Plantas de ocorrência espontânea como substratos alternativos para fitoseídeos (Acari, Phytoseiidae) em cultivos de seringueira Hevea brasiliensis Muell. Arg. (Euphorbiaceae) Weeds as alternative substrates to phytoseiids (Acari, Phytoseiidae) in rubber tree Hevea brasilienis, Muell. Arg. (Euphorbiaceae) cultivation

O objetivo deste estudo foi determinar as espécies de plantas espontâneas em áreas de cultivo de seringueira que poderiam servir com reservatório de ácaros predadores. O trabalho foi conduzido em Olímpia, Estado de São Paulo, Brasil, em dois cultivos de seringueira. A cada três meses, cerca de 1.000 cm³ de folhas de cada uma das cinco espécies de plantas espontâneas dominantes em cada cultivo foi tomada para determinar os fitoseídeos. Como as plantas espontâneas dominantes variaram durante o estudo, um total de 20 espécies foi verificado. Somente Cecropia sp. foi dominante em todo estudo, em ambos os cultivos. Um total de 336 fitoseídeos pertencentes às seguintes espécies foi encontrado: Euseius citrifolius Denmark & Muma, 1970, E. concordis (Chant, 1959), Galendromus annectens (DeLeon, 1958), Iphiseiodes zuluagai Denmark & Muma, 1972, Neoseiulus anonymus (Chant & Baker, 1965) e N. tunus (DeLeon, 1967). E. citrifolius (189 espécimes) e N. tunus (138 espécimes) foram os mais abundantes. A maior abundância (231espécimes) e diversidade (5 espécies) foram observadas sobre Cecropia sp. Sobre esta planta foi encontrado o maior número de ácaros por amostra (29 espécimes), seguida por Piper duncum Linnaeus (22), Guarea sp. (18) e Ageratum conyzoides Linnaeus (12). E. citrifolius tem sido determinado como um dos ácaros predadores mais abundantes sobre seringueiras cultivadas na região onde este trabalho foi conduzido. Cecropia sp. parece ser uma das plantas espontâneas mais importantes consideradas como reservatório de E. citrifolius porque está continuamente presente nos cultivos. Estudos complementares poderiam indicar a viabilidade de se manejar esta planta nas áreas de cultivo de seringueira para permitir o controle biológico dos ácaros-praga desta cultura.<br>The objective of this study was to determine weed species of rubber tree cultivation areas that could serve as reservoirs of predatory mites. The work was conducted in Olímpia, State of São Paulo, Brazil, in two rubber tree plantations. Every three months, about 1.000 cm³ of leaves of each one of the five dominant weeds in each plantation was taken to determine the phytoseiids. As the dominant weeds varied during the study, a total of 20 species were evaluated. Only Cecropia sp. was a dominant weed throughout the study, in both plantations. A total of 336 phytoseiids of the following species were found: Euseius citrifolius Denmark & Muma, 1970, E. concordis (Chant, 1959), Galendromus annectens (DeLeon, 1958), Iphiseiodes zuluagai Denmark & Muma, 1972, Neoseiulus anonymus (Chant & Baker, 1965) and N. tunus (DeLeon, 1967). E. citrifolius (189 specimens) and N. tunus (138 specimens) were the most abundant species. The highest abundance (231 specimens) and diversity (5 species) were observed on Cecropia sp. On this plant was found the largest number of mites per sample (29 specimens), followed by Piper duncum Linnaeus (22), Guarea sp. (18) and Ageratum conyzoides Linnaeus (12). E. citrifolius has been determined as the most abundant predatory mite on rubber trees in the region where this work was conducted. Cecropia sp. seems to be the most important of the weeds considered as reservoir of E. citrifolius because it is continuously present in the plantations. Complementary studies could indicate the viability of managing this weed in or around rubber tree plantations to promote the biological control of mite pests on that crop

Operation and performance of RPCs in the ARGO-YBJ experiment

The ARGO-YBJ array for EAS detection at high altitude (4300m a.s.l.) is the largest RPC-based detector in operation at present (active area of 6700m2 out of a total instrumented surface of about 104m2). The constant monitoring of the main operational and environmental parameters is essential for both keeping the detector status under control and understanding the detector behaviour more deeply. Exploiting the information provided by the ARGO-YBJ Detector Control System, the present status of the detector is described and some correlations between the environmental and the operational parameters of the ARGO-YBJ RPCs are shown. This study was performed using the monitored data from the complete ARGO-YBJ array which has been in operation since October 2007. Preliminary results on the observations of the Moon shadow and of g-ray point sources are also presented

Search for gamma ray bursts with the ARGO-YBJ detector in scaler mode

The ARGO-YBJ experiment has been designed to decrease the energy threshold of typical Extensive Air Shower arrays by exploiting the high altitude and the full coverage, consisting of a 6700m2 carpet of Resistive Plate Chambers located at Yangbajing (Tibet, PR China, 4300m a.s.l.). The lower energy limit of the detector (1 GeV) is reached with the ‘‘Scaler Mode’’, recording the counting rate at fixed time intervals. Here we present results concerning the search for emission from Gamma Ray Bursts (GRBs) in coincidence with satellite detections