Table 1.
Parasitoid propensity to parasitize (PP) and infestation rate (IR).
Table 2.
Suitability of D. suzukii L1 and L2 larval stages for the parasitoid species/strains.
Fig 1.
Time-course of the wasp-host interaction in parasitized D. suzukii larvae.
Live larvae of D. suzukii parasitized by the different parasitoid strains or D. melanogaster YR (YR) parasitized by L. boulardi ISy were dissected at different time (0h-240h) and the main observed steps of the encapsulation response are reported. E, free parasitoid egg; EE, encapsulated parasitoid egg; FL, free parasitoid larva; LC, free parasitoid larva with a thin coat of light-colored cells; DL, dead parasitoid larva; EL, encapsulated parasitoid larva; W, developing wasp. Aj, Asobara japonica; Lv, Leptopilina victoriae; LhGoth, L. heterotoma Gotheron; LhJapan, L. heterotoma Japanese strain; Lbm, L. boulardi ISm strain; Lby, L. boulardi ISy strain; Lb16, L. boulardi strain 16.
Fig 2.
Encapsulation of L. boulardi ISy (Lby) eggs by the D. melanogaster YR strain.
D. melanogaster flies were observed and/or dissected at different times after parasitism: (A) after two hours, only free parasitoid eggs were recovered; (B) after 48h, almost all larvae contained an encapsulated egg. The capsules can be observed in the pupae 7 day (7d) post-parasitism (C) and in newborn flies (D) (arrows).
Fig 3.
Timing of encapsulation of L. boulardi Ism (Lbm) and L. heterotoma Gotheron eggs in D. suzukii larvae.
Host larvae were observed and/or dissected at different times following parasitism by L. boulardi ISm (Lbm) (A-D) or L. heterotoma Gotheron (E-I). 48h post-parasitism, free-living larvae were mainly observed for the two parasitoids (A and E). At 72h, Lbm larvae were entangled in a thin layer of cells, and a few melanization spots (arrows) were observed (B, C), whereas only a few cells were found on L. heterotoma larvae, without melanization (F, G). Most larvae parasitized by Lbm showed an over-melanization response, and the fly was unable to pupate and died (D). Surviving larvae parasitized by L. heterotoma continued to develop and pupae (H) and emerged adult flies contained a capsule (I). The size of the capsule formed by D. suzukii against L. heterotoma (J) and by D. melanogaster YR against L. boulardi ISy (Lby) (K) are compared. Bar is 0.2 mm.
Fig 4.
Analysis of D. suzukii physiological interaction with L. heterotoma and L. boulardi parasitoids.
D. suzukii L1 and L2 larvae parasitized by the French strain of L. heterotoma (LhGoth) or the field strain of L. boulardi (Lb16) were dissected 48h (L1 and L2) or 72h (L1) post-parasitism to evaluate the state of the immune response, as described in Fig 3. Pie charts give the percentage of alive or dead fly larvae containing free parasitoid larvae, free floating eggs, wasp eggs or parasitoid larvae only surrounded by a thin coat of lightly-colored cells, wasp eggs or larvae partially melanized (coat of lightly-colored cells with a few black spots), completely encapsulated parasitoid larvae (fully melanized) and completely encapsulated eggs.