This hymenopteran insect is glued by its efflux towards the plant. I know, that insects like grasshoppers or ants are parasited by specific fungi, which fix the insect in a exposed place.
Is the yellow colour natural or also a result of parasitism?
Thank you for your answers!
Rudolf Ritt
Hi Rudolf,
Nice photo. I agree that it is a secretion related with oviposition and I would say that it is possibly used to close the perfuration on the stem made by the ovipositor after laying the eggs, in order to protect the eggs. We can see on the left of the photo, the line of the secretion after oviposition.
Hi Rudolf: Its look like Entomophthora fungus , it will produce spores outside the insects when the fungus will be more develop and matures.
Dear Rudolph,
this insect is clearly a female sawfly of the genus Arge (cf. Arge pagana) during oviposition. The yellow is the natural colour of its abdomen. I don't see signs of fungal pathogens (it is better to use the term 'pathogens' rather than 'parasites'). But is the insect alive or dead? It seems to be alive. The endophytic oviposition (a delicate and demanding activity), with the ovipositor inserted into a stem (of Rosa sp., in this case), perhaps 'glued' temporarily (together with the secretion of colleterial glands) the insect to the stem itself. This is my hypothesis. Kind regards,
Rinaldo
Dear Rinaldo,
thank you for your answer - I think you are, like so often, right!
I appreciate your answers, they are precise, substanciated and well-grounded!
The insect is, like you supposed, alive. I try to do photographs whenever it is possible in "not-influenced nature", and often there is, like here, an accessory benefit in the photo, it is not only a photo of this animal.
Best wishes
Rudolf
I don't know the insect and its biology but I don't see any fungus on the body
Regards
Anna
There are no vestiges of fungus on the body of the sawfly which seems very healthy. The fluid where the tip of the abdomen touches the stem probably is secreted by the insect itself (to facilitate the cut? to protect or glue the eggs?) or is sap from the plant (least probable I think).
Dear Antonio,
I think, you are right. It is, like Rianaldo already said, no Entomophthora fungus, but the deposition of eggs into the stem.
When I took this photo, I was accompanied by a friend, who is a mycologist. He told me about Entomophtora fungi. If the insect is hyphenated it is very simply to see, but at the beginning of the infection the insects seem to be "forced" to climb to a exhibited position for example on a blade of grass and will be fixed to this howsoever even if they die. This was the background of my question.
Thank you for your answer!
Dear All,
Rinaldo’s diagnosis is right. This sawfly must be an Arge pagana (Argidae). The female puts her eggs in double lines into the Rosa stem and the larvae (“false caterpillars”) feed on the Rosa leaves. Generally the stem split some days after oviposition.
I can observe this pest every year in my wife’s rose garden. I could not see any fungal pathogen on this sawfly’s body.
Hi Rudolf,
Nice photo. I agree that it is a secretion related with oviposition and I would say that it is possibly used to close the perfuration on the stem made by the ovipositor after laying the eggs, in order to protect the eggs. We can see on the left of the photo, the line of the secretion after oviposition.
Hi Rudolf
There is a very good picture. I agree with Rinaldo's determination, in the picture does not appear any kind of fungus infection.
Best regards
Dear Noor,
thank you for your answer, meanwhile I know, this was no fungal infection but the oviposition of a female sawfly (see the answer of Rinaldo Nicoli Aldini above).
Best wishes
Rudolf
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