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Invasive Drosophila suzukii facilitates Drosophila melanogaster infestation and sour rot outbreaks in the vineyards

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ABSTRACT

How do invasive pests affect interactions between members of pre-existing agrosystems? The invasive pest Drosophila suzukii is suspected to be involved in the aetiology of sour rot, a grapevine disease that otherwise develops following Drosophila melanogaster infestation of wounded berries. We combined field observations with laboratory assays to disentangle the relative roles of both Drosophila in disease development. We observed the emergence of numerous D. suzukii, but no D. melanogaster flies, from bunches that started showing mild sour rot symptoms days after field collection. However, bunches that already showed severe rot symptoms in the field mostly contained D. melanogaster. In the laboratory, oviposition by D. suzukii triggered sour rot development. An independent assay showed the disease increased grape attractiveness to ovipositing D. melanogaster females. Our results suggest that in invaded vineyards, D. suzukii facilitates D. melanogaster infestation and, consequently, favours sour rot outbreaks. Rather than competing with close species, the invader subsequently permits their reproduction in otherwise non-accessible resources and may cause more frequent, or more extensive, disease outbreaks.

No MeSH data available.


Oviposition preference of D. melanogaster female in 2-choices assays. Females had to choose between (a) untreated, wounded grapes and grapes with sour rot and (b) untreated, wounded grapes and grapes with D. suzukii larvae. For each experiment, there were 27 replicates each involving a different female fly. Black dots indicate means and boxes confidence intervals of estimated means. We used the following formula to represent the preference index: 100 × [no. of eggs on treated grape − no. of eggs on untreated grape]/total number of eggs. **p ≤ 0.01 from a pairwise Wilcoxon's signed-rank test.
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RSOS170117F3: Oviposition preference of D. melanogaster female in 2-choices assays. Females had to choose between (a) untreated, wounded grapes and grapes with sour rot and (b) untreated, wounded grapes and grapes with D. suzukii larvae. For each experiment, there were 27 replicates each involving a different female fly. Black dots indicate means and boxes confidence intervals of estimated means. We used the following formula to represent the preference index: 100 × [no. of eggs on treated grape − no. of eggs on untreated grape]/total number of eggs. **p ≤ 0.01 from a pairwise Wilcoxon's signed-rank test.

Mentions: Finally, we determined whether D. suzukii larvae and/or sour rot were attractive for D. melanogaster with two-choices oviposition assays. The presence of D. suzukii larvae on the grape had no significant effect on D. melanogaster oviposition preference (Wilcoxon-paired, V = 11.5, p > 0.4; figure 3b). However, sour rot disease significantly attracted ovipositing D. melanogaster females (Wilcoxon-paired, V = 109, p < 0.006; figure 3a).Figure 3.


Invasive Drosophila suzukii facilitates Drosophila melanogaster infestation and sour rot outbreaks in the vineyards
Oviposition preference of D. melanogaster female in 2-choices assays. Females had to choose between (a) untreated, wounded grapes and grapes with sour rot and (b) untreated, wounded grapes and grapes with D. suzukii larvae. For each experiment, there were 27 replicates each involving a different female fly. Black dots indicate means and boxes confidence intervals of estimated means. We used the following formula to represent the preference index: 100 × [no. of eggs on treated grape − no. of eggs on untreated grape]/total number of eggs. **p ≤ 0.01 from a pairwise Wilcoxon's signed-rank test.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5383864&req=5

RSOS170117F3: Oviposition preference of D. melanogaster female in 2-choices assays. Females had to choose between (a) untreated, wounded grapes and grapes with sour rot and (b) untreated, wounded grapes and grapes with D. suzukii larvae. For each experiment, there were 27 replicates each involving a different female fly. Black dots indicate means and boxes confidence intervals of estimated means. We used the following formula to represent the preference index: 100 × [no. of eggs on treated grape − no. of eggs on untreated grape]/total number of eggs. **p ≤ 0.01 from a pairwise Wilcoxon's signed-rank test.
Mentions: Finally, we determined whether D. suzukii larvae and/or sour rot were attractive for D. melanogaster with two-choices oviposition assays. The presence of D. suzukii larvae on the grape had no significant effect on D. melanogaster oviposition preference (Wilcoxon-paired, V = 11.5, p > 0.4; figure 3b). However, sour rot disease significantly attracted ovipositing D. melanogaster females (Wilcoxon-paired, V = 109, p < 0.006; figure 3a).Figure 3.

View Article: PubMed Central - PubMed

ABSTRACT

How do invasive pests affect interactions between members of pre-existing agrosystems? The invasive pest Drosophila suzukii is suspected to be involved in the aetiology of sour rot, a grapevine disease that otherwise develops following Drosophila melanogaster infestation of wounded berries. We combined field observations with laboratory assays to disentangle the relative roles of both Drosophila in disease development. We observed the emergence of numerous D.&nbsp;suzukii, but no D.&nbsp;melanogaster flies, from bunches that started showing mild sour rot symptoms days after field collection. However, bunches that already showed severe rot symptoms in the field mostly contained D.&nbsp;melanogaster. In the laboratory, oviposition by D.&nbsp;suzukii triggered sour rot development. An independent assay showed the disease increased grape attractiveness to ovipositing D.&nbsp;melanogaster females. Our results suggest that in invaded vineyards, D.&nbsp;suzukii facilitates D.&nbsp;melanogaster infestation and, consequently, favours sour rot outbreaks. Rather than competing with close species, the invader subsequently permits their reproduction in otherwise non-accessible resources and may cause more frequent, or more extensive, disease outbreaks.

No MeSH data available.