only generally small‐bodied, but also molt throughout development, meaning that traditional surface marks are not persistent.Visible implant elastomer (VIE) offers a potential solution as small amounts of the inert polymer can be implanted under the skin or cuticle of an animal. VIE has proved useful for individually marking fish, crustaceans, and amphibians in both field and laboratory studies and has recently been successfully trialed in laboratory populations of worms and fly larvae. We trialed VIE in the single‐piece nesting termite Zootermopsis angusticollis, a small hemimetabolous insect.We found that there was no effect of VIE on survival and that marks persisted following molting. However, we found some evidence that marked termites performed less allogrooming and trophallaxis than controls, although effect sizes were very small.Our study suggests that VIE is an effective technique for marking small hemimetabolous insects like termites but we advocate that caution is applied, particularly when behavioral observation is important.

Highlights

Marking animals is a useful tool in the study of animal populations, ecology, and behavior in both field and laboratory research (Hjort & Lindholm, 1978)
Since the effect size considered acceptable for a given study will depend on the application of Visible implant elastomer (VIE), we report the median of the effect size distribution from our models and 89% highest posterior density intervals (HDI)
We investigated the effect of visible implant elastomer (VIE) implants on the survival and behavior of Z. angusticollis to evaluate the suitability of VIE for use as a marker in small, hemimetabolous insects

Summary

| INTRODUCTION

Marking animals is a useful tool in the study of animal populations, ecology, and behavior in both field and laboratory research (Hjort & Lindholm, 1978). Hemimetabolous insects molt during development, meaning that surface marks widely used on other insects— such as paint or correction fluid—only persist until the molt, which is often difficult to predict in standard natural or laboratory populations This makes medium-or long-term studies of individuals challenging as surface marks would require regular reapplication, and it could be difficult or impossible to reidentify individuals that have lost their marks. Workers of “higher” termite species (Termitidae; Korb, 2007), as in other eusocial Hymenoptera, are permanently sterile Despite these behavioral differences between higher and lower termites, the application of VIE is likely to be useful to both since both are hemimetabolous (to some extent) and undergo transitional and developmental molts. We censused small groups of termites that had been injected with VIE alongside noninjected control groups and conducted behavioral assays to establish whether VIE affected survival or behavior of laboratory-cultured termites

| METHODS

Findings

| DISCUSSION

| CONCLUSIONS