Nepidae Research Articles

Chromosome-level genome assembly of Chinese water Scorpion Ranatra chinensis (Heteroptera: Nepidae)

Heteroptera (the true bugs), one of the most diverse lineages of insects, diversified in feeding strategies and living habitats, and thus become an ideal lineage for studies on adaptive evolution. Chinese water scorpion Ranatra chinensis (Heteroptera: Nepidae) is a predaceous bug living in lentic water systems, representing an ideal model for studying habitat transition and adaptation to water environment. However, genetic studies on this water bug remain limited. Here, we obtained a chromosome-level genome of R. chinensis using PacBio HiFi long reads and Hi-C sequencing reads. The total assembly size of genome is 867.89 Mb, with a scaffold N50 length of 26.48 Mb and the GC content of 39.50%. All contigs were assembled into 23 pseudo-chromosomes (N = 19 A + X1X2X3X4), and we predicted 18,424 protein-coding genes in this genome. This study will provide valuable genomic resources for future studies on the biology, water adaptation, and genome evolution of water bugs.

Study Of Aquatic Hemipteran And Coleopteran With Their Ecological Impacts: A Review

In the natural world, utilitarian diversification of the earthbound is predominantly composed of the amazing numerous and enormously sophisticated bugs and beetles. Investigation of biodiversity is one of the crucial ways of dealing with evaluating structure, overflow, and examination of occupying species in the different aquatic ecosystems. Aquatic bugs (water striders, water scorpions) and beetles (diving beetles, water scavenger beetles) are great signs of the organic soundness of an aquatic ecosystem since some of them are harmless and sensitive to contamination, while others can live in upset and incredibly dirtied waters. Hemiptera and Coleoptera are two significant orders that normally exist in oceanic frameworks, feeding on dead leaves or predaceous, interdependent for predation and competition, sometimes acting as a nuisance and structuring the foundation of aquatic habitats. Hence, there is need for a regular identification, habitat modification, monitoring, and conservation of these essential orders.

THE FAUNA OF AQUATIC HEMIPTERA (HETEROPTERA) IN CHARYN NATURE PARK

The material for this research resulted from the authors’ work during 2018–2020 at the Charyn Nature Park in different floodplain reservoirs of the Charyn and Temirlik Rivers, Almaty region, Kazakhstan. Their study of the fauna and ecology of Hemiptera followed the methods of route surveys and stationary observations. The simplest way to collect is to catch aquatic Hemiptera using aquatic entomological nets and account for potential water bugs. Corixidae has 21 species, while other families have one or two species. Their density comprised Gerridae (8–10), Corixidae (16–20), Naucoridae (3–5), Notonecta (8–9), and Ranatra (3–5) specimens/m2, respectively. The mass species found included Ilyocoris cimicoides, Noton ecta glauca, Nepa cinerea, and Gerris costae. During the autumn survey, an observation revealed that the previously studied reservoirs have decreased in size, and some have even dried up. In the coastal part of the reservoirs, water scorpions (Nepa cinerea) were crawling along the bottom of the pool. Water backswimmers (Notonectidae) and toad bugs (Naucoridae) moved to deeper pond areas. Representatives of the Corixidae family were zoophytophages (21 species), with the remaining species being zoophages (12 species). Under the Charyn Nature Park conditions, most species were mono or univoltine (21 species), bivoltine (five species), and poly or multivoltine (seven species). The fauna of the Charyn State National Nature Park (SNNP) has the main characteristic of species of Hemiptera with Western Asia (40%), Trans-Palearctic (21%), Western Palearctic (18%), and Trans-Eurasian (12%) ranges. All the recognized species have a wide selection of hunting objects, feeding on aquatic invertebrates, including regulating the numbers of blood-sucking mosquito larvae (Culicidae).

Correction to: Jekyll and Hyde: Day–night personality differences in the water scorpion Nepa hoffmanni

<b>Correction to:</b> Jekyll and Hyde: Day–night personality differences in the water scorpion <i>Nepa hoffmanni</i>

Jekyll and Hyde: Day–night personality differences in the water scorpionNepa hoffmanni

AbstractDifferences between daytime and night-time behaviors are common in insects due to potential trade-offs between predator avoidance and foraging. While diel effects on average behavior are well documented, it remains unclear whether individuals differ in how they adjust their behavior between daytime and night-time. In this study, we focused on two light dependent behaviors, activity and tonic immobility, in the water scorpion (Nepa hoffmanni). Each individual was assayed for each behavior six times during the day and six times at night. Then, we explored diel differences in (1) average behavior, (2) among-individual variation in behavior, (3) individual rank order of behavioral expression, and (4) the sign and magnitude of behavioral syndromes (among-individual correlations between behaviors). At night, N. hoffmanni was more active and exhibited shorter periods of tonic immobility. Among-individual variation in activity was greater at night than during the day, but among-individual variation in tonic immobility did not differ between day and night. Individuals also differed in their diel plasticity in activity but not in tonic immobility. Thus, both (1) day–night differences in among-individual variation and (2) individual variation in diel plasticity contributed to the light-dependent sign of the behavioral syndromes. Our findings highlight the need for individual-level studies to fully elucidate diel influences on animal behavior. We suggest that day–night differences in behavioral syndromes as well as in selection might be key to behavioral evolution, especially in animals active during both day and night.

Nutritional Composition of Some Commonly Available Aquatic Edible Insects of Assam, India.

The nutritive value of five edible aquatic insects of Assam-Hemipterans; water bug (Diplonychus rusticus Fabricius) family belostomatidae; giant water bug (Lethocerus indicus Lepeletier and Serville) family belostomatidae; water scorpion (Laccotrephes sp.) family nepidae, water stick (Ranatra sp.) family nepidae; Coleopterans diving beetle (Cybister sp.) family dytiscidae-based on their proximate and elemental composition, antioxidant and antinutritional properties were assessed by using standard methods of analysis. Analytical studies revealed that the selected aquatic insect species have high nutritive value and are rich sources of protein (50.03 to 57.67%) and other nutrients (fat, carbohydrate and crude fiber, etc.) along with superior energy contents (331.98 to 506.38 kJ/100 g). The aquatic insect species also contained appreciable amounts of major and trace dietary elements. Phenol and flavonoid contents reflect its high antioxidant activity (80.82 to 91.47% DPPH inhibition). Tannin (18.50 to 60.76 mg tannic acid equivalent/100 g), phytic acid (11.72 to 97.30 mg/100 g) and oxalic acid (2.93 to 5.34 mg/100 g) as antinutritional compounds were registered below the toxic level (0.52% or 520 mg/100 g). The present findings indicate that the selected aquatic insect species can be considered as ideal candidates for exploration as food and feed to ensure nutritional and livelihood security of this region.

Phylogenetic diversity of water scorpions (Nepa spp., Insecta, Hemiptera)

Water scorpions belonging to the genus Nepa are predatory freshwater aquatic insects of the order Hemiptera. There are currently five accepted species, with a Holarctic distribution: N. cinerea (Eurasia and Northern Africa), N. sardiniensis (Sardinia and Corsica), N. anophthalma (endemic to Movile Cave, Romania), N. apiculata (North America) and N. hoffmanni (Eastern Asia). Mitochondrial and nuclear genetic markers indicate a correlation between genetic diversity and geographic distribution. Analyses also reveal a cryptic diversity in the Western Mediterranean basin, with specimens of the cinerea clade being assigned to the sardiniensis clade. The cave-adapted N. anophthalma is genetically closest to N. cinerea, suggesting surface populations of N. cinerea as possible ancestors. N. cinerea samples from three cave systems in Italy indicate various degrees of gene flow between surface and subterranean populations and an instance of a possible incipient speciation event. Despite the overlap in distribution range in mainland Eastern Asia between N. cinerea and N. hoffmanni, there is a high genetic distance between the two species. A similar value of genetic distance is found between N. cinerea and N. apiculata, but also between N. hoffmanni and N. apiculata, suggesting the assignment of N. hoffmanni and N. apiculata to different genera. The single species currently considered as stygobiotic, N. anophthalma, deserves more research to understand the timing of colonization of Movile groundwater by its surface ancestors.

Predatory influence of dragonfly larvae and water scorpions on eggs and tadpoles of Indosylvirana temporalis (Anura: Ranidae)

We assessed in the laboratory the vulnerability of Bronzed frog (Indosylvirana temporalis) eggs and tadpoles to two potential sit-and-wait insect predators, larvae of a dragonfly (Pantala flavescens; Odonata: Libellulidae) and adult water scorpions (Laccotrephes sp.; Hemiptera: Nepidae). We exposed a series of different developmental stages of I. temporalis (from eggs to metamorphic climax stage) to these two predators. The results of this study showed that larvae of P. flavescens preyed on eggs and tadpoles of I. temporalis but only to stage 36. Laccotrephes sp. did not prey on eggs of I. temporalis but on tadpoles of all stages (22 to 42). This difference in predation rate was likely due to the gape size of the predators. The larvae of P. flavescens are gape-limited and cannot prey on larger tadpoles (above stage 36). Adults Laccotrephes sp. are non-gape-limited predators, using a segmented beak to pierce I. temporalis and suck the body fluids. They captured small to large tadpoles by quickly grabbing and immobilizing them using the front pair of raptorial legs. The present study shows that both predatory insects are a threat to I. temporalis at early and later stages of larval development.

Comparative vulnerability of Indosylvirana temporalis and Clinotarsus curtipes (Anura: Ranidae) tadpoles to water scorpions: importance of refugia and swimming speed in predator avoidance

The comparative vulnerability of two co-existing tadpole species (Indosylvirana temporalis and Clinotarsus curtipes) to their common predator, water scorpions (Laccotrephes sp.; Hemiptera: Nepidae), and the importance of refugia in predator avoidance were studied in the laboratory. In a total of 60 experimental trials, 10 tadpoles each of I. temporalis and C. curtipes of comparable body sizes were exposed to water scorpions (starved for 48 h). Thirty trials included refugia while 30 did not. The results of this study showed that in both the absence and the presence of refugia C. curtipes tadpoles fell prey to water scorpions more frequently than I. temporalis tadpoles. A main difference between the two species is the speed of swimming; Vmax of C. curtipes (24.73 cm/s) tadpoles is lower than that of I. temporalis (30.78 cm/s) tadpoles. This is likely to be the reason why more C. curtipes tadpoles were preyed upon than were I. temporalis tadpoles. Predation risk of tadpoles of both species was affected significantly by the presence of refuge sites. The vulnerability of both tadpole species was lower where refuge sites were available. The present study clearly shows that I. temporalis tadpoles avoid predation by water scorpions more effectively than do C. curtipes tadpoles.

Water Scorpions, Water Stick-Insects Ranatra spp. (Insecta: Hemiptera: Nepidae)

Commonly mistaken for other objects due to its appearance, hence the common name water stick-insect, this slender reddish-brown insect is commonly found in fresh or brackish water (a mix of salt and fresh water) (Anufriyeva et al. 2016). They are ambush predators and will spend most of its time in the water waiting for prey. They are limited to the length of their raptorial forearms in terms of catching prey. In the southeastern United States, these insects are commonly referred to as water scorpions.&#x0D; Also published on the Featured Creatures website at http://entnemdept.ufl.edu/creatures/AQUATIC/Ranatra.html

Carotenoids of hemipteran insects, from the perspective of chemo-systematic and chemical ecological studies

Carotenoids of 47 species of insects belonging to Hemiptera, including 16 species of Sternorrhyncha (aphids and a whitefly), 11 species of Auchenorrhyncha (planthoppers, leafhoppers, and cicadas), and 20 species of Heteroptera (stink bugs, assassin bugs, water striders, water scorpions, water bugs, and backswimmers), were investigated from the viewpoints of chemo-systematic and chemical ecology. In aphids, carotenoids belonging to the torulene biosynthetic pathway such as β-zeacarotene, β,ψ-carotene, and torulene, and carotenoids with a γ-end group such as β,γ-carotene and γ,γ-carotene were identified. Carotenoids belonging the torulene biosynthetic pathway and with a γ-end group were also present in water striders. On the other hand, β-carotene, β-cryptoxanthin, and lutein, which originated from dietary plants, were present in both stink bugs and leafhoppers. Assassin bugs also accumulated carotenoids from dietary insects. Trace amounts of carotenoids were detected in cicadas. Carotenoids of insects belonging to Hemiptera well-reflect their ecological life histories.

周伊勢湾地域におけるヒメタイコウチ（Nepa hoffmanni）の 分子系統地理学的解析

周伊勢湾地域におけるヒメタイコウチ（Nepa hoffmanni）の 分子系統地理学的解析

Activity Patterns and Feeding Ecology of the Semi-Aquatic &lt;i&gt;Varanus flavescens&lt;/i&gt; (Reptilia: Varanidae)

The study was conducted on activity patterns and feeding ecology of semi-aquatic yellow monitor ( Varanus flavescens ) in the Chalan Beel area of Bangladesh by following focal sampling method. Overall, V. flavescens spent highest proportion (37.73 ± 0.65) of their active time in moving in search of food and lowest proportion (3.05 ± 0.05) of time in conflicting. Maximum (22.80 ± 3.19) and minimum (5.82 ± 1.06) moving activity were recorded in the month of August and December respectively. Two peak feeding times; from 6.30 AM to 10.30 AM and from 3.00 p.m. to 4.30 p.m. were recorded throughout the day. Total 15 prey groups were recorded as yellow monitor’s diet. The diet consisted mainly of beetles, which comprised 15% of the number of prey items in stomach samples. Others diet comprises of spider, dragonfly, water scorpions, mole crickets, crickets, ants, fresh water crabs, grasshopper, frog, small fish, house mouse and bird eggs. Most of the activities of V. flavescens varied significantly (χ 2 test, P < 0.05) in different month in response to changing weather conditions. During heavy cold V. flavescens shows basking activity to regulate their body temperature and the highest proportion (50.48 ± 3.03) of basking activity was recorded in December. The population of V. flavescens is decreasing at an alarming rate all over Bangladesh. This warrants for further study regarding the ecology and conservation of the yellow monitor.

A chromosomal analysis of Nepa cinerea Linnaeus, 1758 and Ranatra linearis (Linnaeus, 1758) (Heteroptera, Nepidae).

An account is given of the karyotypes and male meiosis of the Water Scorpion Nepa cinerea Linnaeus, 1758 and the Water Stick Insect Ranatra linearis (Linnaeus, 1758) (Heteroptera, Nepomorpha, Nepidae). A number of different approaches and techniques were tried: the employment of both male and female gonads and mid-guts as the sources of chromosomes, squash and air-drying methods for chromosome preparations, C-banding and fluorescence in situ hybridization (FISH) for chromosome study. We found that N. cinerea had a karyotype comprising 14 pairs of autosomes and a multiple sex chromosome system, which is X1X2X3X4Y (♂) / X1X1X2X2X3X3X4X4 (♀), whereas R. linearis had a karyotype comprising 19 pairs of autosomes and a multiple sex chromosome system X1X2X3X4Y (♂) / X1X1X2X2X3X3X4X4 (♀). In both N. cinerea and R. linearis, the autosomes formed chiasmate bivalents in spermatogenesis, and the sex chromosome univalents divided during the first meiotic division and segregated during the second one suggesting thus a post-reductional type of behaviour. These results confirm and amplify those of Steopoe (1925, 1927, 1931, 1932) but are inconsistent with those of other researchers. C-banding appeared helpful in pairing up the autosomes for karyotype assembly; however in R. linearis the chromosomes were much more uniform in size and general appearance than in N. cinerea. FISH for 18S ribosomal DNA (major rDNA) revealed hybridization signals on two of the five sex chromosomes in N. cinerea. In R. linearis, rDNA location was less obvious than in N. cinerea; however it is suggested to be similar. We have detected the presence of the canonical “insect” (TTAGG)n telomeric repeat in chromosomes of these species. This is the first application of C-banding and FISH in the family Nepidae.

Some morphological characteristics of the water scorpion Nepa cinerea (Heteroptera: Nepomorpha) are associated with habitat type

Morphological variation can enable species to successfully survive and reproduce in distinct habitats. Water scorpion (Nepa cinerea Linnaeus, 1758) occurs in different aquatic habitats from lentic to lotic conditions. We examined the morphology of N. cinerea collected from a diverse array of habitat types (creeks, canals, ponds) in order to explore possible morphological adaptations to the habitat. We addressed the following specific questions: (i) is there any morphological differences between specimens collected from distinct habitats, and if so, (ii) is it possible to relate differences in morphology of the N. cinerea to characteristics of the habitat structure? Altogether 121 individuals (69 males and 52 females) were sampled from 17 sampling sites in the catchment area of Lake Balaton (Hungary). 54 body parameters were determined on all individuals. According to five habitat parameters (bottom quality, current velocity of the water, water depth, submerse plant density, shading) sampling sites were clustered into two distinct groups. Submerse plant density proved to be the most important discriminating factor between the two groups. The morphology of the N. cinerea (both males and females) sampled from the two contrasting habitat types were different. No relationship was found between geographical position of the habitat type and body morphology of N. cinerea. Leg morphology, especially claws on the third leg and some body shape parameters showed relationships with habitat characteristics. These morphological variations, which may be the result of phenotypic plasticity, could contribute to an opportunistic habitat choice of the species.

Invasive Cane Toads as Prey for Native Arthropod Predators in Tropical Australia

Abstract: The successful spread of invasive Cane Toads (Rhinella marina) across tropical Australia has been attributed to a lack of biotic resistance, based upon the inability of most anuran-eating vertebrate predators to tolerate the powerful chemical defenses of the toads. However, despite their high species richness, invertebrates have been much less studied than vertebrates as predators of Cane Toads. Our field and laboratory studies show that toads are killed and consumed by a phylogenetically diverse array of arthropod taxa. No arthropod predators consumed toad eggs in our laboratory experiments, but fishing spiders, water beetles, water scorpions, and dragonfly nymphs killed toad tadpoles, and ants and fishing spiders killed metamorph toads. Published accounts report predation on toads by crustaceans and hemipterans also. In our experiments, no predators showed any overt ill effects from consuming toad tissue. Dragonfly nymphs (Pantala flavescens) and fishing spiders (Dolomedes facetus) selectivel...

Mosquito larvae change their feeding behavior in response to kairomones from some predators.

The efficacy of using predators for the biological control of mosquito disease vectors will be reduced if mosquito larvae respond to predator presence. The larvae of two mosquito species were investigated to study whether they responded to predator kairomones by increasing surface filter-feeding, which is a less active and thus less risky feeding strategy than bottom feeding. Culex quinquefasciatus Say is normally found in highly polluted water, where it will have little contact with predators. Except for some third instars, its larvae showed no response to four different types of predators. Culiseta longiareolata Macquart, living in rain-filled rock pools, is frequently attacked by a range of predators. All instars tested (second, third, and fourth instars) strongly responded to chemicals from dragonfly nymphs (Crocothemis erythraea Brullé), damselfly nymphs (Ischnura evansi Morton), and the fish Aphanius dispar Ruppel. However, they did not respond to final-instar water scorpions (Nepa cinerea L.), which would not feed on the mosquito larvae. Second- and third-instar Cs. longiareolata produced the same response to chopped up mosquito larvae as they did to dragonfly nymphs, but fourth instars produced a significantly stronger response to dragonfly nymphs-both those unfed and those fed in situ. Thus, Cs. longiareolata not only identified different predators and responded accordingly, but also responded to conspecific alarm pheromones. Cx quinquefasciatus showed little response to predators or to alarm pheromones from damaged conspecific larvae.

The adipokinetic hormones of African water bugs of the Heteropteran families Nepidae and Belostomatidae

AbstractFour African species of true water bugs (Nepomorpha: Hemiptera: Heteroptera) are studied by mass spectrometry and biological assays to gain information on the presence, structure and function of peptides from the adipokinetic hormone (AKH) family, which are produced in the corpora cardiaca (CC). The water scorpion Laccotrephes fabricii Stål (Nepidae) has the peptide code‐named Peram‐CAH‐I with the sequence pGlu‐Val‐Asn‐Phe‐Ser‐Pro‐Asn‐Trp amide, whereas Appasus grassei Poisson (Belostomatidae) produces Anaim‐AKH, which is a Ser7 analogue of Peram‐CAH‐I (pGlu‐Val‐Asn‐Phe‐Ser‐Pro‐Ser‐Trp amide). The giant water bug Hydrocyrius columbiae Spinola (Belostomatidae) has two adipokinetic hormone family members: Anaim‐AKH and Letin‐AKH, which again differ only at position 7 (Ser7 versus Tyr7). When the sequence data are compared with current molecular phylogenetic analyses of Nepomorpha, they are essentially in agreement with the newest ideas on phylogenetic relationships among the families. Functional investigation of these peptides reveals a mainly lipid‐based energy metabolism in these insects, as demonstrated by a hyperlipaemic response after injecting crude CC extract or the appropriate peptide into the respective species. The carbohydrate concentration in the haemolymph is not affected by such injections, and the carbohydrate level in most cases is lower than that of the circulating lipids. During physical exercise, such as swimming for 1 h, carbohydrates may contribute to some extent to the provision of energy; the substantial increase in the concentration of lipids in the haemolymph, however, is a strong indicator that the peptides are released from the CC and act primarily as true adipokinetic hormones during this period of intense muscular activity.

First report for the Neotropics of predation by the waterscorpion Ranatra (Hemiptera: Nepidae) on a member of Gerromorpha (Hemiptera)

The water scorpion Ranatra pittieri was observed preying on an adult of the water strider Eurygerris flavolineatus in a closed laboratory system. This is the first report for the Neotropics of the predation by a member of the infraorder Nepomorpha on a species of Gerromorpha.KEYWORDWaterscorpions, Heteroptera, Gerridae, Nepomorpha, Costa Rica, Central America

Molecular Cloning, Gene Structure, Expression, and Enzyme Activity of a Serine Protease from Water Scorpion, Laccotrephes japonensis (Hemiptera: Nepidae)

Serine proteases are major insect enzymes involved in the digestion of dietary proteins and in the process of blood meal digestion. In this study, cDNA was constructed using the whole body of Laccotrephes japonensis. The flanking sequences of the 5- and 3- end of this gene were characterized by RACE-PCR. Sequence analysis showed that this gene contained a 963-bp ORF encoding 320 amino acids. The deduced amino acid sequence showed 62% identity with the Creontiades dilutus serine protease, 58% with the Lygus lineolaris trypsin precursor, and 54% with the Triatoma infestans salivary trypsin. To assess the expression of the L. japonensis serine protease (JGsp), the JGsp gene was cloned into a baculovirus transfer vector, pBac-1, and expressed in Sf9 cells (Spodoptera frugiperda). SDS-PAGE and western blot analysis have shown that the JGsp recombinant protein was a monomer with a molecular weight of about 32 kDa. Recombinant JGsp has shown activity in the protease enzyme assay using gelatin as a substrate.