Parasitoid-induced transgenerational fecundity compensation in an aphid

Increased reproductive effort by organisms in response to attack by consumers (fecundity compensation') is well documented in both plants and animals, although most examples only involve direct compensation by the individuals exposed to consumers. We used the parasitoid wasp Lysiphlebus orientalis Stary & Rakhshani (Hymenoptera: Braconidae) and the soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), to determine whether reproduction by parasitized aphids can lead to fecundity compensation. Although parasitism by L.orientalis strongly decreased fecundity for parasitized aphids, offspring of parasitized aphids reproduced at a greater rate at maturity than did the offspring of non-parasitized aphids. Also, parasitized aphids contained fewer but larger embryos developing within them. The presence of these larger embryos may explain how the offspring of parasitized aphids can produce more progeny with no apparent reduction in progeny quality. Mature and nearly mature soybean aphids successfully reproduced after parasitism, a prerequisite for transgenerational fecundity compensation, and L.orientalis showed a preference for these age classes of aphids as hosts when foraging. Transgenerational fecundity compensation may allow for higher than expected densities of both hosts and consumers to persist and may be adaptive for both the host and consumer in this system. The phenomenon could also reduce the strength of biological control interactions.