Biology Reference
In-Depth Information
American forest pests, the potential for invasions from eastern Asia is great
(Baranchikov 1997). Many of the genera of woody plants of western
North America are represented in Siberia, and about 90 species of forest
insects of significant economic potential occur there. A recent North
American invader from this region is the Asian long-horned beetle
(
Anoplophora glabripennis
), which appeared on Long Island, New York, in
1996. This wood-boring beetle has established infestations in New York
and Illinois and has attacked at least 18 species of deciduous trees belong-
ing to 12 genera (Smith et al. 2002).
Numerous herbivorous pests of agriculture, forestry, and horticulture
have shifted or expanded their feeding activity to include native plants in
areas to which they have been introduced. The Hessian fly (
Mayetiola
destructor
), for example, is able to use many species of North American
grasses, such as western wheatgrass (
Elymus smithii
), which belongs to the
tribe to which its principal hosts, various wheats, belong (Jones 1938,
1939). Similarly, the cabbage butterfly (
Pieris rapae
), introduced worldwide
from its native region in Europe, is able to complete its life cycle on many
plants of the mustard family native to the United States.The gypsy moth
(
Lymantria dispar
) feeds on a wide variety of woody plants in North
America. Several major dipteran pests of fruits, including the Mediter-
ranean fruit fly (
Ceratitis capitata
), Mexican fruit fly (
Anastrepha ludens
), and
oriental fruit fly (
Bactrocera dorsalis
), are capable of attacking many species
of plants. The corn earworm (
Helicoverpa zea
), a lepidopteran, feeds on a
wide variety of crop and wild plants.
Numerous host shifts by deliberately introduced insect herbivores also
have been recorded. Pemberton (2000) summarized information on host
shifts by invertebrates introduced for biological control of weeds in the
United States, the Caribbean, and Hawaii. Of 114 species, 15 have been
recorded to use nontarget species. In all but one case, these were mem-
bers of the same genus or genera closely allied to that of the target plant.
So far, instances appear mainly to involve ecological adaptation, and
genetic specialization by the introduced invertebrate for the new hosts is
rare (see chapter 17).
A recent example of ecological host shifts by an introduced biological
control agent involves a weevil (
Rhinocyllus conicus
; Coleoptera: Cur-
culionidae) intended for control of musk thistle (
Carduus nutans
) and
other species of this genus in North America (Louda et al. 1997). By
2000, this weevil had been recorded from 23 species of thistles of the
genus
Cirsium
, most of which are native North American species, and sev-
