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Plum - grass aphidsOn this page: Hysteroneura setariae
Hysteroneura apterae are brown with little or no dorsal sclerotization. The antennal tubercles are only weakly developed. The antennae are 6-segmented, with a long terminal process, about 5 times the base of antennal segment VI. Compound eyes and triommatidia are present in both aptera and alate. The rostrum has the apical segment short, and slightly tapered, with the apex rounded. The prothorax has marginal tubercles. Marginal abdominal tubercles are normally present on abdominal segments II-VII. Siphunculi are black, elongate, tapering, nearly cylindrical, heavily imbricated and lack hairs; the apical flange is vestigial. The cauda is elongate, tapering and pale. Hysteroneura alatae have round secondary rhinaria without ciliate margins present on antennal segment III. The forewing media vein has 3 branches, and the branches of the cubitus are widely separated at the base, and somewhat divergent. The hind wing has a single cross vein (cf. Rhopalosiphum and Schizaphis, whose hind wings have two oblique veins). Marginal sclerites are present on the abdomen.
In temperate climates the single known Hysteroneura species host alternates from Prunus species, where pseudogalls of deformed leaves are produced, to various species of grasses (Poaceae) and sedges (Cyperaceae). In warmer countries populations are often anholocyclic on grasses.
Hysteroneura setariae (Rusty plum aphid) Cosmopolitan in warmer parts of world
Adult apterae of Hysteroneura setariae (see first picture below) are dark chocolate brown, usually with a slight olive tint. The antennae have segments I, II, V and VI dark brown, and segments III to IV shading from yellowish white to brown (cf. Rhopalosiphum and Schizaphis spp., which usually have antennal segment IV completely pigmented). The antennal terminal process is 5.0-6.3 times the length of the base of antennal segment VI. The apical rostral segment (RIV+V) is 0.9-1.5 times the length of the second hind tarsal segment (HTII). The femora are mostly dark, but pale at the base; the tibiae are mostly pale, but dark distally. The siphunculi are black and slightly swollen on the basal half; they are 0.8-2.5 times the caudal length. The cauda is long and very pale, with only 4 hairs. The body length of adult Hysteroneura setariae apterae is 1.3-2.1 mm.
First image above by permission, copyright Sunil Joshi & Poorani, J. Aphids of Karnataka (accessed 12/2/20),
The Hysteroneura setariae alate (see second picture above) is similarly coloured to the aptera. The basal 0.7 of antennal segment IV is pale. The hind wing has only one oblique vein.
In temperate North America Hysteroneura setariae host alternates from domestic plum (Prunus domestica) to many species of grasses (Poaceae) and sedges (Cyperaceae). In warmer parts of the world (Australia, Africa, India, China, South America) the rusty plum aphid is anholocyclic on grasses, sedges and on seedlings of oil palms and coconuts (Arecaceae). They commonly feed at the bases of the spikelets or sometimes on the leaves or unripe seeds (see pictures above). The rusty plum aphid is often attended by ants (see second picture above).