Risk reduction strategies in Branchipus schaefferi (Crustacea: Anostraca: Branchiopoda) as adaptation to a variable environment

Mud from a temporary pool in Morocco was sequentially inundated and dried at the laboratory to follow the life history of Branchipus schaefferi. Once adult, each female was coupled to a male in order to study their life history and reproduction. The average percentage of hatching decreased during the successive inundations, presumably as an adaptation to the unpredictability of the habitat. However, there was no indication that the offspring of the first inundation would preferentially hatch during their first inundation too, neither was there any such preference in the offspring of the delayed hatchings. Each female reduced risk by spreading hatching time of her resting eggs over consecutive inundations. Eggs did not hatch all at the same moment, reducing the chance that a female's entire offspring would die before reaching maturity if the pool would dry out too soon. There was a significant difference between the mean value of the number of resting eggs produced by the females from a large clutch size, and those produced by females from a small clutch size. There thus appears to be a genetic base for the clutch size of females

Effect of salinity stress on the life history variables of Branchipus schaefferi Fisher, 1834 (Crustacea: Anostraca)

BACKGROUND: Freshwater anostracans inhabit ephemeral water bodies in which as the water level decreases due to evaporation the salt concentration increases. Thus, for most anostracans salinity becomes the major stress factor. RESULTS: We tested five concentrations of NaCl (0 to 8 g/l) on the life table demography of Branchipus schaefferi fed Chlorella (alga). Age-specific survivorship curves of male and female B. schaefferi showed nearly a similar pattern in that increased salt concentration resulted in decreased survivorship. The age-specific reproduction (m(x)) of females showed several peaks of cyst production at 0 and 1 g/l salinity while in treatments containing salt at 4 or 8 g/l, there were fewer peaks. Average lifespan, life expectancy at birth, gross and net reproductive rates, generation time and the rate of population increase were all significantly influenced by the salt concentration in the medium. The highest value of net reproductive rate (970 cysts/female) was in treatments containing 0 g/l of salt, while the lowest was 13 cysts/female at 8 g/l. The rate of population increase (r) varied from 0.52 to 0.32 per day depending on the salt concentration in the medium. CONCLUSION: The low survival and offspring production of B. schaefferi at higher salinity levels suggests that this species is unlikely to colonize inland saline water bodies. Therefore, the temporary ponds in which it is found, proper conservative measures must be taken to protect this species

On the occurrence of Lepidurus apus (Linnaeus, 1758) (Crustacea, Notostraca) from Iran

The occurrence of Lepidurus apus in Iran is reported for the first time. this species was found in Aigher goli located in the mountains area, east Azerbaijan province (North east, Iran). details on biogeography, ecology and morphology of this species are provided

Effects of temperature on survival, growth, reproductive and life span characteristics of Branchinecta orientalis G. O. Sars, 1901 (Branchipoda, Anostraca) from Iran

Branchinecta orientalis G. O. Sars, 1901 is a common inhabitant of seasonal water catchments in the northwest of Iran. Hatching, growth, survival, and reproductive characteristics of this species were studied at different temperatures in the laboratory. The Cumulative Hatching Success was significantly higher for specimens cultured at 21 degrees C (85.27 +/- 12.21%) compared to those hatched at 12, 15 and 27 degrees C (P < 0.05). Hatching started on the same day (48.00 h after inundation) at temperatures of 21, 24 and 27 degrees C), whereas this took more time at lower temperatures, slowest at 12 degrees C (126.00 +/- 0.58 h after inundation). The initial hatching fraction was the highest at 21 degrees C (44.60 +/- 18.69%) and lowest at 12 degrees C (9.10 +/- 8.28%). Total length was significantly longer at high temperatures, 12.38 +/- 0.71 mm at 27 degrees C, compared to 4.07 +/- 0.42 mm at 12 degrees C on day 15. Nevertheless, contrasting results were obtained for survival, being the lowest at 27 degrees C (22 +/- 4.00%) and highest at 12 degrees C (93.07 +/- 2.08%) on day 15 of growth. The animals reached sexual maturity significantly faster at 27 degrees C (9.38 +/- 1.09 days) compared to all other treatments. A significantly longer life span was detected at 12 and 15 degrees C (63 days), and the higher cyst production at 18 degrees C, compared to other experimental conditions (P < 0.05)

The importance of feeding status and desiccation rate in successful anhydrobiosis of Panagrolaimus detritophagus

We examined the effect of nutritional status and desiccation rate on the ability of Panagrolaimus detritophagus to undergo anhydrobiosis, as well as to survive high temperatures in the dried state. Both nutrition and drying rate were found to be important, with starvation and slow drying providing better success at anhydrobiosis. The upper temperature for survival of dried animals in laboratory studies was 80 degrees C. Starved worms recovered from drying more successfully when the starvation period was followed by a smooth, gradual dry period prior to undergoing desiccation. Thus, the ability of these worms to enter and leave anhydrobiosis is dependent on critical stress signals

Communautés d’araignées (Arthropoda, Araneae) dans différentes forêts de pins de la réserve de chasse de Zéralda (Alger, Algérie) : taxinomie et biodiversité

La réserve de chasse de Zéralda est située dans le nord de l’Algérie, à environ 30 km à l’ouest d’Alger. Elle couvre une superficie de 1078 ha dont 460 ha sont principalement une forêt naturelle de Pinus halepensis, et des plantations de Pinus pinea et Pinus canariensis. Ces différents biotopes sont favorables à la présence de différentes faunes en général et de la faune du sol en particulier. L’échantillonnage a été effectué en utilisant des pièges Barber. Au total, 48 espèces d’araignées ont été collectées, appartenant à 33 genres et à 17 familles. Les résultats n’ont montré aucune différence dans la richesse des espèces entre les trois types de forêts, mais en ont montré d’une part entre les forêts fermées et celles ouvertes, et d’autre part entre les formations selon qu’elles sont pures ou mixtes. Les facteurs abiotiques comme l’humidité du sol, le pH et la couverture végétale ont un impact sur certaines espèces. Les sites ouverts avec une couverture herbacée dense sont les plus riches et les plus diversifiés. Ils présentent les niches écologiques favorables pour les espèces les plus rares en particulier.The game reserve of Zéralda located in northern Algeria, at about 30 km West of Algiers, covers an area of 1078 ha of which 460 ha are mainly Pinus halepensis natural forest, with planted stands of Pinus pinea and Pinus canariensis. This mixed forest is favourable to the invertebrate fauna in general and the soil fauna in particular. The sampling was done using pitfalls traps. A total of 48 spider species were collected, belonging to 33 genera and 17 families. The results showed no difference in species richness between the three forest types but there were differences between closed and open forests on the one hand and between pure and mixed forests on the other. Abiotic factors such as soil humidity, pH as well as vegetation cover had an impact on some species. Open sites with dense herbaceous cover are the richest and the most diverse and provided favourable ecological niches for the rarest species

Use of endospore-forming bacteria as an active oxygen scavenger in plastic packaging materials

In this study the use of heat resistant endospore-forming aerobic microorganisms of the genus Bacillus amyloliquefaciens as an active oxygen scavenger in multilayer PET bottles was evaluated. Therefore a modelsystem was developed in which Bacillus amyloliquefaciens spores were incorporated in a PET copolymer (PETG) at 220°C. The effectiveness of the OS was evaluated directly by measuring the oxygen absorption rate and indirectly by determining the viability of the incorporated spores

Life-history omnivory in the fairy shrimp Branchinecta orientalis (Branchiopoda: Anostraca)

Very little is known about the feeding of naupliar and juvenile life stages of omnivorous fairy shrimps (Crustacea: Anostraca). Here, we aim to reveal whether the fairy shrimp Branchinecta orientalis is an ontogenetic omnivore and at which age and ontogenetic stage they gain the ability to feed on zooplankton. We assess how food uptake rates change with age until reaching maturity by providing algae (pico- and nanoplanktonic unicellular algae) and zooplankton (rotifers and copepod nauplii) as food in individual experiments. We found that the fairy shrimp B. orientalis started to feed on both types of algal prey immediately after hatching. Nanoplanktonic algae likely represented the most important food source until reaching maturity. Moreover, fairy shrimps started to feed on zooplankton already when they were 7 days old. Slow-moving rotifers gradually gained importance in the fairy shrimp diet with time. Our results reveal an ontogenetic change in the prey spectrum of fairy shrimp. The systematic shift towards omnivory likely affects both phyto- and zooplankton community composition, possibly contributing to temporal changes in food web dynamics in fairy shrimp habitats, and temporary ponds, which may warrant more detailed investigations in future studies

Electrospinning repellents in polyvinyl alcohol-nanofibres for obtaining mosquito-repelling fabrics

Recently, the use of repellents for preventing the transmission of mosquito-borne diseases is getting increasingly more attention. However, most of the current repellents are volatile in nature and must be frequently re-applied as their efficacy is only limited to a short period of time. Therefore, a slow release and abrasion-resistant mechanism is needed for prolonging the protection time of the repellents. The focus of this study is on the direct micro-encapsulation of repellents from an emulsion and integration of already encapsulated repellents into nanofibres via electrospinning. Different repellents were electrospun in polyvinyl alcohol (PVA) nanofibrous structures, namely p-menthane-3,8-diol micro-capsules, permethrin, chilli and catnip oil. The repellents were successfully incorporated in the nanofibres and the tensile properties of the resulting samples did not have a significant change. This means that the newly created textiles were identical to current PVA nanofibrous textiles with the added benefit of being mosquito repellent. Principally, all incorporated repellents in the nanofibrous structures showed a significantly reduced number of mosquito landings compared to the control. Consequently, the currently described method resulted in a new and very effective repelling textile material that can be used in the prevention against mosquito-associated diseases