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Black-backed currant aphidOn this page: Identification & Distribution Other aphids on the same host
Identification & Distribution
Adult apterae of Nasonovia grossa (see first picture below) are a vivid green, with black crossbars on the dorsum, not extending to the spiracles. The cross bars are fused into a dark shield from metanotum to abdominal tergite V or VI, with separate bars on tergites VI-VIII and postsiphuncular sclerites (cf. Nasonovia houghtonensis & Nasonovia cynosbati, which never have an extensive dark area on the dorsum). Siphunculi and cauda are both dark. The antennae have segments III-V dark apically, and segment VI dark; they are 1.0-1.2 times the body, with the terminal process 6.4-7.1 times the base of antennal segment VI. Rather small secondary rhinaria are distributed 6-10 on the basal half of antennal segment III, with none on segments IV and V. The longest hair on antennal segment III is 1.3-1.9 times the basal diameter of that segment. The apical rostral segment is 2.3-2.7 times the second hind tarsal segment. Small marginal tubercles are present on the prothorax, and some or all of tergites II-V. First tarsal segments have 3 or 4 hairs. The siphunculi are 0.20-0.22 times body length, and 2.6-3.0 times the cauda. The cauda is tongue-shaped, broad, not constricted, with 5(-7) hairs. Body length of adult Nasonovia grossa apterae is 2.9-3.2 mm.
Images above copyright Andrew Jensen, under a creative common licence.
The alate Nasonovia grossa (second picture above) has the abdomen with cross bars forming a large spot, with small "windows" on segment I-V or III-V. Marginal sclerites are rather small, and indistinctly limited. The siphunculi are dark, somewhat paler towards the apices, and the cauda is dusky or rather dark. Secondary rhinaria on the antennae are distributed 16-28 on segment III, 0-3 on IV, and 0 on V. Wing veins are dark. Body length is 2.9-3.4 mm.
First image above copyright Ellyne Geurts, second image copyright Walter Siegmund,
Nasonovia grossa has been found on several Ribes species, including wax currant (Ribes cereum), whitestem gooseberry (Ribes inerme), and sticky currant (Ribes viscosissimum) (see first picture above). It has long been thought to be monoecious on Ribes, but Jensen in AphidTrek has reported that it appears to host alternate to monkeyflower (Erythranthe = Mimulus), in particular purple monkeyflower (Erythranthe lewisii) (see second picture above). He has also found the oviparae and alate males on Ribes in September, and what appear to be the fundatrices the following spring. Unlike the apterous viviparae, the oviparae are very small, pale yellowish, blending almost perfectly among the veins of the Ribes leaves as they are yellowing and dropping from the plants. Nasonovia grossa is found in the Rocky Mountain region, USA.
Other aphids on the same host
Nasonovia grossa has been reported on 3 Ribes species (Ribes cereum, Ribes inerme, Ribes viscosissimum).