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

Despite the significant global impact of oil spills on the environment, little is known about the effects of oil spills on animals in terrestrial ecosystems, particularly in desert environments. In contaminated areas, habitat selection can be a crucial behavior determining individuals survival as well as a potential indicator of an ecosystem’s condition. This is especially relevant for ground-dwelling insects, whose close interactions with the soil make them valuable bioindicators of soil quality. This study aimed to determine the long and short-term effects of oil spills on the microhabitat selection behavior of ground-dwelling insects in a hyper-arid desert. Soil samples were collected from a nature reserve that experienced two oil spills, one in 1975 and another in 2014. We conducted microhabitat selection experiments in laboratory conditions using the ground-dwelling Mesostena angustata beetles and Myrmeleon hyalinus antlion larvae. When given a choice between clean soil (control) and soil contaminated in 2014, both beetles and antlions selected the clean soil, with antlions exhibiting reduced movements and no pit-trap digging in contaminated soil. Surprisingly, both beetles and antlions selected the soil contaminated in 1975 over other soil types. However, the antlions kept relocating their pit-falls traps in the 1975 polluted soil, which may indicate they perceived this soil as less suitable for pit digging. When given a choice between three types of soil, the beetles clearly preferred dark, oil-contaminated soils and avoided the clean soil. Our study highlights the complex and varied effects of oil spills on microhabitat selection behavior in ground-dwelling insects, indicating the importance of considering long-term effects in future restoration efforts. Implications for insect conservation: This study shows that oil contamination impacts ground dwelling insects behavior even more than four decades after an oil spill. The attraction of both insect species to the contaminated soil from 1975 may be an indication of an ecological trap for these species in the field. We conclude in this study that the habitat selection behavior of the antlion larvae may be a good behavioral indicator for habitat restoration purposes.