InfluentialPoints.comBiology, images, analysis, design...
| Aphids | Find them | How to ID | ID by host |
| InfluentialPoints.com Biology, images, analysis, design... |
|
"It has long been an axiom of mine that the little things are infinitely the most important" |
|
|
Aphis idaeiSmall raspberry aphidOn this page: Identification & Distribution Biology & Ecology Other aphids on the same host Damage & ControlIdentification & DistributionViviparous apterae of Aphis idaei are small mottled green and yellow aphids, with dusky siphunculi and a pale cauda. They are covered with a rather even wax pulverulence giving an overall pale green colour. The frons is W-shaped. Antennae are normally 6-segmented, but 5-segmented in summer dwarfs. Antennae are 0.5-0.6 times the body length, with the terminal process 1.9-2.7 times the base of antennal segment VI. The longest hair on antennal segment III is 0.5-0.8 times the basal diameter of that segment. The rostrum hardly reaches the front coxae, with the apical rostral segment 1.4-1.7 times the second hind tarsal segment. The abdomen has marginal tubercles on segments I & VII, and rarely on other segments. The dorsum is membranous with dorsal hairs distinctly thicker than ventral hairs. The siphunculi are very long, slender and dusky, and are 2.4-3.3 times the cauda (cf. Aphis ruborum, which has siphunculi 1.1-2.0 times cauda). The cauda is short, thick and blunt, with 6-11 hairs. The body length of adult Aphis idaei apterae is 1.3-2.2 mm, but in midsummer the progeny of alate viviparae develop into dwarf apterae (see second picture below) with a length of 0.8-0.9 mm. The dwarf apterae are pale cream, and live dispersed between the veins of the underside of the leaves.
Alatae of Aphis idaei (see picture below) are similarly coloured to the spring apterae, but have little or no wax pulverulence.
Secondary rhinaria are distributed 3-6 on antennal segment III and 0-1 on segment IV. The abdomen has dark postsiphuncular and marginal sclerites, and bands across tergites VII & VIII. Their siphunculi are 2.1-2.7 times the length of the cauda, and the body length is 1.5-1.9 mm. The small raspberry aphid does not host alternate. Aphis idaei feeds on raspberry (Rubus idaeus) causing strong leaf curl in early summer (see picture below).
Aphis idaei also occurs on loganberry. It is considered one of the most damaging pests of raspberry canes (Gordon et al., 1997). Sexual forms occur in autumn with apterous males. It occurs through most of Europe, west Siberia and in New Zealand and North America. Biology & EcologyDicker (1940) describes the biology of Aphis idaei on raspberry at East Malling in Kent. The eggs are laid singly on the current year's cane, usually on the upper half, and always either at the junction of a petiole with the cane or between the axillary bud and the cane. The first young aphids can be observed in mid-March, and hatching is usually complete by early April. The fundatrices mature about a month after hatching, when the fruiting laterals have developed and the young blossom buds are free from unfolding leaves. The fundatrices and their progeny migrate from leaf to leaf and congregate in large colonies round the stalks of the cluster of fruit buds (see pictures below).
They are often attended by ants. The first and second generations are apterous (see image below).
In contrast, most of the third generation are alate. These alate viviparae first appear at the beginning of June, are most numerous a month later and disappear at the end of July or in early August. The alatae shown below were present in late June/early July.
They do not migrate to an alternate food-plant species, but disperse chiefly to the young raspberry canes, where they feed singly on the lower surfaces of the leaves. Their progeny are cream-coloured dwarf apterous viviparae (see picture of adult below).
No other forms are produced until early October, when sexuales appear. By November, only the sexual forms are present, and these persist in diminishing numbers until the canes have lost all their leaves (about mid-December). Borowiak-Sobkowiak (2005) described the bionomy and ecology of Aphis idaei on raspberry in Poland. Egg hatching took place at the end of March and the beginning of April. 7-8 generations in a season were observed. The highest fecundity was recorded in the fundatrix. High summer temperatures (greater than 35°C) caused high aphid mortality, curbed development and reduced fecundity. Other aphids on the same hostAphis idaei has been recorded on 10 Rubus species (Rubus caesius, Rubus fissus, Rubus idaeus, Rubus idaeus var melanolasius, Rubus occidentalis, Rubus phoenicolasius, Rubus sachalinensis, Rubus saxatilis, Rubus strigosus, Rubus ursinus var loganobaccus).
Damage and controlAphis idaei is a major pest of raspberry. Direct feeding by spring colonies at the tips of the young canes causes severe leaf curl. It is the vector of Raspberry leaf mottle virus (RLMV), Raspberry leaf spot virus (RLSV), Black raspberry necrosis virus (BRNV) and Rubus yellow net virus (RYNV). Because aphid-resistant raspberry genotypes additionally show a reduced occurrence of viruses, Schliephake (2010) investigated whether the feeding behaviour of Aphis idaei differed between aphid resistant and susceptible plants. The investigations of the aphid development showed clearly that the tested cultivars differed in their suitability for aphids as host plants. But the probing and feeding behaviour of Aphis idaei, which is responsible for virus transmission, was not sufficiently different between resistant and susceptible cultivars to be the reason for virus resistance.
|
