Abstract
Heat coma temperatures (HCTs) and super cooling points (SCPs) were examined for nearly 1000 oceanic sea skaters collected from in the Pacific and Indian Oceans representing four Halobates species; H. germanus, H. micans, H. sericeus, and H. sp. Analysis was conducted using the entire dataset because a negative correlation was seen between the HCTs and SCPs in all four species. A weak negative correlation was seen between HCTs and SCPs with a cross tolerance between warmer HCTs and colder SCPs. The weakness of the correlation may be due to the large size of the dataset and to the variability in ocean surface temperature. The negative correlation does however suggest that oceanic sea skaters may have some form of cross tolerance with a common physiological mechanism for their high and low temperature tolerances.
Highlights
IntroductionOceanic sea skaters (Heteroptera, Gerridae) are a biologically unique group among insects because they inhabit a wide range of water types from fresh water (e.g., Metrocoris histrio) to brackish water and sea water (coastal and pelagic)
There are three main types of cold hardiness in insects [1]: (1) cold tolerance in which liquid inside cells does not freeze; (2) cold avoidance in which freezing of liquids inside and outside cells is prevented with a lower super cooling point; and (3)chill injury in which damage accumulates with prolonged exposure to low temperatures around 0 ◦ C.Oceanic sea skaters (Heteroptera, Gerridae) are a biologically unique group among insects because they inhabit a wide range of water types from fresh water (e.g., Metrocoris histrio) to brackish water and sea water
The aim of this study is to determine whether the negative correlation between heat coma temperatures (HCTs) and super cooling point (SCP) is a general phenomenon
Summary
Oceanic sea skaters (Heteroptera, Gerridae) are a biologically unique group among insects because they inhabit a wide range of water types from fresh water (e.g., Metrocoris histrio) to brackish water and sea water (coastal and pelagic). Oceanic sea skaters have a relatively high cool coma temperature (CCT; temperatures at which the body stem is cool damaged and sticks to the water surface and the insect can no longer stride) of 10–15 ◦ C or higher. Their CCT may be much higher than their super cooling point (SCP; lowest temperature reached just before an exothermic event caused by the release of latent heat) [2,3]. Aquarius paludum water striders that live in fresh water in a warm temperate zone in Kochi, Japan (33◦ N) have a lower lethal point of around −3 ◦ C and SCP of around
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