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MYCOPHAGOUS MITES AND FOLIAR PATHOGENS: LEAF DOMATIA MEDIATE TRITROPHIC INTERACTIONS IN GRAPES
Author(s) -
Norton Andrew P.,
English-Loeb Greg,
Gadoury David,
Seem Robert C.
Publication year - 2000
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1890/0012-9658(2000)081[0490:mmafpl]2.0.co;2
Subject(s) - biology , powdery mildew , botany , mildew , mite
Acarodomatia are small structures found on the underside of the leaves of many woody plant species. Several taxa of nonphytophagous mites are frequently associated with these small tufts of hair or invaginations of the leaf surface. Botanists, and more recently ecologists, have hypothesized that these structures mediate a mutualistic association between the plants and predaceous and microbivorous (microbe‐feeding) mites. We examined the influence of domatia on the abundance of a tydeid mite, Orthotydeus lambi, on the riverbank grape, Vitis riparia, and its impact on a key fungal pathogen, grape powdery mildew, Uncinula necator. In two field experiments, we manipulated domatia (by blocking them with glue or using clones that varied in domatia size) and O. lambi densities on V. riparia vines that we had inoculated with mildew. Mite densities were significantly higher on plants with intact domatia than on plants with blocked domatia (38% and 200% greater in experiments 1 and 2, respectively). In addition, clones with larger domatia had significantly more mites than clones with smaller domatia. In the first experiment, the greater number of mites on plants with domatia relative to plants without domatia did not translate into reduced incidence of mildew; mites reduced mildew to very low levels in both treatments. In the second experiment, plants with intact domatia had a significant 48% reduction in leaf area covered with mildew relative to plants with blocked domatia. In addition, clones with larger domatia (and thus more O. lambi ) had less mildew than clones with smaller domatia. This study represents the first experimental evidence that acarodomatia benefit plants through increased abundance of a mycophagous mite, which resulted in decreased severity of a plant disease.