Agricultural Chemicals - Fundamentals of Industrial Chemistry: Pharmaceuticals, Polymers, and Business - page 205

are removed in soybean seed and need to be replenished. Soybean is a source
of protein and protein is about 16% nitrogen [17]. Phosphorus is used in key
constituents such as adenosine triphosphate (ATP), which is used in photosyn-
thesis. Potassium serves as an important cation for various plant processes and
is required for plant growth. Nitrogen, phosphorus, and potassium are some-
times called macronutrients. Other elements required include sulfur, calcium,
and magnesium; sometimes these are called secondary macronutrients. Many
other elements are also required but in smaller quantities and these are called
micronutrients [18].

12.3 INSECTICIDES

The Insecticide Resistance Action Committee (IRAC) was formed in 1984
to promote the development of insecticide resistance management strategies
with the ultimate goal of sustainable agriculture and improved public
health [19]. IRAC has classified insecticides based upon their mode of action
(MoA) in 30 groups (28 groups plus a group for unknown action and another
group for non-specific action).
Organophosphates and carbamates are in group 1, acetylcholinesterase
inhibitors. Organophosphate insecticides are potent and effective
anti-cholinergic agents and represent the largest class of insecticides
sold worldwide [20]. Most organophosphates are not persistent and do not
bioaccumulate [21]. Through their inhibition of acetylcholinesterase, the
enzyme responsible for catalyzing the breakdown of the neurotransmitter
acetylcholine, the organophosphates are highly toxic to insects. This chem-
ical class includes over 200 pesticides and includes diazinon, chlorpyrifos,
and malathion [22]. Malathion is the most common organophosphate
insecticide applied in the United States [23]. Diazinon and chlopyrifos are
not approved for residential use in the United States. Chlorpyrifos demand
is growing in Asia, especially in China where it is replacing more toxic
organophosphates [24].

Cl

Cl

NN S N S

CO 2 Et

P P S

O O O O

O O P

Cl O O

O

EtO 2 C

Diazinon Chlorpyrifos Malathion