Vando Miossi Rondelli

Insecticidal activity of citronella grass essential oil on Frankliniella schultzei and Myzus persicae

The thrips, Frankliniella schultzei, and green peach aphid, Myzus persicae, cause direct damage to plants of economic importance and transmit phytoviruses, causing large economic losses. Chemical constituents of essential oils present a wide range of biological activities. The aim of this work was to evaluate insecticidal activity of essential oil from citronella grass, Cymbopogon winterianus, on F. schultzei and M. persicae. This essential oil was obtained by steam distillation and components were identified by GC/FID and GC/MS. A Potter spray tower was used to spray insects with the essential oil. The major constituents are geraniol (28.62%), citronellal (23.62%) and citronellol (17.10%). Essential oil of C. winterianus at 1% (w v-1) causes mortality in F. schultzei and M. persicae at 34.3% and 96.9%, respectively. The LC50 value for M. persicae was 0.36% and LC90 0.66%. Thus, citronella grass essential oil at 1% (w v-1) is more toxic to M. persicae than F. schultzei. This essential oil shows promise for developing pesticides to manage M. persicae.

Associação do óleo de mamona com Beauveria bassiana no controle da traça-das-crucíferas

Abstract – The objective of this work was to evaluate the efficiency,the stability, the application mode and the compatibility between castor bean oil and the entomopathogenic fungus Beauveria bassiana , for diamondback moth ( Plutella xylostella ) control. In the firstexperiment, the efficiency,the stability after 70 days of storage, and the application mode of castor bean oil were evaluated. In the second one, the compatibility of castor bean oil with B. bassiana was evaluated. The insecticidal activity of the castor bean oil is unstable over time. The castor bean oil is compatible with B. bassiana against P. xylostella .Index terms: Beauveria bassiana , Plutella xylostella , Ricinus communis , entomopathogenic fungus. A traca‑das‑cruciferas, Diaphania nitidalis Plutella xylostella (L.) (Lepidoptera: Plutellidae), e a praga mais importante de plantas da familia Brassicaceae. Para o seu controle, utilizam-se basicamente inseticidas (Castelo Branco & Medeiros, 2001). No entanto, outros metodos para o controle desta praga tambem devem ser avaliados, entre os quais, a utilizacao de fungos entomopatogenicos, como

Chemical Composition of Essential Oil from Eucalyptus citriodora Leaves and Insecticidal Activity Against Myzus persicae and Frankliniella schultzei

Abstract Essential oils, volatile compounds obtained from plants, provide an alternative approach for controlling agricultural pests due to problems with conventional chemical products, such as insect resistance, environmental issues and human health concerns. This work aimed to extract essential oil from Eucalyptus citriodora to assess its chemical composition and insecticidal activity against the green peach aphid (Myzus persicae) and thrips (Frankliniella schultzei). The essential oil was obtained by hydrodistillation using the Clevenger apparatus and analyzed by gas chromatography with a flame ionization detector and mass spectrometry (GC-FID and GC-MS). A Potter tower was used to spray the insects with the essential oil solutions. The major components found in E. citriodora essential oil were citronellal (29.31 %), geraniol (27.63 %), β-citronellol (14.88 %) and δ-cadinene (6.32 %). Mortality of M. persicae and F. schultzei nymphs were 85.5 % and 34.8 %, respectively, using essential oil at 1 % (w v−1). Estimated values of LC50 (0.40 % w v−1) and LC90 (1.15% w v−1) for M. persicae evidences the potential use of E. citriodora essential oil in controlling this pest.

Seleção de isolados de Beauveria bassiana potenciais para o controle da traça-das-crucíferas

Diamondback moth (DBM), Plutella xylostella (Lepidoptera: Plutellidae), is considered the most important pest of brassicas worldwide and the use of insecticides is the most used method to control this pest. Thus, the objective of this research was to select isolates of Beauveria bassiana with viability to control DBM. Seventeen isolates and one commercial product of B. bassiana were tested. DBM 2nd instar larvae were treated with conidial suspension at concentration of 107 conidia mL-1. For lethal concentration (LC) bioassay seven concentrations spaced on logarithmic scale were tested. The isolates CCA/UFES-4, 18, 31 and 35 were selected for LC bioassay because they caused over 90% confirmed mortality. The standard isolate ESALQ-447 and the commercial product had similar results and were also selected for LC bioassay. Based on the values estimated for LC50, the isolates CCA/UFES-4, 18, 31, ESALQ-447 and the commercial product can be selected for use in DBM control.

Selection of Beauveria bassiana (Bals.) Vuill. isolates for controlling Sitophilus zeamais (Mots.) (Coleoptera: Curculionidae)

Sitophilus zeamais (Mots.) (Coleoptera: Curculionidae) is considered a major pest of maize, responsible for reducing grain quality and making the corn inappropriate for industrial use and human consumption. S. zeamais has been controlled exclusively with chemical products. The objective of this research was to select isolates of Beauveria bassiana (Bals.) Vuill. to control S. zeamais. Beetles were immersed in conidia suspensions of each isolate for five seconds and placed in a gerbox container with maize grains. In pathogenicity tests, the isolates that caused the highest mortality to the maize weevil were ESALQ-447 (68.0%), CCA-UFES/ Bb-36 (57.3%) and CCA-UFES/Bb-31 (51.3%). ESALQ-447 was the most virulent, with an LC50 of 1.7 x 107 conidia/ml and shows promise for controlling maize weevils. These isolates of B. bassiana can be used as effective substitutes for conventional chemical control, normally carried out with phosphine. Further tests should be performed under field and semi-field conditions to develop an appropriate strategy for the use of this entomopathogen to manage S. zeamais.

CARACTERIZAÇÃO QUÍMICA E EFEITO DO ÓLEO ESSENCIAL DE ERVA-DE-SANTA-MARIA SOBRE O ÁCARO-RAJADO DE MORANGUEIRO

The twospotted spider mite, Tetranychus urticae Koch (1836)(Acari: Tetranychidae), is the major pest in strawberry. The objective of this study was the chemical characterization of the essential oil of Chenopodium ambrosioides L. and the evaluation of their effects on twospotted spider mite. The compounds of the essential oil were identified by GC/FID and GC/MS analysis. The mortality and oviposition were evaluated after spraying the oil (2.5, 5.0, 7.5 and 10.0% v v-1) on twospotted spider mite females. The yield of the essential oil was of 0.3% and the compounds identified were (Z)-ascaridol (87%), (E)-ascaridol (5.04%), p-cymeno (4.83%), a-terpinene (1.24%) and piperitone (0.7%). The highest values for mortality and reduction of oviposition observed were 85% and 69%, respectively. C. ambrosioides essential oil is a promising option for the management of twospotted spider mite.