Can habitat preferences of ground-dwelling insects be a good indicator for terrestrial ecosystem recovery after an oil-spill?

Although oil spills are a major source of global pollution, little is known about the effects of oil spills on animals in terrestrial ecosystems. We investigated two oil spills that occurred in 1975 and 2014 in a nature reserve within a hyper-arid desert, aiming at determining the long- and short-term effects of oil spills on the habitat selection behavior of desert insects, as a possible behavioral indicator for restoration success. We performed habitat selection experiments under lab conditions, giving ground-dwelling Mesostena angustata beetles and Myrmeleon hyalinus antlion larvae choice trials between various combinations of clean and oil-contaminated soils from the new and old oil spills sites. When given a choice between clean and 2014 contaminated soil, beetles and antlions selected the clean soil. Moreover, antlions in contaminated soil from 2014 reduced their movements and did not dig pit-traps. Surprisingly, both beetles and antlions selected the 1975 contaminated soil over other soil types, and antlions dug many pit-traps in the 1975 contaminated soil. Implications for insect conservation: The antlions' behavior reflects the status of its population in the field and can be used as an indicator for habitat restoration. In contrast, the beetle's behavior may not be a reliable behavioral indicator. Beetles were scarce in 1975 contaminated areas in the field. The disparity between individual behavior of beetles in the lab and field population distribution raised the question: Can old oil spills become an ecological trap for these species? This remains an open question for further research.