HD - The life cycle of Lathrolestes erythrocephalus

Lathrolestes erythrocephalus (Gravenhorst, 1829) (Hymenoptera: Ichneumonidae, Ctenopelmatinae) is an endoparasitoid that parasitizes the larvae of Aprosthema tardum (Klug, 1814) (Hymenoptera: Tenthredinoidea, Argidae).
The freshly laid Lathrolestes erythrocephalus egg is white and darkens in a few hours. After about 5 days the endoparasitoid larva hatches, and is visible inside the host’s body. This first instar larva is has a big head and mandibles for fighting competitors, and moves actively inside the host in search of them. Generally, when there are two endoparasitoids eggs, the larva from the first egg to hatch will win because it can kill the other egg easily. If they are both first instar larvae at the same time, though, they have to fight!
The host larva continues its development and in its fifth instar will spin a cocoon. Aprosthema tardum has at least 3 generations, from March to the beginning of August, and spins summer as well as winter cocoons. Inside the host cocoon, the parasitoid larva kills its host and spins its own darker cocoon, inside the host cocoon. Lathrolestes erythrocephalus emerges after about 30 days from a summer cocoon, but overwinters in a winter cocoon and emerges the following spring. There are strong indications that Lathrolestes erythrocephalus can diapauses for two winters.
Lathrolestes erythrocephalus has at least 2 generations and can parasitize all larval instars of the host from the second instar, 5 mm, up to the fifth instar, 15 mm.
Shaw, M.R., Kan, P., Kan-van Limburg Stirum, B. & Wahl, DB. (2022) - Biological and morphological studies on the parasitoids (Hymenoptera, Ichneumonidae) of Aprosthema tardum (Klug) (Hymenoptera, Argidae, Sterictiphorinae) in Var, southern France. Journal of Hymenoptera Research.
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