Paulo Roberto Valle da Silva Pereira

Wheat curl mite, Aceria tosichella, and transmitted viruses: an expanding pest complex affecting cereal crops

The wheat curl mite (WCM), Aceria tosichella, and the plant viruses it transmits represent an invasive mite-virus complex that has affected cereal crops worldwide. The main damage caused by WCM comes from its ability to transmit and spread multiple damaging viruses to cereal crops, with Wheat streak mosaic virus (WSMV) and Wheat mosaic virus (WMoV) being the most important. Although WCM and transmitted viruses have been of concern to cereal growers and researchers for at least six decades, they continue to represent a challenge. In older affected areas, for example in North America, this mite-virus complex still has significant economic impact. In Australia and South America, where this problem has only emerged in the last decade, it represents a new threat to winter cereal production. The difficulties encountered in making progress towards managing WCM and its transmitted viruses stem from the complexity of the pathosystem. The most effective methods for minimizing losses from WCM transmitted viruses in cereal crops have previously focused on cultural and plant resistance methods. This paper brings together information on biological and ecological aspects of WCM, including its taxonomic status, occurrence, host plant range, damage symptoms and economic impact. Information about the main viruses transmitted by WCM is also included and the epidemiological relationships involved in this vectored complex of viruses are also addressed. Management strategies that have been directed at this mite-virus complex are presented, including plant resistance, its history, difficulties and advances. Current research perspectives to address this invasive mite-virus complex and minimize cereal crop losses worldwide are also discussed.

Desenvolvimento de Zabrotes subfasciatus (Boh.) (Coleoptera: Chrysomelidae, Bruchinae) em genótipos de Phaseolus vulgaris L. (Fabaceae) cultivados no Estado do Paraná e contendo arcelina

O presente trabalho objetivou avaliar o desenvolvimento de Zabrotes subfasciatus (Boh.), praga de graos armazenados, em genotipos de feijoeiro (Phaseolus vulgaris L.) comumente cultivados no Parana e com arcelina, e a possivel resistencia desses materiais ao bruquineo. Foram realizados testes em laboratorio (27oC, 50 ± 10% UR, fotofase 12h) com os genotipos TPS-Bionobre, IAC-Una, IPR-Uirapuru, IAPAR 44, IPR Juriti, IAPAR 81, Perola, Carioca e Bolinha, alem de dois outros contendo arcelina, Arc 1 e Arc 2. Os genotipos com os alelos Arc 1 e 2 sugerem resistencia do tipo antibiose, com elevada mortalidade das fases imaturas, e Arc 1, com periodo de desenvolvimento prolongado e drastica reducao de peso de machos e femeas. A resistencia do tipo nao-preferencia para oviposicao nao foi observada para estes dois genotipos. Dentre os genotipos sem arcelina, IAPAR 44 destacou-se como o mais resistente a Z. subfasciatus, pois foi o menos preferido para oviposicao, promovendo baixo percentual de ovos viaveis, longo periodo de desenvolvimento e reduzido peso de machos e femeas. As cultivares Perola, IPR Juriti e Bolinha foram os mais suscetiveis, com alto numero de ovos e ovos viaveis, alem de baixa porcentagem de mortalidade de fases imaturas.

Keys for the identification of Coleoptera (Insecta) associated with stored products

An illustrated key to identify nine families of Coleoptera commonly found in stored products is presented. Keys for the identification of Anobiidae [Lasioderma serricorne (Fabricius, 1792), Stegobium paniceum (Linnaeus, 1761)], Bruchidae [Acanthoscelides obtectus (Say, 1831), Zabrotes subfasciatus (Boheman, 1833)], Curculionidae [Sitophilus oryzae (Linnaeus, 1763), S. zeamais Motschulsky, 1885], Silvanidae [Ahasverus advena (Waltl, 1832), Cathartus quadricollis (Guerin, 1892), Oryzaephilus mercator (Fauvel, 1889), O. surinamensis (Linnaeus, 1758)] and Tenebrionidae [Gnathocerus cornutus (Fabricius, 1798), Tribolium castaneum (Herbst, 1797), T. confusum du Val, 1868] are also provided. These keys cover the most frequent Coleoptera found in stored products, specially grains, and are to the adult stage only. Illustrations of external morphology and general characteristics are provided for each species reported.

First report of Maconellicoccus hirsutus(Green, 1908) (Hemiptera: Coccoidea: Pseudococcidae) and the associated parasitoid Anagyrus kamali Moursi, 1948 (Hymenoptera: Encyrtidae), in Brazil

The pink hibiscus mealybug (PHM), Maconellicoccus hirsutus (Green) (Hemiptera: Pseudococcidae) and the associated hymenopterous parasitoid, Anagyrus kamali Moursi, 1948 (Hymenoptera: Encyrtidae), are reported for the first time in Brazil. Specimens of the PHM were collected on nine hosts plants, Annona muricata L. (Anonnaceae), Glycine max (L.) Merr. (Fabaceae), Centrolobium paraensis Tul. (Fabaceae), Inga edulis Mart. (Fabaceae), Hibiscus rosa-sinensis L. (Malvaceae), Psidium guajava L. (Myrtaceae), Averrhoa carambola L. (Oxalidaceae), Citrus sinensis (L.) Osbeck (Rutaceae) and Solanum lycopersicum L. (Solanaceae), in four municipalities in the north-northeast of the state of Roraima. The plants C. paraensis, I. edulis and C. sinensis are recorded for the first time as a hosts for PHM. Characteristic injuries observed on the host plants infested by PHM and suggestions for its management are presented.

Occurrence of Aceria tosichella in Brazil.

The objective of this work was to evaluate the occurrence of Aceria tosichella Keifer (Prostigmata: Eriophyidae), the wheat curl mite, in Rio Grande do Sul, Brazil. Samples to detect A. tosichella specimens were collected in wheat, corn, oat crops and potential host grasses in 46 localities, in October 2006, August and October 2007. Samples of wheat were also collected in experimental greenhouses at Embrapa Trigo, Passo Fundo, RS, Brazil. A. tosichella specimens were found in wheat samples from Passo Fundo, Palmeira das Missoes, Sao Luis Gonzaga, and Santo Antonio das Missoes, RS, Brazil. Symptoms due to A. tosichella infestations were observed only in greenhouse conditions. This is the first report of A. tosichella in Brazil and the second in South America.

Aspectos biológicos de Zabrotes subfasciatus (Bohemann, 1833) (Coleoptera, Bruchidae) em Phaseolus vulgaris L., cv. Carioca (Fabaceae), sob condições de laboratório

Zabrotes subfasciatus is a serious pest of common beans, P. vulgaris L.. In Brazil there are several studies dealing with resistance of bean genotypes to this insect, while other studies have emphasized the utilization of oils and powders from plants to repel their attack. In this paper, fecundity, fertility, pattern of oviposition, life cycle and longevity were evaluated for a Brazilian stock from the Goias State on P. vulgaris cv. Carioca, at 30oC and 70% R.H. The mean fecundity was 38 eggs per female and 73% of viability. Egg laying showed an aggregated pattern. Males and females lived an average of 13 and 9 days, respectively. The total life cycle lasted for about 28 days.

Primeiro registro de Thaumastocoris peregrinus para o estado de Santa Catarina, e novas áreas de ocorrência para o Rio Grande do Sul, Brasil

Thaumastocoris peregrinus is recorded for the first time in the state of Santa Catarina attacking isolated plants of Eucalyptus camaldulensis, Eucalyptus tereticornis and reforestation of Eucalyptus grandis located within the municipalities of Chapeco, Cordillera Alta, Xaxim and Xanxere. In Rio Grande do Sul this insect is already found in 10 locations, and new areas of occurrence are recorded in the municipalities of Ernestina, Passo Fundo, Marau, Coxilha, Getulio Vargas, Erechim, Sao Valentim, Erval Grande, Nonoai, Tres Palmeiras, Ronda Alta, Pontao and Quatro Irmaos.

Identificação sorológica de espécies de potyvirus em melancia, no estado de Roraima

Leaf samples were collected from watermelon plants (Citrullus lanatus) from 21 different fields in the state of Roraima from May/2003 to March/2004. The samples were sent to the Plant Virus Laboratory of the Federal University of Ceara, to be tested by indirect enzyme linked immunosorbent assay (Elisa) against antisera specific to Cucumber mosaic virus (CMV), Papaya ringspot virus strain watermelon (PRSV-W), Watermelon mosaic virus (WMV) and Zucchini yellow mosaic virus (ZYMV). The Elisa tests were processed using the universal conjugate, anti-imunoglobulim (IgG) from rabbit produced in goat, conjugated to alkaline phosphatase. All samples were also tested by double immunodifusion against antiserum specific to Squash mosaic virus (SqMV). The presence of PRSV-W was detected in 84.2% of the samples collected in May/2003, in 7.1% of the samples collected in December/2003 and 55,6% in March/2004. The presence of ZYMV was detected in 10.5% of the samples collected in May, in 21.4% in December/2003 and in 25.9% in March/2004. The WMV was detected only in eight of the samples collected in March/2004 (29.6%). These results confirm the world widespread dispersion of PRSV-W in cultivated cucurbit fields in Brazil and rise a concern about the ZYMV expansion, which has caused serious yield lost in other parts of the world.

Injúrias de quatro espécies de percevejos pentatomídeos em plântulas de milho

Injuries caused by the stink bugs Dichelops furcatus (F.), Nezara viridula (L.) and Euschistus heros (F.), compared with Dichelops melacanthus (Dallas), to corn (Zea mays L.) seedlings were studied. The experiment was conducted in a greenhouse in a completely randomized design with five treatments (four species of stink bugs and control, without infestation) using eight replications. In the vegetative stage (V1 to V3) D. melacanthus, at the density of one adult/plant, caused reduction in height, in the number of expanded leaves, in root dry matter, and caused injuries and winding of the central leaves. D. furcatus, E. heros and N. viridula caused injuries, but at different intensities. Injuries caused by D. furcatus and N. viridula were similar in intensity to those by D. melacanthus and the injuries caused by E. heros were less intense than those of the other species.

Épocas de colheita e qualidade fisiológica das sementes de arroz irrigado cultivar BRS 7 TAIM, em Roraima

Harvesting time is one of most important factors which influence rice seed characteristics for the purpose of planting or milling. With the objective to determine the proper period of harvesting of irrigated rice (Oryza sativa L.) the seeds of BRS 7 TAIM cultivar were harvested at at 15, 22, 29, 36, 43 and 50 days after flowering, dryed, processed for cleaning purpose and evaluated in relation to moisture, productivity, dry weight of 100 seeds, undamaged rice yield, viability and storability. Seeds harvested at 15 and 22 days after flowering showed low performance exhibiting deficiency in all variables studied, besides high initial humidity. Seeds harvested at 29 days showed hight quality, but yield was lower than those of later periods. Those obtained from harvest at 50 days showed good performance, with exception for undamaged rice yield. The best harvesting period considering TAIM cultivar is between 38 an 42 days after flowering, when seeds present high rates of quality, yield, dry weight, undamaged rice yield, physiological quality and storability.