The Remaining Endopterygote Orders

FIGURE 10.28. Chalcidoidea. (A) The wheat jointworm, Harmolita (= Tetramesa) tritici (Eurytomidae); (B) Aphelinus mali (Eulophidae), a parasitoid of the woolly apple aphid (Eriosoma lanigerum); and (C) ovipositing Trichogramma minutum (Trichogrammatidae), a parasitoid of the eggs of more than 200 species of Lepidoptera. [From L. A. Swan and C. S. Papp, 1972, The Common Insects of North America. Copyright 1972 by L. A. Swan and C. S. Papp. Reprinted by permission of Harper & Row Publishers, Inc.]

parasites, especially of Lepidoptera. Some species are reared in large numbers to control certain pests. The MYMARIDAE are some of the smallest insects, with adults of some species having a length of 0.21 mm! Members of this cosmopolitan family of about 1400 species are egg parasites, especially of Coccoidea and other Hemiptera. The ENCYRTIDAE (3800 species worldwide) are one of the most important groups from the perspective of biological control. They are endoparasitoids, especially of Coccoidea, though eggs, larvae, and pupae of species from many other orders, as well as spiders, are attacked. Like members of the previous family, PTEROMALIDAE (4100 species) attack a wide range of insect hosts, at all stages of their life history. The cosmopolitan APHELINIDAE (1120 species) are mainly parasitoids of aphids, scale insects, whitefly, and psyllids, for which they are important biological control agents. However, some species attack the eggs of Lepidoptera and Orthoptera, the eggs and larvae of Diptera, and even other chalcidoids. The mainly tropical to subtropical EUPELMIDAE (900 species) are predators, parasitoids, or hyperparasites of the eggs, larvae, or pupae of a wide range of insects and spiders.

Infraorder Aculeata

As noted earlier, the Aculeata is widely accepted as a monophyletic group. Earlier classifications split the infraorder into as many as eight superfamilies but, more recently, it has been appreciated that several of these were superfluous and that a system of only three super-families reflected the natural relationships and evolution of the infraorder (Brothers, 1975; Gauld and Bolton, 1988). The Chrysidoidea (Bethyloidea of earlier classifications) are the most primitive aculeates and form the sister group to the other members of the infraorder. The Vespoidea (including Tiphioidea, Scolioidea, Formicoidea, Pompiloidea, and Vespoidea of older systems) require further study and may be paraphyletic. The Apoidea (= Apoidea + Sphecoidea of earlier classifications) is now clearly established as a monophyletic taxon.

Superfamily Chrysidoidea

The great majority of the more than 7500 species in this group are arranged in three families, CHRYSIDIDAE, BETHYLIDAE, and DRYINIDAE, the last two being placed in a separate superfamily Bethyloideaby some earlier workers. Chrysidids (3000 species) are especially diverse in temperate deserts of both hemispheres. Their common name, cuckoo wasps, is derived from their habit of laying an egg in the cells of solitary wasps or bees. Usually, the egg does not hatch until the host larva has consumed its own food supply. Bethylidae (2200 species) are primarily tropical and subtropical wasps, females of which paralyze the host (typically beetle larvae or caterpillars, sometimes much larger than the bethylid). Some species drag the prey into a sheltered location, a habit that foreshadows the situation in the Scoliidae (digging wasps), prior to laying several eggs on it. Dryinids (1100 species worldwide) are parasitoids of immature and adult Auchenorrhyncha, especially Fulgoridae and Cicadellidae, and several species have been used as biological control agents, for example, against pests of sugarcane in Hawaii.

Superfamily Vespoidea

As presently constituted, the Vespoidea contains 10 families, though the vast majority of the approximately 24,000 described species (including 2000 in North America) fall into five large groups. The SCOLIIDAE (digging wasps) (Figure 10.29A) form a small but distinctive family (300 species) of large, hairy wasps with a cosmopolitan distribution. The female burrows into soil, rotting wood, etc., and locates a beetle larva, usually a scarabaeid, which she paralyzes, then lays an egg on it. In some species the female builds a special cell around the host larva. Female TIPHIIDAE (1500 species worldwide) also attack mainly scarabaeid larvae, though some species search out larvae of tiger beetles, cerambycids, solitary and social bees and wasps, and mole crickets. Females of about half of the species are wingless and are either transported to flowers by males, or fed by males on nectar or honeydew. MUTILLIDAE (velvet ants) (Figure 10.29B) form a large, cosmopolitan family (5000 species) of strongly sexually dimorphic wasps, the males being winged, the females wingless and somewhat resembling ants in their form and behavior. Both sexes are densely hairy and often aposematically colored. Mutillids are mainly parasitoids of both social and solitary bees and wasps, though some species oviposit on the larvae of Diptera, chrysomelid and other beetles, and Lepidoptera, and on cockroach oothecae. Members of the primarily tropical family POMPILIDAE (Figure 10.30), with some 4200 species, are commonly called spider wasps. These large, solitary, often strikingly marked wasps are parasitoids of spiders, rarely other Arachnida. Prey is paralyzed or killed and usually deposited in a nest, which may contain one to several cells, in the ground. The female lays a single egg in each cell. Some species are cleptoparasites of other pompilids; they detect the provisioned nest, dig down to it, consume the original wasp egg and lay their own in its place.

The ants (FORMICIDAE) form a worldwide, though mainly tropical, family containing between 9000 (Goulet and Huber, 1993) and 15,000 (Gauld and Bolton, 1988) described species, including about 600 in North America. They are social, with the exception of a few secondarily solitary parasitic forms. In the latter there is no worker caste, and a female deposits her eggs in the nest of a closely related species whose workers then rear the resulting

FIGURE 10.29. Vespoidea. (A) A digging wasp, Scolia dubia (Scoliidae); and (B) a velvet ant, Dasymutilla occidentalis (Mutillidae), male and female. [A, from L. A. Swan and C. S. Papp, 1972, The Common Insects of North America. Copyright 1972 by L. A. Swan and C. S. Papp. Reprinted by permission of Harper & Row, Publishers, Inc. B, from D. J. Borror, D. M. Delong, and C. A. Triplehorn, 1976, An Introduction to the Study of Insects, 4th ed. By permission of Brooks/Cole, a division of Thomson Learning.]

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