Joana M. S. Ferreira

Interactions between Acetoin, a Plant Volatile, and Pheromone In Rhynchophorus palmarum: Behavioral and Olfactory Neuron Responses

Aggregation of Rhynchophorus palmarum weevils on host plants is mediated by a male pheromone (rhynchophorol: R) and host-plant volatiles (PVs) acting in synergy. Synthetic PV blends synergizing pheromone contain acetoin (A) and ethyl acetate (EtAc). R, A, and EtAc are detected by specialized olfactory receptor neurons (ORNs). In addition, particular types of ORNs are tuned to both A and R. To specify the role played by acetoin in pheromone perception, we recorded the responses of ORNs to 100 ng of A or R presented either separately or mixed. Behavioral responses to R, A, and EtAc were studied in a four-armed olfactometer and by field trapping. We screened 59 R-, A-, and AR-tuned ORNs by recording specific responses to odors presented either separately or mixed. Stimulations by blends elicited complex response profiles from the three ORN types: some gave synergistic responses, others were inhibited, and the remainder responded as though both odors were detected independently. Several gave either a weak or no response to a first stimulation by R, but responded clearly to a second stimulation after an intercalary stimulation by A. In the olfactometer, both sexes were more attracted to a blend of A + R (1 + 0.01 ng/sec) than to pure compounds, whereas EtAc did not enhance response to R. Pheromone-baited traps (1 mg/day) containing PV blends (650 mg/day) based on an ethanol/EtAc blend (1:1), plus either 5 or 10% A, or a more complex reference blend, or sugarcane (natural pheromone synergist), caught similar numbers of weevils and about twice as many insects as a control ethanol/EtAc blend. Traps with only pheromone caught about 10 times fewer insects. Behavioral results support the role of acetoin as a pheromone synergist for R. palmarum, and electrophysiological data provide evidence of modulation of peripheral sensory responses to pheromone by acetoin. Sexual dimorphism was observed neither at the ORN nor at the behavioral levels.

Determination of pesticides in coconut (Cocos nucifera Linn.) water and pulp using modified QuEChERS and LC-MS/MS

The use of pesticides is directly linked to improvements in productivity and to the preservation of coconut palms. However pesticide analysis is necessary to determine whether pesticide residues in the food products containing coconut are within the maximum residue limits (MRLs), ensuring the quality of these products. This work aimed to develop a method for multiresidue determination of ten pesticides in coconut water and pulp using QuEChERS and LC-MS/MS. The method was effective in terms of selectivity, linearity, matrix effect, accuracy and precision, providing LOD of 3μgkg(-1), LOQ of 10μgkg(-1) and recoveries between 70 and 120% with RSD lower than 20%. The developed method was applied to 36 samples in which residues of carbendazim, carbofuran, cyproconazole and thiabendazole were found below the LOQ in coconut water and pulp.

Determination of pesticide residues in coconut tree trunks by modified QuEChERS method and ultra-high-performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry

A rapid and reliable method for the determination of 10 pesticide residues in coconut (Cocos nucifera L.) tree trunks after endotherapy treatments has been established. A modified QuEChERS (quick, easy, cheap, effective, rugged and safe) method, using an homogeneous sample slurry and acetate buffer, followed by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed and validated. Under the best extraction conditions, the average recoveries for all pesticides spiked at 40, 80 and 200 μg kg−1 ranged from 70 to 93%, with RSD <10%. Intermediate precision expressed as RSD, ranged between 3 and 6% for all compounds. Calibration curves showed a wide linear range between 10.0 and 1000.0 μg kg−1 for all compounds studied. Limit of quantification was established as 40.0 μg kg−1. The developed procedure was employed in the analysis of real coconut tree trunk samples obtained 45 h after pesticides application using endotherapy treatment. Concentrations of pesticides were between 44.7 ± 5 and 938.3 ± 20 μg kg−1. These results prove the translocation of pesticides in different heights, in the coconut tree trunk, from the application point. Imidacloprid presented the highest acropetal translocation and was found near the leaves at 61 ± 6 μg kg−1.

Aspectos da biologia e morfologia da broca do pedúnculo floral do coqueiro, Homalinotus coriaceus (Gyllenhal) (Coleoptera: Curculionidae)

A broca do pedunculo floral do coqueiro, Homalinotus coriaceus (Gyllenhal), e uma praga limitante a producao de coco no Brasil, provocando a queda das flores e dos frutos imaturos. Sua biologia e pouco conhecida o que tem dificultado a seu manejo adequado no campo. Dessa forma, foi realizado o estudo da biologia desse inseto no Laboratorio de Entomologia da Embrapa Tabuleiros Costeiros - CPATC, em Aracaju, SE, a temperatura de 25 ± 2°C, umidade relativa de 70% e fotofase de 12h. Para alimentacao e oviposicao dos adultos coletados no campo foram utilizados toletes de cana-de-acucar como substrato, nos quais as femeas colocaram ovos individualizados, cujo periodo de incubacao variou de seis a 14 dias. As larvas foram criadas no mesocarpo de coco, desenvolvendo-se em 144 dias em media, passando por cinco a sete instares. O periodo pupal medio foi de 31 dias. A longevidade do adulto variou de 303 a 695 dias para femeas e de 246 a 635 dias para machos, sendo o ciclo de ovo a adulto de 181,9 dias para femeas e 188,5 para machos. Foram observadas diferencas morfologicas nas pupas e nos adultos, que podem ser utilizadas para separacao dos sexos. Ao contrario dos machos, as femeas apresentam, na fase de pupa, duas estruturas arredondadas e elevadas situadas na face ventral e final do abdome e, na fase adulta, o penultimo tergito abdominal projeta-se sobre o ultimo.

Feeding substrates to black coconut bunch weevil, Homalinotus coriaceus (Gyllenhal) (Coleoptera: Curculionidae), rearing in laboratory

A broca do cacho do coqueiro, Homalinotus coriaceus (Gyllenhal), e uma praga limitante da producao de coco no Brasil, sendo que tanto as larvas como os adultos provocam a queda das flores femininas e dos frutos imaturos, pela interceptacao do fluxo de seiva ou pela alimentacao direta nas estruturas reprodutivas. Em virtude da escassez de informacoes sobre sua biologia, realizou-se esse trabalho com o objetivo de desenvolver uma metodologia mais adequada para a criacao da praga em laboratorio. Foram utilizados os parâmetros biologicos para avaliacao e comparacao dos sistemas de criacao estudados.Toletes de cana-de-acucar foram utilizados como substrato para alimentacao dos adultos coletados no campo e obtencao dos ovos. As larvas foram criadas em tres substratos alimentares no Laboratorio de Entomologia da Embrapa-CPATC (Centro de Pesquisa Agropecuaria dos Tabuleiros Costeiros), em Aracaju, SE. Os substratos alimentares estudados foram: o mesocarpo do coco, dieta para criacao da broca dos citros e dieta para criacao da broca do olho do coqueiro, sendo esta a que proporcionou o melhor desenvolvimento larval num menor tempo, com boa viabilidade, maior facilidade no preparo e manutencao.

First report on the whitefly, Aleurodicus pseudugesii on the coconut palm, Cocos nucifera in Brazil

Abstract The coconut palm, Cocos nucifera L. (Arecales: Arecaceae), is currently grown extensively throughout the intertropical zones of the world, including Brazil, where it constitutes an important source of income for growers. Although whiteflies are not normally considered coconut pests, these insects can damage crops directly by sucking the sap, which weakens the plant; indirect damage may be caused by sooty mold formation over the excreted honeydew and by the transmission of pathogens. Whiteflies have infested coconut plants in the northeastern, northern, and southeastern regions of Brazil. Infested materials were collected and the causative insect was identified as Aleurodicus pseudugesii Martin (Hemiptera: Aleyrodidae). This is the first report of A. pseudugesii in Brazil as a pest of the coconut palm.

Parisoschoenus obesulus Casey (Coleoptera: Curculionidae) não é praga de frutos novos do coqueiro

This study aimed to evaluate if Parisoschoenus obesulus Casey only attacks naturally aborting coconuts and, consequently, is not a pest of young fruits of coconut tree. Aiming to test this hypothesis, inflorescences at diverse stages of physiological development were offered to individuals of P. obesulus. The results showed that only aborting fruits were colonized by P. obesulus corroborating the established hypothesis.

The invasive red palm mite, Raoiella indica Hirst (Acari: Tenuipalpidae), in Brazil: range extension and arrival into the most threatened area, the Northeast Region

ABSTRACT Raoiella indica Hirst (Acari: tenuipalpidae), commonly known as the red palm mite (RPM), is an invasive polyphagous pest, which has emerged as a threat to agriculture in the Americas. In the Americas, the mite has not only spread quickly, but also greatly extended its host range in the new areas where it has been observed. We present here new records of the RPM in Brazilian states, with focus on its arrival into the most threatened area, the Northeast Region. Coconut and banana are important crops in this region of Brazil and represent the main threatened crops by this pest. These new records of RPM reinforce the idea that this species is already widely distributed throughout Brazil eight years after its introduction into the extreme North state of Roraima. Comments on the possible economic, social and environmental impacts are presented.