Arthropod Appreciation Day image showing a butterfly

Arthropod Appreciation Day

With Arthropod Appreciation Day upon us, we turn to soil arthropods, invertebrate animals with exoskeletons. Common arthropods include ants, termites and millipedes, which munch their way through plant litter that ends up as the nutrient rich soil upon which complex terrestrial life depends. However, most of us are likely only dimly aware of the essential roles arthropods play in maintaining ecosystems. We are more apt to regard arthropods as pests, and thus with a vague annoyance, or in a fearful context. Termites, for example, are arthropods that are likely far better recognized for the terror they instill in homeowners, than for the fact that they process up to 60% of plant debris. This is no small feat, and it is worth understanding the critical role arthropods play as either plant litter ‘transformers’ or ‘ecosystem engineers’.

As ‘transformers’, arthropods ingest plant debris and excrete it back into the environment. Their feces thus contain the now disintegrated matter, with a significantly higher surface area than before. As such, this enhances further degradation by microorganisms able to convert this organic material into even simpler inorganic substances for plant nutrition.

Arthropod engineers

Arthropod soil ‘engineers’, present in areas such as coniferous forests where earthworms are rare, are not nearly as well recognized as their earthworm counterparts for their role in soil structure. Arthropods in such areas  burrow through the soil and transport materials, necessary for the mixing of organic and mineral fragments and to promote porosity, essential for multiple critical aspects of soil, including aeration, water retention, and root penetration.

Thomas W. Culliney is an entomologist with the U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Center for Plant Health Science and Technology in Raleigh, North Carolina USA, where he conducts analyses, based on standards of the International Plant Protection Convention and the World Organisation for Animal Health, of the risks involved in the importation of agricultural commodities and introduction of alien species. His main research interests are in population ecology and biological control of weeds and arthropod pests. He has published more than 40 articles and book chapters on subjects, such as paleoentomology, insect ecology, biological control, ecotoxicology, and sustainable agriculture.

More about the article

To learn more about the wide diversity and abundance of soil arthropods and the roles they play in ecosystem maintenance, see: Culliney, T.W. Role of Arthropods in Maintaining Soil FertilityAgriculture 20133, 629-659.