Persistence of a Yeast-Based (Hanseniaspora uvarum) Attract-and-Kill Formulation against Drosophila suzukii on Grape Leaves

Abstract

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 week.

Minimizing insecticides for control of spotted wing drosophila (Drosophila suzukii) in soft fruit using bait sprays

“…The current work confirms laboratory experiments, which showed that a suspension of H. uvarum can improve the efficacy of spinosad for control of D. suzukii (Bianchi et al, 2020;Mori et al, 2017;Noble et al, 2019). However, the results here, and in previous laboratory experiments (Noble et al, 2019), have shown that Combi-protec is at least as effective as H. uvarum as a D. suzukii bait and easier to use than a live yeast suspension.…”

Culturable Yeasts as Biofertilizers and Biopesticides for a Sustainable Agriculture: A Comprehensive Review

“…Another promising approach is the use of food-associated microbial VOCs to trap insect pests in crops. D. suzukii seems to respond to olfactory signals produced mainly by H. uvarum in field experiments, which could be translated into an opportunity for the development of an attract-and-kill control technique [ 129 , 130 , 131 ]. Similarly, pheromone-based methods for pest management are frequently used.…”

Behavioral manipulation of Drosophila suzukii for pest control: high attraction to yeast enhances insecticide efficacy when applied on leaves

“…(4) Vitis vinifera leaves and (5) H. uvarum applied on filter paper were tested to control for leaf and yeast volatiles, respectively. For the insecticide treatments, two leaves were sprayed, each with 250 μL of a formulation of yeast culture and spinosad (5.4 mg L –1 , treatment (2), comparable to doses applied in other studies, 31,35 ) or deltamethrin (7.5 mg L –1 , treatment (3)), respectively. Sprayed leaves were dried for 1.5 h at room temperature prior testing.…”

“…A promising approach to meet this need is the use of attractants or phagostimulants to control D. suzukii 26–31 . In fruit production, formulations of insecticides with attractants allow application without the need to spray the fruit.…”

“…[40][41][42] Not surprisingly, H. uvarum has been suggested for the development of attract-and-kill formulations against D. suzukii. 31,35,43 Moreover, H. uvarum suppresses plant pathogens 44 and was evaluated with qualified presumption of safety as biological control agent intentionally added to food or feed. 45 In viticulture, D. suzukii causes significant problems in the cultivation of certain Vitis vinifera (grapevine) varieties, such as Vernatsch (synonymous Trollinger, Schiava) traditionally grown in parts of Italy, Austria and Germany.…”