SOUTHERN JOURNAL OF AGRICULTURAL ECONOMICS DECEMBER 1992
AN ECONOMIC EVALUATION OF SOYBEAN STINK BUG
CONTROL ALTERNATIVES FOR THE SOUTHEASTERN
UNITED STATES
David Chyen, Michael E. Wetzstein, Robert M. McPherson, and William D. Givan
Abstract
Methyl parathion or Penncap M (an encapsulated
methyl parathion) are used extensively throughout
the United States for controlling stink bug pests in
soybeans, Glycine Max (L.) Merrill. However, this
insecticide is highly toxic to mammals, birds, and
non-target arthropods, and thus is less environmen-
tally sound than other insecticides. For environ-
mental and human health considerations,
investigating alternative insecticides for control is
desired. For this investigation, research based on
field experimental data from Florida, Georgia, and
Louisiana during the 1988 and 1989 growing sea-
sons were employed. Results indicate that alterna-
tive, currently available, and less toxic insecticides
may reduce producer costs, increase yield, and im-
prove soybean quality. These alternative insecti-
cides include Scout (tralomethrin), Karate
(Iambda-Cyhalothrin), Orthene (acephate), and
Baythroid (cyfluthrin). In terms of improved profits
these alternative insecticides may dominate methyl
parathion or encapsulated methyl parathion.
Key words: pest management, risk efficiency,
stochastic dominance, soybean,
Glycine max, stink bug, Nezara
viridula
In the southeastern United States, stink bugs, pri-
marily Nezara viridula (L.), are major pests that
contribute to serious quality damage and annual
yield losses in soybean, Glycine max (L.) Merrill
(McPherson et al.). Florida, Georgia, Louisiana, and
South CaroUna are the southeastern states most in-
fested with stink bugs. In 1989, stink bug was the
number one soybean insect pest in Georgia, and
chemical control and crop losses cost over 13 million
dollars (Adams et al,). Among the species in the
stink bug complex associated with soybean, south-
ern green stink bug (N. viridula) is the most common
species (Tumipseed and Kogan).
Stink bugs damage both quantity and quaUty of the
soybean crop (Todd). Seeds damaged by stink bugs
will result in price reductions, with dockage based
on percent damaged kernels. Some foreign buyers
may even completely reject seeds with stink bug
damage. Thus, stink bugs can lower a producer’s
yield, price, and profits.
An immediate response to combat the threat of
pests is to apply pesticides. The Environmental Pro-
tection Agency (EPA) places pesticides into four
toxicity categories (1-4) based on the results of acute
toxicity studies on test animals, usually rats and
rabbits (EPA). These four categories are: (1) highly
toxic, (2) moderately toxic, (3) sUghtly toxic, (4) and
low toxicity (Georgia Cooperative Extension Serv-
ice). Toxicity is measured in LDso, the dosage re-
quired to kill 50 percent of the test animals (Cohrssen
and Covello, p.39). The lower the LDso, the more
toxic the chemical.
In the past decade, methyl parathion, used for
soybean stink bug control, was one of the most
widely adopted pesticides throughout the southern
region. Application of methyl parathion mitigates
the economic impact of stink bugs; however, as listed
in Table 1, methyl parathion is a highly toxic chemi-
cal, a Category 1 insecticide. Even the other formu-
lation of methyl parathion, Penncap M, which is also
known as micro-encapsulated methyl parathion, is
moderately toxic, a Category 2 insecticide. Both of
these formulations provide good stink bug efficacy
(Wier and Boethel). According to the 1991 Georgia
Pest Control Handbook (Georgia Cooperative Ex-
tension Service), methyl parathion and micro-encap-
sulated methyl parathion are very toxic, compared
with other insecticides, to beneficial insects and
spiders, which help control insect pest infestations,
and are insecticides considered hazardous to honey-
bees. Application of methyl parathion on soybeans
is reserved for late season use when conservation of
beneficial insects is not as critical as it is in the early
season. In addition, methyl parathion is restricted to
David Chyen is a former graduate student and Michael E. Wetzstein and William D. Givan are professors in the Department of
Agricultural and Applied Economics at the University of Georgia, Athens, Georgia. Robert M. McPherson is an associate professor in
the Department of Entomology at the Coastal Plain Experiment Station, Tifton, Georgia.
Copyright 1992, Southern Agricultural Economics Association.
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