Sucking insects and their predators on tree canopies of a monocultural stand of Caryocar brasiliense

Abstract Caryocar brasiliense Camb. (Malpighiales: Caryocaraceae) trees are widely distributed throughout the Cerrado ecosystem. The fruits of C. brasiliense trees are used by humans for food and as the main income source in many communities. C. brasiliense conservation is seriously threatened due to habitat loss caused by the land-use change. Sucking insects constitute an important ecological driver that potentially impact C. brasiliense survival in degraded environments. In addition, insects sampling methodologies for application in studies related to the conservation of C. brasiliense are poorly developed. In this study, sucking insects (Hemiptera) and their predators were recorded in three vertical strata of Caryocar brasiliense canopies. The distribution of sucking species showed vertical stratification along the canopy structure of C. brasiliense. The basal part of the canopy had the highest numbers of sucking insects Aphis gossypii (Glover 1877) (Hemiptera: Aphididae) and Bemisia tabaci (Genn. 1889) (Hemiptera: Aleyrodidae), and their predators Chrysoperla sp. (Neuroptera: Chrysopidae), spiders (Araneae), and Zelus armillatus (Lep. & Servi., 1825) (Hemiptera: Reduviidae). Predators' distribution follows the resource availability and preferred C. brasiliense tree parts with a higher abundance of prey.

Resumo Caryocar brasiliense Camb. (Malpighiales: Caryocaraceae) é amplamente distribuído por todo o ecossistema de cerrado. Os frutos de C. brasiliense são utilizados na alimentação humana e constitui uma importante fonte de renda para muitas comunidades. A perda de habitat provocada pelas mudanças de uso da terra coloca em risco a conservação de C. brasiliense. Insetos sugadores constituem um importante fator ecológico que, potencialmente, afeta o fitness de C. brasiliense em ambientes degradados. Além disso, as metodologias de amostragem de insetos para aplicação em estudos relacionados à conservação de C. brasiliense são pouco desenvolvidas. Neste estudo, o número de insetos sugadores (Hemiptera) e seus predadores foram avaliados em três estratos verticais do dossel de C. brasiliense. A distribuição das espécies sugadoras apresentou estratificação vertical ao longo da estrutura do dossel. O estrato basal do dossel apresentou o maior número de insetos sugadores Aphis gossypii (Glover 1877) (Hemiptera: Aphididae) e Bemisia tabaci (Genn. 1889) (Hemiptera: Aleyrodidae), e seus predadores Chrysoperla sp. (Neuroptera: Chrysopidae), aranhas (Araneae) e Zelus armillatus (Lep. & Servi., 1825) (Hemiptera: Reduviidae). Os predadores distribuíram-se de acordo com a disponibilidade de recursos, ocorrendo em maior número nas partes do dossel com maior abundância de suas presas.

Sucking insects and their predators on tree canopies of a monocultural stand of Caryocar brasiliense / Insetos sugadores e seus predadores na copa de Caryocar brasiliense em sistema de monocultura

Abstract Caryocar brasiliense Camb. (Malpighiales: Caryocaraceae) trees are widely distributed throughout the Cerrado ecosystem. The fruits of C. brasiliense trees are used by humans for food and as the main income source in many communities. C. brasiliense conservation is seriously threatened due to habitat loss caused by the land-use change. Sucking insects constitute an important ecological driver that potentially impact C. brasiliense survival in degraded environments. In addition, insects sampling methodologies for application in studies related to the conservation of C. brasiliense are poorly developed. In this study, sucking insects (Hemiptera) and their predators were recorded in three vertical strata of Caryocar brasiliense canopies. The distribution of sucking species showed vertical stratification along the canopy structure of C. brasiliense. The basal part of the canopy had the highest numbers of sucking insects Aphis gossypii (Glover 1877) (Hemiptera: Aphididae) and Bemisia tabaci (Genn. 1889) (Hemiptera: Aleyrodidae), and their predators Chrysoperla sp. (Neuroptera: Chrysopidae), spiders (Araneae), and Zelus armillatus (Lep. & Servi., 1825) (Hemiptera: Reduviidae). Predators' distribution follows the resource availability and preferred C. brasiliense tree parts with a higher abundance of prey.

Resumo Caryocar brasiliense Camb. (Malpighiales: Caryocaraceae) é amplamente distribuído por todo o ecossistema de cerrado. Os frutos de C. brasiliense são utilizados na alimentação humana e constitui uma importante fonte de renda para muitas comunidades. A perda de habitat provocada pelas mudanças de uso da terra coloca em risco a conservação de C. brasiliense. Insetos sugadores constituem um importante fator ecológico que, potencialmente, afeta o fitness de C. brasiliense em ambientes degradados. Além disso, as metodologias de amostragem de insetos para aplicação em estudos relacionados à conservação de C. brasiliense são pouco desenvolvidas. Neste estudo, o número de insetos sugadores (Hemiptera) e seus predadores foram avaliados em três estratos verticais do dossel de C. brasiliense. A distribuição das espécies sugadoras apresentou estratificação vertical ao longo da estrutura do dossel. O estrato basal do dossel apresentou o maior número de insetos sugadores Aphis gossypii (Glover 1877) (Hemiptera: Aphididae) e Bemisia tabaci (Genn. 1889) (Hemiptera: Aleyrodidae), e seus predadores Chrysoperla sp. (Neuroptera: Chrysopidae), aranhas (Araneae) e Zelus armillatus (Lep. & Servi., 1825) (Hemiptera: Reduviidae). Os predadores distribuíram-se de acordo com a disponibilidade de recursos, ocorrendo em maior número nas partes do dossel com maior abundância de suas presas.

Combined effect of corn in the barrier crop and plant extracts against Cowpea mild mottle virus infecting soybean [Glycine max (L. ) Merr. ] in the field

Cowpea mild mottle virus (CpMMV) is one of the problems that can decrease soybean production. The research was conducted on the combined effects of corn in the barrier crop with plant extracts against CpMMV infecting soybean in the field. The field data was conducted using a Completely Randomized Design. The mean of disease incidence and disease severity is measured from total plants in each replicate plot on each treatment. Planting one or two of corn lines were grown at the edge four weeks before planting soybeans. Cashew nut shell (CNS), pagoda leaf, and rhizome of ginger extracts were applied using the sprayer and applied at 24 h before virus acquisition and transmission by whiteflies. The result showed that the virus incubation period ranged from 9−38 days after transmission longer than the untreated control. Planting two corn lines at the edge with CNS extract as bioactivator on soybean was the most extended incubation period of the virus and the lowest absorbance value DAS-ELISA of 0.20. There was a 73.11 % increase in the relative inhibition level of the virus. Planting corn at the edge with CNS extract proved to be more effective than soybean monoculture with CNS extract. However, soybean monoculture with CNS extract provides a better relative inhibition level of the virus (64.32 %) than planting two rows of corn on the edge combined with ginger of rhizome extract and planting two rows of corn on the edge with pagoda leaf extract as bioactivator on a soybean plant.

Comparative Study of Morphology and Developmental Biology of Two Agriculturally Important Whitefly Species Bemisia tabaci (Asia II 5) and Trialeurodes vaporariorum from North-Western Himalayan Region of India

Abstract: Bemisia tabaci (Asia II 5) and Trialeurodes vaporariorum are the two devastating species of whiteflies infesting a wide range of vegetable crops in the North-Western Himalayan region. Therefore, the present investigation deals with a comparative study of the morphology and developmental biology of these two whitefly species. The total developmental period from egg to adult was 22.82 and 23.40 days for B. tabaci (Asia II 5) and T. vaporariorum, respectively, which did not differ significantly. The adult longevity, fecundity, and adult emergence in T. vaporariorum is quite higher than B. tabaci (Asia II 5) which were observed as 10.40 days, 118.00 eggs/female, 90.69 per cent and 6.80 days, 73.33 eggs/female, 86.59 per cent, respectively. Similarly, the egg hatching and the survival rate is higher in T. vaporariorum than in B. tabaci (Asia II 5) (95.11, 81.44 per cent and 91.68, 78.09 per cent). Morphological characters such as marginal setae, abdominal setae, vasiform orifice, lingula, and antennae, which were reliable characters for the identification of both whitefly species and diagnostics of the two whiteflies, were explicated in a comparative discussion.

Achievements in the epidemiology of begomoviruses and their vector Bemisia tabaci in Costa Rica

Since the early 1990s, and almost simultaneously, unknown diseases started to be observed in many crops, especially in tropical and subtropical regions. These diseases were predominantly caused by begomoviruses, which were poorly known at that time. Their vector, the whitefly Bemisia tabaci (Hemiptera: Aleyrodidae), often reached unprecedented huge populations in agricultural areas. This elicited a serious production crisis worldwide, that caused losses of millions of dollars for farmers in many countries, including the Mesoamerican region. Fortunately, in Costa Rica, some local research centers, with the collaboration of foreign specialists, have been able to study the causes of this phenomenon, in the search for solutions based on solid epidemiological information. In addition to the previously reported native Bemisia tabaci species, New World (NW), two exotic species, -Mediterranean (MED) and Middle East-Asia Minor 1 (MEAM1)- were found. Moreover, native and exotic bipartite begomoviruses have been detected, especially in common bean, cucurbits, tomato and sweet pepper, as well as the worldwide spread monopartite begomovirus Tomato yellow leaf curl virus (TYLCV). Based upon biological and ecological knowledge accumulated to date, this review offers a comprehensive overview of the very dynamic ways in which the interactions of the different whiteflies and begomovirus species have expressed in Costa Rica, with emphasis on vegetable pathosystems. Hopefully, the information provided in this paper may allow farmers, extension agents, and researchers involved in vegetable production to develop sound practical responses to current and unforeseen problems regarding whiteflies and their associated viruses.

Desde inicios del decenio de 1990 y de manera casi simultánea, se empezaron a observar afecciones desconocidas en numerosos cultivos, sobre todo en regiones tropicales y subtropicales. Dichas enfermedades eran causadas por begomovirus hasta entonces poco estudiados. Su vector es la mosca blanca Bemisia tabaci (Hemiptera: Aleyrodidae), de la que no se habían registrado poblaciones tan desmedidas en áreas agrícolas. Ello originó una seria crisis de producción a nivel mundial, con pérdidas millonarias para los agricultores de numerosos países, incluyendo la región de Mesoamérica. Por fortuna, en Costa Rica, algunos centros de investigación, con la colaboración de especialistas extranjeros, han podido profundizar en las causas de este fenómeno, para buscar soluciones fundamentadas en información de carácter epidemiológico. Además de la especie de B. tabaci New World (NW), nativa y previamente conocida, en años recientes han ingresado sendas especies del Mediterráneo (MED) y el Medio Oriente-Asia Menor 1 (MEAM1). Asimismo, se ha detectado la presencia de begomovirus bipartitas, nativos y exóticos, especialmente en frijol común, cucurbitáceas, tomate y chile; además, se detectó el begomovirus monopartito conocido a nivel mundial Tomato yellow leaf curl virus (TYLCV) en tomate. Con base en el conocimiento biológico y ecológico acumulado hasta ahora, en la presente revisión se aporta una panorámica del dinamismo con que se han expresado en Costa Rica las interacciones entre las diferentes especies vectoras y los distintos begomovirus, con énfasis en patosistemas de hortalizas. Se espera que la información aquí presentada permita mejorar el tipo de respuestas prácticas y eficaces de parte de agricultores, extensionistas agrícolas e investigadores involucrados en la producción de hortalizas, frente a problemas actuales o imprevistos.

Genome complexity of begomovirus disease and a concern in agro-economic loss

Significant agro-economic loss becomes a foremost concern in terms of productivity and feeding the expandingpopulation. Among all plant pathogens, begomovirus is also one of the contagions which affect most monocot anddicots. Begomovirus is transmitted by the whitefly vector Bemisia tabaci and causes potential yield reduction in anumber of economically important crops. The evolution of the new strain of begomovirus through genetic changes,climatic factors, and mutation drastically affects the agricultural yield and thus the economic loss. A strategicBegomo management would foster the healthier agricultural environment. The review focus on classification,genome organisation, replication, pathogenecity, phylogeny, genetic diversity, technology behind its suppression,concealment and kayo.

Phenotypic and Molecular Screening of Okra (Abelmoschus esculentus L. Moench) Genotypes against Okra Leaf Curl Disease

Okra leaf curl disease (OLCD) is a major constraint on okra (Abelmoschus esculentus L. Moench) production in West Africa. The most effective way of managing this disease is through breeding and planting of resistant varieties. In order to identify sources of resistance and or tolerance, 21 okra genotypes were screened against OLCD in field trials which were conducted from May to October, 2015 (rainy season) and November 2015 to March 2016 (dry season). Field resistance was assessed at 2, 6 and 10 weeks after sowing (WAS) based on disease symptoms, and then confirmed by PCR amplification of viral coat protein gene. Populations of whitefly (Bemisia tabaci), the vector of begomoviruses associated with OLCD, as well as fruit yields were also assessed. Both PCR and field trials showed that all the okra genotypes were susceptible to the viral infection. The genotypes varied significantly (P<0.05) among them in terms of severity of OLCD, whitefly infestation, mean fruit yield (t ha-1), and the average fruit weight per plant. Higher cumulative average population of whitefly and mean fruit yield (t ha-1) were recorded in the dry season than in the rainy season. Genotypes GH5332 and GH6105 consistently showed mild symptoms of OLCD and also had very high fruit yields of 11.88 t ha-1 and 9.34 t ha-1 respectively in the rainy season, and 6.108 t ha-1and 4.05 t ha-1 respectively in the dry season, far above the overall mean yields for all the okra genotypes. Both genotypes GH5332 and GH6105 should be evaluated multi-locationally at farmers’ fields prior to their release as varieties or they should be incorporated into breeding lines.

Weeds associated with cotton crop and hosting whitefly / Plantas daninhas associadas à cultura do algodoeiro e hospedeiras de mosca-branca

The whitefly can be hosted by weeds and cause damage to cotton crops. The objective of this work was to identify which species of weeds among the floristic compositions occurring in the cotton crop are hosts of whiteflies (Bemisia tabaci biotype B). Bi-weekly evaluations were performed in a cotton area (FM 975 WS) in Sinop, Mato Grosso, Brazil, during the reproductive phase of the crop. An inventory square (0.25 m side) was randomly cast 15 times between the cotton rows. The weeds were cut close to the ground, conditioned and taken to the laboratory to identify the family and species, and to quantify the eggs and nymphs of whiteflies. Eleven families were detected, with the most frequent being Amaranthaceae (16.67%), Convolvulaceae (12.5%), Rubiaceae (12.5%) and Poaceae (12.5%). The most frequent species were Amaranthus spp. (13.79%) and Alternanthera tenella, Ipomea spp., Richardia brasiliensis and Eleusine indica, with 10.34% each. From the 15 collected species, the presence of whitefly eggs or nymphs was only not observed in Portulaca oleracea and E. indica. The highest incidence of B. tabaci occurred in Euphorbia heterophylla. The occurrence of these species should be monitored, so that the whitefly population does not interfere in the cotton fiber quality.(AU)

A mosca-branca pode hospedar-se em plantas daninhas e causar prejuízos ao algodoeiro. O objetivo deste trabalho foi identificar, entre a composição florística de plantas daninhas que ocorrem na cultura do algodoeiro, quais são hospedeiras da mosca-branca (Bemisia tabaci biótipo B). Em uma área de algodoeiro (FM 975 WS) em Sinop, Mato Grosso, Brasil, foram feitas avaliações quinzenais na fase reprodutiva da cultura. Um quadrado inventário (0,25 m de lado) foi lançado aleatoriamente 15 vezes nas entrelinhas do algodoeiro. As plantas daninhas foram cortadas rente ao solo, acondicionadas e levadas para o laboratório para identificação da família e da espécie, quantificação dos ovos e ninfas de mosca-branca. Foram detectadas 11 famílias, sendo as mais frequentes Amaranthaceae (16,67%), Convolvulaceae (12,5%), Rubiaceae (12,5%) e Poaceae (12,5%). As espécies mais frequentes foram Amaranthus spp. (13,79%) e Alternanthera tenella, Ipomea spp., Richardia brasiliensis e Eleusine indica, com 10,34% cada uma. Das 15 espécies coletadas, apenas em Portulaca oleracea e E. indica não foi constatada a presença de ovos ou ninfas de mosca-branca. A maior incidência de B. tabaci ocorreu em Euphorbia heterophylla. A ocorrência dessas espécies deve ser monitorada para que a população de mosca-branca não interfira na qualidade da fibra do algodoeiro.(AU)

Synthetic acylsugars and their effects on the control of arthropod pests / Acilaçúcares sintéticos e seu efeito no controle de artrópodes-praga

ABSTRACT One of the main problems facing agriculture is the loss of production as a result of the attack of agricultural pests. Alternative ways to work around this problem are being sought. There are substances called acylsugars that are naturally produced by the wild tomato species S. pennellii and affect arthropod pests. The objectives of this work were to synthesize two acylsugars and assess the biological effect of these on the arthropod pests Bemissia tabaci and Tetranycus urticae. The syntheses were performed via the reactions of glucose and sucrose (saccharose) with acetic anhydride using sodium acetate as the catalyst. The products of these reactions were sucrose octa-acetate and glucose penta-acetate, the structures of which were confirmed by spectroscopic techniques. In a resistance test against the mite, a linear correlation between the concentration of the synthesized substances, and the dislocation of the mite was obtained. A delay in the hatching of the arthropod eggs was observed, causing a mortality rate of approximately 95% in the 1st instar larvae of mites that was confirmed in adults. In the biological tests with Bemisia tabaci, there was a low rate of hatching and emergence, and the effect on the nymphs was the deformation of the emergent adults.

RESUMO Um dos grandes problemas que a agricultura enfrenta é a perda de produção causada pelo ataque de pragas agrícolas. Assim, buscam-se maneiras alternativas de contornar esse problema. Dentre esses, encontram-se substâncias, denominadas de acilaçúcars, que são produzidas naturalmente por espécies selvagens do tomate S. pennellii e que apresentam efeito sobre artrópodes-praga. Os objetivos desse trabalho foram sintetizar dois compostos de acilaçúcares e avaliar o efeito biológico destas sobre os artrópodes-praga Bemissia tabaci e Tetranycus urticae. A síntese foi feita via as reações de glicose e sacarose com anidrido acético, utilizando acetato de sódio como catalisador. Os produtos dessas reações foram o octa-acetato de sacarose e o penta-acetato de glicose, cujas estruturas foram confirmadas por técnicas espectroscópicas. No teste de resistência do ácaro, foi possível obter um ajuste linear entre a concentração das substâncias sintetizadas e o deslocamento do ácaro. Ambas as substâncias obtidas apresentaram um atraso na eclosão dos ovos do artrópode, ocasionando uma mortalidade de aproximadamente 95% em ácaros de 1º ínstar que foram confirmadas em adultos. Nos testes biológicos com Bemisia tabaci, verificou-se uma baixa taxa de eclosão e emergência, sendo que o efeito sobre as ninfas foi a má formação para adultos emergidos.

Biological traits and Life table parameters A and B biotype of Bemisia tabaci (Genn.) on cotton and rapeseed

The aim of this work was to construct life table of Bemisia tabaci (Gen.) A and B (silverleaf whitefly B. argentifolii Bellows and Perring) biotype (Hem.: Aleyrodidae) on two host plants; cotton, (Gossypium hirsutum L.) and rapeseed, (Brassica napus L.). Experiments were conducted in a growth chamber under 24 ± 2ºC, 55±3% RH and 16:8 (L:D) h photoperiod on caged plants of cotton G. hirsutum L. (Varamin 76 variety) and rapeseed B. napus L. (global variety. The intrinsic rate of natural increase (r m), net reproductive rate (R0) and mean generation time (T) for B. tabaci A biotype was 0.1010 females per female per day, 18.4075 females per female and 30.079 day (d) on cotton; 0.1286, 30.6760 and 26.77 d on rapeseed; and for B biotype (B. argentifolii) those above respective parameters averaged 0.1033, 27.8426 and 32.74 d on cotton and 0.1750, 40.75 and 21.27 d on rapeseed. The total survival of A and B biotype from the egg to adult on cotton was 22.08 and 22.25, respectively. The results showed significant differences between the two biotype reared on either host plant for gross reproductive rate (GRR), net reproductive rate (R0 or NRR), intrinsic rates of increase (r m), finite rate of increase (λ), doubling time (DT) and mean generation times (Tc). To obtain a better understanding of the biology of these biotypes, Stable age distribution (Cx) and some other aspects of life history related to their hosts were also studied. Based upon the results, both biotypes showed a greater reproduction capacity on rapeseed than on cotton. Thus, rapeseed was more suitable host than cotton for two biotypes and this was an important factor in host plant selection for optimizing the control strategies of these major pests.

Influence of Additives on the Yield and Pathogenicity of Conidia Produced by Solid State Cultivation of an Isaria javanica Isolate

Recently, the Q biotype of tobacco whitefly has been recognized as the most hazardous strain of Bemisia tabaci worldwide, because of its increased resistance to some insecticide groups. As an alternative control agent, we selected an Isaria javanica isolate as a candidate for the development of a mycopesticide against the Q biotype of sweet potato whitefly. To select optimal mass production media for solid-state fermentation, we compared the production yield and virulence of conidia between 2 substrates (barley and brown rice), and we also compared the effects of various additives on conidia production and virulence. Barley was a better substrate for conidia production, producing 3.43 x 10(10) conidia/g, compared with 3.05 x 10(10) conidia/g for brown rice. The addition of 2% CaCO3 + 2% CaSO4 to barley significantly increased conidia production. Addition of yeast extract, casein, or gluten also improved conidia production on barley. Gluten addition (3% and 1.32%) to brown rice improved conidia production by 14 and 6 times, respectively, relative to brown rice without additives. Conidia cultivated on barley produced a mortality rate of 62% in the sweet potato whitefly after 4-day treatment, compared with 53% for conidia cultivated on brown rice. The amendment of solid substrate cultivation with additives changed the virulence of the conidia produced; the median lethal time (LT50) was shorter for conidia produced on barley and brown rice with added yeast extract (1.32% and 3%, respectively), KNO3 (0.6% and 1%), or gluten (1.32% and 3%) compared with conidia produced on substrates without additives.

Optimización de las condiciones de inoculación por biobalística de un Begomovirus en tomate y tabaco / Optimizing conditions for biolistic inoculation of Begomovirus in tomato and tobacco

La transmisión experimental de Begomovirus es problemática. La mayoría de estos virus se pueden transmitir de planta a planta por su vector biológico, Bemisia tabaci. Las inoculaciones experimentales con mosca blanca son problemáticas debido a sus hábitos de alimentación, requerimiento de una planta viva infectada e instalaciones de contención para el vector. Por su parte la inoculación mecánica de Begomovirus es posible, pero generalmente a tasas bajas y no en todos los casos. Por esta razón el bombardeo de partículas (biobalística) de DNA viral como una estrategia de inoculación fue desarrollada. La posibilidad de utilizar el dispositivo de mano Helios Gen Gun System (Biorad®), un equipo de biobalística, para la transmisión de un Begomovirus bipartita a plantas de tomate y tabaco fue ensayado y optimizado. Los parámetros evaluados fueron: número de disparos (1-2), presión de helio (220 y 320 psi) y diámetro de las partículas de oro (0.6 y 1.6µm). Los síntomas característicos de la enfermedad viral (clorosis, mosaico y deformación de la hoja) aparecieron 3 semanas después del bombardeo en las hojas jóvenes no inoculadas. La replicación del DNA viral en las plantas se confirmó por Reacción en cadena de la polimerasa. Plantas infectadas en un 100 se obtuvieron cuando en el bombardeo se emplearon partículas de oro de 1.6 µm recubiertas con DNA viral a una presión de 320psi. A nuestro entender este es el primer reporte en Colombia de la inoculación directa de plantas de tomate y tabaco con un Begomovirus bipartita usando un dispositivo portátil de biobalística.

Experimental transmission of Begomovirus is problematic. Most Begomoviruses can be transmitted readily from plant to plant by the whitefly vector, but this also requires a live infected plant and extensive facilities to maintain the insect. Whitefly inoculations can also be problematic because of their preferential feeding habits on certain plants. Mechanical inoculation of Begomovirus is possible but generally at low rates and for others not at all. For this reason particle bombardment (biolistic) of DNA viral as an inoculum was developed. The possibility of using the Helios Gen Gun System (Biorad®), a biolistic hand-held device, for transmitting Begomovirus bipartite to tomato and tobacco plants was assayed and optimized. Biolistic inoculation was carried out with the hand held device at 220 or 320 psi, applying 1 or 2 shots /plant and using gold particles of 0.6 or 1.6µm in size. Characteristic symptoms of viral disease (chlorosis, mosaic and leaf deformation) appeared 3 weeks post-inoculation in the newly developing leaves. Replication of the viral DNA in plants was confirmed by Polymerase Chain Reaction. All bombarded plants became infected when biolistic inoculation was carried out with the hand held device at 320psi and using 1.6 µm gold particles in size. To our knowledge this is the first report in Colombia of successful direct inoculation of tomato and tobacco plants with Begomovirus bipartite geminivirus using a biolistic hand-held device.

Compatibilidad in vitro de un bioplaguicida a base de Lecanicillium lecanii (Hypocreales: Clavicipitaceae) con agroquímicos empleados en los cultivos de algodón y berenjena / In vitro compatibility of the biopesticide based on Lecanicillium lecanii (Hypocreales: Clavicipitaceae) with agrochemicals used in cotton and eggplant crops

El aislamiento colombiano de Lecanicillium lecanii Vl026 formulado como un granulado dispersable WG, ha demostrado una alta eficiencia para el control de Bemisia tabaci en los cultivos de algodón y berenjena. Teniendo en cuenta el potencial de este bioinsumo, el objetivo del siguiente fue determinar la compatibilidad in vitro del bioplaguicida a base de L. lecanii con agroquímicos (insecticidas y fungicidas) que se utilizan con mayor frecuencia en dichos cultivos. La compatibilidad in vitro se estableció determinando el porcentaje de germinación (%) y las Unidades Formadoras de Colonia (UFC) en presencia de los plaguicidas y estimando la concentración inhibitoria 10 (CI10). Cada plaguicida se evaluó a la dosis recomendada, a la mitad y a un cuarto de ésta. Los fungicidas químicos (Benomil®, Vitavax®, Ridomil® y Manzate®) no fueron compatibles con L. lecanii, ya que inhibieron la germinación y las Unidades Formadoras de Colonia del hongo en las tres dosis evaluadas. En cuanto a los insecticidas químicos, el producto Confidor® no inhibió la viabilidad en comparación con el tratamiento control, considerándose compatible con el bioplaguicida. Cuando se evaluó la dosis completa de los demás insecticidas (Oportune®, Actara®, Match® y Malathion®) se obtuvieron germinaciones inferiores al 80%, por lo que dichos productos se clasificaron como no compatibles con el bioplaguicida a base de L. lecanii. El único agroquímico que fue compatible en condiciones in vitro con L. lecanii fue el producto Confidor®. Sin embargo, se recomienda evaluar el efecto in vivo de los productos químicos habitualmente utilizados por los agricultores sobre L. lecanii, con el propósito de desarrollar y establecer estrategias de manejo integrado de la mosca blanca Bemisia tabaci.

A colombian isolate of Lecanicillium lecanii formulated as dispersible granules WG, has shown high efficiency to control Bemisia tabaci in cotton and eggplant crops. Considering that, the objetive of this work was to determine the in vitro compatibility of biopesticide based on L. lecanii with agrochemicals (insecticides and fungicides) that are most frequently used in tobacco and eggplant crops. In vitro compatibility of L. lecanii with agrochemicals was determinated by germination (%) and Colony Forming Units (CFU) in the presence of pesticides and also estimating the inhibitory concentration 10 (IC10). Each agrochemical was evaluated at the recommended dose, a half and a quarter of it. For the three doses tested (Benomyl®, Vitavax®, Ridomil® and Manzate®) were not compatible with L. lecanii, because these inhibited germination and Colony Forming Units of the fungus. Confidor® did not inhibit viability compared to control treatment, and it was considered compatible with the biopesticide. When the recommended dose (Oportune®, Actara®, Match® and Malathion®)was used, the germination of the L. lecanii was lower than 80%, then these products were classified as non-compatible with the biopesticide based on L. lecanii. The only agrochemical that was compatible in vitro with L. lecanii was Confidor®. However, is necesary to evaluate the in vivo effect of agrochemicals commonly used by farmers on L. lecanii, in order to develop and establish integrated management strategies for the control of the whitefly Bemisia tabaci.

Insecticidal effects of plant extracts on immature whitefly Bemisia tabaci Genn. (Hemiptera: Aleyroideae)

Background: The whitefly (Bemisia tabaci Genn.) is a widely distributed and highly harmful plant pest species. The management of B. tabaci has been typically carried out by chemical pesticides. In the last decade however, there has been an increasing interest in natural products, particularly those of plant origin, to control this pest species. In the present work, aqueous and ethanolic extracts of native plants from the flora of the Yucatán peninsula (Acalypha gaumeri, Annona squamosa, Carlowrightia myriantha, Petiveria alliaceae and Trichilia arborea) and the introduced plant Azadirachta indica were collected and evaluated for insecticidal activity against eggs and nymphs Bemisia tabaci. Results: Most of the aqueous and ethanolic extracts showed high insecticidal effects on B. tabaci eggs. The lowest LC50 values were recorded in the aqueous extracts of A. gaumeri (0.39% w/v), A. squamosa (0.36% w/v), P. alliaceae (0.42% w/v) and A. indica (0.30% /v), as well as in the ethanolic extracts of P. alliaceae (2.09 mg mL-1) and T. arborea (2.14 mg mL-1). On the other hand, B. tabaci nymphs were not affected by the aqueous extracts, but were highly sensitive to the ethanolic extracts of the tested plants. The lowest LC50 values were recorded in the ethanolic extracts of P. alliaceae (1.27 mg ml-1) and T. arborea (1.61 mg mL-1). The GC-MS analysis showed that phytol was the major component of the ethanolic extract of P. alliaceae and fatty acids were the major components of ethanolic extract of T. arborea. Conclusions: Overall, results suggest that ethanolic extracts of P. alliaceae and T. arborea leaves showed the highest insecticidal effects on eggs and nymphs B. tabaci. The extracts from P. alliaceae and T. arborea are good candidates to be developed as sources of natural insecticides for the management of immature B. tabaci since their effects were comparable with that showed by the extracts of A. indica, a well-known plant species for its insecticidal activity.

Detección, identificación y localización geográfica de Begomovirus que afectan al tomate en Colombia / Detection, identification and geographical localization of tomato-infecting Begomovirus in Colombia

En la actualidad, los Begomovirus (Familia Geminiviridae) se han convertido en la mayor amenaza para los cultivos de interés agrícola ubicados en las zonas tropicales y templadas del planeta. Estos virus son transmitidos por la mosca blanca Bemisia tabaci, la cual en los últimos años en Colombia ha tenido un aumento significativo en sus poblaciones y se ha asociado con la aparición de síntomas virales en cultivos de tomate. Muestras de tomate con síntomas virales típicos fueron recolectadas en las cinco principales zonas productoras de esta solanácea en el país. Los Begomovirus fueron detectados por medio de la técnica de hibridación de ácidos nucleicos tipo Dot blot así como por medio de la reacción en cadena de la polimerasa (PCR) en todas las muestras colectadas. Con la excepción de un reporte previo en el Valle del Cauca, este es el primer reporte de Begomovirus afectando cultivos de tomate en los departamentos de Antioquia, Santander, Boyacá y Cundinamarca. Asimismo, es la primera vez que se informa sobre Begomovirus que afectan cultivos de tomate localizados por encima de 1500 msnm en Colombia.

The begomoviruses (Family Geminiviridae) have recently emerged as samples with typical Begomovirus symptoms were collected in five different departments, comprising the mayor tomato growing areas of the country. Begomovirus were detected by Polymerase Chain Reaction (PCR) or Dot Blot Hybridization in all tomato samples collected in whole tomato growing areas of the country. With exception for Valle del Cauca, this is the first report of tomato-infecting Begomovirus in Antioquia, Santander, Boyacá and Cundinamarca departments. Also this is the first report of tomato-infecting Begomovirus crops located above 1500 masl in Colombia.

RNA interference for the control of whiteflies (Bemisia tabaci) by oral route.

RNA interference (RNAi)-mediated gene silencing was explored for the control of sap-sucking pest Bemisia tabaci, commonly known as whitefly. dsRNAs and siRNAs were synthesized from five different genes – actin ortholog, ADP/ ATP translocase, α-tubulin, ribosomal protein L9 (RPL9) and V-ATPase A subunit. A simplified insect bioassay method was developed for the delivery of ds/siRNA through the oral route, and efficacy was evaluated. ds/siRNA caused 29–97% mortality after 6 days of feeding. Each insect ingested nearly 150 nl of insect diet per day, which contained a maximum of 6 ng of RNA. Knocking down the expression of RPL9 and V-ATPase A caused higher mortality with LC50 11.21 and 3.08 μg/ml, respectively, as compared to other genes. Semi-quantitative PCR of the treated insects showed significant decrease in the level of RPL9 and V-ATPase A transcripts. siRNAs were found stable in the insect diet for at least 7 days at the room temperature. Phloem-specific expression of dsRNAs of RPL9 and V-ATPase A in transgenic plants for the protection against whiteflies might be an interesting application of this technology.

Efeito do tratamento de sementes com inseticidas no controle de pragas iniciais e na qualidade fisiológica das sementes em girassol / The effect of various insecticides on the control of initial pests and on the physiological quality of sunflower seeds

Avaliou-se o uso de inseticidas em tratamento de sementes de girassol no controle das pragas Cerotoma arcuatus (Olivier) (Coleoptera: Chrysomelidae), Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae) e Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) e a influência desses inseticidas na qualidade fisiológica das sementes, durante o armazenamento. Os resultados obtidos mostraram que tiodicarbe 600 g i.a./ 100 kg de sementes proporcionou aproximadamente 80, 100 e 85% de controle de A. gemmatalis de 1º ínstar, S. frugiperda de 2º ínstar e adultos de C. arcuatus, respectivamente. Entretanto, esse mesmo tratamento foi ineficiente no controle de lagartas de S. frugiperda de 3º ínstar e de B. tabaci. No controle de adultos de C. arcuatus, além de tiodicarbe 600 g i.a./100 kg sementes que apresentou bons resultados, tiodicarbe + imidacloprido 157,5 + 52,5 g i.a., tiametoxam 210 e 280 g i.a., imidacloprido 245 e fipronil 50 g i.a./100 kg de sementes apresentaram eficiência acima de 80% no controle dessa praga. No controle da A. gemmatalis apenas fipronil 50 g i.a./100 kg sementes e azadiractina 10 e 20 g. i.a./100 kg de sementes proporcionaram valores menores que 80% de controle, nas doses testadas, enquanto que, para o manejo da mosca-branca, nenhum dos tratamentos estudados proporcionou controle superior a 80%. Nenhum dos inseticidas avaliados nos diferentes tempos de armazenamento (até quatro meses após o tratamento) prejudicou a germinação e a emergência das sementes.

The aim of this study was to test various insecticides in the treatment of sunflower seeds for the control of Cerotoma arcuatus (Olivier) (Coleoptera: Chrysomelidae), Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae) and Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), and assessing their influence on the physiological quality of seeds during storage. The results showed that tiodicarb 600 g.a.i./100 kg of seeds achieved close to 80, 100 and 85% of control against first-instar A. gemmatalis, second instar S. frugiperda and adult C. arcuatus, respectively. However, this treatment was inefficient against third instar S. frugiperda and B. tabaci. Tiodicarb + imidacloprid 157.5 + 52.5; thiamethoxan 210; thiamethoxan 280; imidacloprid 245 and fipronil 50 g.a.i./100 kg of seeds also achieved 80% control against C. arcuatus adults. Against A. gemmatalis, only fipronil 50 g.a.i. and azarachtin 10 and 20 g.a.i./100 kg of seeds did not achieve more than 80% control. Against B. tabaci no tested treatment reached 80% of efficacy. None of the tested insecticides harmed seed germination or emergence during the different storage periods (up to 4 months after seed treatment).

Selection of Lecanicillium Strain with High Virulence against Developmental Stages of Bemisia tabaci

Selection of fungal strains with high virulence against the developmental stages of Bemisia tabaci was performed using internal transcribed spacer regions. The growth rate of hyphae was measured and bioassay of each developmental stage of B. tabaci was conducted for seven days. All of the fungal strains tested were identified as Lecanicillium spp., with strain 4078 showing the fastest mycelium growth rate (colony diameter, 16.3 +/- 0.9 mm) among the strains. Compared to strain 4075, which showed the slowest growth rate, the growth rate of strain 4078 was increased almost 2-fold after seven days. Strains 4078 and Btab01 were most virulent against the egg and larva stages, respectively. The virulence of fungal strains against the adult stage was high, except for strains 41185 and 3387. Based on the growth rate of mycelium and level of virulence, strains 4078 and Btab01 were selected as the best fungal strains for application to B. tabaci, regardless of developmental stage.

Actividad fagodisuasiva de las plantas Tithonia diversifolia y Montanoa hibiscifolia (Asteraceae) sobre adultos del insecto plaga Bemisia tabaci (Homoptera: Aleyrodidae)

Phagodeterrent activity of the plants Tithonia diversifolia and Montanoa hibiscifolia (Asteraceae) on adults of the pest insect Bemisia tabaci (Homoptera: Aleyrodidae). Bemisia tabaci (Gennadius) is a polyphagous, cosmopolitan and worldwide relevant pest, mainly acting as a virus vector on many crops. A sound preventive approach to deal with it would be the application of repellent or deterrent substances hopefully present in tropical plants, which in turn may contribute to take advantage of the remarkable rich Mesoamerican biodiversity. Therefore, extracts of two wild plants belonging to family Asteraceae, titonia (Tithonia diversifolia) and "tora" (Montanoa hibiscifolia), were tested for phagodeterrence to B. tabaci adults. The crude leaf extract of each one, as well as four fractions thereof (hexane, dichlorometane, ethyl acetate, and methanol) were tested under greenhouse conditions; in addition, the extracts were submitted to a phytochemical screening to determine possible metabolites causing phagodeterrence. Both restricted-choice and unrestricted-choice experiments were conducted. In the former ones, each fraction was tested at four doses (0.1, 0.5, 1.0 and 1.5% v/v), which were compared with four control treatments: distilled water, endosulfan, an agricultural oil (Aceite Agrícola 81 SC), and the emulsifier Citowett. Tomato plants were sprayed and placed inside sleeve cages, where 50 B. tabaci adults were released. The criterion to appraise phagodeterrence was the number of landed adults on plants at 48h. For the unrestricted-choice experiments, only the two highest doses (1.0 and 1.5%) of the crude extracts of each species were tested, and compared to distilled water and the agricultural oil. The titonia and "tora" crude extracts caused phagodeterrence, and for both plant species the methanol fraction stood out. Results suggest that metabolites causing phagodeterrence are several sesquiterpenic lactones, polyphenolic compounds (flavonoids and tannins) and saponins. Rev. Biol. Trop. 57 (4): 1201-1215. Epub 2009 December 01.

Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) es una plaga polífaga, cosmopolita y de gran relevancia mundial, sobre todo como vector de virus en numerosos cultivos, por lo que sería deseable un enfoque preventivo para su manejo. En tal sentido, podría recurrirse a la utilización de sustancias repelentes o disuasivas, algunas de ellas presentes en plantas tropicales, lo cual contribuiría al aprovechamiento de la rica biodiversidad mesoamericana. Por tanto, se evaluó la posible actividad fagodisuasiva sobre los adultos de B. tabaci de dos especies silvestres de la familia Asteraceae: titonia (Tithonia diversifolia (Hemsl.) A. Gray) y tora (Montanoa hibiscifolia Benth.). Para ello, en condiciones de invernadero se evaluaron los extractos crudos y cuatro fracciones (hexano, diclorometano, acetato de etilo y metanol) de ambas especies, a los cuales se les hizo un análisis fitoquímico (tamizaje) el cual permitió determinar cuáles metabolitos presentes en T. diversifolia y M. hibiscifolia podrían causar fagodisuasión en B. tabaci. Se realizaron dos tipos de experimentos: de escogencia restringida y de escogencia irrestricta. En los primeros, cada fracción se evaluó a cuatro dosis (0.1, 0.5, 1.0 y 1.5% v/v), y se comparó con cuatro tratamientos testigo: aceite agrícola, endosulfán, un emulsificante (Citowett) y un testigo absoluto (agua). Se asperjaron plantas de tomate colocadas dentro de jaulas de manga, donde se liberaron 50 adultos de B. tabaci. Para determinar si existía fagodisuasión se utilizó como criterio el número de adultos posados a las 48h. Para el experimento de escogencia irrestricta se utilizaron las dos concentraciones más altas (1.0 y 1.5%) del extracto crudo de cada especie y se compararon con el aceite agrícola y agua. Los extractos crudos de titonia y tora causaron fagodisuasión, y para ambas especies la fracción de metanol fue la que más sobresalió. En conclusión, los resultados obtenidos en los bioensayos junto con los obtenidos en el análisis de los componentes químicos presentes, sugieren que los metabolitos causantes de la fagodisuasión son algunas lactonas sesquiterpénicas, compuestos polifenólicos (flavonoides y taninos) y saponinas.

Antifeedant activity of botanical crude extracts and their fractions on Bemisia tabaci (Homoptera: Aleyrodidae) adults: I. Gliricidia sepium (Fabaceae)

Bemisia tabaci is an important virus vector on a number of crops worldwide. Therefore, a preventive approach to deal with viral epidemics may be the deployment of repellents or phagodeterrents at earlier stages of plant development (critical period). Thus, the crude extract and four fractions thereof (water, water:methanol, methanol, and diethyl ether) of mother-of-cocoa (Gliricidia sepium, Fabaceae) were tested for phagodeterrence to B. tabaci adults under greenhouse conditions, on tomato plants, in Costa Rica. Both restricted-choice and unrestricted-choice experiments showed that the crude extract and some fractions exerted such effect on the insect. In the former (in sleeve cages), three fractions caused deterrence at doses as low as 0.1% (methanol), 0.5% (water:methanol) and 1.5% (diethyl ether). However, in the latter (plants exposed in a greenhouse) no one of the fractions performed well, suggesting that the deterrent principles somehow decomposed under the experimental conditions. Rev. Biol. Trop. 56 (4): 2099-2113. Epub 2008 December 12.

Mundialmente, Bemisia tabaci es un importante vector de virus en numerosos cultivos. Por tanto, un enfoque preventivo para enfrentar las epidemias virales podría ser el empleo de sustancias repelentes o fagodisuasivas en las etapas tempranas del desarrollo de las plantas (período crítico). Así, tanto el extracto crudo como cuatro fracciones (agua, agua:metanol, metanol y éter dietílico) del madero negro (Gliricidia sepium, Fabaceae) fueron evaluadas en cuanto a su actividad fagodisuasiva sobre los adultos de B. tabaci en condiciones de invernadero, utilizando plantas de tomate, en Turrialba, Costa Rica. Tanto los experimentos de escogencia restringida como los de escogencia irrestricta revelaron que el extracto crudo y algunas fracciones mostraron dicha actividad. En los primeros experimentos (en jaulas de manga), tres fracciones causaron fagodisuasión a dosis tan bajas como 0.1% (metanol), 0.5% (agua:metanol) y 1.5% (éter dietílico). Sin embargo, en los segundos (plantas expuestas dentro de un invernadero) ninguna de las fracciones lo hizo, lo cual sugiere que los principios fagodisuasivos perdieron su actividad en esas condiciones experimentales.