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Opportunistic huckleberry aphidOn this page: Identification & Distribution Other aphids on the same host
Identification & Distribution
Adult apterae of Macrosiphum opportunisticum are medium to dark green, or sometimes reddish pink, and are without any wax covering (cf. Macrosiphum parvifolii on Vaccinium, which is pale green or pink, and is covered with white powdery wax). The antennae are dusky at the base, but darken towards the apices, with segments V and VI dark brown. The longest hair on antennal segment III is 0.40–0.75 times the basal diameter of that segment (cf. Macrosiphum euphorbiae, which has the longest hair 0.6-1.0 times the basal diameter). Antennal tubercles are relatively large, slightly diverging, and with 1–3 hairs medially, 1 hair ventrally. The rostrum reaches to the front edge of the metacoxae. The apical rostral segment (RIV+V) is 0.88–0.97 times the second hind tarsal segment (HTII) and bears 7–12 accessory hairs. The abdominal tergum is sclerotic, and marginal tubercles are often present on abdominal segments II–VI. There are 3-4 hairs on tarsal segment I (cf. Illinoia menziesiae, which has 5 hairs on that segment). The siphunculi are dusky at the base, darkening to brown apically, and are cylindrical or very slightly swollen on the distal half. They have about 7 rows of polygonal reticulations distally, with the reticulated area often constricted (cf. Ericaphis wakibae, which has no subapical polygonal reticulation). The cauda is pale or dusky, and bears 6-8 hairs. The body length of adult Macrosiphum opportunisticum apterae is 2.05-3.11 mm.
Macrosiphum opportunisticum alatae have the thorax and head dark brown, and the abdomen dark green or pink. The abdomen has brown marginal sclerites, and brown pleural intersegmental sclerites on segments II–VI. Abdominal segments II and III sometimes have irregular brown sclerotic patches in the spinal region. Tergite VI sometimes has a small spinal patch, and tergites VII and VIII have complete dorsal bands. The postsiphuncular sclerites are large. The siphunculi are usually entirely dark brown, sometimes paler at the extreme base, and the cauda is dusky to dark.
Macrosiphum opportunisticum is monoecious holocyclic, with an unusually large range of host plants. Its hosts are mainly broad-leaved shrubs in the Ericaceae (Menziesia [= Rhododendron], Azaleastrum, Bryanthus, Pieris, Vaccinium), but it has also been found on Altingiaceae (Liquidambar), Caprifoliaceae (Symphoricarpos), Celastraceae (Paxistima myrsinites), Rosaceae (Holodiscus, Sorbus and Spiraea), and Tsuga. Jensen (2012) named the species opportunisticum to reflect its ability to take advantage of whatever shrub in its montane habitat is able to first produce young growth in spring. They live dispersed on the host plants and drop readily when disturbed. An unusually large proportion of specimens are alate. Macrosiphum opportunisticum occurs mostly in the mountainous areas of north-western USA and British Columbia, but also sometimes near sea level.
Other aphids on the same host
Macrosiphum opportunisticum has been recorded on 3 Vaccinium species (Vaccinium membranaceum, Vaccinium parvifolium, Vaccinium scoparium).
Macrosiphum opportunisticum has been recorded on 1 menziesia species (Menziesia ferruginea).
Macrosiphum opportunisticum has been recorded on 1 Holodiscus species (Holodiscus discolor).