Differential activity of non-fluorinated and fluorinated analogues of the European corn borer pheromone

Summary.  The differing antagonist activity of (Z)-13-hexadecen-2-one (Z11 – 14 :MK, 1) and its 1,1,1-trifluoro derivative (Z11 –14 :TFMK, 2), two closely related analogues of the European corn borer pheromone Ostrinia nubilalis (Z strain), and their rationale is reported. Both chemicals exhibited some electrophysiological activity, and topical application of 10 pg of pheromone analogue on male antennae was sufficient to induce significantly lower depolarization responses to the pheromone versus untreated insects. In a wind tunnel, the number of European corn borer males attracted to sources containing mixtures of 1 + pheromone in ratios ≥ 1 :1 was significantly lower than the number attracted to a source containing pheromone alone. Source contact behaviour was dramatically impaired when the 1 + pheromone blend reached a ratio of 10 :1, in which only 2% of males displayed source contact in the presence of antagonist. When compound 1 was present at the source, males usually flew upwind with occasional downwind reversals; when compound 2 was present at the lure, males performed wider crosswind reversals, with little progress toward the source. In the field, traps baited with mixtures of both compounds with the pheromone in ratios of 5 :1 and 10 :1 elicited a significantly decreased number of male catches. In esterase inhibition assays, compound 2 was a potent inhibitor (IC₅₀ = 70 nM), whereas the non-fluorinated compound 1 was not. The different activity of both compounds is presumed to be due to different mechanisms of action; considerations for using methyl ketone analogues as new behavioural antagonists of the pheromone are outlined.     

Multiple color signals may reveal multiple messages in male Schreiber’s green lizards, <Emphasis Type="Italic">Lacerta schreiberi</Emphasis>

Multiple traits may either signal different characteristics of a male or be redundant. These multiple signals may convey different messages if they are intended for different receivers (e.g., male or females) that have different interests. We examined the functions of multiple colorful visual traits of male Schreiber’s green lizard (Lacerta schreiberi). Results showed that interindividual variation in the characteristics of coloration of males can be related to variation in morphology, health state, dominance status, and pairing status, but that different relationships were found for each color signal. For example, dominant males had brighter “blue” throat and with higher values of ultraviolet (UV) and bluish coloration and darker and greenish dorsal coloration than subordinate males. Health state was also reflected in coloration; males with a higher immune response had “blue” throats with lower amounts of UV coloration, but had “yellow” chests with higher amounts of UV coloration. Males found guarding females also differed in coloration from males found alone. These data suggest that characteristics of coloration of the different multiple signals may reveal different messages for different receivers, either male or female conspecifics. The development of the different signals, based on different morphological and physiological mechanisms and trade-offs, may allow signal reliability of multiple colorful traits in different social contexts.     

Influence of emergence success on the annual reproductive output of leatherback turtles

Reproductive output of leatherback turtles (Dermochelys coriacea) is affected by the stochastic nature of emergence success. Average emergence success of nests at Playa Grande, Costa Rica was 0.38 ± 0.27. Incubation temperature affected development of leatherback turtle eggs and emergence of hatchlings from the nest. We found that high temperatures reduced hatching success and emergence rate and increased embryonic mortality both early and late during incubation at Playa Grande. There was a temporal effect on emergence success that resulted in more hatchlings being produced at the beginning of the season, because of higher emergence success, than toward the end. Likewise, production of hatchlings varied from year to year. The average annual reproductive output was 252 ± 141 hatchlings per female. The 2005–2006 nesting season had the highest emergence success and produced the greatest number of hatchlings per female compared to the 2004–2005 (+120%) and 2006–2007 (+41%) seasons. However, average clutch size (62 ± 10) and clutch frequency (9.45 ± 1.63), were not different among years. Turtles that had nested a high number of years exhibited greater clutch frequency and arrived earlier to nest than turtles that had nested in fewer numbers of years. Nesting when environmental conditions favor high developmental success and emergence rate may constitute an advantageous reproductive strategy.     

An engineered plant that accumulates higher levels of heavy metals than Thlaspi caerulescens, with yields of 100 times more biomass in mine soils

Nicotiana glauca transformed with TaPCS1 was tested for its application in phytoremediation. When plantlets were grown in mine soils containing Cu, Zn, and Pb (42, 2600, and 1500 mg kg(-1)) the plant showed high levels of accumulation especially of Zn and Pb. Adult plants growing in mine soils containing different heavy metal concentrations showed a greater accumulation as well as an extension to a wider range of elements, including Cd, Ni and B. The overexpressed gene confers up to 9 and 36 times more Cd and Pb accumulation in the shoots under hydroponic conditions, and a 3- and 6-fold increase in mining soils. When the hyperaccumulator Thlaspi caerulescens was compared, the results were higher values of heavy metal and Boron accumulation, with a yield of 100 times more biomass. Thlaspi was unable to survive in mining soils containing either a level higher than 11000 mg kg(-1) of Pb and 4500 mg kg(-1) of Zn, while engineered plants yielded an average of 0.5 kg per plant.     

Chemosensory assessment of rival body size is based on chemosignal concentration in male Spanish terrapins

Assessment of the fighting ability of potential opponents is an essential skill to minimize the costs of agonistic interactions between males. Previous research showed that chemical cues released in the water by male turtles may convey information about body size, which is important for intrasexual competition. However, the mechanistic basis of such chemical signaling of body size remains poorly understood. Here, we aimed to experimentally examine whether the release of chemosignals is quantitatively or qualitatively dependent on body size in male Spanish terrapins Mauremys leprosa. We compared the time that turtles spent in a pool with clean water versus water containing chemical stimuli of conspecific males of different body sizes at two different concentrations (“diluted” or “undiluted”). Male terrapins avoided water with chemicals secreted by relatively larger males when these chemicals were undiluted, but not after the chemical stimuli were diluted. In contrast, male terrapins did not avoid chemicals of relatively smaller males in any treatment. Thus, male M. leprosa may assess the size of their rivals on the basis of the concentration or the amounts of their chemical cues released into the water and consequently avoid occupying these ponds with higher concentrations of chemicals. This study gives important hints about the mechanism of chemical signaling in freshwater turtles and demonstrates that male turtles may discriminate different concentrations of chemosignals of conspecifics and modify their behavior accordingly. Likewise, our results support the notion that relative body size is a key factor during male interactions in Spanish terrapins.     

In vitro effects of lead on fatty acid composition,oxidative stress biomarkers and quality of ram spermatozoa

The sperm quality and several parameters associated with oxidative stress were evaluated in ram (Ovis aries) spermatozoa suspensions incubated with 0, 50 or 500 ng/mL Pb during 0, 1, 3 or 6 h. The presence of Pb during incubation, reduced the integrity of the acrosome, % sperm motility and integrity, and the functionality of membrane. On the contrary, % polyunsaturated fatty acids and the activities of glutathione peroxidase and superoxide dismutase in the spermatozoa suspensions were not affected by Pb. Moreover, glutathione peroxidase activity was decreased and the fatty acid composition changed due to the relative increase in % stearic acid during the incubation time independently on Pb presence. Data showed that several effects of Pb on sperm quality usually observed in vivo also occurred in vitro, but without any relationship with oxidative stress biomarkers.     

Effects of Management on Understory Diversity in the Forest Ecosystems of Northern Spain

Pine plantations are an alternative to marginal agriculture in many countries, and are often presented as an option that improves biodiversity. However, these plantations can have adverse environmental effects if improperly managed. To evaluate the effect of forest management practices on biodiversity, the diversity, species richness, dominance and frequency of understory woody plant species in different forests of the Basque Country (northern Spain) were compared. Plantations of exotic conifers (Pinus radiata [D.] Don) of different ages were compared with deciduous forests of Quercus robur L. and Fagus sylvatica L. The effects of different types and intensities of management were taken into account. The differences observed were mainly conditioned by the intensity of forestry management, although the response varied according to forest type and age. In unmanaged pine plantations, the diversity and species richness of the understory increased rapidly after planting (while dominance decreased), remained stable in the intermediate age range, and reached a maximum in plantations more than 25 years of age. Management practices resulted in decreased understory diversity and species richness, as well as greater dominance. This was more pronounced in younger than in older stands. Moderate management, however, favored a greater diversity of the understory in deciduous forests. The species composition of the plantations and deciduous forests were different, the latter having a wider range of characteristic species. Knowledge of how forestry practices influence biodiversity (in terms of diversity, richness, dominance, and species composition) may allow predictions to be made about the diversity achievable with different management systems.     

Reliable analysis of chlorophenoxy herbicides in soil and water by magnetic solid phase extraction and liquid chromatography

Environmental Chemistry Letters - There is no previous work on the determination of chlorophenoxy acid herbicides in soils. Here we analysed six chlorophenoxy acid herbicides using magnetic solid...     

Polycyclic aromatic hydrocarbon composition in soils and sediments of high altitude lakes

Polycyclic aromatic hydrocarbons (PAH) in lake sediments and nearby soils of two European high mountain regions, Pyrenees and Tatra, have been studied. Similar mixtures of parent PAH were observed in all cases, indicating predominance of airborne transported combustion products. Nevertheless, the composition of these atmospherically long-range transported PAH was better preserved in the superficial layers of soils than sediments. This difference points to significant PAH degradation process, e.g. during lake water column transport, before accumulation in the latter. Post-depositional transformation was also different in both types of environmental compartments. Thus, lake sediments exhibit higher preservation of the more labile PAH involving lower degree of post-depositional oxidation. However, they also show the formation of major amounts of perylene by diagenetic transformation in the deep sections. This compound is not formed in soils where downcore enrichments of phenanthrene are observed, probably as a consequence of diagenetic aromatization of diterpenoids.