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Cryptomyzus alboapicalis

White dead nettle aphid

Identification & Distribution  Biology & Ecology 

Identification & Distribution:

Cryptomyzus alboapicalis apterae are pale greenish with a green median stripe or yellowish with greenish transverse intersegmental stripes. The antennae are much longer than the body, and the antennal terminal process is more than ten times the length of the base of antennal segment VI. The siphunculi are slightly swollen and 1.0-1.5 times the length of the cauda. The body length of Cryptomyzus alboapicalis apterae is 1.6-2.9 mm.

 

The body and appendages have numerous thick, capitate hairs, clearly visible in the micrographs of an aptera in alcohol below.

 

The clarified slide mounts below are of an adult viviparous female Cryptomyzus alboapicalis : wingless, and winged. Alates of Cryptomyzus alboapicalis have a dark brown dorsal abdominal patch, deeply indented along the sides.

 

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

Cryptomyzus alboapicalis feeds on the undersides of the lower leaves of white dead nettle (Lamium album) and occasionally on other related species. It does not host alternate, and it is not attended by ants. Oviparae and males are produced in autumn, and the species (usually) overwinters in the egg stage. It is found in Britain and across northern and central Europe to western Siberia and the Caucasus.

 

Biology & Ecology:

We have found that in Britain Cryptomyzus alboapicalis is always present on white dead nettle from very early in the year, usually from February / March onwards. The pictures below show adult apterae in March 2015, one of which was depositing nymphs.

 

We cannot say for certain whether these adult apterae were derived from eggs laid in autumn by sexual forms or from overwintering viviparae, but it seems likely that in mild winters part of the populations overwinters as viviparae. The early population peak enables the aphids to avoid predator and parasitoid pressures later in the season. The images below show a syrphid larva predating Cryptomyzus alboapicalis later that year, in May.

 

Guldemond (1990a)  studied the evolution of host plant relationships and life cycles of Cryptomyzus species in Europe. As regards Cryptomyzus alboapicalis he recognised two closely related taxa - one feeding on Lamium album, and the other on Lamium maculatum. The latter form was subsequently assigned the name of Cryptomyzus ulmeri. Guldemond (1990b)   showed that host plant preference of the two taxa promoted their reproductive isolation.

Basilova et al. (2008, 2010)  analysed the karyotypes of the seven Cryptomyzus species found in Europe. Cluster analysis produced two main clusters: One consisted of Cryptomyzus alboapicalis and Cryptomyzus galeopsidis together with Cryptomyzus leonuri and Cryptomyzus ulmeri. The other comprised only species using Ribes as a winter host, namely Cryptomyzus korschelti, Cryptomyzus maudamanti and Cryptomyzus ribis.

Acknowledgements

Our particular thanks to Roger Blackman for images of his clarified slide mounts.

We have made provisional 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).

Useful weblinks 

References

  •  Basilova, J. (2010). Biosystematics study of the aphid (Hemiptera, Sternorhyncha: Aphididae) genus Cryptomyzus Oestlund, 1922 in Lithuania. PhD thesis. Full text 

  •  Basilova, J. et al. (2008). Karyotypes of seven European aphid species of the genus Cryptomyzus ((Hemiptera, Sternorhyncha: Aphididae). Ecologija 54(4), 256-259. Full text 

  •  Guldemond, J.A. (1990a). On aphids, their host plants and speciation: a biosystematic study of the genus. Cryptomyzus. PhD thesis, Wageningen. Full text 

  •  Guldemond, J.A. (1990b). Choice of host plant as a factor in reproductive isolation of the aphid genus Cryptomyzus (Homoptera, Aphididae). Ecological Entomology 15(1), 43-51. Abstract