The cyclamen mite (Phytonemus pallidus) is a harmful strawberry pest as well as a common pest found in cyclamen, gerbera and other ornamentals.
Mites belonging to the family of tarsonemids (Tarsonemidae) display a greater diversity of feeding habits than any other mite family. There are species that feed on fungi, algae, plants, as well as insect and mite predators and parasites. Those living on plants can cause considerable damage to their host.
Tarsonemids like the cyclamen mite (Phytonemus pallidus) can occur both on vegetable and ornamental crops.
Life cycle and appearance of Cyclamen mite
The life cycle of the cyclamen mite (Phytonemus pallidus) has the following stages: egg, larva, and adult. However, pharate females remain in their larval skin until they emerge. This stage is often considered a fourth stage called pupa, false pupa or quiescent nymph.
Adult females are yellowish brown, about 0.25 mm long, with the hind legs reduced to slender threadlike structures that are not used for walking. The males are smaller than the females and their hind legs are modified and used to transport pharate females.
Eggs of the cyclamen mite are about half the size of the adult mite. They are oval in form, smooth, transparent and twice as long as they are wide. Both ends are equally rounded. The larvae are opaque white and have only three pairs of legs. They develop into the resting stage (pharate nymph). This is a transitional stage between larva and adult mite during which the mite remains immobile on the leaf surface and does not feed.
The cyclamen mite (Phytonemus pallidus) feeds on plant sap by penetrating the plant tissue with its piercing-sucking mouth parts. The mites are mostly found within the flower buds, growing tips and young folded leaves, where the humidity is highest and they are protected from direct sunlight. In such spots, they are difficult to observe. Damage occurs in localized patches, because the mite spreads very slowly.
Symptoms vary depending on the host plant and can resemble the damage caused by viruses. Infested leaves are twisted or curled, distorted, brittle and smaller than usual.
In cyclamen, the flowers are damaged and leaf growth is inhibited. In hedera, a mite attack can cause baldness in parts of the stem. Gerbera flowers deform and discolour with the leaves turning bronze, mainly along the midrib. Even a mild infestation can cause enormous damage, and with heavier infestations plant growth is arrested and the flower buds are so badly affected that they shrivel and die.
Damaged strawberry leaves are wrinkled and irregularly folded. Affected plants have an unnaturally dense appearance because the petioles remain short. Severely attacked leaves become brittle, turn brown or silvery and die. Flowers and young fruits become brown near the base.