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reproductive larvae consume the host, pupate and emerge as adult wasps,

which seek mates (males) or new hosts (females) (Fig. 7.4). However,

some embryos in the polymorula develop into what are called precocious

Interactions between Larval Parasitoids and Their Hosts 143

100

75

50

25

0

0122448

Time between ovipositions (h)

Survival

100

75

50

25

0

0122448

Time between ovipositions (h)

Survival

First clutch survival (%)

Second clutch survival (%)

Fig. 7.3. The effects of clutch size and time between ovipositions on larval

competition in the gregarious ectoparasitoidBracon hebetor. In these experiments,

host size was held constant. The first wasp was allowed to lay a clutch (four or ten

eggs) and then a second wasp was allowed to lay a clutch of equal size at the same

time (0 h) or 12, 24 or 48 h later. When the first wasp laid four eggs, the amount of

host resources available exceeded the capacity of the larvae to consume them. As

a result, most offspring in the second clutch survived, even if laid 24 h later than the

first clutch. Survival of a second clutch was low with a 48 h penalty, because the

host desiccates from the feeding damage caused by the first clutch. When the first

wasp laid ten eggs, offspring of the first clutch were able to rapidly consume all

available host resources, resulting in low survival of a second clutch with any

temporal penalty. For example, when two females simultaneously oviposited ten

eggs each, 78% of larvae from both clutches survived to adulthood. However, when

oviposition by females was separated by 12 h, 84% of the first clutch survived, but

only 4% of the second clutch survived. (Adapted from Strand and Godfray, 1989.)