Endoparasitoidism Reflections on the Structure of a Cecidomyiid-Gall on Piptocarpha macropoda (DC.) Baker (Asteraceae)

Piptocarpha macropoda (DC.) Baker (Asteraceae) hosts globoid galls induced by cecidomyiid, which may occur as clusters or as solitary stem galls. The cecidomyiid in clustered galls is attacked by a Platygaster sp. (Hymenoptera: Platygastridae), a polyembryonic endoparasitoid. As each individual cecidomyiid supports many parasitoids, we suppose that high consumption of nutrients by the parasitized galling insect will impact gall structural and histochemical profiles. The parasitized and unparasitized galls were morphologically and histochemically evaluated and, in addition, the bodies of parasitized and unparasitized galling larvae were measured. The main consequence of the presence of the endoparasitoids over gall structure is the increase in gall size and nutritive cell layers. Despite the difference in size between galls with and without the endoparasitoids, the parasitized and unparasitized cecidomyiid larvae had similar sizes. This is evidence of a positive impact of the Platygaster sp. feeding demand over gall growth, but of a null impact on the cecidomyiid body. This scenario indicates a hyperstimulation on plant cells and tissues by the parasitized cecidomyiid.

Automated summary

Piptocarpha macropoda is a plant species that can develop globoid galls induced by insects. These galls can be attacked by parasitoid insects, which have a positive impact on gall size and nutritive cell layers. However, the parasitoid insects do not affect the size of the host insects, indicating an overstimulation on plant cells and tissues by the parasitized insects.