Halobates Micans Research Articles

Evidence of new strains of Wolbachia symbiont colonising semiaquatic bugs (Hemiptera: Gerroidea) in mangrove environment of the Lesser Antilles.

Wolbachia Hertig, 1936 is an intracellular bacterial symbiont colonizing many arthropods. Of the studies done on the bacteria present in the superfamily Gerroidea Leach, 1815, no report of Wolbachia infection had yet been made. Thus, we checked the presence of Wolbachia in six Gerroidea species which colonize tropical aquatic environments by PCR using wsp primer set before sequencing and phylogenetic analyses. Insects were collected in the marine fringe of mangroves, in river estuaries, in swampy mangroves, and in ponds from Guadeloupe islands (Caribbean). Two new strains of Wolbachia were detected in these Gerroidea. They were named wLfran and wRmang. The wsp sequences suggest that the strains belong to the already described E supergroup or similar. wLfran is present in Limnogonus franciscanus Stål, 1859 and Rheumatobates trinitatis (China, 1943) while wRmang appears to be present exclusively in R. mangrovensis (China, 1943). Three other species were analysed, but did not appear to be infected: Brachymetra albinerva (Amyot & Serville, 1843), Halobates micans Eschscheltz, 1822, and Microvelia pulchella Westwood, 1834. The results presented here highlight for the first time the presence of new intracellular Wolbachia strains in Gerroidea colonising tropical aquatic environments like mangrove habitats from inlands to sea shore.

The First Finding of Six Instars of Larvae in Heteroptera and the Negative Correlation between Precipitation and Number of Individuals Collected in Sea Skaters of Halobates (Heteroptera: Gerridae).

This study, conducted during a scientific cruise, MR15-04, aims, first, to examine species and larval/adult components of Halobates (Heteroptera: Gerridae) inhabiting the tropical Indian Ocean of 4°00′ S–7°00′ S, 101°00′ E–103°00′ E and, second, to examine the correlative relationship between precipitation just before collection and the number of sea skaters collected in November and December 2015. Near Sumatra (50 km south-west), larvae and adults of four species of Halobates (Halobates germanes White, 1883; Halobates micans Eschscholtz, 1822; Halobates princeps White, 1883; undescribed species: Halobates sp.) were collected. Adults of an undescribed species had about a 5 mm long body in a gourd-like shape. One male adult specimen of H. princeps was collected. Body length, body width, and head width was measured in all specimens of Halobates. Six larval stages were detected in all three species of sea skaters as the first finding for Heteropteran insects. There was a negative correlation between amount of precipitation for 19 h before collection and the number of Halobates individuals collected by the neuston net. Death or (positive or passive) sinking by sea skaters could be due to occasional rain fall on the sea surface.

Heat coma temperature, relative contents of saturated/unsaturated fatty acids and reproductive maturation in the oceanic sea skaters Halobates micans

This study was performed to clarify how the relative volume of saturated/unsaturated lipid and reproductive maturation relate to resistance to high temperature in the oceanic sea skaters, Halobates micans. Heat coma temperature (HCT) was measured in H. micans adults collected from a fixed sampling location (12°00′N, 135°00′E) in the western tropical Pacific Ocean. After measuring HCT, the specimen were dissected to measure the testes size and to determine the presence and number of oocytes in females. Bodies of the specimen were assessed by lipid analysis to evaluate saturated and unsaturated lipid content. A negative trend was seen between heat coma temperature and percentage of a saturated fatty acid, myristic acid (ratio of carbon number to number of double bonds=14:0) (Pearson's correlation test: r=−0.520, p=0.101). In contrast, a positive trend was detected between heat coma temperature and percentage of an unsaturated fatty acid, palmitoleic acid (16:1) (r=478, p=0.137). Young males with small testes showed lower heat coma temperatures, whereas females that showed relatively high heat coma temperatures of 36–40°C tended to have fewer mature oocytes in their ovaries than those that showed low heat coma temperatures of 30–34°C. As Halobates appears to exhibit embryonic diapause rather than adult diapause, males of H. micans may develop both testes and resistance to high temperature in the parallel as they grow. In females, a trade-off may occur between heat tolerance function and oogenesis in the oceanic sea skaters.

Comparative Study of Salinity Tolerance an Oceanic Sea Skater, <i>Halobates</i> <i>micans</i> and Its Closely Related Fresh Water Species, <i>Metrocoris</i> <i>histrio</i>

This study aims, first, to examine the limit for tolerance to lower salinity by an oceanic sea skater, Halobates micans, and , second, to make it clear whether exclusively fresh water Halobatinae species, Metrocoris histrio has salinity tolerance. Adults of H. micans were collected using Neuston Net from the starboard side of R/V MIRAI on a fixed station at 8°S, 80°E, whereas those of M. histrio were collected from a small pond filled with a spring fresh water in Kochi (33°N, 133°E), Japan. Time in survival was measured in starved condition under several salinity conditions: 0‰, 2‰, 4‰, 6‰, 8‰, 9‰ and 10‰ for H. micans; 0‰, 5‰, 10‰, 12.5‰, 15‰ for M. histrio. Half of adults were in coma due to lower salinity under 10‰ and time in survival was less than 10 hours under less than 4‰ for H. micans. Time in survival was half at 5‰ of 80 hours on average at 0‰ as a control and less than 10 hours at 10‰ or higher salinity for M. histrio. Relatively flexible osmo-regulation ability by H. micans would be related to wide variety of salinity condition of surface oceanic water, whereas very limited tolerance even to lower salinity of 5‰ may be permitted by the no chances to be exposed to brackish water in natural habitats of M. histrio. This study showed that salinity tolerance of Halobatinae species would reflect, directly, the salinity condition of their habitats.

Lowered Salinity Tolerance in Sea SkatersHalobates micans,Halobates sericeus, andHalobatessp. (Heteroptera: Gerridae)

Adult specimens of three species of oceanic sea skater, Halobates sericeus Eschscholtz, Halobates micans Eschscholtz, and Halobates sp. were placed in one of four solutions of different salinity (sea water [35-36‰], sea water : fresh water = 2:1 [23-24‰], sea water : fresh water = 1:2 [11-13‰], and fresh water [0‰]) after collection from the temperate and subtropical Pacific Ocean, tropical Indian Ocean, and Tomini Gulf in Indonesia, and observed in 2-h intervals until they died. H. micans collected from the tropical Indian Ocean survived twice a long (80-100 h) on average as H. sericeus collected from the temperate and subtropical Pacific Ocean (35-45 h) under salinities of 12-36‰. Paralysis from freshwater treatment occurred within 2-9 h in all specimens of both species of H. sericeus from the Pacific Ocean and H. micans from the Indian Ocean, and all insects died within 2 hr of starting the paralysis. In fresh water, oceanic sea skaters of H. sp. collected from the inner water of Tomini Gulf survived for ≍24 h on average, significantly longer than those collected from the open ocean. Significantly longer length of survival was shown by the three species on one-thirds, two-thirds brackish, and 100‰ sea water than on fresh water. The long length of survival shown by oceanic sea skaters even in brackish water may be an adaptation to the occasional rain fall on the sea water film.

Supercooling points and heat coma temperatures in four species of oceanic sea skaters of the genus Halobates (Heteroptera: Gerridae: Halobatinae)

The only insects known to live in the open ocean are several species of sea skaters of the genus Halobates (Heteroptera: Gerridae). We have collected four species in the tropical western Pacific Ocean and measured heat coma temperature (HCT) and supercooling point (SCP) in 132 specimens. The SCPs were relatively low (ranging between −18°C and −19°C) and similar in all species. Significant inter-species differences were found in the level of HCT. The lowest HCT 32.9°C was found in Halobates micans Eschscholtz, 1822, which is distributed in thermally stable tropical waters. The highest HCT levels of 36.6°C and 36.0°C were observed in Halobates sericeus Eschscholtz and Halobates germanus White, 1883, respectively, mostly occurring in thermally more fluctuating habitats (subtropical and warm temperate waters, and coastal waters, respectively). A new species, H. sp. (under process of description) showed an intermediate HCT of 34.8°C. In addition, we found significant negative statistical correlation between HCT and SCP values at the species and individual levels. We discuss our results in the light of putative relationship between thermal physiology of sea skaters and their distribution.

Comparison of temperature preference for habitat among three species of oceanic sea skaters, <i>Halobates micans</i>,<i> H. germanus</i> and <i>H. sericeus</i>

The main purpose of this study is to investigate temperature preference for habitat of three species of oceanic sea skaters, Halobates micans, H. germanus and H. sericeus. For each of the three species, we examined the relationship between population density and surface water and air temperatures in the sampling sites during three science cruises in the tropical to temperate zone of the Pacific Ocean. A higher density of H. micans was observed in sites with higher water and air temperatures at 28℃ - 30℃ than that at site with lower temperatures of 23℃ - 28℃. A higher density of H. germanus was observed in sites with extremely high temperatures of 29.6℃ and 30℃ than that in sites with moderately high temperatures of 28℃ - 29℃ in the Pacific Ocean, while a relatively high density was observed in sites with a wide range of temperatures from 24℃ - 30℃ in the southern hemisphere Pacific Ocean. The relatively low temperature preference of 23℃ - 28℃ exhibited by H. sericeus may be related to its size as the smallest among the three species and its relatively wide latitudinal distribution ranging up to 40?N.

Plastic pellets as oviposition site and means of dispersal for the ocean-skater insect Halobates

Microplastics are omnipresent in the oceans and generally have negative impacts on the biota. However, flotsam may increase the availability of hard substrates, which are considered a limiting resource for some oceanic species, e.g. as oviposition sites for the ocean insect Halobates. This study describes the use of plastic pellets as an oviposition site for Halobates micans and discusses possible effects on its abundance and dispersion. Inspection of egg masses on stranded particles on beaches revealed that a mean of 24% (from 0% to 62%) of the pellets bore eggs (mean of 5 and max. of 48 eggs per pellet). Most eggs (63%) contained embryos, while 37% were empty egg shells. This shows that even small plastic particles are used as oviposition site by H. micans, and that marine litter may have a positive effect over the abundance and dispersion of this species.

Occurrence, distribution and abundance of Halobates micans Eschscholtz, 1822 (Heteroptera, Gerridae) along the southeastern Brazilian coast

Data collected during an oceanographic cruise along the southeastern Brazilian coast from Cape Frio (22 degrees 58' S) and Paraná (27 degrees 50' S) in March 1982 showed that the marine insect Halobates micans occurred along the Southeastern Brazilian Bight, but in lower abundance in low-temperature areas due to the intrusion and upwelling of South Atlantic Central Water, and in low-salinity areas in Coastal Water. Insect capture was higher at night and in the oligotrophic Tropical Water. The number of nymphs and adult females was higher, probably because of an active breeding season during the austral summer. Adult sex ratio was 1.3:1.0 (F:M). Floating gas vesicles of benthic Sargassum spp. and petroleum lumps were used by females for egg-laying.

Occurrence and density of Halobates micans (Hemiptera: Gerridae) in the eastern South Indian Ocean

AbstractTwo species of ocean skaters, Halobates germanus and Halobates micans, live in the tropical and subtropical waters of the Indian Ocean. From December 1992 to December 1993, Halobates was intensively sampled in the easternmost region of the South Indian Ocean (13–18.5°S, 114–121E°), from which there have been a small number of records of Halobates. No H. germanus was caught, but a total of 1190 H. micans were collected, with densities estimated at 13 900–28 100 individuals/km2. This suggests that H. micans lives in the study area at high densities comparable to those in the Atlantic and the Pacific Oceans. We also discuss the possible effects of ocean currents and winds on the geographic distributions of the two Halobates species in the eastern South Indian Ocean.

Biogeography and phylogeny of the sea-skaterHalobates

Members of the genusHalobates are the only insects to be found in the open oceans, generally roughly between latitudes 40°N and 40°S. Of the 40-old species, only five (Halobates micans, H. sericeus, H. germanus, H. sobrinus andH. splendens) are pelagic, the others being found in near-shore habitats, often endemic to islands or island groups.H. micans is the only cosmopolitan species, being found in the Atlantic, Pacific and Indian Oceans. All five species are found in the Pacific Ocean but only two,Halobates micans andHalobates germanus, occur also in the Indian Ocean. Their ranges of distribution are probably limited by physical as well as historical factors. Halobates probably originated from a near-shore brackish-water ancestor in the Indo-Malaysian region. This is the area where the majority of the near-shore sea-skater species are found; it is also where related brackish-water genera (Asclepios, etc.)occur. There are indications that the open-oceanH alobates are more highly evolved than their near-shore cousins, but we do not yet know how the various species are related. Eventually, cladistic analyses coupled with molecular biological techniques may provide data on this point.

Abundance and distribution of Halobates micans (Insecta : Gerridae) in the northwest Atlantic

A seven-year survey of the marine water-strider Halobates micans in the northwest Atlantic Ocean showed highest abundance of the insects in the Caribbean Sea and Gulf Stream. The Bahama Islands and northern Sargasso Sea regions yielded relatively low abundances, and few H. micans were collected north of 35°N latitude. Regional patterns of insect abundance appear to be directly related to surface water temperature, but biotic factors such as predation and abundance of gelatinous food organisms may be important. Water strider abundance does not appear to be related to regional differences in the abundance of floating substrata. Estimates of absolute density ranged from 0 to 53,000 H. micans km −2, with densities in tropical Caribbean waters averaging 7000 km −2. Using data from 9 to 48°N latitude as an extension of data from the central Atlantic ( Cheng and Schulz-Baldes, 1981, “Meteor” Forschungsgemeinschaft-Ergebnisse, 33, 17–21), density of H. micans approximates an inverse logarithmic function of latitude. In those geographic regions where repeated annual transects have been made, the year to year variations in standing stocks of the insect are low, except in the southwest Sargasso Sea.

Cadmium in Halobates micans from the central and south Atlantic Ocean

The concentrations of cadmium in 428 samples of the sea-skater Halobates micans from 57 locations in the central and south Atlantic Ocean ranged from 1.7 to 122 μg Cd g-1 dry wt. The concentrations in females, males and nymphs were not significantly different. The data suggest that the cadmium concentrations in these insects are somehow related to surface currents. The highest values (50 to 70 μg g-1, maximum value 122 μg g-1) were recorded from the South Equatorial Current region; intermediate values (10 to 20 μg g-1) from the Equatorial Counter Current and the North Equatorial Current; and relatively low concentrations (>10 μg g-1) from the Canary Current in the north and the Benguela Current in the south. A remarkable feature of these data lies in the fact that they reveal areas of high Cd content which correspond closely with those indicated by data obtained by Bull et al. (1977) from a different set of samples, analyzed by different methods and obtained in different years.