Submitted to: Australian Journal of Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/20/2004
Publication Date: 6/1/2005
Citation: Freeman, T., Goolsby, J., Ozman, S., Nelson, D.R. An ultrastructural study of the relationship between the mite floracarus perrepae (eriophyidae)and the fern lygodium microphyllum (cav) r. br (lygodiaceae).. Journal of Australian Entomology. 44:57-61. Interpretive Summary: Old World climbing fern, Lygodium microphyllum, is native to the wet tropics of Australia, Africa and Asia and has become a serious invasive weed in the Florida Everglades. One of the most common herbivores in the native range of L. microphyllum is a plant-feeding mite, Floracarus perrepae. This paper provides high magnification pictures using an electron microscope of the mite, its feeding behaviour and the unique leaf rolls that it induces in its host plant, L. microphyllum. We determined that mites mouthparts were able to penetrate the leaf tissue of all the different genotypes or forms of the fern. The mites inability to induce leaf rolls in some genotypes is likely caused by specific biochemical processes that are developed between the each mite genotype and its local fern genotype. This is significant because it explains why the mite is so host specific to its host plant, which means that it poses little or no risk to other related ferns and plants in Florida where it is proposed for release as a biological control agent.
Technical Abstract: The ultrastructure of Floracarus perrepae was investigated in relation to its host, Lygodium microphyllum. Feeding by the mite induces a change in epidermal cell size and cell division is stimulated by mite feeding, causing the leaf margin to curl over into a roll with two to three windings. The enlarged epidermal layer greatly increases cytoplasmic contents which becomes a nutritive tissue for the mite and its progeny. The structure and depth of stylet penetration by the mite, and the thickness of the epidermal cell wall of L. microphyllum, does not appear to account for its differential ability to induce leaf rolling in its co-adapted host from southeast Queensland and not the invasive genotype of the fern in Florida.