Pest: hop aphid

Hop aphid Phorodon humuli (Schrank) - English. damson-hop-aphid

The hop aphid is a widespread host-changing aphid species, which in most years strongly populates the hops and is often confused with other species.
(After: Dubnik, Heinz, Blattläuse Artbestimmung-Biologie-Bekämpfung, Verlag Th. Mann - Gelsenkirchen-Buer, 1991)

Development: The hop aphid overwinters in the ice stage on the sloe (Prunus spinosa), the plum or plum (Prunus domestica). The mother (Fundatrix) hatch from the egg around the end of March. Winged morphs are mainly observed only in the second fundatrigenic generation, which then fly to hops. There are 8-10 generations of unwinged females. It is noteworthy that in the summer no wings are formed on the hops.
From September on, winged females (gynopares) are born on the summer inn and later the males, which fly to the winter inn. The subsequently laid females lay the eggs predominantly between buds and twigs.

Body type:
Unwinged: On the winter inn the aphids are light green with green dorsal stripes. On the other hand, the body colour of the hop aphid on the hops is almost white. Remarkable are the long finger-shaped forehead bumps as well as the triangular extension located at the first sensory link on the inside. The posterior tubes of the 2,1 to 3,0 mm long unwinged are cylindrical.
Winged: The body of the winged is 1. 8 to 2. 1 mm long. Head, chest and the feelers reaching up to the tail are dark brown. The spine pattern and the cylindrical abdominal tubes are light brown. On the forehead socket there are two finger-shaped forehead bumps and on the first sensory limb protruding inwards projections. There are several partly interconnected transverse ligaments on the abdomen.

Fig. 1: Colony of aphids


Fig. 2: 220 aphids on one leafe

Differences:
Similar species - Distinguishing features: The hemp aphid (Phorodon cannabis) differs from the hop aphid by its weakly lobed posterior tubes and the stronger pattern on the posterior back, especially between the posterior tube approaches. The hop aphid can also be confused with the green peach aphid Myzus persicae.

Damage:
The hop aphid reproduces very quickly, so that in a short time a dense colonization of the hops takes place. Due to the suction activity on the flowers, fruit stems and leaves, the plants are significantly damaged. Phorodon humuli is also a vector of the hop mosaic virus.

Cycle:
Schematic representation of the development cycle with pictures. Gratefully made available by Dr. Benker - Bavarian State Institute for Soil Cultivation and Plant Production (LBP)

Abb. 3: the cycle of life of Phorodon humuli