Resistance of True Citrus species to Diaphorina citri

This is the peer reviewed version of the following article: Eduardo, W. I., Miranda, M. P., Volpe, H. X. L., Garcia, R. B., Girardi, E. A., Alquezar, B., ... & Peña, L. (2022). Resistance of True Citrus species to Diaphorina citri. Pest management science, 78(11), 4783-4792, which has been published in final form at [https://doi.org/10.1002/ps.7098]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.[EN] BACKGROUND Host genetic resistance is a promising strategy for the management of Diaphorina citri Kuwayama (Hemiptera: Psyllidae), and consequently Huanglongbing (HLB). To date, no study has investigated the resistance to D. citri in the clonal and vegetatively propagated plants of the Microcitrus, Eremocitrus, and Atalantia genera. This study assesses Near and True Citrus genotype antixenosis and antibiosis against D. citri, with trichome density and volatile emission as possible mechanisms of resistance. RESULTS All genotypes were oviposited by D. citri, however, 8 of 14 genotypes were less oviposited than Citrus x sinensis 'Valencia' (susceptible control). Diaphorina citri nymphs had lower nymphal viability in E. glauca (31%) and M. warburgiana (58%) than that in Citrus x sinensis (77%). The behavioral assay showed that 30% of D. citri nymphs in the last instars evaded E. glauca shoots, whereas no nymphs evaded Citrus x sinensis shoots. A higher trichome density was observed in E. glauca shoots compared to the other genotypes. Chemical analysis revealed differences in the volatile profiles of E. glauca and Citrus x sinensis. CONCLUSION Eremocitrus glauca and M. warburgiana genotypes were more resistant to D. citri than Citrus x sinensis. Higher trichome density in the shoots may negatively influence the development of D. citri nymphs. Eremocitrus glauca volatiles may also be involved in their resistance to D. citri.This work was funded by the Fund for Citrus Protection (Fundecitrus), the European Union H2020 Innovation Action Program (grant #817526), and the project PID2019-104569RB-I00 from AEI-Spain. WIE received a postdoctoral fellowship (Proc. 2019/19649-3) from SAo Paulo Research Foundation (FAPESP). MPM received a research fellowship (Proc. 301805/2018-0) from Council for Scientific and Technological Development (CNPq), Brazil. The authors thank the Metabolomic service from Instituto de Biologia Molecular y Celular de Plantas, CSIC/UPV (IBMCP), Valencia, Spain for their help with the volatile emission analysis. The authors also acknowledge Fundecitrus and EMBRAPA Cassava & Fruits for providing plant materials.Eduardo, WI.; Miranda, MP.; Linhares Volpe, HX.; Garcia, RB.; Alquézar-García, B.; Girardi, EA.; Espinosa Ruiz, A.... (2022). Resistance of True Citrus species to Diaphorina citri. Pest Management Science. 78(11):4783-4792. https://doi.org/10.1002/ps.709847834792781

Eficiência de fungos entomopatogênicos para o controle de Sitophilus oryzae L. (Coleoptera: Curculionidae) em condições de laboratório

O objetivo da pesquisa foi avaliar, em condições de laboratório, a eficiência de isolados dos fungos entomopatogênicos Beauveria bassiana, Metarhizium anisopliae e Isaria fumosorosea no controle populacional de Sitophilus oryzae. Foram realizados bioensaios com os isolados de B. bassiana, IBCB 01, IBCB 17 e IBCB 18, e I. fumosorosea, ARSEF 7050, os produtos comercias a base de B. bassiana (Boveril®, PM) e M. anisopliae (Metarril®, PM) e os isolados de B. bassiana e M. anisopliae cultivados em arroz, produzidos em usinas de cana-de-açúcar. Adultos não separados por sexo de S. oryzae foram imersos em solução de conídios na concentração de 1,0 x 108 conídios viáveis / mL e acondicionados em placas de Petri contendo grãos de milho. Para cada isolado foram realizadas quatro repetições, com quinze insetos cada, e a mortalidade avaliada diariamente, por um período de 15 dias. Com exceção do isolado de M. anisopliae obtido de usina de cana-de-açúcar, os demais entomopatógenos analisados foram patogênicos à S. oryzae, porém, causaram baixa mortalidade, que variou entre 5 a 25%, sendo pouco promissores para adoção como medida de controle desse inseto em grãos de milho armazenados

Engineered Orange Ectopically Expressing the Arabidopsis beta-Caryophyllene Synthase Is Not Attractive to Diaphorina citri, the Vector of the Bacterial Pathogen Associated to Huanglongbing

[EN] Huanglongbing (HLB) is a destructive disease, associated with psyllid-transmitted phloem-restricted pathogenic bacteria, which is seriously endangering citriculture worldwide. It affects all citrus species and cultivars regardless of the rootstock used, and despite intensive research in the last decades, there is no effective cure to control either the bacterial species (Candidatus Liberibacter spp.) or their insect vectors (Diaphorina citri and Trioza erytreae). Currently, the best attempts to manage HLB are based on three approaches: (i) reducing the psyllid population by intensive insecticide treatments; (ii) reducing inoculum sources by removing infected trees, and (iii) using nursery-certified healthy plants for replanting. The economic losses caused by HLB (decreased fruit quality, reduced yield, and tree destruction) and the huge environmental costs of disease management seriously threaten the sustainability of the citrus industry in affected regions. Here, we have generated genetically modified sweet orange lines to constitutively emit (E)-beta-caryophyllene, a sesquiterpene repellent to D. citri, the main HLB psyllid vector. We demonstrate that this alteration in volatile emission affects behavioral responses of the psyllid in olfactometric and no-choice assays, making them repellent/less attractant to the HLB vector, opening a new alternative for possible HLB control in the field.This work was funded by the Fundo de Defesa da Citricultura (Fundecitrus), Sao Paulo Research Foundation (FAPESP, grant #2015/07011-3), and EU H2020 Innovation Action Program (grant #817526). Consent for research and field trial of genetically modified organisms was granted by the National Technical Biosafety Commission from Brazil (CTNBio) to Fundecitrus.Alquézar-García, B.; Linhares Volpe, HX.; Facchini Magnani, R.; Pedreira De Miranda, M.; Almeida Santos, M.; Vieira Marques, V.; Rodrigues De Almeida, M.... (2021). Engineered Orange Ectopically Expressing the Arabidopsis beta-Caryophyllene Synthase Is Not Attractive to Diaphorina citri, the Vector of the Bacterial Pathogen Associated to Huanglongbing. Frontiers in Plant Science. 12:1-15. https://doi.org/10.3389/fpls.2021.6414571151

Métodos para avaliar a liberação e o parasitismo de Cotesia flavipes (Cameron, 1891) (Hymenoptera: Braconidae) em cana-de-açúcar

Métodos adequados para avaliar o parasitismo de um agente de controle biológico auxiliam na determinação de sua capacidade de busca e no desenvolvimento de técnica de liberação. O estudo da área de cobertura do parasitismo natural e após liberações inundativas auxiliam na determinação de técnica de liberação de um agente de controle biológico. O objetivo desta pesquisa foi estudar três métodos de infestação do hospedeiro para a adoção do mais viável na avaliação do parasitismo por Cotesia flavipes (Cameron, 1891) (Hymenoptera: Braconidae) com liberação de 6000 parasitoides em quatro pontos por hectare, além de avaliar a influência do controle biológico natural e métodos liberação de C. flavipes para o controle de Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae). Foram testadas infestação artificial com lagartas “sentinelas” em colmos de cana, posturas fixadas na planta e infestação natural de D. saccharalis. Para cada método, as áreas foram amostradas antes e após a liberação de C. flavipes, com três repetições para cada método de infestação e 100 pontos amostrados por área. O melhor método de infestação foi usado para estudar liberações de 8 e 12 pontos por hectare, com densidade fixa de 6000 parasitoides por hectare. Contabilizou-se o número de lagartas recuperadas e parasitadas por ponto amostral para cálculo da porcentagem de parasitismo, índices de dispersão, distribuição de frequências e construção de gráficos geoestatísticos bidimensionais. Para o método usando infestação artificial com posturas de D. saccharalis ocorreu baixa recuperação de lagartas e não permitiu a amostragem da área para obter informações a respeito da presença ou ausência de parasitismo. A infestação com lagartas “sentinelas” e natural quantificam o parasitismo e permite coleta do hospedeiro na maioria dos pontos amostrais, o que viabiliza estudos relacionados ...Suitable methods to assess the parasitism of a biological control agent assist in the determination of its search capacity and to develop release methods. The study of the cover area of the natural parasitism and after massive releases is helpful to determine an eficient release method of a natural enemy. The aim of the research was to study three methods to infest the host to adopt the the more suitable to evaluate the parasitism by Cotesia flavipes (Cameron, 1891) (Hymenoptera: Braconidae) after releasing 6,000 parasitioids arranged in 4 release points per hectare as well as evaluating the influence of the natural biological control to control Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae). Methods using sentinel larvae, egg masses fixed on sugarcane plants and natural infestation of D. saccharalis were tested. For each method, areas were sampled before and after releases of C. flavipes, with three replications for each method of host infestation and 100 points were sampled by area. The best method was used to study releases in 8 and 12 points per hectare, keeping the density of 6,000 released parasitoids per hectare. The number of recovered and parasititized larva were counted to calculate dispersion indices, distribution of frequencies and to generate bidimensional maps. For the method using egg masses was found a low recovery of hosts and did not allow collecting information about the presence or absence of parasitism. Infestation with sentinel larva and the use of natural infestation allow recovering the host and to quantify the parasitistim to the majoritory sample points. The use of sentinel hosts allows studies during seasons with low density of hosts, however this method interfere on the environment. The natural infestation excludes questions about previous manipulation of the environment that can influence on the dispersal of the parastoid and it is recommended when the density of the host is sufficient ..

Push-pull and kill strategy for Diaphorina citri control in citrus orchards

The development of sustainable methods to control Diaphorina citri Kuwayama (Hemiptera: Liviidae) is crucial to improve management of huanglongbing (HLB), the most important citrus disease worldwide. In a flushing Citrus × sinensis L. Osbeck (Rutaceae) orchard, this study assessed the combined effects of insecticide-treated Bergera koenigii L. (Rutaceae) trees in the orchard border, as a lethal trap crop, and the application of processed kaolin to the citrus crop, as a repellent (push-pull and kill strategy), in reducing D. citri infestation and dispersal. Additionally, the volatile organic compound (VOC) emission profile and attractiveness of B. koenigii shoots were investigated in indoor experiments. The push-pull and kill strategy reduced the number of D. citri adults on citrus trees by 95, 84, and 63% compared to the untreated control, trap crop only, and kaolin only treatments, respectively. These high reductions can be attributed to the combination of attractive stimuli (VOCs) and repellent stimuli by the trap crop and kaolin, respectively. The number of psyllids observed on citrus trees subjected to treatments with trap crop and kaolin separately was 69 and 86% lower than on untreated control trees, respectively. In addition, all treatments reduced and delayed D. citri dispersal inside the orchard, especially the push-pull and kill strategy. In olfactometric assays, D. citri females showed a significant preference for B. koenigii odors over C. × sinensis cv. ‘Valencia’ flush odors, likely related with the different VOC emission profiles of the two plants. This study shows the effectiveness of push-pull and kill as a new management strategy to control D. citri and consequently HLB.Peer reviewe

Efeito de sinigrina aplicada em folhas de brássicas sobre características biológicos de Plutella xylostella (L.) (Lepidoptera: Plutellidae) = Effect of sinigrin applied on brassics leaves on biological aspects of Plutella xylostella (L.) (Lepidoptera: Plutellidae)

O objetivo deste trabalho foi avaliar o efeito da ingestão de sinigrina aplicada em folhas de couve e brócolis sobre algumas características biológicas de Plutella xylostella. Foram utilizadas duas cultivares de brássicas: couve-manteiga Da Geórgia e brócolisRamoso Piracicaba Precoce, sendo elas tratadas com soluções de sinigrina a 0,2; 0,4; 0,8; 1,6 e 3,2 mg mL-1, contendo 5% de Tween20®, e uma testemunha, apenas com solução de Tween20®. Avaliou-se a duração e viabilidade das fases larval e pupal, peso de pupas, longevidade e razão sexual dos adultos, fecundidade das fêmeas, período de incubação e viabilidade da fase de ovo, tendo-se calculado o potencial reprodutivo corrigido (PRC). As médias foram avaliadas pela análise multivariada de agrupamento e de componentesprincipais. O maior potencial reprodutivo foi apresentado pela dose de 0,2 mg mL-1 em couve. As análises multivariadas proporcionaram melhor discriminação dos tratamentos em relação à menor concentração testada. Concluiu-se que baixa concentração de sinigrina, em couve e em brócolis, favorece o desenvolvimento de P. xylostella.The objective of this work was to evaluate the effect of sinigrin applied to cabbage and broccoli leaves of biological aspects of Plutella xylostella. Two brassica cultivars, cabbage Da Georgia and broccoli Ramoso Piracicaba Precoce, were used and were treated with the following sinigrin solutions: 0.2, 0.4, 0.8, 1.6 and 3.2 mg mL-1 in solution 5% of Tween 20® and a control with Tween solution. Duration and viability of larval and pupal periods, pupal weight, longevity and sex ratio, female fertility, incubation period and egg viability were evaluated. The corrected reproductive potential index (PRC) was also calculated. The means were analyzed by the multivariate analysis of grouping and of main components. The PRC treatments presented 0.2 mg mL-1 in cabbage with larger reproductive potential. The multivariate analysis provided discrimination of treatments regarding the smaller tested concentration. By theresults it is possible to conclude that low concentrations of sinigrin, in cabbage and broccoli, allow better development for P. xylostella