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Genus Megoura

Vetch aphids

On this page: Genus Megoura Megoura viciae

Genus Megoura [Macrosiphini]

Megoura are medium to large aphids, the adult viviparae of which may be winged or wingless. The head has well-developed antennal tubercles, the inner faces of which are smooth and broadly divergent. Their siphunculi are somewhat swollen in middle, and either entirely black or dusky with black apices.

The Megoura genus has about 9 species, feeding on members of the bean family (Fabaceae). They have a sexual stage in the life cycle overwintering as eggs, but there is no host alternation. Megoura aphids are not attended by ants. One species (Megoura viciae) is an important vector of bean viruses which result in considerable yield loss.

 

Megoura viciae (Vetch aphid)

Megoura viciae are large apple green to dark bluish green aphids. The adult aptera (see first picture below) has a black head and antennae, the latter being longer than the body. The prothorax is black, much narrower than the body which is green and globular. Black crescent-shaped sclerites are present in front of the siphunculi which are black and swollen in the middle, and about the same length as the cauda. The legs and cauda are also black.

The alate (see second picture above) has a green abdomen with black antesiphuncular and marginal sclerites, and dorsal cross bands on abdominal tergites 7 and 8.

The clarified slide mounts below are of adult viviparous female Megoura viciae : wingless, and winged.

Micrographs of clarified mounts by permission of Roger Blackman, copyright AWP all rights reserved.

The vetch aphid does not host alternate but spends it entire life cycle on leguminous plants, especially vetch, Lathyrus and broad beans. Eggs are laid at the base of vetch or pea plants and hatch in spring. Populations build up and after three generations winged forms are produced which disperse to other plants. Megoura viciae generally move to the seed pods in autumn.

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Acknowledgements

Whilst we make every effort to ensure that identifications are correct, we cannot absolutely warranty their accuracy. We have mostly made identifications from high resolution photos of living specimens, along with host plant identity. In the great majority of cases, identifications have been confirmed by microscopic examination of preserved specimens. We have used the keys and species accounts of Blackman & Eastop (1994) and Blackman & Eastop (2006) supplemented with Blackman (1974), Stroyan (1977), Stroyan (1984), Blackman & Eastop (1984), Heie (1980-1995), Dixon & Thieme (2007) and Blackman (2010). We fully acknowledge these authors as the source for the (summarized) taxonomic information we have presented. Any errors in identification or information are ours alone, and we would be very grateful for any corrections. For assistance on the terms used for aphid morphology we suggest the figure provided by Blackman & Eastop (2006).

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References

  • Blackman, R.L. & Eastop, V.F. (2006). Aphids on the world's herbaceous plants and shrubs. Vols 1 and 2. John Wiley & Sons.