Field and greenhouse application of an attract-and-kill formulation based on the yeast Hanseniaspora uvarum and the insecticide spinosad to control Drosophila suzukii in grapes

BACKGROUND The invasive insect Drosophila suzukii (Matsumura) is an important pest of several red grape varieties. The yeast Hanseniaspora uvarum (Niehaus), which is associated with D. suzukii, strongly attracts flies and stimulates them to feed on yeast-laden food. In the present study, a formulation based on H. uvarum culture with spinosad insecticide was applied to the foliage of vineyards and control of D. suzukii was compared to applying spinosad to the whole plant. After successful H. uvarum and insecticide application in the vineyard, we tested additional H. uvarum-based formulations with spinosad in a greenhouse to determine their capacity to control D. suzukii. RESULTS Application of the H. uvarum-spinosad formulation at 36.4 g of spinosad per hectare reduced the D. suzukii field infestation at the same rate as applying 120 g of spinosad per hectare and prevented spinosad residues on grapes. Leaves treated with H. uvarum and spinosad in the field and transferred to a laboratory assay caused high mortality to flies and reduced the number of eggs laid on fruits. Formulations with spinosad applied in the greenhouse showed that both H. uvarum culture and the yeast cell-free supernatant of a centrifuged culture increased fly mortality and reduced the number of eggs laid compared to the unsprayed control. CONCLUSION In comparison to typical spinosad spray applications, the use of H. uvarum in combination with spinosad as an attract-and-kill formulation against D. suzukii reduces pesticide residues on the fruits by targeting the treatment to the canopy and decreasing the amount of insecticide per hectare without compromising control efficacy

Yeast species affects feeding and fitness of Drosophila suzukii adults

Yeasts play an important role in the life cycle and biology of the insect pest Drosophila suzukii (Matsumura), commonly known as the spotted wing drosophila (SWD). Adult and larvae of this species are known to feed and benefit from yeast in their diet. In addition, yeasts were found to be attractive to SWD and were repeatedly found to be associated with SWD. Among those, Hanseniaspora uvarum is the most commonly mentioned. The present study explores the chemical composition and the effects of three H. uvarum strains and five yeast species (Saccharomyces cerevisiae, Candida sp., Issatchenkia terricola, Metschnikowia pulcherrima and Saccharomycopsis vini) in the diet of SWD adults. The different yeast species used in this study influenced mortality, fecundity and ingestion by SWD females. Hanseniaspora uvarum and S. vini were preferably ingested and increased fecundity of SWD females. The intra- and extracellular concentrations of compounds, such as amino acids, carbohydrates, sugar alcohols and organic acids, produced or consumed by yeasts differed among the species. Knowledge of the interaction of different yeast species with SWD and specific differences in the profile of compounds of yeast can help to improve the development of control strategies against the insect pest by promoting the ingestion of attract-and-kill formulations based on the combinations of yeasts and an appropriate insecticide

Persistence of a yeast-based (Hanseniaspora uvarum) attract-and-kill formulation against Drosophila suzukii on grape leaves

The production of phagostimulant and attractive volatile organic compounds (VOCs) by yeasts can be exploited to improve the efficacy of attract-and-kill formulations against the spotted wing drosophila (SWD). This study evaluated the persistence over one week of a yeast-based formulation under greenhouse conditions. Potted grape plants were treated with: (i) potato dextrose broth (PDB), (ii) PDB containing spinosad (PDB + S), and (iii) H. uvarum fermentation broth grown on PDB containing spinosad (H. u. + S). Laboratory trials were performed to determine the survival and the oviposition rate of SWD after exposure to treated leaves. Ion-exchange chromatography was performed to measure carbohydrates, sugar alcohols, and organic acids on leaf surfaces, while amino acids were assessed through liquid chromatography–mass-spectrometry. Additionally, the VOCs released by plants treated with H.uvarum were collected via closed-loop-stripping analysis and compared to those emitted by untreated leaves. A higher mortality was observed for adult SWDs in contact with H. uvarum containing spinosad compared to PDB containing spinosad. Generally, a decrease in the amounts of non-volatile compounds was observed over time, though numerous nutrients were still present one week after treatment. The application of the yeast-based formulation induced the emission of VOCs by the treated leaves. The concentration of 2-phenylethanol, one of the main VOCs emitted by yeasts, decreased over time. These findings describe the presence of potential phagostimulants and compounds attractive to SWD in a yeast-based attract-and-kill formulation and demonstrate the efficacy of the formulation over one wee

Phenylpropanoids and Polyacetylenes from Ligusticum mutellina (Apiaceae) of Tyrolean Origin

Roots of Ligusticum mutellina (L.) CRANTZ afforded five major compounds, the phenylpropanoids trans-isoelemicin (1), sarisan (2), and trans-isomyristicin (3), and the polyacetylenes falcarindiol (4) and falcarindiol-3-O-acetate (5). Structures were assigned by 1D- and 2D-NMR spectroscopy. Close inspection of the NMR spectra of falcarindiol-3-O-acetate (5) and comparison with the literature revealed that published NMR data for this compound are most probably attributable to cis or trans Δ2-isofalcarindiol-1-O-acetate (6a/6b). 1H and 13C NMR data for falcarindiol-3-O-acetate are given and trans-isoelemicin (1), sarisan (2), and trans-isomyristicin (3), falcarindiol (4), and falcarindiol-3-O-acetate (5) are reported for the first time from Ligusticum mutellina. Chemosystematic and ethnopharmacological implications of the findings are discussed briefly

Mead fermentation monitoring by proton transfer reaction mass spectrometry and medium infrared probe

Mead is a traditional alcoholic beverage similar to wine, but obtained by the fermentation of a diluted solution of honey. The rate of fermentation is generally monitored by the measurement of a set of physicochemical variables such as pH, titratable acidity, Brix degrees, sugars and ethanol concentration. This work aims at developing a new monitoring method for alcoholic fermentations that is based on two on-line approaches: a proton transfer reaction mass spectrometry (PTR-MS) and a fibre optic coupled attenuated total reflection (FTIR-ATR) spectroscopy. Microfermentations are performed on 100 mL musts in isothermal conditions at 20 °C. Musts consist on diluted honey solutions (24 Bx) with pollen (0.4 % w/v) and yeast (Saccharomyces cerevisiae subsp. bayanus). The effect of flavour enhancers [chilli (Capsicum annuum), clove (Eugenia caryophyllata) and a mixture of both] on the rate of fermentation was also evaluated. The results show that clove inhibits fermentation, whereas chilli increases the rate of fermentation. PTR-MS and FTIR-ATR are simple, fast and nondestructive techniques able to monitor the fermentation process without the need of sample preparation, extraction or pre-concentration steps