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Gooseberry - willowherb aphid, Gooseberry aphidOn this page: Identification & Distribution Biology & Ecology Life cycle Ant attendance Natural enemies Damage and Control Other aphids on the same host
Identification & Distribution
Dense colonies of Aphis grossulariae at the growing tips of gooseberry cause severe deformation and clumping of young leaves (see first picture below) . The adult aptera of Aphis grossulariae (see second picture below) is dull green to dark green and is slightly to moderately wax powdered. The antennae are shorter than the body, and the hairs on the third antennal segment are straight or curved and at most 1-2 times the least width of that segment (cf. the very similar Aphis schneideri which has the hairs on the third antennal segment fine and wavy and conspicuously erect, 1.8-4.0 times the basal diameter of that segment). The abdominal dorsum is entirely membranous or at most has narrow dusky bands across tergites VII and VIII. Aphis grossulariae has marginal tubercles present on at least some of abdominal tergites II-VI (cf. Aphis epilobii and Aphis epilobiaria which have no marginal tubercles on abdominal tergites 2-6.) The siphunculi and legs are pale except for the tibial apices and tarsi which are dusky. The longest tibial hairs are greater than the least width of the hind tibia. The cauda is pale or slightly dusky. The body length of adult apterae is 1.2-2.1 mm.
The alate (see third picture above) has the head and thorax black, the abdomen green with dark stripes, the siphunculi and antennae dark and the cauda pale. Immature future alatae have paired pale white wax patches on the dorsum. The pictures below are micrographs showing (first) the marginal tubercles on the abdominal tergites, and (second) the hairs on the third antennal segment. In Europe there is evidence of natural hybridisation with Aphis schneideri (Rakauskas 2003).
The gooseberry - willowherb aphid host alternates between gooseberry (Ribes uva-crispa) where it curls the leaves and willowherb (Epilobium species). Certain members of the Onagaceae (Clarkia, Fuchsia, Oenothera) can also be used as secondary hosts. Sexual forms occur in autumn. Aphis grossulariae occurs throughout most of Europe to Russia and central Asia.
Biology & Ecology
Primary host (gooseberry)
The eggs of Aphis grossulariae are laid on gooseberry in autumn. They hatch in March and early April the following year to give the fundatrices (see picture below).
The fundatrices feed on the growing shoot and produce large numbers of apterous viviparae (see picture below).
These apterae then feed on the fruit buds and the tips of young shoots and produce large numbers of apterous and alate offspring. The immature apterous and alate viviparae are shown below.
Image above copyright Alan Outen, all rights reserved.
As numbers build up, an increasing proportion of aphids develop to alatae. The species produces an especially large number of alatae from May onwards which leads to rapid dispersal to other host plants. Third and fourth instar developing alatae (first) and a mature alate (second) are shown below.
Some Aphis grossulariae remain on gooseberry all year round, but others migrate to the secondary hosts.
Secondary host (willowherb)
The main secondary hosts are the smaller willowherb species such as Epilobium montanum and Epilobium lanceolatum. It lives on the stem and flower heads of willowherb often forming mixed species colonies with Aphis epilobii. The picture below shows a mixed colony of Aphis grossulariae with Aphis epilobii on Epilobium montanum.
Aphis grossulariae can also be found in the summer on evening primrose (see picture below):
Colonies of the gooseberry-willowherb aphid are often, but not always attended by ants.
The picture above shows the garden black ant (Lasius niger) attending Aphis grossulariae on currant. The picture below shows a red ant (Myrmica) attending the same species.
They are also sometimes ant-attended on the secondary host. The picture below shows a Lasius ant attending Aphis grossulariae on willowherb (Epilobium montanum)
Despite the attentions of ants such as Lasius, Aphis grossulariae may be subject to high rates of parasitism especially by Lysiphlebus confusus (Starý & Havelka, 2008).
Lysiphlebus confusus appears to possess specific adaptations, chemical and behavioural, that negate the aggressive responses of various ant species (Völkl & Mackauer, 1993). Evidence of ant mimicry by the closely related Lysiphlebus fabarum which parasitizes Aphis fabae was presented by Rasekh et al. (2010). They showed that the parasitoid used ant-like antennation to reduce Aphis fabae defensive behaviour, and their attacks primed Aphis fabae to be more responsive to subsequent honeydew solicitation from both ants and the parasitoids themselves.
Various predators attack Aphis grossulariae on gooseberry including cecidomyiid larvae (see picture below).
We have not yet observed any predators on the secondary host, but Gilbert (2005) notes that Aphis grossulariae is a preferred prey of the larvae of Episyrphus balteatus on willowherb.
Other aphids on same host:
Aphis grossulariae has been recorded from 29 Ribes species.
Damage and Control
The severe deformation and clumping of young leaves caused by the dense colonies of the gooseberry-willowherb aphid at the growing tips of gooseberry can result in stunting of growth. Hence in commercial crops of gooseberry an insecticide spray is often applied in spring just before flowering. Since Aphis grossulariae overwinter in the egg stage and hatch soon after bud burst, this approach usually gives good control (Gratwick, 1992). Foliar sprays may be needed subsequently to control winged aphids on the tips of the young shoots. A winter wash may also be applied to kill the overwintering eggs.