Phenological and physiological evaluation of first and second cropping periods of sorghum and maize crops

Environmental conditions influence phenology and physiological processes of plants. It is common for maize and sorghum to be sown at two different periods: the first cropping (spring/summer) and the second cropping (autumn/winter). The phenological cycle of these crops varies greatly according to the planting season, and it is necessary to characterize the growth and development to facilitate the selection of the species best adapted to the environment. The aim of this study was to characterize phenological phases and physiological parameters in sorghum and maize plants as a function of environmental conditions from the first cropping and second cropping periods. Two parallel experiments were conducted with both crops. The phenological characterization was based on growth analyses (plant height, leaf area and photoassimilate partitioning) and gas exchange evaluations (net assimilation rate, stomatal conductance, transpiration and water-use efficiency). It was found that the vegetative stage (VS) for sorghum and maize plants was 7 and 21 days, respectively, longer when cultivated during the second cropping. In the first cropping, the plants were taller than in the second cropping, regardless of the crop. The stomatal conductance of sorghum plants fluctuated in the second cropping during the development period, while maize plants showed decreasing linear behaviour. Water-use efficiency in sorghum plants was higher during the second cropping compared with the first cropping. In maize plants, in the second cropping, the water-use efficiency showed a slight variation in relation to the first cropping. It was concluded that the environmental conditions as degree-days, temperature, photoperiod and pluvial precipitation influence the phenology and physiology of both crops during the first and the second cropping periods, specifically cycle duration, plant height, leaf area, net assimilation rate, stomatal conductance and water-use efficiency, indicating that both crops respond differentially to environmental changes during the growing season.     

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Assessment of relevant factors and relationships concerning human dermal exposure to pesticides in greenhouse applications

Principal component analysis (PCA) was applied to the gas chromatographic data obtained from 23 different greenhouse trials. This was used to establish which factors, including application technique (very small, small, medium and large drop-size), crop characteristics (short/tall, thin/dense) and pattern application of the operator (walking towards or away from the treated area) are relevant to the dermal exposure levels of greenhouse applicators. The results showed that the highest exposure by pesticides during field applications in greenhouses, in the climatic conditions and in the crop conditions typical of a southern European country, occurs on the lower legs and front thighs of the applicators. Similar results were obtained by hierarchical cluster analysis (HCA). Drop-size seems to be very important in determining total exposure, while height and density of crops have little influence on total exposure under the conditions of the present study. No pesticide type is a major factor in total exposure. The application of multiple regression analysis (MRA) allowed assessment of the relationships between the pesticide exposure of the less affected parts of the body with the most affected parts.     

Field attraction of Cerambyx welensii to fermentation odors and host monoterpenes

Cerambyx welensii Küster is one of the greatest threats to Quercus suber L. and Quercus ilex L. in Spain. Efficient control methods for this species are currently being tested, and the use of traps baited with food-related products for their monitoring and control has been proposed. Cerambyx welensii adults prefer to colonize old or decayed trees, in which cortical exudates frequently release fermentation odors. Fermentation-related compounds, such as ethanol, have been cited as attractants to various hardwood woodborers (as Cerambyx cerdo L.), used either alone or sometimes in combination with other host odors. In this work, we conducted field experiments to ascertain whether chemical blends mimicking fermentation odors were attractive for C. welensii. To this end, we used three types of traps (multiple funnel, cross-vane and single-funnel) baited with six synthetic blends including one or more fermentation-related chemicals (ethanol, ethyl acetate, 3-methyl-1-butanol, acetaldehyde, 2-methyl-1-propanol and 2-methyl-1-butanol), various food-related products (beer, melon and red wine mixed with peach juice) and host monoterpenes (α-pinene, β-pinene, limonene, α-phellandrene and camphene). At high release rates (5–11 g/day), various synthetic blends proved attractive irrespective of trap type. Our results contribute to understand the impact of volatile organic compounds in host selection by woodborers infesting deciduous trees. The results hold promise for optimizing trapping strategies to control C. welensii within an integrated pest management framework.     

Influence of gamete density,salinity and temperature on the normal embryonic development of the mangrove oyster Crassostrea rhizophorae Guilding, 1828

Laboratory experiments were undertaken to determine the optimal environmental conditions and some of the other factors concerned in the development of Crassostrea rhizophorae embryos.Critical variables such as the number of spermatozoa per ovocyte during fertilization, the time of fertilization after gamete liberation, egg density, temperature and salinity were related to the proportion of normal D-larvae of C. rhizophorae in the resulting broods.The highest proportion of normal D-larvae was obtained at concentrations of 500–5000 spermatozoa/ovocyte, under conditions of 25‰ salinity at 25 ± 1°C. The optimal density of eggs, for the production of normal D-larvae, was 10⁴?4 × 10⁴ ovocytes/l. If fertilization was delayed for more than 45 min after liberation of spermatozoa the proportion of normal D-larvae was greatly reduced. The experiments demonstrated that the temperature for developing embryos should be below 30°C. At 20 and 25°C there was a high proportion of normal D-larvae 24 h after fertilization. The ideal salinity for embryonic development in C. rhizophorae was 25–37‰. Below a salinity of 16‰, less than 2.5% of the D-larvae were normal.     

Maximum foraging ranges in solitary bees: only few individuals have the capability to cover long foraging distances

To preserve populations of endangered bee species, sound knowledge of their maximum foraging distance between nest and host plants is crucial. Previous investigations predicted maximum foraging distances of 100-200 m for small bee species and up to 1100 m for very large species based on mainly indirect methods. The present study applied a new and direct approach to experimentally investigate maximum foraging distances in solitary bees. One endangered and two common species of different body sizes, all of which restrict pollen foraging to a single plant genus, were established in a landscape lacking their specific host plants. Females were forced to collect pollen on potted host plants that were successively placed in increasing distance from fixed nesting stands. The maximum foraging distance recorded for the small Hylaeus punctulatissimus was 1100 m, for the medium sized Chelostoma rapunculi 1275 m and for the large Hoplitis adunca 1400 m, indicating that maximum foraging distances at species level have been underestimated. However, the capability to use resources on such a large spatial scale applied only to a small percentage of individuals as 50% of the females of H. punctulatissimus and H. adunca did not forage at distances longer than 100-225 m and 300 m, respectively. This finding suggests that a close neighbourhood of nesting and foraging habitat within few hundred meters is crucial to maintain populations of these species, and that threshold distances at which half of the population discontinues foraging are a more meaningful parameter for conservation practice than the species specific maximum foraging distances.     

Nesting ground abandonment by the maleo (Macrocephalon maleo) in North Sulawesi: Identifying conservation priorities for Indonesia’s endemic megapode

The maleo (Macrocephalon maleo) is an endemic bird of Sulawesi that lays eggs in communal nesting grounds incubated by solar or geothermal sources. In recent years, maleo nesting grounds have become increasingly vulnerable to threats associated with the growing human population of the island. Consequently, the maleo has become one of the most imperiled bird species in Indonesia and is classified as Endangered on the IUCN Red List. We report on the 2004 status of maleo nesting grounds in North Sulawesi focusing on the Bogani Landscape, the region in and around Bogani Nani Wartabone National Park, where the nesting grounds are concentrated. We compare our results to those of a similar study in 1990-1991, examining changes in nesting ground status in relation to habitat and land use factors such as protection status, geographic position (coastal or inland), and distance to forest, human settlements, and roads. Nesting grounds were more likely to be abandoned if they were: (a) in coastal areas; (b) near settlements and roads; and (c) not in protected areas. Binary logistic regression identified connectivity between nesting grounds and forest in 1991 as the best predictor of whether or not sites were abandoned by maleo over the next 12 years; a loss of local continuity between nesting grounds and forest is associated with a sixfold increase in the probability of abandonment. Access to forest was itself highly correlated with other variables examined, and thus represented a composite index of threats to maleo. The application of this model to the 2004 data identified six active nesting grounds that are at high risk of abandonment in the near future, seven at intermediate risk, and five at low risk. These results offer conservationists priorities for future maleo conservation.     

Antioxidant activity of ethanolic extracts from several asparagus cultivars

Three different methods (antiradical activity, inhibition of primary oxidation, and ferric reducing power) have been used to evaluate the antioxidant activity of eight different asparagus cultivars and byproducts: white and green asparagus from Alcalá del Río (Guadalquivir Valley, Seville) and American hybrids, native spears, and their byproducts from Huétor-Tájar (Vega de Granada). The correlation between antioxidant activity and total phenol content was studied. Six standards were also tested to validate the modified methods for antioxidant activity determination. Results obtained for antiradical capacity and reducing power were very similar, and a high correlation with phenols was found (R > or = 0.9 for both tests). Sample origin was an important factor, spears from Huétor-Tájar having higher values (ARC between 7 and 10 and P(R) of 0.25-0.33) than those from Alcalá del Río (ARC 0.6-2 and P(R) of 0.05-0.07). Significant differences were found between spears with the same origin, suggesting that genetics are another factor to take into account. Asparagus inhibits lipid primary oxidation, but no correlation between the inhibition percentage and phenols was observed. Asparagus origin was the only factor that led to significant differences: samples from Huétor-Tájar had higher values (POIC between 18 and 32) than those from Alcalá del Río (POIC of 5-9). Byproducts from the canning industry at Huétor-Tájar were also assayed for antioxidant activity; the results obtained suggested that byproducts could be considered as an excellent source of natural antioxidants.     

Comparison of assays for the detection of West Nile virus antibodies in chicken serum

Six tests for the detection of West Nile virus (WNV) antibodies in the serum of experimentally infected chickens were compared. The tests included the hemagglutination-inhibition test (HIT), immunoglobulin M (IgM)-capture enzyme-linked immunosorbent assay (ELISA) with WNV-infected mouse brain antigen, immunoglobulin G (IgG) indirect ELISA with tickborne encephalitis viral antigen, the microtitre virus neutralization test, the standard plaque reduction neutralization test (PRNT), and the microtitre PRNT (micro-PRNT). Thirty adult chickens, intravenously and intramuscularly inoculated with 10⁷ plaque-forming units (PFU) of WNV strain Egypt 101, were bled and given a booster of 10⁷ PFU at 7, 15, and 21 d postinoculation; the final blood collection was on day 28. Although the micro-PRNT is capable of detecting the highest antibody titres during both early and late infection, because of the technical complexity and time requirements of this test a combination of IgM and IgG ELISAs is recommended for serologic screening. Serum samples that give positive results in the ELISAs can then be tested by the micro-PRNT to determine the specificity of antibodies to WNV.