Effect of temperature on development and population growth of Acarophenax lacunatus (Cross and Krantz) (Prostigmata: Acarophenacidae) on Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae)

The parasitic mite Acarophenax lacunatus kills the eggs upon which it feeds and seems to have potential as a biological control agent of stored grain pests. The lack of biological studies on this mite species led to the present study carried out in laboratory conditions at eight different temperatures (ranging from 20 to 41°C) and 60% relative humidity using Rhyzopertha dominica as host. The higher the temperature, the faster: (1) the attachment of female mites to the host egg (varying from 1 to 5 h); (2) the increase in body size of physogastric females (about twice faster at 40°C than at 20°C); and (3) the generation time (ranging from 40 to 220 h). In addition, the higher the temperature, the shorter the maximum female longevity (ranging from about 75 to 300 h). The two estimated temperature thresholds for development of A. lacunatus on R. dominica were 18 and 40°C. The average number of female and male offspring per gravid mite were 12.8 and 1.0, respectively, with sex ratios (females/total) ranging from 0.91 to 0.94 (maximum at 30°C). The net reproductive rate and intrinsic rate of increase also presented maximum values at 30°C (12.1 and 0.04, respectively).

Little cicada of sugarcane Mahanarva posticata (Homoptera: Cercopidae). A Brazilian agricultural pest. Morpho-histological study of salivary glands

Little cicadas are homopteran insect pests of sugarcane plantations. As these insects suck out the sap from the leaf parenchyma, they inoculate a toxic saliva that damages the plant vessels, thus promoting the loss of glucose by the affected plant. The morphological and histological analyses of the salivary glands of the little cicada Mahanarva posticata, revealed that these glands are formed by 2 portions: one portion comprises a group of acini and has been denominated as the principal gland; the second portion is filamentous in nature and has been denominated as the accessory gland; it is formed by very long and fine filaments. The acinous portion of the gland can be subdivided into 2 lobes: an anterior lobe formed by 3 lobules (I, II, III), and a posterior lobe formed by lobule IV and the excretory duct. Histologically, the salivary glands showed that the filaments are empty sutructures composed by several internal channels with secretion granules being observed in the cytoplasm of the cells of the secretory filaments. Lobules I and II of the principal gland are characterized by being highly basophilic and for accumulating a large amount of secretion in both the cytoplasm of the cells and inside secretion vesicles. Histochemically, we verified that the secretion produced by these glands is lipidic and protein in nature, with the production of polysaccharides being very low. The differences in stain and appearance of the different regions of the salivary gland lead us to believe that the final glandular product is lipoproteic in nature.

Biologia comparada de Trialeurodes vaporariorum (West.) (Hemiptera - Homoptera: Aleyrodidae) em soja e cinco cultivares de feijão

With the development of greenhouse grown crops, the whitefly Trialeurodes vaporariorum (West.) has become an important pest. Aiming at verifying the effect of host on the development of this species, the biology of the whitefly was studied on bean (Phaseolus vulgaris L.) cultivars IAC-Carioca Pyatã, IAPAR-57, Jalo Precoce, IAC-Bico de Ouro, IAC-Maravilha and on soybean (Glycine max L.) cultivar Cristalina. The study was conducted at the Laboratório de Entomologia Agrícola - FCA-UNESP, at 25 ± 3°C temperature, 80 ± 10% RH and 14h photophase. The biological parameters assessed were duration, viability and number of nymphal instars; male and female longevity, oviposition period, number of eggs per female and sex ratio; egg viability and incubation period and the life cycle duration. Based on data obtained, fertility life tables were constructed to allow a comparative analysis of the effect of cultivars on the biological development and consequent population growth of this species. The bean cultivars IAC-Maravilha and Jalo Precoce negatively influenced T. vaporariorum development, whereas, the other bean cultivars studied, as well as the soybean cultivar Cristalina, provided good conditions for development of this pest.

Cysts reabsorption in the testis of the bee wax pest Achroia grisella (Lepidoptera, Pyralidae) during spermatogenesis

The present paper reports the occurrence of testicular cysts degeneration during spermatogenesis of Achroia grisella, a Lepidoptera with dimorphic spermatogenesis, through ultrastrucutural studies. Signs of cysts degeneration can be detected in the last larval instar but it increases during pupation and early adulthood. The degeneration affects the eupyrene, as well apyrene cysts but it is not always possible to recognize which cysts are degenerating. Some morphological features of cysts degeneration resemble apoptosis.

Water table effects on bean yield and nitrate distribution in the soil profile

In order to evaluate the bean yield under different water table levels as well as the moisture and nitrate distribution in the soil profile, a field experiment was carried out at the experimental area from the College of Agronomic Sciences - UNESP, Botucatu, SP, Brazil. Beans were grown in field lysimeters and subjected to five water table depths:30; 40; 50; 60 and 70 cm. The moisture in the soil profile was gravimetrically determined through samples obtained at 10; 20; 30; 40; 50; 60 and 70cm of depth. The water table depths of 30cm and 40cm showed the highest productivities (3,228.4 kg.ha-1 and 3,422.1 kg.ha-1, respectively), showing no statistical differences between each other. The highest productivity was related to the two most elevated water table levels (30 and 40cm), which provided the highest moisture average values on basis of volume in the soil profile (33.3 e 31%) as well as the consumptive use of water (416 and 396 mm). The nitrate content during the bean cycle at the extraction depth of 60cm has been under the safe drinking limit of 10 mg.1-1 for water table depths of 30; 40; 50 and 60cm, showing the denitrification effectiveness as a way of controlling water table from nitrate pollution. The water table handling allowed the attainment of high bean productivity levels, as well as the reduction of the nitrate level.

Shelf-life of tail meat of the giant river prawn, Macrobrachium rosenbergii, stored on ice

The objective of this study was to evaluate the shelf-life of peeled giant river prawn Macrobrachium rosenbergii stored directly in contact with ice (DCI), and without direct contact with ice (WCI). The prawns from DCI treatment showed an intense leaching of non-protein nitrogen (NPN) and total volatile bases nitrogen (TVB-N), thus suggesting that NPN or TVB-N should not be used as freshness indicators of peeled tails stored directly in contact with ice. Loss of flavor and a quick texture tactile decrease with time occurred in both treatments. The shelf-life of peeled tails prepared from M. rosenbergii was 7 days for DCI and 10 days WCI. © 2006 by The Haworth Press, Inc. All rights reserved.

Water table effects on bean yield and nitrate distribution in the soil profile

In order to evaluate the bean yield under different water table levels as well as the moisture and nitrate distribution in the soil profile, a field experiment was carried out in the experimental area of the College of Agricultural Sciences - UNESP, Botucatu, SP, Brazil. Beans were grown in field lysimeters under five water table depths: 30; 40; 50; 60 and 70 cm. The moisture in the soil profile was determined gravimetrically using samples collected at 10; 20; 30; 40; 50; 60 and 70 cm deep. The water table depths of 30cm and 40cm showed the highest productivities (3,228.4kg.ha-1 and 3,422.1kg.ha-1, respectively), with no statistical differences between them. The highest productivity was related to the two highest water table levels (30 and 40cm), which provided the highest moisture average values on the basis of volume in the soil profile (33.3 e 31%) as well as the consumptive use of water (416 and 396mm). The nitrate content during the bean cycle at the extraction depth of 60cm was below the safe drinking limit of 10mg.1-1 for water table depths of 30; 40; 50 and 60cm, which shows the denitrification efficiency as a way of controlling nitrate pollution in water tables. The management of water table can lead to high levels of bean yield and to a better control of nitrate pollution in underground water.

Management of vomplex systems: Modeling the biological pest control

The aim of this paper is to study the cropping system as complex one, applying methods from theory of dynamic systems and from the control theory to the mathematical modeling of the biological pest control. The complex system can be described by different mathematical models. Based on three models of the pest control, the various scenarios have been simulated in order to obtain the pest control strategy only through natural enemies' introduction. © 2008 World Scientific Publishing Company.

Heminested reverse-transcriptase polymerase chain reaction (hnRT-PCR) as a tool for rabies virus detection in stored and decomposed samples

Background. The use of methods, both sensitive and specific, for rabies diagnosis are important tools for the control and prophylaxis of the disease. Reverse-Transcriptase Polymerase Chain Reaction (RT-PCR) has been used in rabies diagnosis with good results, even in decomposed materials. Additionally, molecular techniques have been used for epidemiological studies and to gain a better knowledge of viral epidemiology. Findings. The aim of this work was to evaluate the RT-PCR and hnRT-PCR for rabies virus detection in original tissues stored at -20°C for different periods considering their use for rabies virus detection in stored and decomposed samples. RT-PCR and hnRT-PCR were evaluated in 151 brain samples from different animal species, thawed and left at room temperature for 72 hours for decomposition. The RT-PCR and hnRT-PCR results were compared with previous results from Direct Fluorescent Antibody Test and Mouse Inoculation Test. From the 50 positive fresh samples, 26 (52%) were positive for RT-PCR and 45 (90%) for hnRT-PCR. From the 48 positive decomposed samples, 17 (34, 3%) were positive for RT-PCR and 36 (75%) for hnRT-PCR. No false-positives results were found in the negatives samples evaluated to the molecular techniques. Conclusion. These results show that the hnRT-PCR was more sensitive than RT-PCR, and both techniques presented lower sensibility in decomposed samples. The hnRT-PCR demonstrated efficacy in rabies virus detection in stored and decomposed materials suggesting it's application for rabies virus retrospective epidemiological studies. © 2008 Arajo et al; licensee BioMed Central Ltd.

Estudio de la compactación de un Ferralsol manejado con un sistema de no laboreo en Selvíria (MS, Brasil)

No tillage management is widely used by the Brazilian farmers and technicians like a soil conservation system, which reduces the soil losses by water erosion, increasing the infiltrated and stored water in soil, warranting environmental sustainability. No-tillage system does not invert the soil; it causes the creation of a compacted layer. The samples were taken in the agricultural year 2005/2006 in an Oxisoil at Selviria (MS/Brazil). The tillage management in the last 15 years was no-tillage system with crop rotation (maize -Zea mays L./bean - Phaseolus vulgaris L.). The analyzed soil physical properties were bulk density (BS), gravimetric water content (U) and mechanical resistance to penetration (RP) at three depths: 0-0.10 m, 0.10-0.20 m and 0.20-0.30 m. The samples were taken in a mesh with 117 sampled points covering an area of 0.16 ha. It was investigated the existence of compacted soil layer, using the mechanical resistance to penetration to 0.60 m depth with soil water content at field capacity. The data shows low coefficient of variation, except the resistance penetration data. Bulk density and gravimetric water content has a normal distribution. Only resistance to penetration at 0.10-0.20 m depth layer has a normal distribution. The correlation between different properties was low. The bulk density increases with depth; the increase of the values of soil bulk density are consistent with data in other papers, indicating there are not compaction problems for the crop development at the study area. Most of the values of resistance to penetration are lower than 2 MPa, being this value restrictive for root development. The analysis of resistance to penetration profile 0 to 0.60 m shows a compacted layer between 0.20-0.30 m. This compacted layer was caused by the conventional tillage system used at this area before the use of no-tillage system. The soil bulk density has higher values at the upper area, that it shows higher values of soil compaction. Although the values of bulk density and resistance to penetration are high, the area does not show great problems of soil compaction.

Éster de sacarose no controle do Varroa estructor em abelhas africanizadas

This study aimed to determine the effect of sucrose ester on the control of Varroa destructor mite infestation in Africanized honeybees. For the in vitro experiments, the product was tested in bees and mites at five concentrations obtained through dilution in water (T0: 100% distilled water; T1: 0.5%; T2: 1%; T3: 2%; T4: 5%; and T5: 10% sucrose ester).For the field studies, the experimental design was completely randomized, with four treatments and seven replicates, totaling 28 colonies, from which seven were the controls, seven were treated with 0.1% sucrose ester, seven with 0.2% sucrose ester, and seven hives with 0.5% sucrose ester diluted in water. In the in vitro study, the sucrose ester at 0.5% concentration caused mite and bee mortality. In the field tests, the product at 0.2% concentration reduced Varroa destructor infestation in Africanized honeybees and, therefore, may be used as a tool to control this pest. At 0.1, 0.2, and 0.5% concentrations, sucrose ester did not impair the establishment of open and capped brood areas, as well as stored food areas in the hive, suggesting it is not toxic to Africanized honeybees.

Dimensional alterations and solubility of new endodontic sealers

This study evaluated the dimensional alterations and the solubility of two experimental endodontic sealers based on Copaifera multijuga oil-resin (Biosealer) and castor oil bean cement (Poliquil), maintained in different storage solutions. Twenty specimens (3 mm diameter and 2 mm height) of each sealer were assigned to 2 groups (n=10) according to the storage solution: simulated tissue fluid (STF) or distilled water (DW). The specimens were stored in these solutions during 90 days, being removed every 30 days for weighting. The solutions were renewed every 15 days. The results were subjected to statistical analysis by Dunn's and Mann-Whitney tests (α=0.05). The solubility of Poliquil was higher in STF (38.4 ± 36.0) than in DW (28.4 ± 15.0), while Biosealer showed higher solubility in DW (34.61 ± 6.0) than in STF (18.59 ± 8.0). The storage solution influenced the behavior of sealers in relation to the weight variation (p=0.0001). Poliquil presented higher variation of weight independent of the solution (p=0.239). Biosealer also presented higher variation of weight regardless of the solution (p=0.0001). The solubility of Biosealer was different from that of Poliquil, but both sealers showed low solubility in STF. Under the tested conditions, neither of the materials were according to the ADA'S specification.

Postharvest decay development on guava stored under several controlled atmosphere conditions

The control of post-harvest fungal decay on guava (Psidium guajava L. 'Pedro Sato') stored under low oxygen controlled atmosphere (5 kPa) was compared with increasing concentrations of carbon dioxide in the atmospheres. The combination of high concentrations of carbon dioxide (1, 5, 10, 15 and 20 kPa) with low oxygen (5 kPa) did not result in additional decay control. The low oxygen level (5 kPa) was the main factor for controlling post-harvest fungal development which resulted in a very low percentage of fruits with symptoms of anthracnose and stylar end rot throughout cold storage, regardless of the CO2 concentration. After transfer to ambient conditions, only the atmospheres with 5 kPa O2 (control), 5 kPa O2 + 1 kPa CO2 and 5 kPa O2 + 5 kPa CO2 resulted in reduced incidence of stylar end rot (P<0.05). There was not a significant interaction among CA combinations and storage duration on the percentage and number of typical anthracnose lesions.

Seleção de isolados de beauveria bassiana (Bals.) Vuill. para o controle de sitophilus zeamais (Mots.) (Coleoptera: Curculionidae)

Sitophilus zeamais (Mots.) (Coleoptera: Curculionidae) is considered a major pest of maize, responsible for reducing grain quality and making the corn inappropriate for industrial use and human consumption. S. zeamais has been controlled exclusively with chemical products. The objective of this research was to select isolates of Beauveria bassiana (Bals.) Vuill. to control S. zeamais. Beetles were immersed in conidia suspensions of each isolate for five seconds and placed in a gerbox container with maize grains. In pathogenicity tests, the isolates that caused the highest mortality to the maize weevil were ESALQ-447 (68.0%), CCA-UFES/ Bb-36 (57.3%) and CCA-UFES/Bb-31 (51.3%). ESALQ-447 was the most virulent, with an LC50 of 1.7 × 107 conidia/ml and shows promise for controlling maize weevils. These isolates of B. bassiana can be used as effective substitutes for conventional chemical control, normally carried out with phosphine. Further tests should be performed under field and semi-field conditions to develop an appropriate strategy for the use of this entomopathogen to manage S. zeamais.

Protective effect of oregano (Origanum vulgar L.) and thyme (Thymus vulgaris L.) oleoresins in stored soybean oil

Purpose: The objective of this study was to evaluate the antioxidant effect of oregano and thyme extracts isolatedly and combinedly applied in soybean oil. Design/methodology/approach: Soybean oil containing 3,000 mg/kg of oregano and thyme oleoresins and the mixture of both, as well as soybean oil containing TBHQ (50 mg/kg) and soybean oil free of antioxidants, were subjected to accelerated oven test (60°C/10 days). Samples were collected every two days and analyzed as to their peroxide and conjugated diene values. Findings: The mixture of oleoresins and consequent increase of concentration were as effective as the antioxidant TBHQ. Practical implications: These studies may prove to be beneficial to the exploitation of natural antioxidant sources for the preservation and/or extension of raw and processed food shelf life. Therefore, they could also be applied in the area of pharmaceuticals for the protection of human life. Originality/value: This study offers information on the use of natural antioxidants as an alternative to the use of synthetic antioxidants, which might be considered toxic. © Emerald Group Publishing Limited.