Comparative studies on the seasonal occurrence,nymphal development and food menu in two giant water bugs,Diplonychus japonicus vuillefroy andDiplonychus major esaki (Hemiptera: Belostomatidae)

We compared the seasonal changes in population density and nymphal development at different water temperatures and under different food conditions between two giant water bugs, Diplonychus japonicus and D. major, in Okayama, Japan. D. japonicus produced 1–2 generations a year, while D. major was strictly inivoltine. The developmental velocity was higher in D. japonicus than in D. major. The thermal constant of D. japonicus was less than that of D. major. These results suggest that D. japonicus is adapted, to higher water temperature than D. major. In the field, D. japonicus preyed predominately on Lymnaeidae and Physidae snails, while D. major preyed on aquatic insects such as dragonfly nymphs.     

Ecology of giant water bugs (Hemiptera: Heteroptera: Belostomatidae)

Giant water bugs (Heteroptera: Belostomatidae) are aquatic predators of freshwater habitats, and include ca. 150 species distributed throughout the world's subtropical and tropical areas. They have unique mating systems, which involve female competition, and exhibit paternal care, wherein males attend eggs laid by the females on emergent plants (Lethocerinae) or on their backs (Belostomatinae). I review here the studies on the predator–prey relationships, morphology, migration, mating behavior and conservation of this family of insects.     

Male counterstrategy against infanticide of the female giant water bugLethocerus deyrollei (Hemiptera: Belostomatidae)

The male giant water bug'sLethocerus deyrollei counterstrategy against egg mass destruction by the female was investigated in the laboratory. When mature females encounter a brooding male, they destroy his egg mass and thereby take over the mate and gain a nurse for their own egg mass. However, when the male stays on egg masses laid above the water surface, females cannot detect the male nor the egg mass. Eggs of this species fail to hatch without being supplied with water by males. In the observation, brooding males frequently ascend the stick to the egg mass and stay there for long periods, although most of the water attached to their body surface flowed down in 90 s. These long stays on egg masses are regarded as countestrategies against females.     

Evidence of population-level lateralized behaviour in giant water bugs, Belostoma flumineum Say (Heteroptera: Belostomatidae): T-maze turning is left biased

Lateralized behaviour occurs in diverse animals, but relatively few studies examine the phenomenon in invertebrates. Here we report a population-level left turn bias in the giant water bug Belostoma flumineum Say (Heteroptera: Belostomatidae) in an underwater T-maze. Individuals made significantly more left turns than right turns, including when they were naïve and first introduced to the maze. Water bugs also showed significantly longer runs of consecutive left turns than right turns (i.e. LLLLL). The length of these runs, however, did not increase with experience in the maze, suggesting that the effect is not the result of learning. There were also no differences in turning bias between male and female water bugs. The proximate mechanism(s) underlying the left turn bias is unknown, but directional cues in the environment were eliminated by rotating the maze 180° between experiments, suggesting the mechanism(s) is endogenous. To our knowledge this is the first study of lateralized behaviour in the Heteroptera or in a swimming invertebrate animal.     

The water system of traditional rice paddies as an important habitatof the giant water bug, <Emphasis Type="Italic">Lethocerus deyrollei</Emphasis> (Heteroptera: Belostomatidae)

The population dynamics of Lethocerus deyrollei, including the seasonal change in the habitat utilization, were studied in five types of waters, permanent and temporary pools, ditch, rice paddy and marsh in a Satoyama, the traditional landscape in Japan consisting of mixtures of coppice woodlands, farmlands, and settlements, in northern Osaka, from June, 1999 to December, 2001. A mark and recapture census was carried out with adults, and the stage and the number were recorded in nymphs. A total of 95 adults were numbered, and 48 (51%) were recaptured in all the five water types during the study period. Adults of the new generation appeared from late July, and disappeared before the winter in all types of waters. A total of three overwintered adults were recaptured in permanent and temporary pools, ditch, and paddy from between early April and early June. Densities of both L. deyrollei adults and their prey, tadpoles and frogs, were high in permanent and temporary pools, and ditch, in which water temperatures were high in the summer season. Third to fifth (final) instar nymphs were also observed in all water types with different densities in summer, while first and second instars were found only in permanent pool, ditch and paddy habitats in which water temperatures were high and oviposition substrata such as the rice plant, other hygrophytes and wooden stakes existed. These results show that the traditional water system of paddy in the Satoyama landscape as a whole provides an important habitat for L. deyrollei which is now under threat by changing agricultural practices like other native biota inhabiting the system.     

Effects of interspecific competition on development and reproduction in two giant water bugs,Diplonychus japonicus vuillefroy andDiplonychus major esaki (Hemiptera: Belostomatidae)

We studied the interpecific competition between 2 species of predatory aquatic bugs, Diplonychus japonicus and D. major by conducting a field experiment. We set up 3 types of experimental plots in the paddy fields where D. major predominated. The two plots contained single species of either D. japonicus or D. major, respectively, and one plot had both species in equal number. We compared the development and the reproductive performance between plots in each species. In D. japonicus, the number of eggs and early instar nymphs were significantly smaller in the plots containing both species than in the monospecific plots. However, the numbers of late instar nymphs and newly emerged adults were not significantly different between plots. The proportions of starved nymphs in both plots were larger than those in the D. japonicus's natural habitats. The final densities of adults in both plots were lower than those in the natural habitats. These results suggest that lower density of D. japonicus in these paddy fields is due to the lack of available food for nymphs rather than the effects of interspecific competition with D. major. In D. major, significant differences were not found in the number of eggs, each instar nymphs and adults. These results suggest that the effects of interspecific competition did not affect the reproductive performance of D. major.     

Egg attendance and brooding by males of the giant water bugLethocerus medius (Guerin) in the field (Heteroptera: Belostomatidae)

Males of the giant water bug Lethocerus medius(Guerin) typify their monobasic subfamily, the Lethocerinae, in that they do not brood eggs attached to their backs as do males of all members of the subfamily Belostomatinae. Exclusive male parental investment as expressed in the Belostomatinae is extremely rare behavior among animals, and evolution of the trait is obscure. Lethocerus mediusmales apparently remain with their mates through oviposition and are consistently found in attendance of eggs after the female has departed. This behavior may enhance paternity assurance at no cost in opportunity for polygyny. Two double clutches of eggs were found, from which we infer the potential for polygynous matings and shared parental investment. Male L. mediusbrood attended egg clutches above the surface of the water, where they may moisten them, shade them, and defend them against predation. Egg attendance/brooding by L. mediusand other Lethocerusspecies may represent a plesiomorphic state from which paternal back- brooding evolved in the Belostomatinae.     

First record of mudskipper Boleophthalmus dussumieri (Gobiidae: Oxudercinae) on the coast of Mozambique and evidence of two putative lineages along its known distribution range

Boleophthalmus dussumieri is one of the most widely distributed mudskippers and is native to the Persian Gulf in Iran down to the northeast of the Arabian Sea and the coast of India. Nonetheless, the present study is the first to confirm the presence of B. dussumieri in the marine areas of the Mozambique coast. In addition, molecular analysis revealed strong evidence for the existence of two lineages with a high level of nucleotide divergence along the sampled area, revealing a still-neglected taxonomic condition for this lineage/species.     

Taxonomic review of the genus Xenolecanium Takahashi and description of the new genus Takahashilecanium Kondo (Hemiptera: Coccidae; Coccinae, Paralecaniini)

The genus Xenolecanium Takahashi is reviewed and transferred from the subfamily Myzolecaniinae to the Coccinae (tribe Paralecaniini). The type species Xenolecanium mangiferae Takahashi is redescribed, and Xenolecanium takahashii Kondo sp. nov. from Indonesia is described based on the adult female and first instar nymph. A taxonomic key is provided to separate adult females of the two species of Xenolecanium. Xenolecanium rotundum Takahashi is transferred to become the type species of a new monotypic genus, Takahashilecanium Kondo, which is also placed in the Paralecaniini. The morphological justification for placing Xenolecanium and Takahashilecanium in the Paralecaniini is discussed, and we provide a taxonomic key for separating both genera from all other members of the Paralecaniini.     

Taxonomic review and phylogenetic inference elucidate the evolutionary history of Mesozoic Procercopidae,with new data from the Cretaceous Jehol Biota of NE China (Hemiptera,Cicadomorpha)

The Mesozoic family Procercopidae is widely treated as the ancient group of Cercopoidea and a transitional unit to recent lineages, but its evolution and diversity are vague due to fragmentary fossil record and confusing taxonomic history. Herein, an extensive taxonomic review of Procercopidae is presented and some new fossils are reported from the Lower Cretaceous Yixian Formation of NE China. As a result, Chengdecercopis Hong, 1983 is transferred from Procercopidae to Sinoalidae; Procercopis longipennis Becker-Migdisova, 1962 and P shawanensis Zhang, Wang and Zhang, 2003 are transferred to Procercopina Martynov, 1937, resulting in Procercopina longipennis (Becker-Migdisova, 1962), comb. n. and P shawanensis (Zhang, Wang and Zhang, 2003), comb. n.; Luanpingia senjituensis Hong, 1984 is transferred to Stellularis Chen, Yao and Ren, 2015, leading to Stellulari senjituensis (Hong, 1984), comb. n.; Anthoscytina macula Hu, Yao and Ren, 2014 is transferred to Sinocercopis Hong, 1982, and Sunoscytinopteris (Scytinopteridae) and Cathaycixius (Cixiidae) are treated as junior homonym names of Sinocercopis, leading to Sinocercopis macula (Hu, Yao and Ren, 2014), comb. n., S lushangfenensis (Hong, 1984), comb. n., S pustulosis (Ren, 1995), comb. n., and S trinervis (Ren, 1995), comb. n. Additionally, two new species are erected: Stellularis bineuris Chen and Wang, sp. n. and S minutus Chen and Wang, sp. n. Our cladistic analysis based on wing (tegmen and hind wing) characteristics recovers the high-level relationships within Cercopoidea: Sinoalidae + (Procercopidae + (Cercopionidae + modern cercopoids)). Within the family Procercopidae, the cladistic analysis reveals that the Middle to Late Jurassic Titanocercopis and Jurocercopis and the Cretaceous Cretocercopis occupy the basal position, and a gradual change in wing venation can be recognized from the Early Jurassic Procercopis and Procercopina to the Jurassic Anthoscytina, and then to the Cretaceous Stellularis and Sinocercopis. The two Cretaceous genera, sharing wing traits with extant cercopoids, likely represent transitional forms between Procercopidae and recent Cercopoidea; however, they are very similar to their Jurassic relatives in body structures, suggesting it is applicable to attribute them to Procercopidae. Furthermore, our analysis suggests that the extinction of Procercopidae and the origin and early diversification of modern Cercopoidea approximately coincided with the rise and explosive radiation of angiosperms in the late Early Cretaceous and onwards.     

First record of Aphelinus paramali Zehavi and Rosen 1989 (Hymenoptera,Aphelinidae), parasitoid of Aphis pomi de Geer (Hemiptera,Aphididae) in Iran,and its phylogenetic position based on sequence data of ITS2 and COI genes

The occurrence of Aphelinus paramali (Zehavi & Rosen) (Hym., Aphelinidae) was evidenced from North east Iran, in association with Aphis pomi (de Geer). This species is reported from Iran for the first time, and A. pomi is introduced as a new host for this parasitoid. Detailed morphological characters were studied with scanning electron microscopy (SEM) photographs. Also, sequences of ribosomal internal transcribed spacer 2 (ITS2) and cytochrome oxidase subunit I (COI) genes were used for determining species boundaries and comparing with other Aphelinus species. Different results were obtained in phylogenetic analysis of these two regions. Analysis of COI gene supported the closer relationship of this species with Aphelinus abdominalis. This is the first data about comprehensive characterization of a parasitic wasp using morphological characters, SEM and two‐locus information from Iran.     

中国狭蚱属分类学综述及一新种记述(直翅目: 短翼蚱科)

系统研究了分布于中国的狭蚱属Xistra的种类, 共计有6种,包括1新种, 即雅安狭蚱Xistra yaanensis sp. nov.。记述了中国己记录种的引证和分布地区, 提供了该属全部种类的分种检索表。新种的模式标本保存于陕西师范大学动物研究所昆虫标本室。     

Water scorpions (Heteroptera, Nepidae) and giant water bugs (Heteroptera, Belostomatidae): sources of new members of the adipokinetic hormone/red pigment-concentrating hormone family

Two novel octapeptide members of the AKH/RPCH family have been identified from the corpora cardiaca (CC) of two species of water bugs. The giant water bug Lethocerus indicus (family: Belostomatidae) contains a peptide code-named Letin-AKH with the sequence pGlu-Val-Asn-Phe-Ser-Pro-Tyr-Trp amide, and the water scorpion Nepa cinerea (family: Nepidae) has the peptide code-named Nepci-AKH with the sequence pGlu-Leu/Ile-Asn-Phe-Ser-Ser-Gly-Trp amide. The sequences were deduced from the multiple MS(N) electrospray mass data from crude CC extracts. Synthetic peptides were made and co-elution on reversed-phase high performance liquid chromatography (RP-HPLC) with the natural peptide from crude gland extract confirmed the accuracy of the deduced sequence for Letin-AKH and demonstrated that Nepci-AKH contains a Leu residue at position 2 and not an Ile residue. A previously characterized member of the AKH/RPCH family was identified in the stick water scorpion Ranatra linearis by mass spectrometry: Grybi-AKH (pGlu-Val-Asn-Phe-Ser-Thr-Gly-Trp amide) has the same mass (919 Da) as Nepci-AKH and differs in two positions from Nepci-AKH (residues 2 and 6). The apparent function of the peptides is to achieve lipid mobilization in the species under investigation; indications for this came from conspecific bioassays using the appropriate synthetic peptides for injecting into the insects. This function is very likely linked to dispersal flight metabolism of water bugs. Swimming activity in N. cinerea also results in an increase in lipid concentration in the hemolymph.     

Chromosomal distribution of interstitial telomeric sequences as signs of evolution through chromosome fusion in six species of the giant water bugs (Hemiptera,Belostoma)

Tandem arrays of TTAGG repeats show a highly conserved location at the telomeres across the phylogenetic tree of arthropods. In giant water bugs Belostoma, the chromosome number changed during speciation by fragmentation of the single ancestral X chromosome, resulting in a multiple sex chromosome system. Several autosome–autosome fusions and a fusion between the sex chromosome pair and an autosome pair resulted in the reduced number in several species. We mapped the distribution of telomeric sequences and interstitial telomeric sequences (ITSs) in Belostoma candidulum (2n = 12 + XY/XX; male/female), B. dentatum (2n = 26 + X₁X₂Y/X₁X₁X₂X₂), B. elegans (2n = 26 + X₁X₂Y/X₁X₁X₂X₂), B. elongatum (2n = 26 + X₁X₂Y/X₁X₁X₂X₂), B. micantulum (2n = 14 + XY/XX), and B. oxyurum (2n = 6 + XY/XX) by FISH with the (TTAGG)_n probes. Hybridization signals confirmed the presence of TTAGG repeats in the telomeres of all species examined. The three species with reduced chromosome numbers showed additional hybridization signals in interstitial positions, indicating the occurrence of ITS. From the comparison of all species here analyzed, we observed inverse relationships between chromosome number and chromosome size, and between presence/absence of ITS and chromosome number. The ITS distribution between these closely related species supports the hypothesis that several telomere–telomere fusions of the chromosomes from an ancestral diploid chromosome number 2n = 26 + XY/XX played a major role in the karyotype evolution of Belostoma. Consequently, our study provide valuable features that can be used to understand the karyotype evolution, may contribute to a better understanding of taxonomic relationships, and also elucidate the high plasticity of nuclear genomes at the chromosomal level during the speciation processes.     

中国霜扁蝽亚科一新记录属(半翅目:扁蝽科)

滑背霜扁蝽属Lissonotocoris Usinger ＆ Matsuda 1959年根据采自越南的1头雌虫建立的。此前中国尚未有此属的报道。我们研究海南的扁蝽标本时,发现此种的雄虫。本文对该属、种进行重新描述。该属主要特征为：体小,长卵圆形。全翅。棕黑色,霜粉被白色。除前胸背板后叶光滑外,体被颗粒。头前叶短钝;颊未达前叶端部;触角短粗。前胸背板前叶深凹,后叶光滑。前翅膜片完整,无翅脉。     

中国短喙扁蝽亚科一新记录属（半翅目：扁蝽科）

长革扁蝽属Dolichothyreus是Usinger ＆ Matsuda 1959年根据采自加里曼丹的1头雌虫建立的。此前中国尚未有此属的报道。我们研究海南的扁蝽标本时,发现此属模式种的雄虫。本文对该属进行重新描述,并记述了该属模式种痣长革扁蝽D. stigmatus Usinger ＆ Matsuda的雄性。该属主要特征为：体小,长卵圆形。全翅。棕红至棕黑色。体被颗粒。头前叶短钝;颊伸达前叶端部;触角短粗。前胸背板前叶中央具倒＂Y＂型脊突。前翅膜片完整,具翅脉。第3腹背板中央具细脊包围的宽浅凹域。     

Breeding ecology and seasonal abundance of the giant water bug Appasus japonicus (Heteroptera, Belostomatidae)

Males of the giant water bug Appasus (= Diplonychus) japonicus Vuillefroy (Belostomatidae: Heteroptera) carry egg masses on their back, but little is known about the relationship between seasonal abundance and breeding ecology of the species. In the present study, therefore, a field survey based on a mark-and-recapture census was carried out at three survey points within a rice paddy area (0.3 km²) where A. japonicus forms a meta-population in northern Okayama, Japan. We investigated the body size, seasonal abundance, dispersion, egg mass size (number of eggs within one egg mass), number of egg masses and the total eggs carried on the back of each male as fundamental parameters of the population and breeding. Significant differences in egg mass size, number of egg masses, and total number of eggs that males carried was found among the survey points. The present results suggested the possibility that the differences in breeding parameters of A. japonicus were influenced by differences in environmental factors among the microhabitats. These results are discussed in conjunction with previous reports on seasonal abundance and breeding systems in Belostomatidae bugs.