The Challenges of Insect Polyembryony

Abstract: Polyembryony is a developmental mode that produces multiple genetically identical individuals from a single egg. It is fairly common in parasitoid wasps, insects that develop within the bodies of other arthropods. Polyembryony enables parents to produce many offspring, but also increases the risk that these offspring would compete for resources. Parasitoids have evolved sophisticated mechanisms to deal with this challenge. Two of them occur in Copidosoma koehleri, a tiny parasitoid studied in my lab.
The first mechanism involves sterile soldiers that develop within clones of genetically identical female larvae, and that attack competitors in multiply parasitized hosts. The soldiers discriminate between kin and unrelated individuals: they are less aggressive towards their identical twins that develop in the same host than towards unrelated competitors.
The second mechanism concerns the host choice behavior of adult females. They readily lay eggs in hosts that had previously been parasitized by non-kin, but avoid repeated self-parasitism of the host. The avoidance of repeated self-parasitism involves a transient increase in the wasps' host selectivity immediately after oviposition.
Taken together, our studies provide a glimpse into the intricate developmental and behavioral mechanisms that reduce the costs of polyembryony.