Broad mite—Polyphagotarsonemus latus and cyclamen mite—Phytonemus pallidus
Broad mite and cyclamen mite are types of thread-footed mites (family Tarsonemidae) so named because of the long, thin appendage on the adults' rear legs.
Identification
Because of their tiny size, their damage symptoms as described below are generally the first and only obvious clue that thread-footed mites are present. Note that similar damage symptoms can be caused by adverse growing conditions, certain nutrient deficiencies (e.g., boron or zinc deficiency), and injury from herbicides including 2,4,-D, other broadleaf herbicides, and glyphosate.
Broad mite and cyclamen mite adult females are about 1/100 inch (0.25 mm) long, about one-fourth the size of spider mites. Males are about one-half the length of females. Thread-footed mites cannot be seen without a microscope or at least a 20× hand lens. Adults have 4 pairs of legs and immatures have 3 pairs.
Broad mites are oval shaped and commonly translucent to amber, greenish, or yellowish. Adult females have a white stripe down the center of their back. Broad mites have a tapered body that is widest between their second pair of legs and narrower toward the rear. Broad mite eggs have rows of tiny pale pegs protruding from the upper surface.
Cyclamen mite adults can be pale yellow, pinkish orange, or translucent white. The sides of their body are nearly parallel, not sharply tapered as with broad mite. Cyclamen mite eggs are pale, smooth ovals about one-half the length of adults.
Life cycle
Cyclamen and broad mites develop through 4 life stages: egg, larva, nymph, and adult. An adult female broad mite lays about 20 eggs during her lifetime. Broad mite is most abundant under warm, humid conditions. Egg to adult development time is about 6 to 10 days when temperatures are warm.
An adult female cyclamen mite lays about 12 to 20 eggs during her lifetime. Cyclamen mite does best under cool, humid or moist conditions. Egg to adult development time is 5 to 21 days, the shorter at warmer temperatures.
Damage
Broad mites and cyclamen mites in California primarily infest and damage herbaceous ornamentals. While feeding they inject plant parts with a toxic saliva. Infested leaves become cupped, curled, dwarfed, and thickened. Leaves or flowers may become bronzed or otherwise discolored and stiff. Infested buds deform, discolor, or drop. Internodes may be short, giving plants a stunted or tufted appearance. Damage does not become apparent until sometime after the mite feeding when plant tissues expand and grow.
Broad mite in California is primarily a pest in greenhouses and ornamental nurseries. Hosts of broad mites include African violet, azalea, begonia, chrysanthemum, dahlia, Exacum, gerbera, impatiens, ivy, peppers, rhododendron, and zinnia. Lemons grown near the coast and sporadically caneberries are also hosts. On coastal lemons broad mites can be abundant from late July through early October, especially on trees with Argentine ants. Broad mites on lemons often occur with citrus rust mites. The citrus rust mite (family Eriophyidae) is usually the more abundant species. Feeding of both of these mites discolors lemon rinds causing fruit to discolor and appear scabby with shallow cracks.
Cyclamen mite hosts include African violet, alyssum, azalea, begonia, bouvardia, carnation, chrysanthemum, cyclamen, dahlia, Exacum, fuchsia, geranium, gerbera, gloxinia, impatiens, ivy, ixia, kalanchoe, larkspur, Marguerite daisy, peppers, petunia, pouch flower, rhododendron, schefflera, snapdragon, strawberry, and verbena.
Solutions
Amblyseius and Neoseiulus species predatory mites and sixspotted thrips provide biological control of broad mites in some situations. That naturally occurring predators can sometimes be important is indicated by the pest mites being more common when Argentine ants that disrupt biological control are present. These predaceous mites are commercially available and sometimes released in greenhouses. To allow natural enemies to be potentially effective, control ants, minimize dustiness (e.g., periodically hose-off plants), and avoid the application of miticides and broad-spectrum, persistent insecticides. See Natural Enemy Releases for Biological Control of Crop Pests and Protecting Natural Enemies and Pollinators for more information.
Establish new plantings from mite-free stock. Avoid planting uninfested hosts near infested plants. Regularly inspect plants and disinfest or dispose of them if their appearance or growth is unacceptable.
Broad and cyclamen mites are difficult to control with pesticides. They are protected from sprays by their habit of feeding in buds or within distorted tissue. By the time tissue grows and damage becomes apparent, the mites may no longer be present or causing damage. Where broad mites or cyclamen mites have been problems and pesticides will be applied, it may be best to delay application until the next growing season and spray terminals as new growth develops. Potentially effective miticides available to home gardeners include horticultural oil, insecticidal soap, neem oil, and wettable sulfur. Effective products available only to professional pesticide applicators include abamectin and fenpyroximate.
For more information see Common Name: Broad Mite Scientific Name: Polyphagotarsonemus latus (Banks) (Arachnida: Acari: Tarsonemidae) and Common Name: Cyclamen Mite Scientific Name: Phytonemus pallidus (Banks) (Arachnida: Acari: Tarsonemidae) from the University of Florida and The World Genera of Tarsonemidae (Acari: Heterostigmata): a Morphological, Phylogenetic, and Systematic Revision, with a Reclassification of Family-Group Taxa in the Heterostigmata from Agriculture Canada.
Adapted from the publications above and Integrated Pest Management for Citrus, Pests of the Garden and Small Farm: A Grower's Guide to Using Less Pesticide, and Pests of Landscape Trees and Shrubs: An Integrated Pest Management Guide, University of California Statewide Integrated Pest Management Program (UC IPM). |
Citrus leaves distorted and undersized from feeding of broad mite.
Leaf distortion from feeding of cyclamen mite.
Adult (top center) and eggs of broad mite.
Adult cyclamen mite.
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