Daily biphasic behaviour in keratin-feeding desert trogid beetles in relation to climate

Abstract. 1. Patterns of daily activity of two ectothermic species of the trogid genus Omorgus were studied in the Kalahari of southern Africa in summer. The relationship between time and type of activity, and environmental temperature, relative humidity and light intensity, was investigated.
2. Beetle activity was biphasic, with peaks in activity at sunset and sunrise in both species.
3. Afternoon activity coincided with high temperatures and low humidity and morning activity with minimum daily temperature and maximum humidity.
4. Afternoon activity, which peaked at about 34°C and 25% r.h., consisted predominantly of complex breeding behaviour and dispersal. High temperatures are necessary for these activities.
5. In the morning feeding predominated. At this time temperature was about 27°C and r.h. above 60%. High r.h. is important because it restricts respiratory loss of water, improves food (moist hair and skin keratin) quality and may compensate for faecal water loss.
6. No evidence of competition between the two species was found.     

'Opportunistic feeding', a serious pitfall in trophic structure analysis of (paleo)faunas

A classification of marine organisms as deposit-feeders, suspension-feeders, carnivores, or scavengers is difficult becausc many species appear to be capable of using more than one feeding method. Thcse species are most probably 'opportunistic', varying their diet with local food availability. Efforts to reconstruct trophic webs and establish deposit-feederisuspension-feeder ratios in (paleo)faunas are seriously hampered by the presence of opportunistic feeders.     

Phylogeny and systematics of the Trogidae (Coleoptera: Scarabaeoidea)

Abstract. A cladistic analysis of the Trogidae using eighteen adult characters resulted in a monophyletic group from which the genera Glaresis Erichson, Afroglaresis Petrovitz and Cryptogenius Westwood are excluded. The Trogidae as here defined comprises three genera, Trox Fabricius (with two subgenera, Trox and Phoberus Macleay), Omorgus Erichson (with three subgenera, Omorgus, Afromorgus subg.n. and Haroldomorgus subg.n.) and Polynoncus Burmeister.     

Ferri- and Ferrocyanide Salts Change the Current/Voltage Relations of Chara corallina: No Correlation with the Transmembrane Redox System

The current/voltage {I/V) relations of the plasma membrane ofChara corallina cells are characteristic when the bathing mediumhas elevated (5-0 mM) concentrations of potassium Addition ofeither 0-5 mM femcyanide or 0-5 mM ferrocyanide usually induceda qualitatively similar increase in the ‘leak’ current,with a concomitant increase in membrane conductance. Both redoxreactants failed for unknown reasons to affect the I/V profileof some of the cells tested In the sensitive cells, femcyanidewas unable to generate extra current over that found upon additionof ferrocyanide Because the feiTocyanide oxidation rate of thecells is only 10% of the femcyanide reduction rate, we concludethat both forms, fern- and ferrocyanide, affect the 'leak' conductanceindependent of the redox state of the reactants, i e ferrocyanidedoes not act indirectly via an oxidation to femcyanide Hence,under the experimental conditions, we were unable to detecta current that could be assigned to the operation of a transmembraneredox system Furthermore, the fern- and ferrocyanide inducedshift in the I/V profile only reversed slowly after withdrawalof the redox reactants. This suggests that the elicited currentis independent of the presence of an extracellular electronacceptor, i.e on the continuous operation of a proposed transmembraneredox system Key words: Current/voltage curves, transmembrane reductase, voltage clamp, femcyanide, ferrocyanide, Chara     

A coral-bryozoan association from the Neogene of northwestern Europe

The Neogene cheilostomatous bryozoan Celleporaria palmata lived facultatively in association with the scleractinian coral Culicia. For Culicia the association was obligatory; the symbiosis was most probably mutualistic. Benefits for the coral appear to have been: (1) the bryozoan provided substrate in a soft-bottom environment; (2) the coral could feed at higher levels above the sediment; (3) the feeding currents generated by the bryozoan provided the corals with food (no competition for food would occur as the coral would collect larger prey); and (4) the surrounding of the cordites by the bryozoan provided strength and lateral protection. Benefits for the bryozoan appear to have been: (1) the stinging cells of the coral provided protection against predators and settlers; (2) the positioning of the corals on the maculae saved the bryozoan subsequent energy expenditure in further construction of polymorphs and secondary calcification. Negative effects for the bryozoan might have been the inhibition of possible functions of the maculae other than as exhalant chimneys, e.g., production and generation of male gametes. *** Symbiosis, mutualism, C ulicia , C ryptangia , C elleporaria , Bryozoa, Scleractinia.     

Phylogenetic systematics of the reptantian Decapoda (Crustacea, Malacostraca)

Although the biology of the reptantian Decapoda has been much studied, the last comprehensive review of reptantian systematics was published more than 80 years ago. We have used cladistic methods to reconstruct the phylogenetic system of the reptantian Decapoda. We can show that the Reptantia represent a monophyletic taxon. The classical groups, the 'Palinura', 'Astacura' and 'Anomura' are paraphyletic assemblages. The Polychelida is the sister-group of all other reptantians. The Astacida is not closely related to the Homarida, but is part of a large monophyletic taxon which also includes the Thalassinida, Anomala and Brachyura. The Anomala and Brachyura are sister-groups and the Thalassinida is the sister-group of both of them. Based on our reconstruction of the sister-group relationships within the Reptantia, we discuss alternative hypotheses of reptantian interrelationships, the systematic position of the Reptantia within the decapods, and draw some conclusions concerning the habits and appearance of the reptantian stem species.     

Possible aversion learning in the Pacific Coast wireworm

The effects of carbon dioxide and the induction of morbidity on aversion learning in larvae of the Pacific Coast wireworm Limonius canus LeConte (Coleoptera: Elateridae) are discussed. Wireworms preconditioned by exposing them one or four times to odour of Tefluthrin 20SC and Dividend XLRTA [Syngenta Crop Protection (Canada), Inc., Canada] during the induction of temporary morbidity subsequently contact tefluthrin‐treated wheat seeds in soil bioassays for as long as naïve (i.e. not preconditioned) larvae but are repelled four to five‐fold more frequently by Dividend‐treated seeds in soil bioassays than naïve wireworms, suggesting that wireworms are capable of associating a novel odour (i.e. Dividend) with morbidity but require a minimum of 10–15 min subsequent contact time with treated seeds before being repelled. Wireworms preconditioned by exposure to peppermint odour during the induction of morbidity are not subsequently repelled by peppermint odour in soil bioassays, suggesting that wireworms are either not capable of aversion learning or that the presence of a CO₂ source and/or a suitable host plant may override a negative cue (i.e. peppermint odour). In studies conducted in the absence of soil, a host plant and CO₂ production, wireworms are repelled slightly by droplets of 1.0% but not 0.1% peppermint oil. Previous exposure to peppermint odour or contact with peppermint oil‐treated filter paper during one induction of morbidity does not increase the repellency of wireworms to 1.0% peppermint oil significantly. Repellency to 1.0% peppermint oil is almost eliminated when morbidity is induced five times in the absence of peppermint odour but is restored when peppermint odour is present during preconditioning. These findings suggest that wireworm sensitivity to repellent compounds decreases when repeatedly made moribund, although the results are not sufficient to conclude that wireworms are capable of associative learning.