Malattie degli agrumi minatrice serpentina phyllocnistis citrella marco beconcini
Adult
Adults of the genus Phyllocnistis are very small moths with wingspans generally not exceeding 5 mm. Both fore- and hindwings are lanceolate and predominantly white. The forewings are marked with yellow to orange, longitudinal and oblique striae, often bordered by gray or black. A few species are known to possess much darker or strikingly color patterns. The compound eyes of Phyllocnistis are reduced, with an interocular index (vertical eye diameter/minimum interocular distance) of approximately 0.9. The maxillary palpi are the most reduced among Gracillariidae, being barely evident as vestigial, non-segmented lobes at the base of the elongate proboscis. The wing venation is also reduced.
Larvae
The larvae of Phyllocnistis are among the most specialized Lepidoptera. Four instars appear to be the norm, with the first three instars possessing a sapfeeding morphology and behavior. Sapfeeding instars create a long serpentine, subepidermal mine on either the upper or lower surfaces of the host leaf. A few species also form subepidermal mines on stems and various fruits, including avocado. A characteristic, median frass trail extends the length of the mine, usually as a dark, unbroken line. The fourth instar is a highly specialized, apodal, non-feeding instar whose primary function is to spin the cocoon, at the mine terminus, prior to pupation.
Pupae
In contrast to the conservative morphology of the larval and adult stages, the pupae of Phyllocnistis are structurally diverse, particularly with regard to the development of the frontal process (cocoon-cutter) of the head. In addition, the mid-dorsal areas of abdominal terga 3–7 possess a mostly symmetrical cluster of recurved spines that frequently differ in their arrangement and form among species.
Ecology
Phyllocnistis can be found on many host plants, and have been noted on plants from at least 20 families. One well-known species is the citrus leafminer (Phyllocnistis citrella), a pest of plants in the family Rutaceae, especially citrus.
Species
As of 2012, about 126 Phyllocnistis species have been described. This is probably a fraction of the true diversity of the genus, especially in the tropics, where there may be hundreds of species yet to be collected.
