Exceptional anoxia resistance in larval tiger beetle, Phaeoxantha klugii (Coleoptera: Cicindelidae)

Abstract. The tiger beetle Phaeoxantha klugii inhabits Central Amazonian floodplains, where it survives the annual inundation period in the third-instar larval stage submerged in the soil at approximately 29 °C for up to 3.5 months. Because flooded soils quickly become anoxic, these larvae should be highly resistant to anoxia. The survival of adult and larval P. klugii was therefore tested during exposure to a pure nitrogen atmosphere in the laboratory at 29 °C. Adult beetles were not resistant (< 6 h). Survival of larvae decreased over time, maximum survival was 15 days, whereas time to 50% mortality was 5.7 days (95% confidence interval 3.8–7.9). Anoxia resistance was additionally tested in third-instar larvae submerged within sediment for 40 days before anoxia exposure in the laboratory. Anoxia resistance was greatly enhanced in these larvae, showing a survival rate of 50% after 26 days of anoxia exposure. It appears that the gradual flooding process and/or the submersion phase induced a physiological alteration, most probably a strong depression in metabolic rate, which requires some days for induction. The degree of anoxia resistance in larval P. klugii is remarkable among terrestrial arthropods worldwide, even more so considering the high ambient temperatures. The species is well-suited to serve as a model organism for studying the physiological mechanisms of anoxia and submersion resistance in terrestrial arthropods inhabiting tropical floodplains.     

Circulatory Responses to Submersion in Larvae of Phaeoxantha klugii (Coleoptera: Cicindelidae) from Central Amazonian Floodplains

The univoltine tiger beetle Phaeoxantha klugii survives an annual inundation period of up to 3.5 months in the third larval stage submerged in the soil. We visually determined the circulatory response to submersion of third-stage larvae in the laboratory. Heart rate depression upon submersion was about 50–67% during the first hours and reached values near zero in most larvae submerged for 2.8–6 days. Apart from a rapid first increase upon removal from the water the heart rate varied greatly within and between individuals. Longer submersion lead to stronger circulatory depression and delayed recovery (time until resuming of digging activity). The heart rate of larvae resuming digging activity was only 66% of the initial rate before submersion. Unlike the duration of recovery the heart rate relative to the initial values before submersion was not correlated with the duration of preceding submersion. The degree of circulatory depression during the first hours of submersion is less drastic than the metabolic depression of 75–95% measured as oxygen uptake in submerged larvae reported in a previous study. Visual determination of heart rate might be an useful tool to study physiological aspects of submersion and hypoxia resistance also in other insects.     

The function of turret building behaviour in the larval tiger beetle, Cicindela willistoni (Coleoptera: Cicindelidae)

Abstract. 1. Cicindela willistoni LeConte (Coleoptera: Cicindelidae) adults and larvae occur only on saline and alkali flats with little or no vegetation in southwestern U.S.A. Unlike other larval tiger beetle species, C.willistoni constructs a chimney-like extension (turret) 1–4 cm above its burrow.
2. The function of these unique turrets was tested in relation to several biotic and abiotic factors in the Sulphur Springs Valley, Arizona, U.S.A.
3. The turrets did not prevent flooding of the larval burrows.
4. They did not prevent or reduce the frequency of parasitoids (mainly bombyliid flies of the genus Anthrax ).
5. The turrets did not make it possible for the adult and larval beetles to feed on obviously different types or sizes of prey.
6. However, larvae with turrets were raised sufficiently above the substrate surface and boundary layer to allow them to thermoregulate in the lower temperatures at these heights and remain active throughout the day.
7. The shade produced by the turrets attracted significantly more potential prey items than were available to turretless larvae in the same habitat.     

Plant anaerobic stress as a novel trend in ecological physiology, biochemistry, and molecular biology: 2. Further development of the problem

This review is a logical development of a previous publication, which summarized the main results of the early period of the systematic and active studying of hypoxic and anoxic stresses in plants. These studies laid a foundation for a new scientific discipline in biology, the investigation relevant to plant anaerobic stress. This review considers a further development of this trend when the investigations embraced a wider set of topics and the discipline acquired an international recognition. The results obtained during last decades by physiologists, biochemists, and molecular biologists engaged in the problem of plant anaerobic stress confirmed the correctness of a concept of the two principal strategies of plant adaptation to hypoxia and anoxia conditions. They are “true” tolerance manifesting at the molecular level under conditions of oxygen deficiency or its absence and “apparent” tolerance, which is realized by avoidance of anaerobiosis due to the long-distance oxygen transport. Therefore, experimental material available now is considered and discussed in this review mainly in the light of these principal notions. Especial attention is paid to the role of stress proteins, which synthesis is induced under hypoxia and anoxia. The results of these experiments confirmed earlier conclusions about the key role of energy (glycolysis and alcoholic fermentation) and carbohydrate (mobilization and utilization of reserved carbohydrates) metabolism in plant adaptation to oxygen deficiency or its absence from the environment. The phenomenon of hypoxic acclimation and its role in plant adaptation to anoxia are also considered. Along with these topics, a further development of pH-stat theory is discussed. A special attention is paid to plant strategy realized by the formation of the net of air-filled spaces (aerenchyma) and long-distance oxygen transport from aerated plant parts to those located in anaerobic environment (apparent tolerance). Among other important aspects, we consider (1) post-anaerobic plant injury by free oxygen radicals; (2) the physiological role of alternative pathways of plant adaptation (nitrate reduction and lipid synthesis); (3) the phenomenon of the adaptation syndrome in plants and possible molecular mechanisms of its realization; and (4) some biotechnological advances in the field of genetic and cell engineering used for the creation of plants more tolerant to anaerobic stress.     

Leishmania (Viannia) utingensis n. sp., a parasite from the sandfly Lutzomyia (Viannamyia) tuberculata in Amazonian Brazil

A leishmanial parasite isolated in 1977 from a specimen of the sandfly Lutzomyia tuberculata from Pará State, Amazonian Brazil, has been characterized following its comparison with other species of Leishmania from the same region, using isoenzyme profiles, monoclonal antibodies and characterization of the miniexon gene repeat, using the polymerase chain reaction technique (PCR). It is described here under the name of Leishmania (Viannia) utingensis n. sp.     

Control of the larvae ofConorhynchus mendicus (Col.: curculionidae) bySteinernema carpocapsae andSteinernema feltiae (nematoda,steinernematidae) in the gharb area (Morocco)

Two entomopathogenic nematodes,Steirnernema carpocapsae andS. feltiae were evaluated in the laboratory and under field conditions against larvae ofConorhynchus mendicus, a pest of sugar beet in the Gharb area of Morocco. Nematodes were applied in an artificially infested field using a knapsack sprayer either during the day or in the evening after sunset. The number of insect cadavers recovered from both soil and sugar beet plants was greater in the treated plots compared with the untreated ones. The percent reduction in live larvae was significantly greater in theS. carpocapsae treated plots (89.5% and 59.5% for night an day application respectively) compared with those treated withS. feltiae (68.5% and 28% respectively). The efficacy of entomopathogenic nematodes was therefore increased by application at night particularly in the case ofS. carpocapsae where control was maintained for 45 days.     

A failed invader in the North Atlantic, the case of Aglenus brunneus Gyll. (Col., Colydiidae), a blind flightless beetle from Iceland

The occurrence of an occasional pest of mouldy stored product residues, the blind flightless beetle Aglenus brunneus Gyll., in samples from the medieval farm at Reykholt in Iceland, along with several other strongly synanthropic beetles, is considered in relation to its fossil record. The species is dependent on man for its dispersal and survival and it probably had its primary habitat in the warm, decaying litter of the undisturbed forest floor in Europe. Now virtually cosmopolitan, it had been introduced to a remote site in the eastern desert of Egypt by the Roman period and was widespread in medieval northern Europe. The processes by which such an apparently stenotopic species could have invaded are discussed in relation to other evidence for anthropochorous dispersal.     

Role of eyestalk hormone in the carbohydrate metabolism of a marine penaeid prawn,Parapenaeopsis hardwickii (MIERS) (Crustacea,Decapoda, Penaeidae)

Data furnished here concern with the role of eyestalk hormone in the regulation of carbohydrate metabolism in Parapenaeopsis hardwickii. Bilateral eyestalk ablation has brought about a significant (P < 0.01) fall and rise in the glycogen content in the midgut gland and abdominal muscle respectively. Although eyestalk ablation resulted in a significant (P < 0.01) depletion of fat in midgut gland, n0 significant (P > 0.05) change was observed in the abdominal muscle. Eyestalk extract administration in eyestalk-less prawns has significantly (P < 0.05) restored the glycogen and fat metabolites in the midgut gland. There was an obvious change in the glycogen content of the midgut gland and abdominal muscle of normal prawns when injected with eyestalk extracts from prawns in different molting stages. Eyestalk extract from intermolt prawns caused a significant (P < 0.05) decrease and increase in the glycogen quantity in the midgut gland and abdominal muscle respectively. Eyestalk extract from premolt and postmolt prawns has, although not significantly (P > 0.05), decreased and increased the utilization of glycogen respectively in the midgut gland. The physiological significance of these findings are discussed briefly.Paper forms part IV of the series

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Take-off capacity as a criterion for quality control in mass-produced predators,Rhizophagus grandis (Col.: Rhizophagidae) for the biocontrol of bark beetles,Dendroctonus micans (Col.: Scolytidae)

Time spent by adult beetles in cold storage at 3–7°C accounted for 81% of the loss of take-off capacity inRhizophagus grandis Gyllenhal in windtunnel experiments. At the age of three weeks, the insects were at their highest take-off capacity at about 80%. This was followed by a steady decrease, 7% of the insects failing to take-off each month. Changes in the fat reserves during cold storage could explain at least partly this reduction of flight capacity although there was no significant difference in fresh weight between insects that were able/unable to take-off. Sex had a significant influence on take-off rates, with an 8.7% higher take-off rate in females. Take-off capacity was further reduced when the insects were mass-produced in cultures using parent beetles submitted to a blend of synthetic oviposition stimulants instead of live prey larvae. Response to synthetic attractants by those insects which took-off, however, was not influenced by cold storage or by the use of synthetic stimulants in the culture medium.

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Résumé Le temps passé en conservation à basse température (3–7°C) depuis la métamorphose est intervenu pour 81% dans la perte de la capacité d'envol chez le coléoptère prédateurRhizophagus grandis Gyll. lors d'expériences en tunnel de vol. A l'age de trois semaines, les insectes sont à leur plus haut niveau d'envol (envol d'environ 80% des insectes). Par la suite, il y a un déclin constant de la capacité d'envol, à raison de 7% des insectes chaque mois. Des changements dans les réserves lipidiques peuvent partiellement expliquer cette réduction, bien qu'il n'y ait pas eu de différence entre le poids frais d'insectes capables de s'envoler et celui d'individus qui en étaient incapables. Le sexe a une influence sur le taux d'envol, avec un taux d'envol significativement plus élevé de 8.7% chez les femelles. La capacité d'envol est encore réduite chez des insectes qui ont été produits dans des élevages de masse où les parents étaient soumis à un mélange de stimuli de ponte de synthèse au lieu d'être mis en présence de larves deD. micans vivantes. Chez les insectes qui prennent leur vol, cependant, la réponse aux attractifs de synthèse est indépendante de l'age ainsi que des conditions d'élevage.

     

Female's preference for oviposition site and larval performance in the water-lily beetle,Galerucella nymphaeae (Coleoptera: Chrysomelidae)

Water-lily beetles prefer younger rather than older water-lily leaves as oviposition sites. By the time of hatching, however, young leaves have aged consieerably. Larval performance of the water-lily beetle was measured on different types of leaves of the yellow water-lily and compared with oviposition preference of females. The leaf types used in the experiments were categorized as (i) young, (ii) natal (medium-aged) and (iii) old. The natal leaves were the ones on which larvae from a particular egg-batch had hatched. There were two sets of experiments. First, larvae were raised from eggs to pupae on young and on old leaves. Second, the growth of the 1st-instar larvae was measured on young, natal, and old leaves. The development time from egg to pupa did not differ between young and old leaves, but larvae growing on young leaves attained a higher pupal weight. In the second experiment the 1st-instar larvae grew fastest on their natal leaves, but there was also variation in the growth rate of progeny from different egg-batches. Larval growth on young and old leaves did not differ significantly. Larvae tried to emigrate much less from natal than other types of leaves. Females tended to lay eggs on leaves where larval growth was fastest. It seems that medium-aged leaves are best for larval growth, but the leaf characteristics responsible for this remain unresolved.     

Suppression of reproductive development and longevity in the redshouldered leaf beetle,Monolepta australis (Col.: Chrysomelidae) by the tachinid,Monoleptophaga caldwelli (Dipt.)

This paper examines the level and seasonal incidence of parasitism of the redshouldered leaf beetle,Monolepta australis (Jacoby), by the tachinid,Monoleptophaga caldwelli Baranov, and assesses the impact of this fly on the beetle's reproductive development and longevity. Highest average numbers ofM. australis were trapped at light in north Queensland in January and February while parasitism peaked at 6.6 and 6.8% in June and July respectively, averaging 4.8% over the entire sampling period and reaching 28% for a single occasion. Overall, only 2.4% of parasitized beetles were represented in the final two stages of ovarian development compared to 29.1% of non-parasitized ones. There was a highly significant (P<0.001) difference in the distribution frequencies of parasitized and non-parasitized females in the various stages of ovarian development, and most parasitized males possessed atrophied testes. For field-collected beetles maintained in the laboratory, average longevity for those parasitized was 15.6 days compared to 72.2 days for those not parasitized.     

Additional Evidence for Morpho-Dimensional Tooth Crown Variation in a New Indonesian H. erectus Sample from the Sangiran Dome (Central Java)

This contribution reports fifteen human fossil dental remains found during the last two decades in the Sangiran Dome area, in Central Java, Indonesia. Among this sample, only one of the specimens had already been briefly described, with the other fourteen remaining unreported. Seven of the fifteen isolated teeth were found in a secured stratigraphic context in the late Lower-early Middle Pleistocene Kabuh Formation. The remaining elements were surface finds which, based on coincidental sources of information, were inferred as coming from the Kabuh Formation. Mainly constituted of permanent molars, but also including one upper incisor and one upper premolar, this dental sample brings additional evidence for a marked degree of size variation and time-related structural reduction in Javanese H. erectus. This is notably expressed by a significant decrease of the mesiodistal diameter, frequently associated to the reduction or even loss of the lower molar distal cusp (hypoconulid) and to a more square occlusal outline. In addition to the hypoconulid reduction or loss, this new sample also exhibits a low frequency of the occlusal Y-groove pattern, with a dominance of the X and, to a lesser extent, of the+patterns. This combination is rare in the Lower and early Middle Pleistocene paleoanthropological record, including in the early Javanese dental assemblage from the Sangiran Dome. On the other hand, similar dental features are found in Chinese H. erectus and in H. heidelbergensis. As a whole, this new record confirms the complex nature of the intermittent exchanges that occurred between continental and insular Southeast Asia through the Pleistocene.     

Autotrophic energy sources for Paracheirodon axelrodi (Osteichthyes, Characidae) in the middle Negro River, Central Amazon, Brazil

The cardinal tetra (Paracheirodon axelrodi) is the most abundant species of the Brazilian ornamental fish trade, constituting more than 80% of the ornamental fish collected in the middle Negro River basin. Stable isotope analyses were used to identify the autotrophic carbon sources and trophic position for the cardinal in relation to the plant groups at the base of its foodchain. Filamentous algae, tree and plant leaves and cardinals were collected in stream habitats, flooded forest and interfluvial swamps (campos) during peak flood, falling water and low water periods. δ¹⁵N values of the cardinal in relation to the plants at the base of the food chain indicated a trophic position of omnivore. Values of δ¹³C for the plants ranged from −43.1 to −26.4‰, with averages of −37.6, −30.4, and −29.4‰ for filamentous algae, flooded forest leaves, and campo leaves, respectively. The δ¹³C values for the cardinal ranged from −35.0 to −27.9‰, with an average of −31.4‰. Relative contributions of plants to fish carbon were estimated in a two end-member mixing model which determined that the leaves (flooded forest and campo leaves combined) and filamentous algae had average relative contributions to cardinal carbon of 71% and 29%, respectively. However, seasonal variation in the relative contributions was encountered throughout the hydrological cycle. The cardinals least enriched in ¹³C were encountered in November during the falling water period, indicating that they had perhaps recently migrated down from interfluvial campos where filamentous algae production is significant. Considering that algal production has been reported to be less than 1% of total primary production in the Negro River, these results could suggest some evidence of selective herbivory in the cardinal’s food chain. Handling editor: J. M. Melack     

Seasonal dynamics and production of Campsurus violaceus nymphs (Ephemeroptera, Polymitarcyidae) in the Baía River, upper Paraná River floodplain, Brazil

The production of Campsurus violaceus nymphs was investigated from October 1987 to September 1988 in the Baía River, a secondary channel of the Paraná River, Brazil. The annual production of this species during this period was 16.48 g dry wt m^-2 y^-1and the P:B ratio was 4.9. This low ratio compared to other rivers occurred because the Baía River was strongly influenced by the hydrological regime of the Paraná River, where nymphs migrated to avoid adverse conditions in the river during the flood phase. This revised version was published online in August 2006 with corrections to the Cover Date.     

Locomotor Activity Patterns in Ilybius fenestratus (Fabricius) (Coleoptera,Dytiscidae) in a Central Norwegian Lake,with Evidence for Breeding-Induced Arrhythmicity

The diel activity of Ilybius fenestratus was studied in Målsj?en, a lake in S?r-Tr?ndelag, Central Norway (63°14'N, 10°26'E), during 1971–1972. Adults and larvae were sampled in activity traps every week during March–October and every 2–3 weeks during November–February. The traps were emptied every 2 hrs during a 24- hr period. The diel locomotor activity of I. fenestratus was clearly nocturnal, except in the second half of July, for the males also in the first half of July, when surprisingly the population showed an arrhythmic activity pattern. The arrhythmicity is connected with the mating and egg-laying period of the species. The larvae were also nocturnal in the autumn, but showed arrhythmicity under the ice during the winter.     

Energy metabolism of Chironomus anthracinus (Diptera: Chironomidae) from the profundal zone of Lake Esrom,Denmark, as a function of body size,temperature and oxygen concentration

The profundal zone of Lake Esrom, Denmark has a dense population of Chironomus anthracinus, which survives 2–4 months of oxygen depletion each summer during stratification. The metabolism of 3rd and 4th instar larvae was examined in regard to variation in biomass and temperature. Respiration at air saturation was described by a curvilinear multiple regression relating oxygen consumption to individual AFDW and temperature. At 10 °C and varying oxygen regimes the O₂ consumption and CO₂ production of 4th instar larvae were almost unaltered from saturation to about 3 mg O₂ l^–1, but decreased steeply below this level. The respiratory quotient increased from 0.82 at saturation to about 3.4 at oxygen concentrations near 0.5 mg O₂ l^–1. This implied a shift from aerobic to partially anaerobic metabolism. At 0.5 mg O₂ l^–1 the total energy production equalled 20% of the rate at saturation of which more than one third was accounted for by anaerobic degradation of glycogen. This corresponded to a daily loss of 12 µg mg AFDW^–1 or approximately 5% of the body reserves. At unchanged metabolic rate the glycogen store would last three weeks, but long term oxygen deficiency causes a further suppression of the energy metabolism in C. anthracinus.