Similar to the rest of the Nation, Arizona and New Mexico’s forests
and grasslands are threatened by invasions of exotic species of insects,
disease pathogens, and plants. Over the past 200 years, several thousand
foreign plant and animal species have been introduced in the United States.
About one in seven of these species has become invasive.
Two invasive pest species that were introduced into the United States in the early 1900s have become established in forested lands of New Mexico and Arizona. White pine blister rust, caused by Cronartium ribicola, was first discovered in southern New Mexico in 1990, and found throughout most of the range of its host in the Sacramento and adjoining White Mountains. Based on the apparent ages of cankers, the rust first became established around 1970, but it is not clear how the fungus was introduced. Infected white pines were later found in nearby Capitan Mountains and Gallinas Peak, and by 2005 a population was observed on the Gila National Forest, in far western New Mexico. The disease was not observed in Arizona until 2009, where it is currently restricted to the east-central mountains. Over time, this disease will have a major impact on white pines in the Sacramento Mountains and some other parts of the Southwest.
The
second species introduced in the region is spruce
aphid, Elatobium abietinum. This was first reported in 1976
on an ornamental tree in the city of Santa Fe, New Mexico, and in a natural
forest setting in the late 1980s. Its distribution extends from the San
Francisco Peaks in northern Arizona, to the Sacramento Mountains of southern
New Mexico. The damage caused by this insect in the Southwest is much
greater than that observed elsewhere in the United States, which may be
due to variations in the insects’ behavior. Research in the Southwest
found that spruce aphid populations increase in the fall, have a sexual
life cycle, and a greater cold-hardiness, all factors that may be contributing
to the insect’s success.
The Animal and Plant Health Inspection Service (APHIS) is responsible
for regulating the movement of plants and plant materials that may carry
pest organisms, and for detection and eradication of new pest introductions.
The USDA Forest Service, the Bureau of Indian Affairs, and other Federal
land managing agencies are responsible for reducing the impact of invasive
exotic plants on lands they manage. Despite the efforts, we expect increased
introductions of nonnative species as well as accidental introductions
of native species of the U.S. (from one part of the country to another)
due to expansion of world and national trade. Early detection and rapid
response are important to minimizing invasive species establishment and
subsequent resource damage.
References: 14, 57,
106
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