Novel, suitable and sustainable alternative control tactics that have the potential to reduce migration of Diaphorina citri into commercial citrus orchards are essential to improve management of huanglongbing (HLB). In this study, the effect of orange jasmine (Murraya paniculata) as a border trap crop on psyllid settlement and dispersal was assessed in citrus orchards. Furthermore, volatile emission profiles and relative attractiveness of both orange jasmine and sweet orange (Citrus × aurantium L., syn. Citrus sinensis (L.) Osbeck) nursery flushes to D. citri were investigated. In newly established citrus orchards, the trap crop reduced the capture of psyllids in yellow sticky traps and the number of psyllids that settled on citrus trees compared to fallow mowed grass fields by 40% and 83%, respectively. Psyllids were attracted and killed by thiamethoxam-treated orange jasmine suggesting that the trap crop could act as a ‘sink’ for D. citri. Additionally, the presence of the trap crop reduced HLB incidence by 43%. Olfactometer experiments showed that orange jasmine plays an attractive role on psyllid behavior and that this attractiveness may be associated with differences in the volatile profiles emitted by orange jasmine in comparison with sweet orange. Results indicated that insecticide-treated M. paniculata may act as a trap crop to attract and kill D. citri before they settled on the edges of citrus orchards, which significantly contributes to the reduction of HLB primary spread.
BACKGROUND RNA interference (RNAi) has been evaluated in several insect pests as a novel strategy to be included in integrated pest management. Lepidopterans are recognized to be recalcitrant to gene silencing by RNAi. As such, double‐stranded RNA (dsRNA) delivery needs to be adjusted to assure its stability until it reaches the target gene transcript for silencing. Gene silencing by RNAi offers the potential to be used in the control of Tuta absoluta (Meyrick), one of the main insect pests of tomato (Solanum lycopersicum) worldwide. Here, we tested the delivery of dsRNA expressed in Escherichia coli HT115(DE3) and supplied to larvae in an artificial diet by screening target genes for silencing. We tested six target genes: juvenile hormone inducible protein (JHP); juvenile hormone epoxide hydrolase protein (JHEH); ecdysteroid 25‐hydroxylase (PHM); chitin synthase A (CHI); carboxylesterase (COE); and arginine kinase (AK). RESULTS Based on larval mortality, the duration of the larval stage in days, pupal weight, and the accumulation of the target gene transcript, we demonstrated the efficacy of bacterial dsRNA delivery for the functional effects on larval development. Providing dsRNA targeted to JHP, CHI, COE and AK by bacteria led to a significant decrease in transcript accumulation and an increase in larval mortality. CONCLUSION Bacteria expressing dsRNA targeting essential T. absoluta genes supplied in artificial diet are efficient to screen RNAi target‐genes. The oral delivery of dsRNA by bacteria is a novel potential alternative for the control of T. absoluta based on RNAi. © 2019 Society of Chemical Industry
This study aimed to evaluate adult emergence and duration of the pupal stage of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), and emergence of the fruit fly parasitoid, Diachasmimorpha longicaudata (Ashmead), under different moisture conditions in four soil types, using soil water matric potential. Pupal stage duration in C. capitata was influenced differently for males and females. In females, only soil type affected pupal stage duration, which was longer in a clay soil. In males, pupal stage duration was individually influenced by moisture and soil type, with a reduction in pupal stage duration in a heavy clay soil and in a sandy clay, with longer duration in the clay soil. As matric potential decreased, duration of the pupal stage of C. capitata males increased, regardless of soil type. C. capitata emergence was affected by moisture, regardless of soil type, and was higher in drier soils. The emergence of D. longicaudata adults was individually influenced by soil type and moisture factors, and the number of emerged D. longicaudata adults was three times higher in sandy loam and lower in a heavy clay soil. Always, the number of emerged adults was higher at higher moisture conditions. C. capitata and D. longicaudata pupal development was affected by moisture and soil type, which may facilitate pest sampling and allow release areas for the parasitoid to be defined under field conditions.
RESUMO--A cigarrinha Bucephalogonia xanthophis (Berg) (Hemiptera: Cicadellidae) é um importante vetor da bactéria Xylella fastidiosa, agente causal da clorose variegada dos citros. Este trabalho teve como objetivo identificar o local preferido de alimentação e o período de maior atividade alimentar desta cigarrinha em citros, no sentido de elucidar o comportamento alimentar relacionado à transmissão da bactéria. O local de alimentação foi estudado em ensaio de escolha, no qual 30 insetos adultos foram liberados em gaiolas de observação (n = 10) contendo uma muda de laranja-doce [Citrus sinensis (L.) Osbeck]. Após 1; 15; 21; 25; 39; 45 e 49 h da liberação, contaram-se os insetos na parte superior (ramos com brotações) e inferior (haste principal, até H"40 cm de altura) da muda. Nos ramos da parte superior, avaliou-se a preferência entre a haste, o pecíolo e o limbo foliar. Em um segundo ensaio, 20 machos e 20 fêmeas de B. xanthophis foram confinados individualmente sobre a haste de 'seedlings' de laranja-doce para determinar os períodos de alimentação, quantificando-se a excreção de 'honeydew' (medida indireta da ingestão) em períodos sucessivos de dia e noite, durante 48 h. A maioria dos indivíduos de B. xanthophis preferiu a haste dos ramos novos (62%), na parte superior da muda cítrica (91%). Nos 'seedlings', observou-se maior volume de excreção e proporção de indivíduos excretando durante a fotofase, independentemente do sexo. Portanto, em estudos de transmissão de X. fastidiosa, deve-se considerar a preferência de B. xanthophis pela haste de brotações cítricas e sua maior atividade alimentar durante a fotofase. Termos para indexação: Cicadellinae, Comportamento alimentar, Clorose variegada dos citros. FEEDING SITES AND FOOD INTAKE OF Bucephalogonia xanthophis (BERG) (HEMIPTERA: CICADELLIDAE), A SHARPSHOOTER VECTOR OF Xylella fastidiosa, ON CITRUS PLANTSABSTRACT -The sharpshooter Bucephalogonia xanthophis (Berg) (Hemiptera: Cicadellidae) is an important vector of Xylella fastidiosa, a bacterium that causes citrus variegated chlorosis. This study aimed to identify the preferred feeding sites and periods of this vector on citrus, in order to improve our understanding of the feeding behavior related to the transmission of this pathogen. The feeding sites were determined in a choice experiment, in which 30 adults were released inside observation chambers (n = 10) containing a sweet orange seedling [Citrus sinensis (L.) Osbeck]. One, fifteen, twenty-one, twenty-five, thirty-nine, forty-five, and forty-nine hours after the release, the number of insects on the upper (stem with sprouts) and bottom (primary stem, up to 40 cm above soil) parts of the plant was recorded. To determine the feeding periods, 20 males and 20 females of B. xanthophis were individually confined on the stems of sweet orange seedlings, and the honeydew excretion (indirect measure of ingestion) was quantified for 48 hours, during periods of day and night. Most B. xanthophis individuals (91%) were observed on the upper part of the plant, mainly o...
Aos meus paisOdair Aparecido Marques e Maria José Neves Marques por todo o apoio, incentivo, carinho e compreensão. Vocês foram e são minha fonte de inspiração durante o caminho percorrido em minha vida. DedicoAo meu irmão e grande amigo Rogério Neves Marques, que possui atuação direta em toda a minha vida. Meu companheiro inseparável. Ofereço 4 AGRADECIMENTOS A Deus, por ter me guiado ao longo de minha vida, com muita saúde, perseverança e força de vontade. Ao Prof. Dr. João Roberto Spotti Lopes, pela orientação, confiança e amizade durante todos os anos de atividades, jornada esta que se iniciou na graduação e perdurou pelo curso de Mestrado. Suas palavras foram fundamentais na concretização deste trabalho. Ao pesquisador Dr. Pedro Takao Yamamoto, pela confiança, apoio, amizade e incentivo durante o desenvolvimento do trabalho. À Nivaldo Marcos Castanharo, proprietário da fazenda Oxford, em Gavião Peixoto-SP, por ceder a área e a estrutura da fazenda para a implantação do plantio-isca. Ao técnico do Fundecitrus, Marcos Rogério Fellipe e sua equipe Luiz Fernando Garbim, Antonio Mamprim, Lúcio Groti e José Barbosa pelo apoio e momentos de descontração durante a implantação e condução do plantio-isca.
O cultivo de frutíferas de caroço está entre as atividades agrícolas de maior importância na fruticultura brasileira, com destaque para o pessegueiro [Prunus persica (L.) Batsch] e a ameixeira (Prunus domestica L.). Insetos-pragas constituem uma grande ameaça para a fruticultura nacional e, para seu manejo eficiente e racional, é primordial o conhecimento quali-quantitivo de insetos potenciais pragas e inimigos naturais. Este trabalho teve como objetivo realizar o levantamento e análise faunística de insetos ocorrentes em pomar de pessegueiro (P. persica vr. Kampai) e ameixeira (P. domestica vr. Reubennel) no município de Buri, São Paulo. Foram utilizados três tipos de armadilhas: caça-mosca, cartões adesivos amarelos e Moericke (com água e sabão). As coletas foram realizadas quinzenalmente de setembro de 2018 a março de 2019. Verificou-se grande diversidade e abundância de insetos na área estudada, sendo as famílias Aphidae, Formicidae, Chrysomelidae, Dolichopodidae, Muscidae, Otitidae as mais frequentes. A análise faunística realizada nesta pesquisa mostrou que houve incidência de potenciais pragas secundárias, membros das famílias Drosophilidae, Membracidae, Aphidae, Formicidae e Chrysomelidae. Também foi observada diversidade de inimigos naturais das famílias Spongiphoridae, Vespidae, Ichneumonidae e Coccinellidae. A adoção de medidas conservacionistas de inimigos naturais é fundamental para evitar surtos populacionais de potenciais pragas em áreas produtoras.
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