380
approximately 75%, resides (Eggleton and Belshaw 1992). Contributing to this preeminence of hymenopteran parasitoids is that about 85% of insect parasitoids have
an adult female as the host-seeking stage (Eggleton and Belshaw 1992). By contrast, the relatively rare life-habit of ectoparasitism (defined below) was identified as
an ecological dead end for insect diversification, occurring prominently in the
Phthiraptera (lice). Importantly, the majority of these parasitoid and ectoparasite
lineages (Rainford and Mayhew 2015), whether or not they led to specialized dead
ends or elevated diversification of taxa, originated during the Middle Jurassic to
Early Cretaceous (Labandeira 2002). During the mid Mesozoic, the diversification
of parasitoid taxa, compared to the slowly evolving ectoparasite taxa, likely was
linked to the presence of complete metamorphosis (holometabolous development)
as a major key innovation (Rainford et al. 2014), rather than any clade-specific
transformation.
This contribution is organized into two sections. The first section is a review of the
biology and fossil history of insect parasitism and parasitoidism. The review includes
relevant definitions of a parasite and parasitoid and their relationship to predation, the
several types of parasitoidism, the kinds of evidence for demonstrating all three feeding behaviors in the fossil record, their evolutionary biology, and an extended exploration of their fossil record. In the second section, the Mid Mesozoic Parasitoid
Revolution (MMPR) is proposed as a major biological event in terrestrial food-web
history. As the MMPR is the principal emphasis of this report, evidence for the
MMPR is provided from the fossil record and modern studies of terrestrial food webs,
indicating that ecological communities were transformed during this prolonged event.
This transformational change started from resource-driven control of consumers that
emphasized bottom–up links in which photosynthesis was regulated by the availability of plant resources for their herbivore consumers. Later, a shift toward parasitoiddriven control of consumers focused on top–down, more efficient regulation. Four
fossil biotas from each of the time intervals—before, during and after the MMPR—
illustrate this trophic transformation of food webs by the dramatic increase of parasitoid groups in the mid Mesozoic. Last, the diversification events of two lineages of
wasp parasitoids, Stephanoidea and Evanioidea, are examined to understand the role
of hymenopteran parasitoids during the early phases of the MMPR. The contribution
concludes by an assessment of the role that trophic specialization provided in launching the MMPR and the consequences of this major ecological event.
11.2 Defining the Insect Consumption of Animals
The terms predation and parasitism are well established in the paleobiological and
entomological literature. The indelicately pronounced term, parasitoidism, has been
a more recent term and formalized concept, and has received a considerable amount
of scrutiny, particularly in the older literature (Clausen 1940; Askew 1971). In the
earlier literature, the term parasitism was used confusingly to mean the traditional
parasitism of insects that often feed on a variety of integumental tissues or less commonly in internal tissues of large animals, often vertebrates, whose hosts remain
C. C. Labandeira and L. Li
approximately 75%, resides (Eggleton and Belshaw 1992). Contributing to this preeminence of hymenopteran parasitoids is that about 85% of insect parasitoids have
an adult female as the host-seeking stage (Eggleton and Belshaw 1992). By contrast, the relatively rare life-habit of ectoparasitism (defined below) was identified as
an ecological dead end for insect diversification, occurring prominently in the
Phthiraptera (lice). Importantly, the majority of these parasitoid and ectoparasite
lineages (Rainford and Mayhew 2015), whether or not they led to specialized dead
ends or elevated diversification of taxa, originated during the Middle Jurassic to
Early Cretaceous (Labandeira 2002). During the mid Mesozoic, the diversification
of parasitoid taxa, compared to the slowly evolving ectoparasite taxa, likely was
linked to the presence of complete metamorphosis (holometabolous development)
as a major key innovation (Rainford et al. 2014), rather than any clade-specific
transformation.
This contribution is organized into two sections. The first section is a review of the
biology and fossil history of insect parasitism and parasitoidism. The review includes
relevant definitions of a parasite and parasitoid and their relationship to predation, the
several types of parasitoidism, the kinds of evidence for demonstrating all three feeding behaviors in the fossil record, their evolutionary biology, and an extended exploration of their fossil record. In the second section, the Mid Mesozoic Parasitoid
Revolution (MMPR) is proposed as a major biological event in terrestrial food-web
history. As the MMPR is the principal emphasis of this report, evidence for the
MMPR is provided from the fossil record and modern studies of terrestrial food webs,
indicating that ecological communities were transformed during this prolonged event.
This transformational change started from resource-driven control of consumers that
emphasized bottom–up links in which photosynthesis was regulated by the availability of plant resources for their herbivore consumers. Later, a shift toward parasitoiddriven control of consumers focused on top–down, more efficient regulation. Four
fossil biotas from each of the time intervals—before, during and after the MMPR—
illustrate this trophic transformation of food webs by the dramatic increase of parasitoid groups in the mid Mesozoic. Last, the diversification events of two lineages of
wasp parasitoids, Stephanoidea and Evanioidea, are examined to understand the role
of hymenopteran parasitoids during the early phases of the MMPR. The contribution
concludes by an assessment of the role that trophic specialization provided in launching the MMPR and the consequences of this major ecological event.
11.2 Defining the Insect Consumption of Animals
The terms predation and parasitism are well established in the paleobiological and
entomological literature. The indelicately pronounced term, parasitoidism, has been
a more recent term and formalized concept, and has received a considerable amount
of scrutiny, particularly in the older literature (Clausen 1940; Askew 1971). In the
earlier literature, the term parasitism was used confusingly to mean the traditional
parasitism of insects that often feed on a variety of integumental tissues or less commonly in internal tissues of large animals, often vertebrates, whose hosts remain
C. C. Labandeira and L. Li