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Short-beaked clover aphidOn this page: Identification & Distribution Biology & Ecology Ant attendance Other aphids on the same host Damage & Control
Identification & Distribution
Adult apterae of Nearctaphis bakeri are light greenish yellow with darker green patches, sometimes suffused with areas of orangey-pink around and anterior to the siphunculi (see first picture below). The dorsal abdomen has variably-developed dark bars on abdominal tergites V-VIII (see second adult aptera from left in second picture below) (cf. Nearctaphis californica, which has dorsal abdomen at least with complete broad dark cross-bands covering most of abdominal tergites V-VIII). All or most of the dorsal hairs arise from dark scleroites (cf. Nearctaphis crataegifoliae which has dorsal hairs mostly not arising from dark scleroites). The antennae are shorter than the body and are mostly pale apart from the apical segment which is dark. The apical rostral segment (R IV+V) is 0.10-0.13 mm long, with 2 (-3) accessory hairs (cf. Nearctaphis crataegifoliae, which has R IV+V 0.14-0.18 mm long, usually with 4 accessory hairs). The femora and tibiae are light brown with dark apices and the hind tibiae are without scent glands. The siphunculi are short tapering with close-set rows of small spinules and a well developed apical flange. The siphunculi are pale (cf. Nearctaphis crataegifoliae, which has dusky or dark siphunculi). The body length of adult Nearctaphis bakeri apterae is 1.1-2.4 mm.
Images above by permission, copyright Claude Pilon, all rights reserved.
Immature Nearctaphis bakeri (see first picture below) have similar colouration to the adult apterae apart from sometimes dusky siphunculi and absence of any dorsal bands.
Alatae of Nearctaphis bakeri (see second picture above) have broad dark dorsal abdominal cross-bands forming a large central patch. Their antennae bear 25-38 secondary rhinaria on segment III, 3-11 rhinaria on segment IV and 0-4 rhinaria on segment V.
First image above copyright CBG Photography Group under a CC BY-NC-SA license.
In its native America Nearctaphis bakeri host alternates from its primary host (members of the apple tribe Maleae, formerly Pomoidea, in the Rosaceae) to herbaceous plants in the pea family (Fabaceae) such as Medicago, Melilotus and Trifolium (also sometimes on Capsella and Veronica). On red clover (Trifolium pratense) all parts of the plants may be colonised from the base of the stem, where populations may be ant-tented, to the flowers. Nearctaphis bakeri has been introduced (on clover?) to many other parts of the world including Europe, the Middle East and parts of Asia. These invasive populations reproduce all year parthenogenetically on the secondary hosts.
Biology & Ecology
Nearctaphis bakeri is usually ant attended, as is the northern species Nearctaphis yohoensis and probably other Neararctaphis spp.. The picture below shows ants attending aphids observed in Quebec, Canada.
Image above by permission, copyright Claude Pilon, all rights reserved.
Favret et al. (2010) recorded the ant Prenolepis imparis attending Nearctaphis bakeri in their aphid survey of the Great Smoky Mountains National Park in the states of Tennessee and North Carolina, USA. Shiran et al. (2013) recorded the ant Tapinoma simrothi attending Nearctaphis bakeri in central and southwestern parts of Iran. Tapinoma simrothi was the ant species most frequently found attending aphids, being associated with half of the 33 aphid species found.
Other aphids on the same host
Nearctaphis bakeri has been recorded on 2 species of hawthorn (Crataegus douglasii, Crataegus rivularis).
Nearctaphis bakeri has been recorded on 2 species of apple (Malus baccata, Malus domestica).
Nearctaphis bakeri has been recorded on 1 species of pear (Pyrus communis).
Nearctaphis bakeri has been recorded on 8 Trifolium species (Trifolium angustifolium, Trifolium hybridum, Trifolium incarnatum, Trifolium macrocephalum, Trifolium microphyllum, Trifolium pratense, Trifolium repens, Trifolium resupinatum).
Nearctaphis bakeri has been recorded on 1 Medicago species (Medicago sativa).
Damage and control
In USA the short-beaked clover aphid is regarded as a major pest of red clover. In Oregon aphid infestations significantly reduce red clover seed yields if not controlled early in the season. When half the stems show signs of aphids, insecticide treatment should be applied - see Pacific Northwest Pest Management Handbooks for recommended insecticides. Pre-bloom spraying is recommended as bloom and postbloom treatments do little to prevent honeydew problems or increase seed yield.