Thiabendazole uptake and persistence in lemons following postharvest dips at 50 degrees C

Thiabendazole (TBZ) uptake and degradation rate in lemon fruits, following prestorage dipping at 50 degrees C in mixtures containing different amounts of fungicide, was compared with those measured after treatment at standard room temperature. TBZ residues were strictly dependent upon the amount of fungicide. Following 1,200 ppm TBZ dipping at 20 degrees C residue uptake in fruit was the same that would have been accumulated with ca. 150 ppm fungicide at 50 degrees C, a value that can be calculated due to the linear relationship between the residue in fruit after treatment and fungicide concentration TBZ residues showed great persistence during fruit storage: after 13 weeks at 8 degrees C and 1 week at 20 degrees C residues in fruit averaged ca. 70% of their initial values. In this study it was shown that it is possible to employ remarkably low amounts of TBZ (ca. 150 mg kg(-1)), when applied in combination with water at 50 degrees C, and keep the same residues of fruit treated at room temperature with high amounts of TBZ (1,200 mg kg(-1)).

Persistence of conidia of Entomophthora muscae in relation to age, temperature, and humidity

In this paper, the effect of age, humidity, and temperature on the conidial survival of Entomophthora muscae was evaluated. E. muscae was obtained from Musca domestica in a dairy in Itatiba (São Paulo, Brazil) and maintained in the laboratory by continuous passage through flies. Furthermore, the ability of conidia to infect flies at three temperatures (17, 21, and 27 degrees C), four ages of conidia (12, 72, 96, and 154 hours) and two humidities (100 and 60% RH) was evaluated. The temperature of 21 degrees C was the most favorable for the infection of house flies. Humidity was a cause of variation at 27 degrees C when the conidia were up to 12 hours old, but had no effect at lower temperatures. Conidia held at 100% RH and aged 72 hours caused no infection at 17 degrees C, but were infective at 21 degrees C. In the present study, conidia retained viability much longer than previously observed. Finally, the effect of humidity, temperature, and conidial age is discussed.

Persistence of insecticide residues in olives and olive oil

The decay rate of six insecticides (azinphos methyl, diazinon, dimethoate, methidathion, parathion methyl, and quinalphos) used to control Dacus oleae was studied. Degradation of pesticides showed pseudo-first-order kinetics with correlation coefficients ranging between -0.936 and -0.998 and half-lives between 4.3 days for dimethoate and 10.5 days for methidathion. Residues in olive oil were greater than on olives, with a maximum concentration factor of 7. Dimethoate was the only pesticide with lower residues in the oil than on the fruits. Olive washing affects pesticide residues ranging from no reduction to a 45% decrease. During 8 months of storage of the olive oil, diazinon, dimethoate, parathion methyl, and quinalphos did not show any remarkable difference, while methidathion and azinphos methyl showed a moderate decrease.

Persistence and effectiveness of pyrethroids in plastic strips against Varroa jacobsoni (Acari : Varroidae) and mite resistance in a mediterranean area

An apiary trial was conducted in 1997 in Sardinia, Italy, to verify the effectiveness of fluvalinate in polyvinyl chloride strips and flumethrin in polyethylene strips against Varroa jacobsoni Oudemans. Two indices to evaluate the efficacy of the treatments were adopted: percentage change in mite infestation of worker-sealed brood cells considering only treated hives and percentage change in mite mortality, and the natural variation in mite populations recorded in control hives during the trial. All acaricide treatments reduced the level of mite infestation of both sealed brood and adult bees. However, their effectiveness was slightly reduced in comparison to previous studies because of mite resistance phenomena. Portions of polyethylene strips of flumethrin from treated hives were sampled weekly to determine acaricide persistence using gas chromatography. After 4 wk, a slight reduction (approximate to9%) of the active ingredient content was observed, A laboratory bioassay also was performed to establish the resistance of adult female mites to fluvalinate, Mites were sampled from the experimental apiary and from various Sardinian apiaries which had primarily been subjected to fluvalinate applications in plastic strips or wood inserts for years. Mite resistance varied from 0 to 96%, depending on the acaricide management adopted, the lowest resistance level occurred in an apiary where pyrethroids had never been used, whereas the highest level occurred in an apiary with intensive use of fluvalinate in wood inserts.

Habitat patch size modulates terrestrial mammal activity patterns in Amazonian forest fragments

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Persistence and stability of cichlid assemblages in neotropical floodplain lagoons

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The ecological causes of individual specialisation

University of Tennessee, KnoxvilleNational Science Foundation (NSF)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Biodiversity, Species Interactions and Ecological Networks in a Fragmented World

Biodiversity is organised into complex ecological networks of interacting species in local ecosystems, but our knowledge about the effects of habitat fragmentation on such systems remains limited. We consider the effects of this key driver of both local and global change on both mutualistic and antagonistic systems at different levels of biological organisation and spatiotemporal scales.There is a complex interplay of patterns and processes related to the variation and influence of spatial, temporal and biotic drivers in ecological networks. Species traits (e.g. body size, dispersal ability) play an important role in determining how networks respond to fragment size and isolation, edge shape and permeability, and the quality of the surrounding landscape matrix. Furthermore, the perception of spatial scale (e.g. environmental grain) and temporal effects (time lags, extinction debts) can differ markedly among species, network modules and trophic levels, highlighting the need to develop a more integrated perspective that considers not just nodes, but the structural role and strength of species interactions (e.g. as hubs, spatial couplers and determinants of connectance, nestedness and modularity) in response to habitat fragmentation.Many challenges remain for improving our understanding: the likely importance of specialisation, functional redundancy and trait matching has been largely overlooked. The potentially critical effects of apex consumers, abundant species and supergeneralists on network changes and evolutionary dynamics also need to be addressed in future research. Ultimately, spatial and ecological networks need to be combined to explore the effects of dispersal, colonisation, extinction and habitat fragmentation on network structure and coevolutionary dynamics. Finally, we need to embed network approaches more explicitly within applied ecology in general, because they offer great potential for improving on the current species-based or habitat-centric approaches to our management and conservation of biodiversity in the face of environmental change.

Foraminiferal ecological zonation along a Brazilian mangrove transect: Diversity, morphotypes and the influence of subaerial exposure time.

Two foraminiferal associations comprising only arenaceous species define two distinct environments in a 340 m-long mangrove transect at Cardoso Island, Trapande Bay (Cananeia-Iguape estuarine system, SP, Brazil). The "lower muddy flat" (LMF), from the outer mangrove fringe inwards towards land (100 m), is positioned in the lower plain between 0.04 and 0.23 m above the mean sea level (msl), and remains subaerially exposed between 48.5 and 65.6% of the time. This environment is characterized by higher foraminiferal diversity and evenness (McIntosh's D = 0.54 [plus or minus] 0.21 and Pielou's E = 0.68 [plus or minus] 0.25, respectively) and is dominated by Arenoparrella mexicana and Trochammina inflata, and to a lesser extent by Ammotium directum and Textularia earlandi. The mangrove plant of this segment is a Rhizophoretum with average height of 8.4 [plus or minus] 1.2 m. The sediment is characterized by higher concentration of organic matter (93.5 [plus or minus] 32.3 g dm-3) and metals (e.g. V = 53.4 [plus or minus] 21.8 ppm and Zn = 46.4 [plus or minus] 21.3 ppm). The "upper sandy flat" (USF), 240 m wide along the transect, is positioned in the upper plain between 0.28 and 0.89 m above the msl, and remains subaerially exposed between 69.7 and 98.5% of the time. This environment is characterized by a lower diversity and evenness (D = 0.33 [plus or minus] 0.17 and E = 0.49 [plus or minus] 0.20, respectively). The association is dominated by species T. inflata and Miliammina fusca. The Rhizophoretum exhibits a lower average height of 3.6 [plus or minus] 0.6 m. The sediment is poorer in organic matter (39.3 [plus or minus] 15.0 g dm-3) and metals (e.g. V = 13.0 [plus or minus] 6.8 ppm and Zn = 6.9 [plus or minus] 3.7 ppm). Whereas "elongate" tests (uniserial, biserial and planospiral followed by a uniserial portion) are restricted to the LMF, "spiraled" species dominate the USF. Subaerial exposure time seems to exert a primary influence on species distribution, in addition to salinity and sediment type. Species may be adapted to different exposure times, a factor dependent on their position on the intertidal zone and the tidal regime, which should be taken into account in relative sea level reconstructions based on intertidal foraminifera. These patterns have important implications for studies investigating the ecology and paleoecology of foraminifera and subtle fluctuations in relative sea level during the Quaternary.

Larval dispersal in Chrysomya megacephala, Chrysomya putoria and Cochliomyia macellaria (Dipt., Calliphoridae): Ecological implications of aggregation behaviour

In this study we investigate aggregated patterns as a consequence of post-feeding larval dispersal in three blowfly species, based on the frequency distribution of sampling units in the substrate having 0, 1, 2,..., n pupae. Statistical analysis revealed that aggregated patterns of distribution emerge as a consequence of larval dispersal, and Cochliomyia macellaria has higher levels of aggregation when compared to Chrysomya megacephala and C. putoria. Aggregation during dispersal is associated with a spatial pattern where most larvae in the species tend to pupariate near the food source. The possible consequences for the population ecology of these species are discussed.

Persistence and metabolism of fenthion in orange fruit

The persistence and metabolism of fenthion in orange fruit were studied in field conditions. The fenthion was transformed to fenthion sulfoxide and fenthion sulfone. Sunlight photodegradation experiments showed that this transformation is due to the action of sunlight. Residues were found only in the fruit peel. Fenthion showed a rapid degradation rate with a half-life of ca. 6 days. Fenthion sulfoxide was degraded more slowly with a half-life of ca. 14 days and represented the major residue. Fenthion sulfone was present in low quantities.

Determination and persistence of methiocarb in artichokes

A simple and rapid method for the determination of methiocarb in artichokes by high-performance liquid chromatography with UV detection is described. No derivatization is needed and the limit of determination (0.01 ppm) is analogous to that of fluorometric detection. The results of trials carried out with granular and liquid formulations of this active ingredient are also reported. Immediately after treatment with the liquid formulation methiocarb residues averaged 1.47 ppm, while after treatment with the granular formulation residues were considered fortuitous. The decay rate of methiocarb residues in artichokes shows that the decrease and eventual disappearance of this active ingredient can chiefly be ascribed to the dilution effect due to head growth.