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 LC 50 value for M. persicae was 0.36% and LC 90 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. Index terms:Cymbopogon winterianus, thrips, green peach aphid, volatile components, natural insecticide. RESUMOO tripes, Frankliniella schultzei, e o pulgão-verde, Myzus persicae, além de causarem danos diretos a plantas de importância econômica, também são importantes transmissores de fitoviroses, acarretando grandes perdas econômicas. Os constituintes químicos dos óleos essenciais têm sido cada vez mais estudados, pois apresentam uma ampla gama de atividades biológicas. Neste trabalho, objetivou-se avaliar a atividade inseticida do óleo essencial de capim-citronela, Cymbopogon winterianus, sobre F. schultzei e M. persicae. O óleo essencial foi obtido por hidrodestilação e a identificação dos seus componentes foi realizada por CG/DIC e CG/EM. Uma torre de Potter foi utilizada para pulverizar os insetos com óleo essencial. Os componentes majoritários encontrados são geraniol (28,62%), citronelal (23,62%) e citronelol (17,10% ) é mais tóxico para M. persicae do que para F. schultzei. Este óleo essencial mostra-se promissor para o desenvolvimento de inseticidas para o manejo de M. persicae. Termos para indexação:Cymbopogon winterianus, tripes, pulgão-verde, componentes voláteis, inseticida natural.

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 LC 50 (0.40 % w v -1 ) and LC 90 (1.15% w v -1 ) for M. persicae evidences the potential use of E. citriodora essential oil in controlling this pest.

Natural enemies are exposed to insecticide sprays for herbivorous species and may evolve field resistance to insecticides. Natural enemies selected for resistance in the field, however, are welcome for pest control. The susceptibility of 20 populations of Eriopis connexa from various crop ecosystems to λ-cyhalothrin was tested. Three bioassays were conducted: (i) topical treatment with lethal dose (LD)50 previously determined for populations considered standard for susceptibility (LD50S) and for resistance (LD50R) to λ-cyhalothrin at technical grade; (ii) dose-mortality assay to calculate the LD for populations exhibiting significant survival to the LD50R; and (iii) determination of survival when exposed to dried residues at field rates. Among the 20 tested populations, seven populations did not survive or survival rates were lower than 10% when treated with LD50R; three populations survived >20%, but lower than 50%; while ten populations exhibited equal or greater survival rates compared with the 50% expected survival for the LD50R. Thus, these ten populations were subjected to dose-mortality response, and the LD50 values varied from 0.046 to 5.44 µg a.i./insect with resistance ratio of 8.52- to 884.08-folds. Adults from these ten populations that were ranked as resistant according to the LD50R exhibited survival from 44.5 to 100% exposed to the lowest and from 38.8 to 100% exposed to the highest field rates of λ-cyhalothrin, respectively. Otherwise, the remaining ten populations ranked as susceptible according to the LD50R showed survival from 3.3 to 56% exposed to the lowest and from 0 to 17.7% exposed to the highest field rates of λ-cyhalothrin, respectively. Therefore, 50% of the tested E. connexa populations exhibited field-evolved resistance to λ-cyhalothrin and the use of a discriminatory LD50 for resistance matched the survival obtained when exposed to the insecticide field rates.

Species of the nitidulid beetle Conotelus found in flowers of Convolvulaceae and other plants across the New World and in Hawaii consistently harbour a yeast community dominated by one or more large‐spored Metschnikowia species. We investigated the yeasts found in beetles and flowers of cultivated passionfruit in Rondônia state, in the Amazon biome of Brazil, where a Conotelus species damages the flowers and hinders fruit production. A sample of 46 beetles and 49 flowers yielded 86 and 83 yeast isolates, respectively. Whereas the flower community was dominated by Kodamaea ohmeri and Kurtzmaniella quercitrusa, the major yeasts recovered from beetles were Wickerhamiella occidentalis, which is commonly isolated from this community, and a novel species of large‐spored Metschnikowia in the arizonensis subclade, which we describe here as Metschnikowia amazonensis sp. nov. Phylogenetic analyses based on barcode sequences (ITS‐D1/D2) and a multigene alignment of 11,917 positions (genes ura2, msh6, and pmt2) agreed to place the new species as a sister to Metschnikowia arizonensis, a rare species known only from one locality in Arizona. The two form sterile asci when mated, which is typical of related members of the clade. The α pheromone of the new species is unique but typical of the subclade. The type of M. amazonensis sp. nov. is UFMG‐CM‐Y6309T (ex‐type CBS 16156T, mating type a), and the designated allotype (mating type α) is UFMG‐CM‐Y6307A (CBS 16155A). MycoBank MB 833560.

In robusta coffee, Coffea canephora, the black twig borer Xylosandrus compactus (Eichhoff) (Coleoptera: Curculionidae) causes considerable damage. Although this has been reported in many crops for years in Brazil, recently, the injury caused by X. compactus in coffee has been ignored. This present study aimed to report the current status of X. compactus in Brazil, and to investigate its attack frequency in different robusta coffee genotypes. In this study, we reported the occurrence of X. compactus in robusta coffee plants in the state of Rondônia for the first time. We also evaluated the occurrence of this pest in different robusta coffee genotypes in the state of Espírito Santo. In all plants, the plagiotropic branches were attacked; however, the genotypes G2, G6, G8, G20, G48, G50, G51 and G52 showed a high number of attacked plagiotropic branches, whereas the genotypes G24 and G41 showed a low attack frequency. Thus, these can be promising candidates for pest resistance studies. Moreover, it was reported that Almeidea rubra, Alseis floribunda, Plinia grandifolia and Casearia Sylvestris can serve as hosts of X. compactus. Thus, our findings suggest that X. compactus is a threat to coffee production, and that future studies are necessary to find appropriate tools for its management.