ABSTRACT
Modelling studies on climate change predict continuous increases in atmospheric carbon dioxide concentration [CO2] and increase in temperature. This may alter carbon-based phytochemicals such phenolics and modify plant interactions with herbivorous. We investigated the effects of enhanced [CO2] and local climatic variation on young coffee plants, Coffea arabica L. cv Catuaí vermelho IAC-144 and Obatã vermelho IAC-1669-20, cultivated in the FACE (Free-Air Carbon Dioxide Enrichment) facility under two atmospheric [CO2] conditions. Coffee leaves were evaluated for total soluble phenolics (TSP), chlorogenic (5-CQA) and caffeic (CAF) acids, diversity and population size of mites, along two dry and two rainy seasons. Elevated atmospheric CO2 (e[CO2]) significantly decreased 5-CQA in cv. Catuaí but did not affect cv. Obatã. Species richness and population size of mites in coffee leaves were not affected by e[CO2] but were strongly related to the seasonal variability of coffee leaf phenolics. In general, high levels of phenolics were negatively correlated with population size while the mite species richness were negatively correlated with 5-CQA and TSP levels. Our findings show that [CO2] enhancement affects phenolics in coffee plants differentially by cultivars, however seasonality is the key determinant of phenolics composition, mite species richness and population size.
Subject(s)
Coffea , Tetranychidae , Animals , Carbon Dioxide , Coffee , Plant Leaves/chemistry , TreesABSTRACT
Citrus leprosis (CL) is one of the most important viral diseases in sweet orange orchards in Latin America. It is caused by members of at least five species of the so-called Brevipalpus-transmitted viruses (BTV), and the prevalent is Citrus leprosis virus C (CiLV-C). This virus has the broadest host range amongst all CL-associated viruses and is transmitted by Brevipalpus yothersi, a polyphagous mite that can colonize a large variety of host plants, including some spontaneous ground cover plants. But if, on one hand, spontaneous plants can host CL virus and vector, on the other hand, they can offer alternative food for predators, equally common in organic citrus orchards. Brevipalpus yothersi and predator mites were surveyed in 33 spontaneous plants of a Westin sweet orange orchard conducted under organic production system in Brazil, from June 2010 to April 2011. Predatory mites were identified as phytoseiids, and Iphiseiodes zuluagai was the prevalent species, representing 58% of all predators. Other phytoseiids were considered accidental species in the area. Ageratum conyzoides and Alternanthera tenella were the most represented plant host species to predators, comprising 28 and 10% of the total surveyed plants, respectively. Brevipalpus yothersi specimens were detected on various spontaneous species: A. conyzoides, A. tenella, Amaranthus deflexus, Bidens pilosa, Ipomoea quamoclit, I. cairica, Merremia cissoides, Solanum americanum, Panicum maximum, and, predominantly, Commelina benghalensis. The latter has been previously reported as host of CiLV-C as well and, therefore, it is recommended to eliminate this species from citrus orchards.
Subject(s)
Citrus , Mites , Plant Diseases/virology , Animals , Brazil , Mites/virologyABSTRACT
Brevipalpus phoenicis (Geijskes) (Acari: Tenuipalpidae) is a polyphagous mite with worldwide distribution and it is also a vector of several plant viruses. In citrus, B. phoenicis transmits Citrus leprosis virus (CiLV), the causal agent of leprosis, a disease that costs millions of dollars per year for its prevention and control. Brevipalpus phoenicis mites reproduce through thelytokous parthenogenesis, producing haploid females. This characteristic is attributable to the presence of an endosymbiont bacterium of the genus Cardinium; however, very little is known about the biological and ecological implications of the presence of this endosymbiont in Brevipalpus mites. In order to investigate the role of Cardinium in the transmission of CiLV to citrus plants, our goal was to eliminate the bacterium from the mite. We assessed the effectiveness of different doses of radiation from a Cobalt-60 source to cure B. phoenicis populations from Cardinium sp. The efficiency of irradiation on the elimination of the endosymbiont was determined by counting the number of females and males obtained in the F(1) generation after irradiation and confirming the presence of the endosymbiont by PCR. Both radiation treatments influenced the oviposition period and the number of eggs laid by irradiated females. Also, irradiation eliminated the Cardinium endosymbiont and increased the number of males in progeny of the exposed populations. Although macroscopic morphological abnormalities were not observed among the treated mites, the mortality was higher compared to the non-irradiated control group.
Subject(s)
Bacteroidetes/radiation effects , Cobalt Radioisotopes , Mites/microbiology , Animals , Dose-Response Relationship, Radiation , Female , Male , Mites/growth & development , Mites/radiation effects , Plant DiseasesABSTRACT
The objectives of this work were to identify the edaphic mites collected in Piracicaba, State of São Paulo, and to determine the specific predominance in each of the environments studied. Soil samples were collected in three different environments, namely in an area of secondary forest, an area of perennial crops, represented by a rubber tree plantation (Hevea brasiliensis Müll. Arg.), clone RRIM 600 and an area of annual crops (corn followed by bean). Litter samples were collected in the patch of secondary forest and the rubber tree plantation. The edaphic mites were extracted through a modification of the Berlese-Tullgren method. A total of 49 species in 30 genera of Gamasida were identified in the soil and litter substrata. In the soil, the most abundant species in the secondary forest were Ologamasus sp. 1 (Ologamasidae) and Cosmolaelaps sp. 1 (Laelapidae). In the rubber tree plantation, Vulgarogamasus sp. (Parasitidae) and Cosmolaelaps sp. 2 (Laelapidae) were the most abundant species. In the area of annual crops, Protogamasellus mica (Athias-Henriot) (Ascidae) was by far the dominant species. In the litter, the most abundant species in the secondary forest were Ologamasus sp. 1 and Ologamasus sp. 2 (Ologamasidae), Podocinum sagax Berlese (Podocinidae) and Cosmolaelaps sp. 1 (Laelapidae), while in the rubber tree plantation the dominant species were Cosmolaelaps sp. 2 (Laelapidae) and Amblyseius hexadens Karg (Phytoseiidae).
Este trabalho teve como objetivos identificar os ácaros da subordem Gamasida em Piracicaba, Estado de São Paulo, bem como determinar a predominância específica em cada um dos ambientes estudados. Coletas de solo foram feitas em três ambientes diferentes, uma área de mata residual secundária do tipo mesófila semidecídua, outra de cultura perene, representada pelo plantio de seringueira (Hevea brasiliensis Müll. Arg.), clone RRIM 600, e outra de culturas anuais (milho seguido de feijão). Coletas de folhedo foram realizadas apenas na mata secundária e no plantio de seringueira. A extração da acarofauna edáfica foi feita através do método de Berlese-Tullgren modificado. Foram identificadas 49 espécies pertencentes a 30 gêneros de Gamasida nos dois substratos, solo e folhedo. No solo, as espécies dominantes na mata secundária foram Ologamasus sp. 1 (Ologamasidae) e Cosmolaelaps sp. 1 (Laelapidae). No plantio de seringueira, Vulgarogamasus sp. (Parasitidae) e Cosmolaelaps sp. 2 (Laelapidae) foram as mais abundantes. Na área de culturas anuais, Protogamasellus mica (Athias-Henriot) (Ascidae) foi a espécie marcadamente dominante. No folhedo, as espécies mais abundantes na mata secundária foram Ologamasus sp. 1 e Ologamasus sp. 2 (Ologamasidae), Podocinum sagax Berlese (Podocinidae) e Cosmolaelaps sp. 1 (Laelapidae), enquanto no plantio de seringueira, foram Cosmolaelaps sp. 2 (Laelapidae) e Amblyseius hexadens Karg (Phytoseiidae).
