Drosophila suzukii (Diptera: Drosophilidae) Contributes to the Development of Sour Rot in Grape

Abstract

This research aimed to more clearly describe the interactions of Drosophila suzukii (Matsumura; Diptera: Drosophilidae) with microorganisms that may contribute to spoilage or quality loss of wine grapes during harvest. Experiments were conducted in controlled laboratory experiments and under field conditions to determine these effects. Laboratory trials determined the role of insect contact and oviposition to vector spoilage bacteria onto wine grapes. In the field, the roles of key organoleptic parameters in grape fruit ripening were assessed to determine their relative contribution to oviposition potential as fruit ripened. Finally, field trials determined the relationships of egg and larval infestation to sour rot levels. Non-ovipositional trials indicated elevated levels of microbiota when D. suzukii was present. D. suzukii oviposition exponentially increased the concentration of acetic acid bacteria. Both incised and sound berries showed a significant increase in concentrations of acetic acid bacteria exposed to D. suzukii. Volatile acidity was higher in treatments infested with D. suzukii. Fruit with only eggs did not develop a significant increase of volatile acidity. Larva-infested grape berries in 9.5% of samples developed higher volatile acidity after 14 d. Sound grape berries were less susceptible to the development of microbiota associated with sour rot and spoilage. D. suzukii oviposition and larval development increase risk of spoilage bacteria vectored by D. suzukii adults. Acetic acid bacteria induced fermentation and produced several volatile compounds contributing to spoilage. Spoilage bacteria may create a positive feedback loop that attracts both D. suzukii and other drosophilids, which may contribute to additional spoilage.

Diurnal and Seasonal Activity Patterns of Drosophilid Species (Diptera: Drosophilidae) Present in Blackberry Agroecosystems With a Focus on Spotted-Wing Drosophila

“…With the exception of Hawaii, D. suzukii has caused economic losses throughout its introduced range. There is zero tolerance for larval infestation in harvested fruit, and in grapes, egg laying alone may result in increased disease incidence (Ioriatti et al 2018). Assuming 20% yield loss, revenue losses to D. suzukii in strawberries, blueberries, raspberries, blackberries, and cherries in California, Oregon, and Washington alone have been estimated at $511 million annually (Bolda et al 2010, Walsh et al 2011.…”

Single and combined effects of Drosophila suzukii and Drosophila melanogaster on sour rot development in viticulture

“…has a microbial contribution as vector for the microorganisms involved in sour rot development (Barata, Santos, et al, ). Previous studies even showed that this transfer can take place without egg‐laying solely through contact (Ioriatti et al, ). However, our findings from 2017 showed that the flies are not only crawling over the berry surface, spreading the agents involved in sour rot, but additionally were able to oviposit, develop through larval stages and emerge as adults (Figure ).…”

“…contributing to sour rot development are proposed. First, the flies are able to vector the yeasts and bacteria associated with the disease (Barata, Santos, et al, ; Ioriatti et al, ). More importantly, a recent study with axenic flies demonstrated that flies also play a non‐microbial role, presumably through the developing larvae, which themselves trigger the decomposition of berries and thereby reinforce sour rot development (Hall, Loeb, Cadle‐Davidson, et al, ).…”

Screening of 25 different natural crop protection products against Drosophila suzukii

“…In addition to the fruit damage caused by the developing D. suzukii larvae, oviposition wounds make attacked fruits more susceptible to later infestations by other insects and pathogenic microorganisms (Hamby, Hernandez, Boundy‐Mills, & Zalom, ; Ioriatti et al., ; Rombaut et al., ; Swett, Carignan, Hamby, & Koivunen, ). Consequently, the small‐fruit industry and the market have a zero tolerance to D. suzukii infestation (Bruck et al., ; Haye et al., ).…”