United States Department of Agriculture
Agricultural Research Administration
Bureau of Entomology and Plant Quarantine
PRELIMINARY TESTS WITH CERTAIN m-NITROBENZAMIDES
FOR SYNERGISTIC ACTION IN ALLETHRIN FLY SPRAYS
By S. I. Gertler, JI W. A. Gersdorff,.! and Norman Mitlini'
In previous publications in this series (E-805, E-828) the authors
reported that certain N-substituted benzenesulfonamides and certain
N-substituted benzamides had been found to show promise as synergists
for pyrethrum fly sprays. In further research the action of certain
m-nitrobenzamides in mixtures with allethrin, a synthetic insecticide,
was examined for synergistic effect. These compounds are characterized
by the general formula
R and R' cover a wide range of chemical groups. All the compounds
were prepared by reacting m-nitrobenzoyl chloride with various amines
under suitable conditions.
The compounds were incorporated in sprays alone and in mixtures
with 0.5 mg. of allethrin per milliliter. Since their solubility in refined
kerosene was low, an equal amount of acetone was used as an auxiliary
solvent. With one exception the concentration of the adjuncts was 20 mg.
per milliliter. Allethrin standards were also prepared in the same
solvent mixture at concentrations of 0.5 and 1 mg. per milliliter. The
allethrin used in all tests was from a distilled sample of high purity.
The tests were made by the Campbell turntable method on adult
house flies (Musca domestic L.) reared by standard laboratory pro-
cedure. Since knock-down is increased by the addition of acetone, it
was not estimated. Mortality only was determined for each spray.
1/ With the Division of Insecticide Investigations.
2/ With the Division of Stored Product Insect Investigations, formerly
the Division of Control Investigations.
Approximately 100 flies averaging 2 days of age were used in each test.
The mixed sprays were replicated four times, the sprays containing the
adjuncts alone but twice. Since it was necessary to make the tests in a
number of series, the two standard allethrin sprays were included in
each series as a base of reference.
To avoid reporting many series and to put the results on a comparable
basis, the following procedure was used: The mortalities obtained for
the standard sprays in each series were plotted on log-probability paper
and straight lines were drawn. From these lines the allethrin equivalents
for the mixed sprays were estimated. Since these figures are all com-
pared with the concentration of 0.5 mg. of allethrin per milliliter, they
give, when multiplied by 2, expressions of relative toxicity. These
results are assembled in table 1. Estimates of the increase in the mean
equivalents required to show significant increase in toxicity were made
by an analysis of variance of the logarithms of the individual equivalents.
At the concentrations used, the adjuncts alone showed negligible
mortality. For 10 of the mixtures the increase in toxicity was significant.
Synergism was therefore shown in the mixtures. The effective adjuncts
are as follows:
Table 1. --Toxicity to house flies of space sprays containing certain
benzamides in mixtures with 0.5 mg. of allethrin per milliliter.
Concentration is 20 mg. per ml. unless otherwise indicated.
Allethrin Allethrin equivalent
Material equivalent required to show
of mixture synergism
N-sec -butyl -m-nitro -
N,N-diethyl-m -nitro -
N,N-diisobutyl -m -nitro-
N,N-diisopropyl -m nitro-
N, N-dipropyl -m -nitro-
N- isopropyl-m-nitro -
Benzanilide, 2' -chloro-3-nitro-
3' -chloro-3 -nitro-
1/ 10 mg. per ml.
UNIVERSITY OF FLORIDA
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