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White dead nettle aphidOn this page: Identification & Distribution Biology & Ecology Other aphids on the same host
Identification & Distribution:
Apterae of Cryptomyzus alboapicalis (see first picture below) 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 body and appendages have numerous thick, capitate hairs. 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.
Alates of Cryptomyzus alboapicalis (see second picture above) have a dark brown dorsal abdominal patch, deeply indented along the sides. The micrographs of Cryptomyzus alboapicalis below are (1) a lateral view of an aptera and (2) a dorsal view of an alate, both in alcohol.
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.
Other aphids on same host:
Cryptomyzus alboapicalis has been recorded from 4 Lamium species (Lamium album, Lamium amplexicaule, Lamium maculatum, Lamium purpureum).
Blackman & Eastop list 24 species of aphid (10 of which are Cryptomyzus) as feeding on white dead nettle (Lamium album) worldwide, and provide formal identification keys.
Of those aphid species, Baker (2015) lists 17 as occurring in Britain: Aphis craccivora, Aphis frangulae, Aphis gossypii, Aphis lamiorum, Aulacorthum solani, Brachycaudus helichrysi, Cryptomyzus alboapicalis, Cryptomyzus ballotae, Cryptomyzus galeopsidis, Cryptomyzus korschelti, Cryptomyzus ribis, Macrosiphum euphorbiae, Myzus ascalonicus, Myzus ornatus, Myzus persicae, Rhopalosiphoninus latysiphon, and Rhopalosiphoninus staphyleae.