Growth characteristics, nitrogen uptake and enzyme activities of the nitrate-utilising ectomycorrhizal Scleroderma verrucosum

The growth characteristics and uptake capacities for NO3- and NH4+, as well as activities of nitrogen assimilating-enzymes have been determined in Scleroderma verrucosum. Biomass, grown on agar or liquid MMN media, was higher on nitrate. When S. verrucosum was grown in the presence of equal amounts of ammonium and nitrate, uptake rate for NH4+ was considerably higher than that of NO3-. In addition, it was found that a limitation in ammonium concentration was a prerequisite for nitrate uptake. Nitrate reductase was stimulated when the fungus was transferred from ammonium to nitrate containing media, indicating that the enzyme was inducible by nitrate and repressed by ammonium. Glutamine synthetase and NAD-glutamate synthase activities were clearly detected in S. verrucosum, while the NADP-glutamate dehydrogenase was almost undetectable. This is consistent with the view that ammonium assimilation occurs through the GS/GOGAT cycle in S. verrucosum

Expression of glutamate dehydrogenase and aspartate aminotransferase in eucalypt ectomycorrhizas

Previous studies of nitrogen-assimilating enzymes in ectomycorrhizal associations of the Pinaceae (Norway spruce, Douglas fir) and the Fagaceae (beech) have suggested that the host plant may regulate the expression of some fungal enzymes. To improve our understanding of the regulation of nitrogen-assimilating enzymes in ectomycorrhizal plants, we have extended this work to a third plant family, the Myrtaceae. Glutamate dehydrogenases, specific either for NAD (NAD-GDH) or NADP (NADP-GDH), and aspartate amminotransferase (AAT) were investigated by enzyme assays and electrophoretic patterns on polyacrylamide gels. Non-mycorrhizal roots of four species of Eucalyptus (E. diversicolor, E. globulus, E. nitens and E. regnans) were characterized by a high activity of NAD-GDH, while only NADP-GDH was found in Hebeloma westraliense in pure culture. In associations of these eucalyptus with Hebeloma westratiense, both NAD- and NADP-GDHs were detected. By contrast, NAD- and NADP-GDHs found in the free-living mycelium of Lacrayia lacrata were not detected in the associated ectomycorrhizas. In ectomycorrhizas of five species of eucalypts (E. diversicolor, E. globulus, E. grandis, E. regnans and E. urophylla) associated with either Laccaria laccata, Scleroderma verrucosum or Pisolithus tinctorius, fungal AAT. which was very active in free-living mycelia, was not detected in the symbiotic tissues. In contrast, the two root AAT isoenzymes remained active in the mycorrhizas and were even stimulated. These results suggest that fungal gene expression is moderated by the host plant but also depends on the fungal associate. Factors which may contribute to the observed differences in enzyme activity between Hebeloma and Laccaria are discussed

Investigation of 6TSWCNT by Cs-Corrected Transmission Electron Microscopy

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 - July 30, 200

Produção orgânica de uva para mesa.

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Control of linepithema micans (hymenoptera: formicidae) and eurhizococcus brasiliensis (hemiptera: margarodidae) in vineyards using toxic baits.

Linepithema micans (Forel) (Hymenoptera: Formicidae) is the main ant species responsible for dispersal of Eurhizococcus brasiliensis (Wille) (Hemiptera: Margarodidae), a root scale that damages grapevines in southern Brazil. The effects of different formulations of toxic baits based on boric acid and hydramethylnon to control L. micans and E. brasiliensis were evaluated. Toxic baits with boric acid (1.0%) mixed in different concentrations of inverted sugar (20%, 30%, and 40%), and hydramethylnon, mixed with sardines (paste), cassava flour and peanut, brown sugar (sucrose), or sardine oil-based gel, were evaluated in a greenhouse and in the field. In the greenhouse experiment, the number of foraging ants was significantly reduced in the pots where the hydrame- thylnon in sardine paste (Solid S), sardine oil-brown sugar-based gel (GEL SAM), and peanut oil-brown-sugar gel (GEL AM) formulations were applied. The GEL SAM toxic bait effectively reduced the infestation of L. micans , and could be used for indirect control of E. brasiliensis on young grapevines. Keywords : hydramethylnon, ant, scale, contro

Biological characteristics of Grapholita molesta (Lepidoptera: Tortricidae) induced to diapause in laboratory.

In southern Brazil, Grapholita molesta (Busck) (Lepidoptera: Tortricidae) uses diapause as survival strategy during the winter (May-August). In our study, we evaluated the effect of diapause on biological characteristics of the species for 4 months in laboratory. Newly hatched larvae of G. molesta were induced to diapause changing the photoperiod and temperature (T) (12 ± 1°C), relative humidity (RH) (70 ± 10%), and a photophase of 12 h and, when they started diapause in the prepupal stage, the conditions were kept for 4 months. Afterwards, the insects were induced to finalize the diapause process at T 25 ± 1°C, RH 70 ± 10%, and a photophase of 16 h. We evaluated the duration and viability of the larval stages and pupae, pupae weight at 24 h and sex ratio (sr), periods of preoviposition, oviposition, and postoviposition; adult life span (males and females); fecundity (daily and total); embryonic period duration and eggs viability, comparing the data with insects nondiapause. The results show that diapause greatly affected the viability of pupal-adult stages of the population (21.8%) when compared with insects' nondiapause (80.0%). Total fecundity (83.0 eggs) and mean life span (12.0 d) of insects diapause was significantly lower compared with insects nondiapause (173.0 and 17.0), respectively. However, these differences were not observed in the sr, which was similar to insects diapause (sr = 0.41) and insects nondiapause (sr = 0.49). The diapause induced for 4 months negatively affects reproduction and life span of adults of G. molesta

Evaluation of insecticides for the control of Linepithema Micans (Hymenoptera: Formicidae).

Linepithema micans (Forel) (Hymenoptera: Formicidae) is the main ant species responsible for the spreading of Eurhizococcus brasiliensis (Wille) (Hemiptera: Margarodidae), a soil scale that damages grapevine plants in southern Brazil. The effect of contact and ingestion of insecticides on the control of L. micans was evaluated in a greenhouse using grapevines (Vitis spp.) infested by L. micans. The insecticides thiamethoxam (250, 187.5, and 125 g/ha), Þpronil (4, 5, and 50 ml/ha), and imidacloprid (650 g/ha) were sprayed on the ground, whereas toxic baits containing boric acid (0.5, 1.0, and 1.2%), pyriproxyfen (0.3 and 0.5%), and hydramethylnon (0.5%) were evaluated in different formulations. Hydramethylnon (toxic bait) and thiamethoxam (chemical barrier) were the most efÞcient active ingredients for the control of L. micans

Efeito de inseticidas reguladores de crescimento sobre ovos, lagartas e adultos de Grapholita molesta (BUSCK) (LEP.: Tortricidae).

O trabalho teve como objetivo avaliar o efeito de inseticidas reguladores de crescimento de insetos (RCI) sobre ovos, lagartas e adultos de G. molesta, em laboratório. Os inseticidas avaliados foram lufenurom e novalurom (4,0g de i.a. 100L-1) metoxifenozida e tebufenozida (9,6g de i.a. 100L-1) e uma testemunha (água destilada). Em aplicação antes da oviposição, somente o metoxifenozida causou mortalidade significativa de ovos (26,3%), quando comparado à testemunha. A aplicação dos inseticidas sobre ovos com diferentes idades (24; 48 e 72 horas) apresentou variações na mortalidade da espécie em função do inseticida e tempo de desenvolvimento embrionário. Somente metoxifenozida e novalurom reduziram a viabilidade de lagartas que eclodiram dos ovos tratados, com um máximo de 35,9 e 39,5% de viabilidade larval quando aplicados em ovos de 48-72 horas, respectivamente. O tratamento dos frutos de maçã com inseticidas causou mortalidade significativa das lagartas, contudo não foram observadas diferenças entre os inseticidas, tanto para lagartas pequenas (eficiência média de 47,2%), quanto para lagartas de 3º-4º instar (média de 45,3%). Lufenurom reduziu sua eficácia com o aumento do tamanho da lagarta. A ingestão de lufenurom, metoxifenozida, novalurom, tebufenozida por adultos de G. molesta reduziu a fecundidade e a fertilidade, porém a longevidade dos adultos somente foi afetada negativamente pela ingestão de metoxifenozida e tebufenozida