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Identification & Distribution

Adult apterae of Lipaphis erysimi are small to medium sized yellowish green, grey green or olive green aphids, with a faint white wax bloom. The antennal terminal process is 0.8-1.15 times times the length of the siphunculi (cf. Lipaphis alliariae  which has the antennal terminal process 1.2-1.35 the length of the siphunculi). In humid conditions they may be more densely coated with wax. The aptera (see first picture below) has two rows of dark bands on the thorax and abdomen which unite into a single band near the tip of the abdomen. The siphunculi are paler than the cauda and have dark tips. The combined length of antennal segment III and the terminal process is usually less than 2.4 times the length of the siphunculus (cf. Lipaphis pseudobrassicae in which that combined length is usually more than 2.4 times as long as the siphunculus). The body length of adult Lipaphis erysimi apterae is 1.4-2.4 mm.

Second image: Lipaphis erysimi alate, copyright Alan Outen & Rothamsted Research, all rights reserved.

Alatae (see second picture above) have a black head and thorax and a dusky green abdomen with black bands near the tip and conspicuous dark marginal sclerites. The body length of Lipaphis erysimi alatae is 1.4-2.2 mm. The clarified slide mounts below are of adult viviparous female Lipaphis erysimi : wingless, and winged.

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

The wild crucifer aphid does not host alternate. It feeds on various different Brassicaceae, including Brassica, Raphanus, and Sinapis spp., although it is not usually found on field Brassica crops. It lives on the undersides of leaves as well as on inflorescences, young shoots and growing points. Males have been found in some countries. Lipaphis erysimi is confined to Britain and northern continental Europe.

 

Biology & Ecology

Lipaphis erysimi is usually regarded as a relatively common aphid in Britain, but until recently we have found it to be rather scarce in southern England. Then in mid-October 2018 we found colonies of wild crucifer aphid on seed heads of hedge mustard (Sisymbrium officinale) (see picture below).

Despite the lateness of the year, there was no sign of any sexual forms and the aphids were reproducing viviparously (see picture below).

Several of the colonies were comprised mainly of immatures (see picture below).

Then in late October we found much bigger colonies of Lipaphis erysimi on seedheads of shepherd’s purse (Capsella bursa-pastoris). These however were mixed species colonies comprised of Lipaphis erysimi, Aphis fabae  and Myzus persicae  (see picture below).

The mixed species colonies of aphids on the seedheads of shepherd's purse were still present up till late November.

 

Other aphids on same host:

Acknowledgements

We especially thank Alan Outen, Bedfordshire Invertebrate Group,  and Chris Shortall, Rothamsted Research,  for permission to reproduce Alan's photo of a Lipaphis erysimi alate and for information about the colony.

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).

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