Delphiniobium junackianum

Identification & Distribution:

Apterae of Delphiniobium junackianum (see first picture below) are shiny bluish-green. The legs are rather dark with distal parts of the femora, tips of tibiae and tarsi black, as are the antennae and cauda. The antennae are 0.9-1.1 times the body length, and the antennal terminal process is 9-12 times the length of the base of the sixth antennal segment. There are no dorsal sclerites on the abdomen. The siphunculi of Delphiniobium junackianum are mainly dark except at their bases, and have a swollen section at about midlength. They are 1.0-1.3 times the length of the thick blunt nearly cylindrical cauda The body length is 2.9-4.7 mm.

Guest images, copyright Nigel Gilligan, all rights reserved.

The monkshood aphid does not host alternate but spends it entire life cycle on monkshood (Aconitum) and Delphinium. The aphids live primarily on the upper parts of the stem and between the flowers. They are not attended by ants. Delphiniobium junackianum is found in north-west and central Europe, eastward to west Siberia.

Biology & Ecology:

Any shade of blue is very rare in aphids, and the vivid blue-green of Delphiniobium junackianum is undoubtedly aposematic. The aphids sequester alkaloids from their foodplant Aconitum which makes them toxic, or at least distasteful, to potential predators. Their feeding behaviour supports this hypothesis - the aphids make no attempt to conceal themselves, and instead spread out over the host plant as shown in our pictures.

Guest image copyright Nigel Gilligan, all rights reserved

As is common for distasteful or toxic aphids, the parasitoids which attack Delphiniobium are specific to this genus of aphids. Two specific parasitoids - Monoctonus leclanti and Aphidius sussi - have been found parasitizing Delphiniobium junackianum in the high montane areas of southeastern Europe (Tomanovic et al (2002),  Havelka et al. (2014) ). We have yet to find any parasitized individuals in Britain.

The picture below shows an alatiform fourth instar Delphiniobium junackianum nymph.

Guest images copyright Nigel Gilligan, all rights reserved

Other aphids on same host:

• Blackman & Eastop list 12 species of aphid  as feeding on monkshood (Aconitum species) worldwide, and provide formal identification keys.

  Of those aphid species, Baker (2015)  lists 5 as occurring in Britain: Aulacorthum solani,  Brachycaudus napelli, Delphiniobium junackianum, Macrosiphum euphorbiae  and Myzus persicae. 

• Blackman & Eastop list 16 species of aphid  as feeding on Delphinium species worldwide, and provide formal identification keys.

  Of those aphid species, Baker (2015)  lists 7 as occurring in Britain: Aphis craccivora,  Aphis fabae,  Aphis gossypii,  Brachycaudus napelli, Delphiniobium junackianum, Macrosiphum euphorbiae  and Myzus persicae. 

Damage and control

Delphiniobium junackianum is a recognised pest of Aconitum and Delphinium species in Poland (Labanowski, 1989 )

Acknowledgements We have mostly made identifications from high resolution photos of living specimens, along with host plant identity. Microscopic examination of preserved specimens was used for confirmation if necessary. We have used the keys and species accounts of Blackman & Eastop (1994)  and Blackman & Eastop (2006)  supplemented with Stroyan (1977),  Stroyan (1984),  Heie (1980-1995),  and Dixon & Thieme (2007).  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  Havelka, J. et al. (2014). Mountain aphid and parasitoid guilds on Aconitum spp. in Europe. Bulletin of Insectology 67 (1), 57-61. Full text   Labanowski, G. (1989). Pests of ornamental plants: the monkshood aphid - Delphiniobium junackianum (Karsch) syn. Myzus junackianus Rhopalosiphum aconiti Van der Goot. Ochrona Roslin 33 (9), pp24. Abstract   Tomanovic, Z. et al (2002). Monoctonus leclanti sp.n. (Hymenoptera: Braconidae: Aphididinae) from high montane areas of southeastern Europe, and key to related species. Entomologica Fennica 13 (3), 159-162.Abstract

 

Identification requests Nigel Gilligan, 15 March 2014, Uroleucon sonchi, but maybe wrong colour This unusually smooth aphid looks like Uroleucon sonchi, except that it is a dark bottle-green, not dark brown. However (though not sure of the significance or correctness of this), I can see what appears to be a definite groove, which is curved, in front of the right-hand siphunculus. The siphunculi do appear to be less than twice the length of the cauda, but the bases are pale, as is the cauda - which does not seem right either. So my summary (for what it is worth), is that it has notable similarities to the suggested species, but features that indicate that it is probably not that. Seen on the leaf of a Daylily, 2/10/2012 (an un-cropped photo for scale is included). Images copyright Nigel Gilligan, all rights reserved.     I also include what appears to be an identical species from another occasion. Seen 7/10/2013. Image copyright Nigel Gilligan Bob, Influentialpoints: Sorry about the slight delay - this aphid took a bit of time. It seems that it was probably an accidental on daylily because there's nothing remotely similar to this that feeds on daylily (Hemerocallis) (or on Lilium). I can see why you went for Uroleucon sonchi - it is smooth - but that species definitely has the cauda much paler than the siphunculi. Yours has a black cauda. Uroleucon sonchi also has a crescent shaped sclerite present in front of each siphunculus - which yours do not have. I have checked through a lot of Uroleucon, Macrisiphum, Megoura and Macrosiphoniella aphids, but can't find anything fitting it yet. Without a definite host plant, I can't key it out. It's possible it is a male Uroleucon which tend to be green, but there is no key available for males. So, I will keep trying but don't hold your breath. Nigel Gilligan, 18 March 2014, Genus Metopeurum, maybe This one is different, in that the basic aphid shape is not there, and the only one in the outline page on aphids that has any similarity of form is the photo for Metopeurum. (In case what I mean is not clear ... I mean it's the lack of an elongate or shorter bulbous shape. This one has a structure more like a beetle for instance, with a distinct abdomen and thorax, and projections at the side, which I assume have nothing to do with wings.) I have only one photo, on an elongate oval leaf with upward pointing teeth. There appear to be some quite small but similar aphids nearby. [Don't know what plant species it was on.] I have just done a quick trawl through the garden, but either it's not about yet, or I don't recognise it as that scale. But at the end of the day, it may not be relevant. So that is as far as I could get with that one - I could see no species like it in the species detail section. Seen 20/6/2013. Image copyright Nigel Gilligan Bob, Influentialpoints: The blue-green aphid is a fourth instar future alate (winged form) - the projections are indeed the wing buds. Without either host plant or an adult, I would just be guessing if I tried to identify it. If I was able to identify the plant that the blue-green 4th instar is on (it does look like a food plant), then you might stand a chance? I haven't given up on that one, and it simply has to be in the garden somewhere. But I may be some time. I think in summary, I have only one blue-green adult aphid can might be identified, but it was walking across a wall. It has some similarity to the previous blue-green one - the various features are at least not entirely different, though maybe some proportions are not the same. It has quite clear venation. So if I can identify the plant, then maybe everything might fall into place. I have a few more aphids that I will have a go at (pale ones with, sometimes, quite notable lines of hairs), so see if I can place then, then pass on for confirmation. I have already promised myself to record plants where relevant to insect images, so maybe this summer I might be able to contribute some more useful obs. ... Nigel Gilligan, March 17, 2014, [dark bottle-green aphid]. Sorry about the duff suggestion for the dark bottle-green aphid. It was in desperation, after looking for quite a long time, and finding that as the best fit so far. I did realise it didn't seem right, but then anomalies do occur (I have found this sometimes with other insects), where it is such-and-such, despite some contrary indicator! And I don't really get the reference to a crescent-shaped sclerite, especially since I could not make it out in any reference photo. But then I am only learning, and this is really new stuff (at least I think I'm learning). The only other useful thought I have had is that we never get infestations of aphids here (too many controlling inverts?), so I don't tend to come across aphids much. Except for infestations on monkshood (Aconitum napellis), which is sort of out-of-season. That has had dark aphids in the autumn, badly. But I never took photos. It fits as far as season is concerned. I strongly suspect that this is the species. Is that any use? I shall struggle on. I think we have some progress on the dark bottle-green aphid. There are very few aphids occurring on Aconitum, probably becauser of its toxicity. But one that does occur is Delphiniobium junackianum. Apterae are described as bluish green, with mainly dark antennae legs, siphunculi and cauda; body length 2.9-4.7 mm. Siphunculi are 1.1-1.3 × cauda and 0.15-0.19 × BL, and mainly dark except at their bases. They form colonies on Aconitum and Delphinium spp, mainly on the upper parts of stems and between flowers. It occurs in north-west and central Europe, and eastward into Russia. I'm fairly certain about this, but if you can get some photos of it on the plant this year, it would be conclusive. There are very few photos of it on the web and they show it markedly paler than yours, but one would expect colour to vary somewhat. Ah, that is good news. And I am relieved that the suggestion was useful. The body size is within parameters - I would have estimated between 3 & 4 mm long. Yes, will certainly look to photos later in the year. The description certainly matches, with aphids in the upper reaches of the plant, between flowers. Nigel Gilligan, 16 May 2014, blue-green aphids on Aconitum plant Trust you are well, and things are geared up for another aphid season. I have not been seeing any except a solitary Depranosiphum platanoidis (on a hawthorn), until today, when I spotted the first aphis on our Monkshood. One general view - it's the species with less deeply divided elongate leaves, so might be Aconitum firmum. It doesn't look exactly like the one I had a possible ID on last year - this one is a blue-green colour. Several photos taken, but I ought to get more. Is it still Delphiniobium janackianum? On the one with a single winged species, it's curious that one to the right is upside down! Images copyright Nigel Gilligan, all rights reserved.       Bob, Influentialpoints: Great pictures! Yes they are still Delphiniobium janackianum. The colour of aphids often varies a bit seasonally.