Chemistry Reference
In-Depth Information
Although it is not typically considered as an agricultural chemical,
N,N-diethyl-3-methylbenzamide (DEET) remains as an important insect
repellent, especially for mosquitoes. About 200 million people use it every
year and over 8 billion doses have been applied over the past 50 years [43].
Estimates are that DEET is used by approximately 30% of the United States
population [44].
Et
O
N
Et
CH
3
N,N-diethyl-m-toluamide
DEET
Calcium channels represent an attractive biological target for insect con-
trol because of their role in multiple cell functions such as muscle contrac-
tion. One new insecticide [45] that causes release of intracellular Ca
2
+
is
Rynaxypyr™. It is in group 28, ryanodine receptor modulators. The ryan-
odine receptors contract the muscles; the contraction requires a release of
calcium ions. Depletion of the calcium ion results in insect death.
O
Cl
CH
3
H
NH
O
CH
3
N
N
Br
N
Cl
Rynaxypyr™
12.4 HERBICIDES
On a global basis, about 250 species are sufficiently troublesome to be termed
weeds, representing approximately 0.1% of the world's flora [46]. Weeds
reduce crop yield and therefore result in a need to plant larger acreage for
the same crop production. Weeds can also reduce crop quality. Herbicides are
“weed-killers' and are used to control unwanted vegetation that hinders the
growth of the desired crop.
Weeds can develop resistance to herbicides. Because of this, herbicides
are often rotated from season to season. For example, target site resistance
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