450
braconid larvae on a caterpillar, at maturity are often within an order of magnitude
the size of their host, whereas parasites (e.g. a mosquito on a human) are typically
multiple orders of magnitude smaller than their host (Morris 1998). These relationships admit of rare exceptions where the ability of a parasitoid to kill its host is
dependent on an elevated number of conspecific parasitoids on the same host
(Blumberg and Luck 1990). Nevertheless, such density dependency is rare and
these arrangements would remain as parasitoid interactions. The close relationship
between predation and parasitism is illustrated in criterion 5, whereby if more than
one host succumbs to the same parasitoid individual, then the relationship becomes
predation (Morris 1998). A related but frequently unstated factor is the size of the
host relative to the size of the parasitoid. If host size is large to very large, such as a
vertebrate, compared to the size of its insect parasitoid, then successful development of the attacker is not contingent upon death of the host. Such a result would
invalidate an essential, obligate feature of the host–parasitoid relationship.
11.5.2.1 Neuroptera (Mantidflies)
Although almost all neuropteran larvae are predators on arthropods, Mantispidae
(mantidflies) are the sole family that is a parasitoid of arthropods (Table 11.1)
(Morris 1998). One subfamily, the diverse Mantispinae, have larvae that are egg
predators of spiders. By contrast, Subfamily Symphrasinae, consisting of about 60
species, are ectoparasitoids of scarab beetle larvae, the pupal cocoons of owlet
moths (Noctuidae), and larvae and pupae of aculeate Hymenoptera, particularly
vespoid and sphecoid wasps and solitary bees (Parfin 1958; Eggleton and Belshaw
1992). Host-seeking parasitoid larvae of Symphrasinae find their host larvae in the
soil or in subterranean cells. Similar to many Coleoptera, larval Symphrasinae
undergo hypermetamorphosis with a mobile triungulin stage for detection of an
appropriate host, and represent a behavior that originated once (Eggleton and
Belshaw 1993). (A triungulin larva is the first larval instar of hypermetamorphic
insects, such as blister beetles, which is mobile, active, sclerified and host seeking
that becomes legless, grub-like and parasitoid in subsequent instars.)
The Mantispinae and Symphrasinae have earliest occurrences in 99 million-yearold mid-Cretaceous Myanmar Amber (Haug et al. 2018; Shi, pers. comm. 2018);
earlier occurrences of Mantispidae extending to the Jurassic lack subfamily placement (Jepson 2015). In Neuroptera, parasitoidism arose once in Symphrasinae,
likely from a life habit of soil predation (Haug et al. 2018). The parasitoid life habit
evolved into egg predation on spider egg sacs associated with a host seeking, first
instar larva that is phoretic on the adult female spider (Gilbert and Rayor 1983;
Eggleton and Belshaw 1992). This larval life habit has been documented for an
undescribed mantispid, attributed to Mantispinae, for a first instar phoretic larva that
is an egg parasitoid on a female disc-web spider (Oecobiidae) in Myanmar Amber
(Haug et al. 2018). The other modern subfamily, Symphrasinae, has a fossil record
(Jepson 2015) and is known from the same deposit (C. Shi, pers. comm. 2018),
although nothing is known of its Cretaceous larval life habits.
C. C. Labandeira and L. Li
braconid larvae on a caterpillar, at maturity are often within an order of magnitude
the size of their host, whereas parasites (e.g. a mosquito on a human) are typically
multiple orders of magnitude smaller than their host (Morris 1998). These relationships admit of rare exceptions where the ability of a parasitoid to kill its host is
dependent on an elevated number of conspecific parasitoids on the same host
(Blumberg and Luck 1990). Nevertheless, such density dependency is rare and
these arrangements would remain as parasitoid interactions. The close relationship
between predation and parasitism is illustrated in criterion 5, whereby if more than
one host succumbs to the same parasitoid individual, then the relationship becomes
predation (Morris 1998). A related but frequently unstated factor is the size of the
host relative to the size of the parasitoid. If host size is large to very large, such as a
vertebrate, compared to the size of its insect parasitoid, then successful development of the attacker is not contingent upon death of the host. Such a result would
invalidate an essential, obligate feature of the host–parasitoid relationship.
11.5.2.1 Neuroptera (Mantidflies)
Although almost all neuropteran larvae are predators on arthropods, Mantispidae
(mantidflies) are the sole family that is a parasitoid of arthropods (Table 11.1)
(Morris 1998). One subfamily, the diverse Mantispinae, have larvae that are egg
predators of spiders. By contrast, Subfamily Symphrasinae, consisting of about 60
species, are ectoparasitoids of scarab beetle larvae, the pupal cocoons of owlet
moths (Noctuidae), and larvae and pupae of aculeate Hymenoptera, particularly
vespoid and sphecoid wasps and solitary bees (Parfin 1958; Eggleton and Belshaw
1992). Host-seeking parasitoid larvae of Symphrasinae find their host larvae in the
soil or in subterranean cells. Similar to many Coleoptera, larval Symphrasinae
undergo hypermetamorphosis with a mobile triungulin stage for detection of an
appropriate host, and represent a behavior that originated once (Eggleton and
Belshaw 1993). (A triungulin larva is the first larval instar of hypermetamorphic
insects, such as blister beetles, which is mobile, active, sclerified and host seeking
that becomes legless, grub-like and parasitoid in subsequent instars.)
The Mantispinae and Symphrasinae have earliest occurrences in 99 million-yearold mid-Cretaceous Myanmar Amber (Haug et al. 2018; Shi, pers. comm. 2018);
earlier occurrences of Mantispidae extending to the Jurassic lack subfamily placement (Jepson 2015). In Neuroptera, parasitoidism arose once in Symphrasinae,
likely from a life habit of soil predation (Haug et al. 2018). The parasitoid life habit
evolved into egg predation on spider egg sacs associated with a host seeking, first
instar larva that is phoretic on the adult female spider (Gilbert and Rayor 1983;
Eggleton and Belshaw 1992). This larval life habit has been documented for an
undescribed mantispid, attributed to Mantispinae, for a first instar phoretic larva that
is an egg parasitoid on a female disc-web spider (Oecobiidae) in Myanmar Amber
(Haug et al. 2018). The other modern subfamily, Symphrasinae, has a fossil record
(Jepson 2015) and is known from the same deposit (C. Shi, pers. comm. 2018),
although nothing is known of its Cretaceous larval life habits.
C. C. Labandeira and L. Li