Influence of storage and drying methods on invertebrate elemental and isotopic measurements

ABSTRACT

Optimised pre-analytical methods for measuring the chemical properties of soil macro-organisms are needed. We tested the effects of ethanol immersion, freezer storage, and drying method on the reliability of estimates of key stoichiometric elements (carbon [C], nitrogen [N], phosphorus [P]) and abundances of ¹³C and ¹⁵N in samples of crickets (Acheta domestica), cockroaches (Nauphoeta cinerea) and mealworms (larval Tenebrio molitor). Ethanol immersion tended to increase A. domestica C and N, and reduced A. domestica P, relative to the reference treatment (deep freezing and oven drying). For N and P these effects were only present after 28-day ethanol immersion. Nauphoeta cinerea and T. molitor samples were generally unaffected by storage treatments, while δ¹³C and δ¹⁵N were not affected by any storage treatment for any species. Thus, five days of ethanol immersion may be acceptable prior to elemental and stoichiometric analyses of hard-bodied soil invertebrates in comparative studies.

KEYWORDS:

• Ethanol
• invertebrates
• soil fauna
• stoichiometry

Acknowledgments

This work was supported by a grant of Australian Research Council Future Fellowship project (FT0990547). Orpheus Butler is a recipient of the South East Queensland Fire and Biodiversity Consortium Research Student Scholarship. The authors would like to thank Dr Sarah Maunsell, Dr Maryam Esfandbod and Scott Byrnes for their contributions to the development of methods, as well as Dr Zhongming Lan and Geoffrey Lambert for their generous assistance during laboratory analyses. Study data are available on request.

Disclosure statement

The authors have no conflicting interests to declare.

Additional information

Funding

This work was supported by the Australian Research Council [FT0990547]and the South-East Queensland Fire & Biodiversity Consortium Student Research Scholarship.