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Trichosiphonaphis aphidsOn this page: Trichosiphonaphis polygonifoliae
Trichosiphonaphis are rather small Myzus-like aphids in East Asia, host alternating between Lonicera and Polygonum. The antennal tubercles are more or less well developed. The antennae have the base of antennal segment III rather broad, and a long terminal process. The siphunculi are squamous (= flattened), rather long, and in some species carrying hairs. The cauda is short and rounded.
There are about 12 Trichosiphonaphis species currently known, subdivided into two subgenera: Trichosiphonaphis s. str. and Xenomyzus. The three Trichosiphonaphis s. str. spp., have hairs on the siphunculi (hence the genus name), and the siphunculi have a distinct apical flange. The 7-9 Xenomyzus spp. may or may not have hairs on the siphunculi, and the siphunculi are flangeless.
The various species typically host alternate between honeysuckle (Lonicera) and knotweed (Polygonum). They are mainly found in east Asia, although two Xenomyzus species are found in north-eastern and central Europe, and one has been introduced into Europe from East Asia (see below).
Trichosiphonaphis polygonifoliae (Asian honeysuckle-knotgrass aphid) East Asia, invasive in Europe
Adult apterae of Trichosiphonaphis polygonifoliae (see colony below) are greenish brown. The antennal and median frontal tubercles of Trichosiphonaphis polygonifoliae are weakly developed. The antennae are a little shorter than the body, with a terminal process that is at least 6 times as long as the base of antennal segment VI. The apical rostral segment is distinctly longer than the base of antennal segment VI. The siphunculi are paler on the middle part, a little constricted near the tip, with a swollen apical rim, and 2.5-3.5 times the caudal length (cf. Trichosiphonaphis corticis & Trichosiphonaphis alpestris, which both have siphunculi completely flangeless, and 3.6-5.0 times the cauda). On the basal two-thirds of the siphunculi there are 8-16 minute hairs, at most only 5-11 µm long. The cauda is constricted on the distal part, with 6-9 hairs. The body length of adult Trichosiphonaphis polygonifoliae apterae is 1.8-2.5 mm. in length.
Images above by permission, copyright Dr László Érsek, all rights reserved.
The alate Trichosiphonaphis polygonifoliae (see second picture above) has the head, antennae and thorax black. The antennal tubercles are very short, slightly rounded, with one or 2 hairs. The antennae are a little shorter than body. The alate emigrant from the primary host has 16-46 oval or round secondary rhinaria on segment III, 0-16 on segment IV, and 0 on V. The alate sexupara returning from the secondary host has far more rhinaria, with 80-100 on III, 40-63 on IV, and 0-9 on V. The siphunculi are paler on the middle part, less imbricated on the distal half, and with some minute blunt hairs on the basal two-thirds. There are large marginal sclerites on tergites II-V & VII and a small one on VI; dorsal sclerites are present on tergites VII-VIII. The body length of adult Trichosiphonaphis polygonifoliae alatae is 1.8-2.0 mm.
In spring Trichosiphonaphis polygonifoliae feed in colonies on twigs of honeysuckle (Lonicera species). They host alternate in June-July to roots of knotgrass (Persicaria and Polygonum spp.). Trichosiphonaphis polygonifoliae is native to east Asia (Japan, China, Korea, east Siberia), but it has been introduced to Europe and seems to be increasing its range. It has been recorded from France, Italy, Serbia, Turkey, Britain (in suction trap), and (from this record) now Hungary.