Potato fungicides interfere with entomopathogenic fungi impacting population dynamics of green peach aphid

Fungicides applied to potato can enhance green peach aphid,Myzus persicae (Sulzer), outbreaks by interference with entomopathogenic fungi. (Order Entomophthorales). Late season aphid numbers were highest in potatoes sprayed with metalaxyl + mancozeb, captafol, or mancozeb, and lowest in potatoes sprayed with benomyl, triphenyltin hydroxide, chlorothalonil, or copper hydroxide. In field-collected aphids,Pandora (= Ernyia) neoaphidis (Remaudière et Hennebert) andEntomophthora planchoniana Cornu (F. Entomophthtoraceae) were the predominant cause of mycoses, 66.7% and 22.3%, respectively.Conidiobolus obscurus (Hall and Dunn) Remaudièe and Keller (F. Ancylistaceae) accounted for 8.5% of mycoses. In the laboratory, fungicides were shown to have direct effects on these entomopathogens. Metalaxyl + mancozeb, mancozeb and captafol were strongly inhibitory of germination of conidia, copper hydroxide was intermediate, and chlorothalonil had little effect. Triphenyltin hydroxide, benomyl, metalaxyl + mancozeb, and mancozeb were strongly inhibitory of growth of mycelia, copper hydroxide was intermediate, and chlorothalonil and copper hydroxide had least effect. Benomyl was highly toxic to green peach aphid, copper hydroxide and chlorothalonil intermediate, and captafol, mancozeb, and metalaxyl + mancozeb least toxic. Possible interference of potato fungicides with aphid pathogens is now an important consideration because of the intensity of spraying required to protect the crop from infection by metalaxyl-resistant strains of the late blight pathogen,Phytophthora infestans (Mont.) de Bary. Minnesota potato growers reported high green peach pressure in both 1995 and 1996, years of intensive fungicide spraying. Concomitantly, there was a marked increased in the incidence of PLRV in seed lots entered for winter testing.     

Use of pathophysiological indicators for individual decision of anthelmintic treatment of ewes against gastro-intestinal nematodes in Morocco

The targeted selective treatments (TST) aim at reducing the number of anthelmintic treatments but also to maintain productivity of animals. The aim of this work was to assess the validity of pathophysiological indicators for detecting individually ewes in need for treatments in two regions of Morocco with different management and climatic environment (Chaouia plain-seven farms, and Middle-Atlas-three farms). Although resistance to benzimidazoles was already present the same drug was used for TST. The indicators tested were: FAMACHA(?) (associated with anaemia), DISCO (diarrhoea score), and BODCON (body condition score). Only FAMACHA(?) and DISCO indicators were well correlated to the EPGs. DISCO only did permit a substantial reduction (up to 85%) of the number of treatment and EPG (nematode eggs per gramme) remained low on average (less than 160).     

Assessment of summer drought tolerance variability in Mediterranean alfalfa (Medicago sativa L.) cultivars under Moroccan fields conditions

This study was undertaken to assess levels of tolerance to summer drought in Medicago sativa genotypes and to comment on their abilities to adapt to Moroccan conditions. Sixteen alfalfa cultivars originating from the Mediterranean basin were tested at an experimental station in Morocco, located in the semi-arid bioclimatic area. Trials were conducted over three years and consisted of one continuously irrigated treatment and another irrigated treatment in which summer watering was withheld for 9 weeks. Results showed that summer water stress significantly reduced aboveground biomass in all of the cultivars tested. This reduction ranged between 23.9 and 42.6% compared with fully irrigated treatment. At the end of stress period, mean summer leaf senescence rate was 83.3%, with a significant difference between cultivars. Ground cover, estimated at the end of summer in the third year, decreased dramatically and ranged between 12 and 30.7%, depending on the cultivar. High intrinsic water-use efficiency was associated with a decrease in stomatal conductance rather than an increase in photosynthesis.     

Breaking seed dormancy in Cupressus atlantica Gaussen, an endemic and threatened coniferous tree in Morocco

Cupressus atlantica Gaussen (Cupressaceae) is an endemic and endangered coniferous tree geographically restricted to the N’Fis valley in South-Western Morocco. Like many forest species, C. atlantica exhibits dormancy which delays and reduces germination. To improveseed germination, different pre-treatments were conducted on C.atlantica seeds after storage for different periods (one, two and five years) including: scarification with sandy paper; soaking seeds in hot distilled water at 60℃and 80℃for 15 min and soaking seeds for 48 h in agibberellic acid (GA3) at 1,000 and 2,000 mg·L-1. Results showed that scarification with sandy paper increased the germination rate of Atlas cypress by up to 67%, indicating that the species possess essentially anexogenous dormancy (physical dormancy) due to the hard seed coat(hardseededness). Exogenous application of gibberellic acid (GA3) at1,000 mg·L-1 was also effective in breaking seed dormancy and germination induction. These two treatments induced faster speed germination expressed by low number of days to first germination (8 10days) and low values of mean germination times (MGT). However,germination rate, under any treatment, is greatly dependent on the year of seed collection. Seeds collected in year 2004 gave the highest value,suggesting that even after five years of storage, the germination capacity of C. atlantica seeds could remain high. This observation is very interesting in the exsitu conservation of such endemic and endangered species where the production of seeds is irregular over the years.     

Medicago sativa-rhizobia symbiosis under water deficit: Physiological,antioxidant and nutritional responses in nodules and leaves

Biological nitrogen fixation has positive effects in the enhancement of soil nutrition and plants growth, especially under difficult conditions. The study assesses the effect of drought (40% field capacity) on growth, physiological and biochemical parameters of six symbioses involving two Moroccan alfalfa populations Adis-Tata (Ad) and Riche (Rc) and Moapa (Mo) variety and ArfRh2 (Rh2) and AufRh8 (Rh8) rhizobia isolated from Arfoud and Aufous, respectively. Results showed that drought decreased plants growth and nodulation. Physiologically, as response to stress, the nodules membrane stability was negatively affected. Biochemically, activities of peroxidase (POX), catalase (CAT), superoxide dismutase (SOD) and acid phosphatase (APase) increased in leaves and nodules. Ad-Rh2, Rc-Rh2 and Ad-Rh8 have been qualified as more drought tolerant. They showed high antioxidant activities and as consequence less membrane damages especially in their nodules. The increase in nodules health and antioxidant defense could results in the enhancement of plant drought tolerance under stress.     

Modelling the transmission of Echinococcus granulosus in dogs in the northwest and in the southwest of Morocco

Echinococcus granulosus (E. granulosus) infection was studied in 151 dogs in two regions of Morocco: 68 dogs in the northwest (Loukkos) and 83 dogs in the southwest (Tiznit). The mean prevalence rates of echinococcosis in dogs were 58.82% (46.23-70.63%) in Loukkos and 55.42% (44.10-66.34%) in Tiznit and the mean abundances of E. granulosus per dog were 75 (59-93) and 547 (504-595), respectively. The mean abundance of E. granulosus in dogs was fitted to a negative binomial distribution by the maximum likelihood techniques to define parameters. E. granulosus was aggregated in dogs in the two regions. The prevalence of infection and the abundance of E. granulosus in dogs were fitted to mathematical models in order to determine if the parasite population is partly regulated by definitive host immunity. The best fit was obtained with the models assuming the presence of immunity. The mean time of exposure to infection was similar in the two regions and ranged from 8 months to about 2 years. The infection pressures (number of E. granulosus) obtained per dog each year were 65 (8-294) in Loukkos and 476 (316-886) in Tiznit. The proportion of dogs susceptible to infection was still high along the life of the dogs in Loukkos, while it was not different from zero in old dogs of Tiznit.     

Water deficit effects on caraway (Carum carvi L.) growth, essential oil and fatty acid composition

The Mediterranean region suffers of drought which affects plant behaviour regarding biochemical responses. Accordingly, the effects of water deficit on growth, essential oil and fatty acid composition of caraway (Carum carvi L.) seeds were investigated. Plants were treated with different levels of water deficit: control, moderate water deficit and severe water deficit. Plant growth (height, fresh and dry matter weight) was significantly reduced by severe water deficit. This last caused also important reductions of the seed yield and yield components. Drought decreased significantly seed total fatty acid contents and particularly the petroselinic ones whose proportions decreased significantly by 12.17 and 18.47%, in comparison with the control, under moderate water deficit and severe water deficit, respectively. Besides, moderate water deficit increased the essential oil yield (expressed as g/100 g on the basis of dry matter weight). The main essential oil constituents were carvone and limonene which showed an increasing of their contents under water deficit levels. Thus, water deficit induced a significant reduction in growth parameters and fatty acid content, and an increase in the essential oil compounds. These bioactive compounds have been required in many industrial products.     

Do reactive oxygen species (ROS) induced by NaCl contribute to ammonium accumulation in Spartina alterniflora?

Growth, activity of antioxidant enzymes viz. glutathione reductase (GR), superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and guaiacol peroxidase (GPX), and some metabolic processes related to ammonium metabolism were investigated in a salt‐tolerant Spatina alterniflora. In comparison to 0 mM–NaCl treatment, growth of S. alterniflora plant increased significantly at 200 mM NaCl, but was highly inhibited at 500 mM NaCl. Ammonium concentration in the leaves and roots increased 2.1–3.4 times when plants were treated with 500 mM NaCl. Under 200 mM NaCl, antioxidant‐enzyme activities increased, however, at 500 mM the antioxidant system was unable to compensate reactive oxygen species induced by NaCl. At this high level of salinity, ammonium production through nitrate reductase (NR) was inhibited, but no significant changes in the activities of glutamine synthetase (GS) or glutamate dehydrogenase (GDH) were found. We conclude that the accumulation of ammonium under high salt stress was not due to inhibition of the assimilatory activities of GS or GDH. Ammonia accumulation under high salinity may result from amino acid and protein catabolism activated by reactive oxygen species (ROS) and/or a lack of carbon skeletons to incorporate ammonium into organic molecules due to a decrease in photosynthetic activity in salt‐stressed plants.     

In Vitro assessment of the nutritive value of expanded soybean meal for dairy cattle

ABSTRACT: Little information is available about the nutritive value of expanded soybean meal, which is produced by expansion of soybeans prior to solvent extraction of the oil. During processing, expanded soybean meal is subjected to additional heat, which might increase the concentration of ruminally undegraded protein. Processing of soybeans with heat during oil extraction could affect lysine availability by increasing ruminally undegraded protein or by impairing intestinal digestion. Our objective was to compare solvent and expanded soybeans with regard to chemical composition and nutritive value for dairy cattle. Samples of expanded soybean meal (n = 14) and solvent-extracted soybean meal (n = 5) were obtained from People's Republic of China to study effects of the expansion process on nutritive value for dairy cattle. Solvent-extracted soybean meal (n = 2) and mechanically extracted (heated) soybean meal (n = 2) from the United States served as references for comparison. Samples were analyzed for crude fat, long-chain fatty acids, crude protein, amino acids, chemically available lysine, in situ ruminal protein degradation, and in vitro intestinal digestibility. No differences were found between solvent-extracted soybean meals from China and expanded soybean meals from China for crude fat, crude protein, amino acids, or chemically available lysine. In situ disappearance of nitrogen, ruminally undegraded protein content, and in vitro intestinal digestion of the ruminally undegraded protein were generally similar between solvent-extracted soybean meals made in China and expanded soybean meals made in China; variation among soybean meals was small. Results indicate that the additional heat from the expansion process was not great enough to affect the nutritive value of soybean meal protein for ruminants. Although expansion may improve the oil extraction process, the impact on the resulting soybean meal is minimal and does not require consideration when formulating ruminant diets.     

In Vitro assessment of the nutritive value of expanded soybean meal for dairy cattle

Little information is available about the nutritive value of expanded soybean meal, which is produced by expansion of soybeans prior to solvent extraction of the oil. During processing, expanded soybean meal is subjected to additional heat, which might increase the concentration of ruminally undegraded protein. Processing of soybeans with heat during oil extraction could affect lysine availability by increasing ruminally undegraded protein or by impairing intestinal digestion. Our objective was to compare solvent and expanded soybeans with regard to chemical composition and nutritive value for dairy cattle. Samples of expanded soybean meal (n = 14) and solvent- extracted soybean meal (n = 5) were obtained from People’s Republic of China to study effects of the expansion process on nutritive value for dairy cattle. Solvent-extracted soybean meal (n = 2) and mechanically extracted (heated) soybean meal (n = 2) from the United States served as references for comparison. Samples were analyzed for crude fat, long-chain fatty acids, crude protein, amino acids, chemically available lysine, in situ ruminal protein degradation, and in vitro intestinal digestibility. No differences were found between solvent-extracted soybean meals from China and expanded soybean meals from China for crude fat, crude protein, amino acids, or chemically available lysine. In situ disappearance of nitrogen, ruminally undegraded protein content, and in vitro intestinal digestion of the ruminally undegraded protein were generally similar between solvent-extracted soybean meals made in China and expanded soybean meals made in China; variation among soybean meals was small. Results indicate that the additional heat from the expansion process was not great enough to affect the nutritive value of soybean meal protein for ruminants. Although expansion may improve the oil extraction process, the impact on the resulting soybean meal is minimal and does not require consideration when formulating ruminant diets.