Effect of soil management on the white grub population and damage in soybean

To evaluate the effect of soil management systems on population of white grubs, (Phyllophaga cuyabana Moser), and on its damage in soybean, experiments were set up under no-tillage and conventional tillage (one disk plow, and a leveling disk harrow) areas. Primary tillage equipment, used in other soil management systems, such as moldboard plow, disk plow, chisel plow and heavy duty disk harrow were also tested. Fluctuation of P. cuyabana population and the extent of its damage to soybean was similar under no-tillage and conventional tillage systems. Results comparing a range of primary tillage equipment showed that it affected soil insect populations differently, depending on the time during the season in which tillage was executed. Larval mortality could mostly be attributed to their exposure to adverse factors, soon after tillage, than to changes in soil conditions. Reduction of white grub population was more evident in plots managed by heavier equipment, such as the moldboard plow. Soil tillage could be one component within the soil pest management system in soybean, however, its use can not be generalized.

Mechanical damage in cotton buds caused by the boll weevil

The boll weevil (Anthonomus grandis Boheman) causes high levels of bud abscission in cotton plants due to feeding or oviposition punctures. It has been reported that abscission is mainly due to enzymes present in the insect's saliva, but mechanical damage could also contribute to square abscission. The objective of this paper was to undertake an analysis of the morphological damages caused by the insect in cotton squares using microscopy. Anthers and ovules are the main target of boll weevil feeding. The process initiates by perforation of young sepal and petal tissues and proceeds with subsequent alimentation on stamen and ovary leading to abscission of floral structures.

Trichogramma pretiosum attraction due to the Elasmopalpus lignosellus damage in maize

The objective of this work was to evaluate if corn plants damaged by the lesser cornstalk borer (Elasmopalpus lignosellus) larvae release volatile organic compounds capable of attracting the egg parasitoid Trichogramma pretiosum. The treatments consisted of plants subjected to harm caused by E. lignosellus larvae, plants subjected to mechanical damage, and undamaged plants. The parasitoid was more attracted by the volatiles released by the insect damaged plants than to those released by undamaged corn plants, after 24 and 72 hours. The volatiles (Z)-3-hexenyl acetate, β-pinene, β-myrcene, (E)-4,8-dimethylnona-1,3,7-triene, and benzothiazole were released in significantly larger quantities by damaged plants. Volatiles released by corn plants damaged by E. lignosellus larvae may act as an indirect defense, attracting by T. pretiosum.

Damage level of the two-spotted spider mite Tetranychus urticae Koch (acari: tetranychidae) in soybeans

Among phytophagous spider mites, the two-spotted spider mite Tetranychus urticae Koch, 1836 is one of the most important agricultural pests, not only because of the damage it causes, but also because it has a wide host range, infesting many commercial crops such as leafy greens, cotton, beans, and soybeans, among others. This study was carried out in a greenhouse of the Faculdade de Ciências Agrárias (FCA) of the Universidade Federal da Grande Dourados (UFGD), located in the city of Dourados, state of Mato Grosso do Sul. The experiment was arranged in a randomized block design with 5 treatments and 4 replicates. The treatments consisted of 5 levels in percentage of chlorotic symptoms (indicating mite damage): 0%, 25%, 50%, 75%, and 100%. All of the characteristics evaluated, except for number of pods per plant, the number of seeds per plant, the total weight (productivity), and the weight of 1000 seeds, were significantly influenced by the different levels of chlorotic symptoms. The economic damage level for the two-spotted spider mite Tetranychus urticae, according to the equation y = 66.63-0.51 x, based on the price of US$ 11.00 per bag of soybeans and a control cost of US$ 16.00, would be 15.80% chlorotic symptoms. At a price of US$ 29.00 per bag with the same control cost, the economic damage level would be 13% of chlorotic symptoms.

Studies in search of a suitable experimental insect model for xenodiagnosis of hosts with Chagas' disease: 3 - On the interaction of vector species and parasite strain in the reaction of bugs to infection by Trypanosoma cruzi

The reaction of nine vector species of Chagas' disease to infection by seven different Trypanosoma cruzi strains; Berenice, Y, FL, CL, S. Felipe, Colombiana and Gávea, are examined and compared. On the basis of the insects' ability to establish and maintain the infection, vector species could be divided into two distinct groups which differ in their reaction to an acute infection by T. cruzi. While the proportion of positive bugs was found to be low in Triatoma infestans and Triatoma dimidiata it was high, ranging from 96.9% to 100% in the group of wild (Rhodnius neglectus, Triatoma rubrovaria)and essentially sylvatic vectors in process of adaptation to human dwellings, maintained under control following successful insecticidal elimination of Triatoma infestans (Panstrongylus megistus, Triatoma sordida and Triatoma pseudomaculata). An intermediate position is held by Triatoma brasiliensis and Rhodnius prolixus. This latter has been found to interchange between domestic and sylvatic environments. The most important finding is the strikingly good reaction between each species of the sylvatic bugs and practically all T. cruzi strains herein studied, thus indicating that the factors responsible for the excellent reaction of P.megistus to infection by Y strain, as previously reported also come into operation in the reaction of the same vector species to acute infections by five of the remaining T.cruzi strains. Comparison or data reported by other investigators with those herein described form the basis of the discussion of Dipetalogaster maximus as regards its superiority as a xenodiagnostic agent.

Studies in search of a suitable experimental insect model for xenodiagnosis of hosts with Chagas' disease: 4 - The reflection of parasite stock in the responsiveness of different vector species to chronic infection with different Trypanosoma cruzi stocks

Previous studies (1982,1987) have emphasized the superiority of sylvatic vector species over domestic species as xenodiagnostic agents in testing hosts with acute or chronic infections by T. cruzi "Y" stock. The present study, which is unique in that it contains data on both infectivity rates produced by the same stock in 11 different vector species and also the reaction of the same vector species to seven different parasite stocks, establishes the general validity of linking efficiency of xenodiagnosis to the biotope of its agent. For example, infectivity rates produced by "São Felipe" stock varied from 82.5% to 98.3% in sylvatic vectors but decreased to 42.5% to 71.3% in domestic species. "Colombiana" stock produced in the same sylvatic vectors infectivity rates ranging from 12.5% to 45%. These shrank to 5%-22.5% in domestic bugs. The functional role of the biotope in the vector-parasite interaction has not been eluddated. But since this phenomenon has been observed to be stable and easy to reproduce, it leads us to believe that the results obtained are valid. Data presented also provide increasing evidence that the infectivity rates exhibited by bugs from xenodiagnosis in chronic hosts, are parasite stock specific. For example, infectivity rates produced by "Berenice", "Y", "FL" and "CL" varied in R. neglectus from 26.3% to 75%; in P. megistus from 56.3% to 83.8%; in T. sordida from 28.8% to 58.8% in T. pseudomaculata from 41.3% to 66.3% and in T. rubrovaria from 48.8% to 85%. Data from xenodiagnosis in the same hosts, carrying acute infections by the same parasite stocks, gave the five sylvatic vectors a positive rating of approximately 100%, thus suggesting that the heavy loads of parasites circulating in the acute hosts obscured the characteristic interspecific differences for the parasite stock. Nonetheless these latter were revealed in the same hosts with chronic infections stimulated by very low numbers of the same parasite stocks. Certain observations here described lead us to speculate as to the possibility of further results from other parasite stocks, allowing the association of the infectivity rates produced in bugs by different parasite stocks with the isoenzymic patterns revealed by these stocks.

Resistance of mice immunized with killed culture trypomastigotes against infection by insect-derived trypomastigotes of Trypanosoma cruzi

Mice immunized with heat or merthiolate-killed culture trypomastigotes of the non-virulent G strain were resistant to the challenge by insect-derived trypomastigotes of the CL strain of Trypanosoma cruzi. No parasitemia was detected, by direct microscopic examination of blood samples, in 90% of immunized mice while all control animals developed a high parasitemia. Trypsinization before heat-inactivation, or fixation with paraformaldehyde, apparently reduced the immunogenicity of the G strain trypomastigotes. Mice immunized with trypomastigotes treated by either of these procedures were not protected against infection by virulent T. cruzi. Analysis of the 13I-labeled surface proteins of G strain trypomastigotes inactivated by the various methods suggests that these components are involved in eliciting protective immunity against T. cruzi infection.

Chronic myocardial damage in experimental T. cruzi infection of a new world primate, Cebus sp. monkey

Eighteen Cebus apella monkeys, (juvenile and adult of both sexes) were inoculated five years ago, with three Trypanosoma cruzi strains (CA1, n = 10; Colombian, n=4 and Tulahuen, n=4), either by conjunctival or intraperitoneal route, once or repeatedly. Parasitological, hematological, serological, enzymatic, radiographic, electro and echocardiographic findings have been peviously published15 and they are similar to those observed in human pathology. The most frequent electrocardiographic alteration was right branch bundle block. Six animals, chosen at random, were sacrificed. Those sacrificed 20 to 25 months post-first inoculation showed focal accumuli of leukocytes with myocytolysis. Foci of diffuse interstitial fibrosis with mild infiltrate of leukocytes among fibers were observed in the animals sacrificed 36 to 47 months post-inoculation. No parasites were seen. The lesions were more prominent in the ventricular walls and the septum. The fact that the infiltrates were predominant in the animals sacrificed at a shorter time after first inoculation and that fibrosis was more severe in those sacrificed at a longer time suggests that there is a progression of the infiltrative lesions to fibrosis, with a leukocytic activity indicative of a chronic phase. These lesions are similar to those described in human chronic Chagas' disease. This would demonstrate that this model is useful in evaluating a progress in the knowledge of the pathogenesis which is still a controversial issue, immunology, immunogenesis and chemotherapeutic agents of the chronic and indeterminate phases of this disease.

Paracoccidioidomycosis: no genetic damage in human peripheral blood cells of patients assessed by single-cell gel (comet) assay

Paracoccidioidomycosis is a systemic fungal infection caused by Paracoccidioides brasiliensis. As infectious diseases can cause DNA damage, the authors aimed at analyzing DNA breakage in peripheral blood cells of patients with paracoccidioidomycosis by using the comet assay. The results suggested that paracoccidioidomycosis does not cause genotoxicity.

Susceptibility of Aedes aegypti (L) to the insect growth regulators diflubenzuron and methoprene in Uberlândia, State of Minas Gerais

Aedes aegypti (L) (Diptera: Culicidae) was reared in several concentrations of diflubenzuron and methoprene under laboratory conditions in Uberlândia, State of Minas Gerais, southeastern Brazil. Characteristics such as LC50 and LC95, the susceptibility of immature stages of different ages to these insect growth regulators and their residual effects were studied. The LC50 and LC95 of diflubenzuron and methoprene were 5.19 and 12.24 ppb; 19.95 and 72.08 ppb, respectively. While diflubenzuron caused great mortality in all larval instars, methoprene was more effective when the mosquito was exposed from the start of the fourth larval instar onwards. Commercial concentrations of these two insect growth regulators close to LC95 presented greater residual activity than did their respective technical formulations. The parameters were compared with those obtained elsewhere. The characteristics investigated here indicate that these insect growth regulators are effective alternatives for controlling the dengue vector in the Uberlândia region.

Degree of disability, pain levels, muscle strength, and electromyographic function in patients with Hansen's disease with common peroneal nerve damage

INTRODUCTION: This study evaluated the degree of disability, pain levels, muscle strength, and electromyographic function (RMS) in individuals with leprosy. METHODS: We assessed 29 individuals with leprosy showing common peroneal nerve damage and grade 1 or 2 disability who were referred for physiotherapeutic treatment, as well as a control group of 19 healthy participants without leprosy. All subjects underwent analyses of degree of disability, electromyographic tests, voluntary muscle force, and the Visual Analog Pain Scale. RESULTS: McNemar's test found higher levels of grade 2 of disability (Δ = 75.9%; p = 0.0001) among individuals with leprosy. The Mann-Whitney test showed greater pain levels (Δ = 5.0; p = 0.0001) in patients with leprosy who had less extension strength in the right and left extensor hallucis longus muscles (Δ = 1.28, p = 0.0001; Δ = 1.55, p = 0.0001, respectively) and dorsiflexion of the right and left feet (Δ = 1.24, p = 0.0001; Δ = 1.45, p = 0.0001, respectively) than control subjects. The Kruskal-Wallis test showed that the RMS score for dorsiflexion of the right (Δ = 181.66 m·s-2, p = 0.001) and left (Δ = 102.57m·s-2, p = 0.002) feet was lower in patients with leprosy than in control subjects, but intragroup comparisons showed no difference. CONCLUSIONS: Leprosy had a negative influence on all of the study variables, indicating the need for immediate physiotherapeutic intervention in individuals with leprosy. This investigation opens perspectives for future studies that analyze leprosy treatment with physical therapeutic intervention.

Antioxidant factors, nitric oxide levels, and cellular damage in leprosy patients

Introduction The immune response caused by Mycobacterium leprae is a risk factor for the development of oxidative stress (OS) in leprosy patients. This study aimed to assess OS in leprosy patients before the use of a multidrug therapy. Methods We evaluated the nitric oxide (NO) concentration; antioxidant capacity; levels of malondialdehyde, methemoglobin and reduced glutathione; and the activity of catalase and superoxide dismutase (SOD) in leprosy patients. Results We observed lower SOD activity in these leprosy patients; however, the NO levels and antioxidant capacity were increased. Conclusions The infectious process in response to M. leprae could primarily be responsible for the OS observed in these patients.

Indicators of inflammation and cellular damage in chronic asymptomatic or oligosymptomatic alcoholics: correlation with alteration of bilirubin and hepatic and pancreatic enzymes

Biochemical and hematimetric indicators of inflammation and cell damage were correlated with bilirubin and hepatic and pancreatic enzymes in 30 chronic male alcoholics admitted into psychiatric hospital for detoxification and treatment of alcoholism. Aspartate aminotransferase, alanine aminotransferase, gamma-glutamyltransferase, alkaline phosphatase, and total bilirubin were altered, respectively, in 90%, 63%, 87%, 23% and 23% of the cases. None of the indicators of inflammation (lactic dehydrogenase, altered in 16% of the cases; alpha-1 globulin, 24%; alpha-2 globulin, 88%; leucocyte counts, 28%) was correlated with alterations of bilirubin or liver enzymes. Lactic dehydrogenase was poorly sensitive for detection of hepatocytic or muscular damage. Alterations of alpha-globulins seemed to have been due more to alcohol metabolism-induced increase of lipoproteins than to inflammation. Among indicators of cell damage, serum iron, increased in 40% of the cases, seemed to be related to liver damage while creatine phosphokinase, increased in 84% of the cases, related to muscle damage. Hyperamylasemia was found in 20% of the cases and significantly correlated with levels of bilirubin, alkaline phosphatase and gamma-glutamyltransferase. It was indicated that injuries of liver, pancreas, salivary glands, and muscle occurred in asymptomatic or oligosymptomatic chronic alcoholics.

Levels of leaf Herbivory in Amazonian trees from different stages In forest regeneration

Leaves from 120 canopy trees and 60 understory tree saplings growing in primary and secondary forests near Manaus, Brazil, were collected for determination of standing levels of herbivory (percent leaf area lost). Overall, levels of herbivory on leaves of central Amazonian trees were low. About one quarter of the leaves examined (n = 855) had no damage at all. In most other Neotropical sites studied the mean percentage of herbivory was found to vary between 5.7 and 13.1%, whereas in Manaus it was only 3.1%. The data presented here support the contention that levels of herbivore damage are positively related to soil fertility. No significant difference was found in herbivory levels between canopy trees and understory saplings. Also, there was no difference in damage between leaves from pioneer and late successional trees. Field assays of preference, however, revealed that leaves from pioneer trees are more palatable to leaf-cutting ants (Atta laevigata). This effect was dependent upon leaf age, being observed in mature leaves, but not in young leaves. The greater rate of leaf production in secondary forests may be a factor accounting for the greater abundance of leaf-cutting ants in secondary compared to primary forests.