Agriculture Reference
In-Depth Information
In US pastures, 45% of weeds are alien species [8]. US pastures provide
about $10 billion in forage crops annually [9], and the estimated loss due to
weeds is $2 billion [10]. Since about 45% of the weeds are alien [8], the
approximate forage losses due to non-indigenous weeds are nearly $1 billion
each year. According to Interior Secretary Bruce Babbitt [11], ranchers spend
about $5 billion each year to control invasive alien weeds in pastures and
rangelands, but these weeds continue to spread (Tab. 3).
Vertebrate pests
The English or house sparrow ( Passer domesticus ) and the European starling
( Sturnus vulgaris ) were introduced into the United States. The English spar-
row was introduced in 1853 to control the canker worm. Both birds have
become agricultural pests, together causing an estimated $1 billion per year in
crop damages [1] (Tab. 3). Pigeons, introduced for agricultural production,
foul structures both urban and rural and have a role in spreading human and
livestock disease; the damage caused by pigeons is estimated at $1.1 billion
per year.
Other serious vertebrate pests in the United States include rats and mice.
Their numbers are estimated to be more than 1.25 billion and they cause more
than $19 billion in damages and control costs per year (Tab. 3). There are about
63 million pet cats in the US plus 30 million feral or wild cats. These cats kill
more than 570 million birds per year with an estimated value of $17 billion per
year (Tab. 3).
Crop insects and mite pests
Pest insects and mites destroy about 13% of potential crop production repre-
senting a value of about $20 billion in US crops [12]. Based on the fact that
about 40% of these pests are alien species [8], the alien pests cause over $7 bil-
lion in crop losses each year (Tab. 3).
Furthermore, about 360 alien insect and mite species have become estab-
lished in US forests [13]. Insects cause the loss of approximately 9% of forest
products amounting to $7 billion per year [3, 14]. Because 30% of the pests
are alien species, annual losses attributed to them are about $2.1 billion/year
(Tab. 3).
Crop plant pathogens
US crop losses due to all plant pathogens total approximately $18 billion per
year [3]. With 65% of all plant pathogens being alien species [8], an estimat-
ed $11 billion per year can be attributed to alien plant pathogens (Tab. 3).
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