Aquatic Bugs Research Articles

The evaluation of individual production and scope for growth in aquatic sow bugs (Asellus aquaticus)

The possibility to assess the instantaneous production of benthic invertebrates in the field avoiding direct measurements of somatic and generative growth is discussed. The scope for growth (SfG) (assimilation minus respiration) and instantaneous individual production (mass increment during growth) for Asellus aquaticus were determined and compared. Results of this study have confirmed the assumption that the difference between SfG and individual production of isopods P is approximately equal to reproductive investment. In juveniles and males these differences should be compensated, in large degree, for the exuviae. As confirmed by the closely identified values of P after summing it with eggs production, excess of SfG in comparison with P may be attributed to the part of energy which is allocated to generative products. So, the predicted coincidence of SfG with P coupled with egg production allows to expect that SfG may be implicated in evaluation of instantaneous population production. To verify this assumption, the data on population production of A. aquaticus previously reported in the literature were drawn. The results have shown a close conformity of compared data, and led to the conclusion that this method should be of more general use, and not limited to the populations exposed to stress, as it is currently treated.

New approach for habitat characterization based on species lists of aquatic and semiaquatic bugs

A new approach is proposed for the environmental impact assessment of fresh waters. New indices and the cenological values of aquatic and semiaquatic bug (Hemiptera) species have been obtained through multivariate analysis based on the species list of 157 localities in Hungary. The 45 species involved in this study can be characterized by their preference for habitat types on a linear scale ranging from small, shallow waters to large, deep waters. The habitats themselves can be characterized by the added cenological values of the species found.

The coxal articulation of the insect striking leg: A comparative study.

The thoraco-coxal muscles and the geometry of the leg suspension inside the prothorax were investigated in a praying mantis Mantis religiosa, an aquatic bug Ranatra linearis, and a neuropterid Mantispa lobata. Comparative observations were carried out on a cockroach Nauphoeta cinerea, a pentatomid bug Graphosoma italicum and a neuropterid Creoleon plumbeus. Adaptation of the thoraco-coxal joint to striking function was attained by different morphological structures, preadapted specifically in each insect order with respect to the articulation of the coxa, the number of muscles and the development of the endoskeleton. Adaptation provides for two main properties: maximal distance of the strike and the required rigidity of the supporting structures. In turn, these goals have given rise to some secondary problems, e.g., the versatility of the thoraco-coxal joint and the supposed coactivation of different muscle groups during the strike. J. Morphol. 236:127-138, 1998. © 1998 Wiley-Liss, Inc.

Idiotrephes meszarosisp.n., a new Helotrephid (Heteroptera: Helotrephidae) from Vietnam

A new species of aquatic bug, Idiotrephes meszarosi sp.n. (Helotrephidae, Helotrephinae, Limnotrephini) is described (male, female, nymphs) from Vietnam and compared with I. chinai Lundblad and I. maior Papacek. All species of the genus Idiotrephes are keyed and their differential characters illustrated.

Phylogeny and classification of aquatic bugs (Heteroptera, Nepomorpha). An essay review of Mahner's 'Systema Cryptoceratum Phylogeneticum'

AbstractThis essay is essentially a review of the monographic work by the German zoologist Martin Mahner : 'Systema Cryptoceratum Phylogeneticum (Insecta, Heteroptera)' (Zoologica, Heft 143, Stuttgart 1993). The monograph is the most comprehensive systematic account of the aquatic bugs to date and the first major work on this group where the principles of phylogenetic (cladistic) systematics are consistently applied. Mahner follows the principles of the 'konsequentphylogenetische oder cladistischen Systematik', being Willi Hennig's phylogenetic systematics as interpreted and modified by Peter Ax. The methodological procedures recommended by this school of systematics is controversial, however, and call for a broader discussion of current trends in systematics as exemplified by the phylogeny and classification of the aquatic bugs.

Natural Enemies of the Rice Caseworm Nymphula Depunctalis (Guenée) (Lepidoptera: Pyralidae)

Larval and adult predators comprise the largest component of the natural enemy fauna which attack the semi-aquatic rice caseworm Nymphula depunctalis (Guenee). Spiders, birds, and adult dragonflies/damselflies were the dominant predators of caseworm adults, while aquatic beetle larvae, aquatic bug nymphs and adults, and ants preyed on caseworm larvae. Egg parasitolds are unknown in nature and larval/pupal parasitoids are rare. A nuclear polyhedrosis virus, the only recorded pathogen, occurs but rarely. A ricefield pulmonate snail Lymnaea quadrasi (Mollendorff), which forages on algae, causes limited caseworm egg mortality in a passive and fortuitous manner. Water beetles—the dytiscid Cybister tripunctatus orientalis Gschwendtner and hydrophilid Sternolophus rufipes Fabricius—are voracious larval predators. Prey consumption by these water beetles is higher on older caseworm larvae whose larger size creates more movement while the larvae are crossing the water surface. Also, older caseworms are more prone to leave the protection of their cases while under attack. Younger caseworm larvae, however, tend to retract and remain motionless when attacked. The last instar dytiscid preyed on an average of 11.4 caseworm larvae per day while that of the hydrophilid preyed on 6.7 larvae per day.

Pregnanes from defensive glands of a belostomatid bug.

The aquatic bug Abedus herberti (Hemiptera: Belostomatidae) secretes a mixture containing four pregnanes (desoxycorticosterone (I), pregnenolone (II), progesterone (III), and 3 alpha-hydroxy-pregn-5-en-20-one (IV)) from its cephalic glands. Pregnanes had previously been characterized from the defensive glands of aquatic beetles (Dytiscidae) and shown to be deterrent to fish. It may be specifically under predation pressure from fish that A. herberti and Dytiscidae evolved their comparable defenses.

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

We studied the interpecific competition between 2 species of predatory aquatic bugs,Diplonychus japonicus andD. major by conducting a field experiment. We set up 3 types of experimental plots in the paddy fields whereD. major predominated. The two plots contained single species of eitherD. japonicus orD. major, respectively, and one plot had both species in equal number. We compared the development and the reproductive performance between plots in each species.

Prey Uncertainty and the Balancing of Antipredator and Feeding Needs

Predation risk often varies in space and time. To respond adaptively to fluctuations in risk, prey must sample to gain information on the current presence or absence of predators. Bayesian statistical decision theory provides a framework for modeling the effects of prey uncertainty about predation risk on prey behavior. The model predicts that due to prey uncertainty, prey should often stay in refuge long after predators have left an area. Prey behavioral time lags should depend on the quality of prey information about predation risk and on the costs and benefits of refuge use. Under biologically reasonable conditions (e.g., if prey escape success is low), uncertainty can cause prey to always stay in refuge even though predators are only occasionally present. Although many studies have examined prey responses to predator addition, few studies have quantified prey responses to predator removal. Observations on the responses of juvenile aquatic bugs, Notonecta hoffmani, to the experimental addition and remo...

Biochemical changes during embryonic development in the aquatic hemipteran bug Laccotrephes griseus

Protein, carbohydrate, free amino acid, lipid, RNA levels, and electrophoretic changes in the protein profile were determined in the eggs of the water scorpion, Laccotrephes griseus, during normal embryonic development. The protein levels remain lower and relatively constant in the eggs of 0, 1 and 2 days of age, while in the eggs of older groups, i.e. between 2 and 6 days, a marked increase in the protein level occurs. Then its level declines. The RNA content shows a rise up to the day 6 stage, later it declines sharply, indicating an increase in the degree of synthetic activity that takes place during such period of embryonic development. Electrophoretic and densitometric analysis show the qualitative and quantitative changes of yolk protein reflecting the utilization of already existing proteins as well as the appearance of new proteins. Water content increases gradually as development proceeds. There is a steady depletion of carbohydrate and lipid during the course of embryonic development. The nature of yolk components as well as their preferential utilization during embryogenesis has been discussed in relation to the generally accepted view that protein serves as the source for the embryonic metabolism in aquatic insects does not hold good for L. griseus and other freshwater insects.

The Effect of Alternative Prey on the Functional Response of Notonecta Hoffmani

Continuous observations were made to determine the effect of alternative prey on the functional response of the aquatic bug Notonecta hoffmani to mosquito larvae (Culex pipiens). Mosquito larvae and two alternative prey, the zooplankter Daphnia pulex and vestigial—winged Drosophila (representing terrestrial prey trapped on the water surface), were presented to the predator at various densities. Preference, searching times, capture times (searching time per prey captured), and handling times for mosquito larvae were estimated. The predator showed a significant preference for Daphnia relative to mosquitoes in three of the nine prey combinations tested, and a significant preference for Drosophila relative to mosquitoes in all prey combinations tested. The presence of Daphnia did not significantly affect searching or capture times for mosquitoes, whereas the presence of Drosophila was associated with a significant decreased in searching time and a significant increase in mean capture time. Mosquito handling time decreased slightly as Daphnia density increased. The results predict that Drosophila will have a greater effect than Daphnia on the ability of notonectids to control mosquito larvae. The prediction was supported by a longer term experiment in which the largest number of mosquitoes reached the pupal stage when Drosophila were present as alternative prey. The study shows that relative preferences alone are not sufficient to predict the effect of alternative prey on a predator's functional response. Factors such as handling time (which affects searching time) and behavioral changes such as a change in capture time, must also be considered when assessing the role of alternative prey in a biological control program.

The life history of Pleurogenoides orientalis (Srivastava, 1934) (Trematoda: Lecithodendriidae).

The life history of Pleurogenoides orientalis (Srivastava 1934), a lecithodendriid trematode of frogs in India is reported and stages in the life history are described. Natural infections with cercariae, which are virgulate xiphidiocercous type, were found in the prosobranch snail Alocinma travancorica. Metacercarial cysts were found in dragon-fly naiads (Tholymis tillarga and Tramea limbata) and aquatic bugs (Laccotrephes griseus and Ranatra elongata) collected from a stream. Adults occurred in the intestine of the pong frog, Rana cyanophlyctis. Laboratory reared A. travancorica fed with eggs of P. orientalis started shedding cercariae from 30 days post feeding. Development of cercariae into infective metacercariae in dragon-fly naiads took 18 days. Mature flukes were recovered from the intestine of experimentally infected R. cyanophlyctis. The entire life cycle from egg to egg producing adult takes 2 1/2 to 3 months.

AQUATIC AND SEMIAQUATIC HEMIPTERA OF PEATLANDS AND MARSHES IN CANADA

AbstractThirteen families containing 138 species of aquatic and semiaquatic Hemiptera have so far been recorded from Canada. The identification of these presents few real difficulties and so the general occurrence of the taxa across the country is fairly well known. Although there has been no intensive study of the Hemipterous insects in peatlands and marshes, the 61 species so far reported from marshes, 32 from fens, and the 33 from bogs appear to be facultative rather than obligatory inhabitants of these habitats. All have been found in other habitats and probably most lentic species occur in marsh habitats. All aquatic and semiaquatic bugs are predators, and most overwinter as adults. Environmental–physiological study of species occurring in bogs has just begun, but evidence suggests that many species have the ability to regulate their internal milieu in water with pH below 4.6–4.7. However, further experiments are needed to determine the physiological limits of tolerance of these insects, the details of osmotic and ionic regulation, and acid–base balance in low-pH water. More collecting is needed in bogs, fens, and marshes, and the life cycle and biology of the Hemiptera occurring in peat-lands still require intensive study.

Water Absorption by Eggs and Serosal Specialization as Clues to Evolutionary Trends in Heteroptera

Water absorption by eggs, expressed by increase in fresh egg weight, was observed in Notonecta triguttata Say, Gerris lacustris latiabdominis Miyamoto, and G. gracilicornis gracilicornis Horvath. In these aquatic and semiaquatic bugs, whose eggs develop in water, serosal specialization at the posterior egg pole (columnar serosa) occurs. Close association was observed between onset of water absorption by the eggs and that of embryonic growth. Fresh weight of the developing eggs hardly changed in Hygia opaca Uhler, the eggs of which develop on damp ground, whereas it decreased steadily in Scotinophora lurida Burmeister and Coptosoma punctissimum Montandon, whose eggs develop on plant leaves. Serosal specialization at the posterior egg pole was never observed in these terrestrial bugs. Rearing of these heteropteran eggs under unusual cultural conditions and topical application of a microcauterizer at the columnar serosa in G. paludum insularis Motschulsky suggested that water absorption by the eggs was necessary to ensure enough oxygen to the embryos. Occurrence of serosal specialization and resulting water absorption by the eggs are considered from the viewpoint of heteropteran evolution.

The movement of water into submerged prey during feeding by the aquatic bug Ranatra dispar (Heteroptera: Nepidae), the water stick insect

By the use of a fluorescent dye it was shown that, during feeding by an aquatic bug, water from the external environment passes into the prey's body though puncture holes from previous feeding sites. Such a phenomenon, resulting in the diluting of the prey's body contents, may be used as a physiological stimulus to detect the quality of the prey, leading to movement to another part of the prey's body or discarding the prey.

Observations on the Diet of the Broad-Shelled Turtle, Chelodina Expansa Gray (Testudines: Chelidae).

Stomach contents were examined of 32 broad-shelled turtles (Chelodina expansa) from the Murray River and associated waters in south east Australia. The main feed items were decapod crustaceans, aquatic bugs and small fish. C. expansa, the largest Australian chelid turtle, was wholly carnivorous and specialized for feeding on highly motile prey.

How Abiotic Factors Affect the Distribution of Two Species of Tropical Predaceous Aquatic Bugs (Family: Naucoridae)

Heavy runoff from watersheds affects lowland streams in two general ways. Either a stream experiences spates (increased forward velocity and scouring of stream bottoms) or it becomes inundated by water from larger rivers, causing the stream to be backflooded. This study shows how these features affect the abundances and distributions of two Costa Rican species of stream—inhabiting predaceous waterbugs, Limnocoris insularis Champion and Cryphocricos latus Usinger (Naucoridae). Backflooding in the Sura was found to have no subsequent effect on the abundances or distribution of either species. But in the Sabalo, which spates, nymphal populations of L. insularis significantly decrease after a spate because of loss of numbers and loss of previous habitat. During severe spates, adults of both species can be washed out, causing abundances to remain low for several months to periods > 1 yr. Abundances of nymphs and adults of C. latus are associated with fast current speeds, large rocks, and coarse—grained pebbles. These sorts of habitats are found in both streams. Even though C. latus is more common in the Sablo than is L. insularis, abundances of adults of the former species fluctuate more in the stream that spates than in the stream that does not, owing both to a high washout rate and to a slow recolonization rate. The basic pattern of distribution is explained by the difference between the flooding characteristics of the two streams.

Influence of temperature and salinity variations on an aquatic bug population in a tropical pond

Variation in sex ratio of Diplonychus indicus, living in a permanent pond in southern India, was studied in relation to seasonal variations in temperature and salinity. Males proved to be less susceptible to changes in these parameters. Protein content and survival of the insect were studied in relation to fluctuations of environmental conditions.

Competition between freshwater fish and goldeneyes Bucephala clangula (L.) for common prey.

Results of a descriptive field study showed that goldeneyes preferred lakes without fish to those with fish. Field experiments were carried out in order to investigate whether or not this preference could be ascribed to a higher food supply in the lakes devoid of fish, as goldeneyes and some freshwater fish (perch and roach in the studied lakes) to some extent feed on the same kinds of prey. Changes in the abundance of prey common to fish and goldeneyes and the use by goldeneyes of lakes after experimentally changed predation pressure from fish were studied. Some aquatic insect groups, Cloeon larvae, Odonata larvae, water bugs, dytiscids, and Chaoborus larvae, proved sensitive to predation from fish. Goldeneyes increased their use of an experimental lake after fish were removed, and they used this lake more than an adjacent control lake. It is suggested that fish are able to reduce the availability of foods common to the goldeneyes to such an extent that the selection by the ducks of feeding localities is affected, and that exploitation competition between freshwater fish and goldeneyes may occur.

The metathoracic scent gland system in Hydrocorisae (Heteroptera: Nepomorpha)

Abstract. The metathoracic scent gland system is a basic feature of the order Heteroptera. It occurs widely not only in the terrestrial forms (Geocorisae) and water‐surface bugs (Amphibicorisae) but also in the totally aquatic bugs (Hydrocorisae) and their littoral relatives (Ochteridae, Gelastocoridae). In Hydrocorisae the metathoracic scent gland conforms to Carayon's (1971) omphalian type (orifice median and undivided or, if divided, orifices close together towards the mid‐ventral line) but shows marked differences in structure and physiological function between species from different families. There is taxonomic interest in the distribution of the three distinctly different types of metathoracic occlusion apparatus. Naucoridae and Belostomatidae have a median lip‐valve, Notonectidae and Gelastocoridae a pair of stop‐valves, Corixidae a median flap‐valve. The valve opener muscles are usually dorso‐ventral but are ventral in Corixidae; the cuticular microsculpture in the metathoracic efferent system specifically in Hydrocorisae with stop‐valves (Notonectidae, Gelastocoridae) is similar to that widely present in Geocorisae. Groupings of Hydrocorisae from variations in the metathoracic occlusion apparatus differ from others based upon variations in the chemical constitution of the secretions. It is considered that the facts now known on metathoracic scent gland structure and function accord well with the hypothesis that Hydrocorisae constitute a polyphyletic assemblage.