Bidder et al.
Assessing the underwater survival of two tick species, Amblyomma americanum and Amblyomma maculatum
Ticks Tick Borne Dis. 2018, in press, doi.org/10.1016/j.ttbdis.2018.08.013
The Gulf Coast tick Amblyomma maculatum and the lone star tick Amblyomma americanum are commonly found in the southeastern region of the USA, an area where heavy rainfall and flooding events have increased due to climate changes over the last decades. The authors have analyzed the ability of these tick species to survive flooding events under laboratory conditions using three different water conditions – freshwater, brackish water and saltwater. There was a significant difference in survival between the species. While most of A. maculatum ticks died during a period of 28 days across all water conditions, A. americanum showed a high survival rate. The highest survival rate of A. americanum was in freshwater compared to brackish water and saltwater. These findings confirm that both tick species are not hindered from continuing to establish populations in habitats prone to flooding. The mechanism by which ticks survive submersion may be plastron respiration; that means that a small bubble of air between the spiracular plate and the water allows diffusion of dissolved oxygen.
In a similar study, published by Bardel and Pfingstl in Soil Organisms 2018; 90: 71-77, the authors have shown that the resistance to flooding of terrestrial mites clearly varied between the tested species, even between closely related species. Survival times in freshwater differed from 30 to more than 165 days.
In summary, ticks and mites may show a basic predisposition for flooding tolerances.