Biological cycle of Lorryia formosa (Acari, Tydeidae) on rubber tree leaves: A case of thelytoky

Lorryia formosa Cooreman has been collected on many different host plants around the world. The biological cycle of this species was studied at 28 degrees C with mites collected from a rubber tree crop. The life table was constructed based on sixty individuals. The average lifetime was 37.43 +/- 20.23 (SE) days, and the r(m) was 0.08. The sex ratio was totally female biased, and unfertilized eggs developed into females. This is the first record of thelytoky in Tydeoidea proved by rearing.

Changes in leaf physiology caused by Calacarus heveae (Acari, Eriophyidae) on rubber tree

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Seasonal suitability of three rubber tree clones to Calacarus heveae (Acari, Eriophyidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Biological cycle of Tenuipalpus heveae Baker (Acari, Tenuipalpidae) on leaflets of three rubber tree clones

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Seasonality of pathogenic fungi in mites of rubber tree plantations adjacent to fragments of Cerrado

Fungos são os patógenos mais freqüentemente observados em populações de ácaros, auxiliando o controle destes em diferentes culturas. Vinte e cinco amostras de folhas foram coletadas de cultivos de seringueiras vizinhas a dois fragmentos de vegetação de Cerrado. em cada seringal, 25 plantas foram selecionadas para coletas e sete folhas ao redor da copa foram coletadas até a altura de sete a oito metros do solo. Aproximadamente 250 indivíduos de Calacarus heveae Feres, Phyllocoptruta seringueirae Feres e Tenuipalpus heveae Baker, coletados aleatoriamente, foram montados. Hirsutella thompsonii Fisher foi observado nas três espécies de ácaros e T. heveae foi a espécie mais infectada. Os maiores níveis de infecção ocorreram de novembro a fevereiro (estação chuvosa). Na estação seca, os níveis de infecção ficaram abaixo dos 5%. H. thompsonii tem potencial para ser usado como micoacaricida na estação chuvosa.

Review about mites (Acari) of rubber trees (Hevea spp., Euphorbiaceae) in Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Nutrient cycling in a RRIM 600 clone rubber plantation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Nonpreference of the lace bug Leptopharsa heveae Drake & Poor (Heteroptera: Tingidae) for rubber tree clones

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Genetics of anthracnose panel canker disease resistance and its relationship with yield and growth characters in half-sib progenies of rubber tree (Hevea brasiliensis)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Study of the thermomechanical and electrical properties of conducting composites containing natural rubber and carbon black

This work describes the preparation and characterization of composite materials obtained by the combination of natural rubber (NR) and carbon black (CB) in different percentages, aiming to improve their mechanical properties, processability, and electrical conductivity, aiming future applications as transducer in pressure sensors. The composites NR/CB were characterized through optical microscopy (OM), DC conductivity, thermal analysis using differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMA), thermogravimetry (TGA), and stress-strain test. The electrical conductivity varied between 10(-9) and 10 S m(-1), depending on the percentage of CB in the composite. Furthermore, a linear (and reversible) dependence of the conductivity on the applied pressure between 0 and 1.6 MPa was observed for the sample with containing 80 wt % of NR and 20% of CB. (C) 2007 Wiley Periodicals, Inc.

Conductive composites of natural rubber and carbon black for pressure sensors

Composites of natural rubber and carbon black have attracted great interest due to their technological applications. In this work natural rubber (NR) and carbon black (CB) were compounded, aiming the development of composites with good mechanical properties, processability and electrical conductivity for use as pressure sensors. The electrical conductivity changes from 10(-11) to 10(-2) S.cm(-1) depending on the percentage of CB in the composite. It was also observed that the conductivity varies reversibly and linearly with the applied pressure. The latter demonstrates that this material can be used as pressure sensors.

Effect of natural rubber latex on the conducting state of polyaniline blends determined by Raman spectroscopy

Blends possessing the elastomeric properties of natural rubber (NR) and the conducting properties of conducting polymer (polyaniline, PANI) were obtained, which are promising for further application in deformation sensors. Blends containing 20% (v/v) of PANI in 80% of NR latex were fabricated by casting in the form of free-standing films and treated either with HCl or with corona discharge, which lead PANI to its conducting state (doping process). Characterization was carried out by Raman spectroscopy, d.c. conductivity and thermogravimetric analysis. Evidence for chemical interaction between PANI and NR was observed, which allowed the conclusion that the NR latex itself is able partially to induce both the primary doping of PANI (by protonation) and the secondary doping of PANI (by changing the chain conformation). Further improvement in the primary doping could be obtained for the blends either by corona discharge or by exposing them to HCl the electrical conductivity reached in the blends was dependent on the doping conditions used, as observed by Raman scattering. Copyright (C) 2003 John Wiley Sons, Ltd.

Structural characterization of blends containing both PVDF and natural rubber latex

Films containing different volumes of latex of natural rubber (NR) in a fixed mass of poly (vinylidene fluoride) (PVDF) powder were fabricated by compressing under annealing a mixture of both materials without using any solvent. This is an important issue keeping in mind that these films have to be used in the future as biomaterials in different applications once the solvents that are used to dissolve the PVDF become toxic to human. The films with different percentage of latex in PVDF were characterized using microRaman scattering and Fourier transform infrared absorption (FTIR) spectroscopies, thermomechanical techniques using thermogravimetry (TG), differential scanning calorimetry (DSC), dynamical-mechanical analysis (DMA) and scanning electron microscopy (SEM). The results showed that the latex of NR and PVDF do not interact chemically, leading to the formation of a polymeric blend with high thermal stability and mechanical properties suitable for applications involving bone (prostheses, for instance). Besides, the results recorded using the micro-Raman technique revealed that for a fixed amount of PVDF the higher the amount of latex in the blend, the better the miscibility between both materials. Copyright (c) 2005 John Wiley & Sons, Ltd.

Decomposition of the rubber tree Hevea brasiliensis litter at two depths

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Population dynamics of Leptopharsa heveae (Hemiptera: Tingidae) and Erythmelus tingitiphagus (Hymenoptera: Mymaridae) in rubber tree plants

The tingid Leptopharsa heveae, known as the lace bug, occurs in large populations in rubber tree plantations, limiting the production of latex due to losses of photosynthetic area and weakening of the infested trees. The alternative for the use of insecticides would be the release of biological control agents, but little is known about the natural enemies of L. heveae. The parasitoid Erythmelus tingitiphagus parasitizes eggs of the lace bug in rubber tree plantations. The knowledge of the population dynamics and the peak of occurrence of economically important insect species and their natural enemies are indispensable requirements for the establishment of efficient and rational control strategies. The objective of this work was to study the population dynamics of L. heveae and E. tingitiphagus in rubber tree plantations in the county of Itiquira, MT, Brazil. Mature folioles were collected weekly from the lower stratum of the canopy of the tree clones RRIM 600, PR 255, GT 1, PB 235 and PB 217, from August/2005 to February/2006. The parasitoid was observed during the whole study period. The population peaks of the populations of the L. heveae and E. tingitiphagus in the study area occurred at the end of October and beginning of November. This result demonstrates that measures for the control of L. heveae and population increase of E. tingitiphagus must be adopted before the peak population of this pest in cultivated rubber plantations.