[Rhopalomyia campestris] Galle sur Armoise champêtre

[pierred]

Si tu le fais, vas-y avec tact, parce que la conclusion pourrait être qu'il a inclus dans sa table une espèce qui n'existe pas.

[zallub]

Bonjour,

Voici les réponses successives de M. W. Ellis, puis de M. S. Carbonnelle, que je remercie grandement. Ils m'ont autorisé à copier leurs réponses sur le forum.

Réponse de M. Ellis :

Dear Laurent

this is an interesting question. Rübsaamen (1916a), in his description of campestris, explicitely writes that he could not find a difference with the gall of artemisiae. He therefore guesses that campestris might be an inquiline of artemisiae.
But on the site, Sébastien Carbonnelle has published pictures of campestris galls. I shall ask hem how he came to that identification, and let you know his reply. Perhaps he reared te adults, but maybe he found a distinction!

all the best — Willem Ellis


Réponse de M. Carbonnelle

Dear Laurent and Willem,

Interesting topic indeed, and a lot to say about all this…

Several things refers to the conversation on the forum, and would be helpful to publish there too.

1) Rhopalomyia genus seems to be incredibly diverse in species, with several species producing similar galls and probably linked to specific host plants. As often encountered with gall midges, old descriptions of galls (and when available adults or larvae) are too brief and lack a good drawing. There are also a fair number of species that have not been precisely described (several are reported as Rhopalomyia sp.) and another fair number of species whose host range is not known. Hans Roskam’s keys are made from available literature, and when the literature is imprecise, the description for the keys are therefore imprecise too ! ;-) Hans also writes at the top of the keys for Artemisia that some literature regarding gall midges and mites on Artemisia (especially literature and descriptions from Southern - Eastern Europe have not been included in the keys, where several other species has been described in this genus...

2) About my record of Rhopalomyia artemisiae, I didn’t check the larvae or adults. As Rubsaamen said, there’s no difference between galls of the two species. So, yes, maybe it’s R. campestris. Only chooses the (supposed) most common one… if Rubsaamen is right, the second species could also only be an inquiline of gall inducing R. « artemisiae ». Based on this, I think it’s reasonable to name your species R. artemisiae. Because at this stage, there’s unfortunately no way to name these species with 100% confidence without further knowledge on this species complex.

3) The pictures posted on the Ukrainian and Danish recording scheme websites are also interesting. I think most of the pictures are not R. campestris or artemisiae ! ;-) I have a guess for some of them, but others are probably simply undescribed or unaddressed to the host plants.

4) Finally, we could gather more clues ! We would need fresh larvae preserved in 70% alcohol and if possible reared adults from the capitulas. If you ever go back to the galls, that would be nice to collect galls and put larvae in vials. I know somebody who would be really interested to barcode the species. With a little chance, we could also get some fresh material from other galls of the artemisiae/campestris complex to have a clearer view of the situation...

Thank you Willem and Laurent for sharing this interring question,

All the best

Sébastien

J'ai eu l'occasion de retourner cette semaine sur des stations d'Artemisia campestris, non loin de celle de 2020, et pu constater que les galles sont très abondantes, présentes en fait sur la plupart des pieds. Elles font plutôt 6 à 8 mm en moyenne.
J'ai dû arriver après le pic d'émergence car la plupart des galles étaient vides, mais j'ai tout de même pu prélever quelques larves et adultes, échantillons qui vont être envoyés à M. Carbonnelle.
A suivre donc, en espérant que les échantillons seront exploitables !

[Numayta]

J'attends la suite

[Thomas Lebard]

Super!
Si je peux donner un conseil, il vaut mieux préserver les échantillons destinés à la génétique dans de l'alcool à 96°. Ce n'est pas dramatique en soi car la matériel est frais et devrait être exploité rapidement, mais je pense qu'il serait mieux que tu lui redemandes si ça ne serait pas mieux de les conserver dans l'alcool à 96° au cas où.

On attends la suite en effet!

[pierred]

C'est super !!

Sinon, tu peux écrire en français à Sébastien.

[zallub]

Oui, Sébastien est passé de lui-même au français pour la suite de notre conversation, je suppose que mon niveau en anglais lui a fait peine
Et merci pour le conseil pour l'alcool à 96 %, pour l'instant je n'en n'ai pas mais je vais lui envoyer les échantillons dès lundi.

[latique]

Des nouvelles ?

[latique]

[latique]

Toujours rien ?

[latique]