Evaluation of synthetic hydrocarbons for mark-recapture studies on the red milkweed beetle

This study evaluates the potential for using blends of synthetic hydrocarbons in mark–recapture studies of insects. To test the durability of hydrocarbons, we applied a blend of five straight-chain hydrocarbons (C₂₄, C₂₅, C₂₆, C₂₈, C₃₀) to detached elytra of the red milkweed beetle, Tetraopes tetrophthalmus (Forster) (Coleoptera: Cerambycidae), mounted the elytra on pins, and placed them in an exposed location outdoors. The amount of hydrocarbons on the elytra did not change over time, even after two months of exposure to sun and rain. Synthetic hydrocarbons applied to the elytra of living beetles did not significantly influence their longevity or mating success in a laboratory study, and the amounts of hydrocarbons did not change with age. The invariability of hydrocarbon ratios over time suggests that blends could provide a nearly infinite variety of ratios to mark individual insects uniquely and indelibly with a hydrocarbon fingerprint. This technique offers a convenient, safe, and durable means of individually marking insects and may find application in field studies of larger bodied insects that are long-lived and sedentary.