Synergistic insecticidal combinations comprising endosulfan and 2-dihalovinyl-3,3-dimethylcyclopropanecarboxylates

Compositions comprising, in combination, the insecticides endosulfan and 2-dihalovinyl-3,3-dimethylcyclopropanecarboxylates exhibit synergistic insecticidal activity. The novel compositions are exemplified and their use for controlling insects is demonstrated.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention pertains to the field of bio-affecting compositions; more 
specifically, it pertains to such compositions containing organic active 
ingredients comprising the insecticide endosulfan and certain esters of 
2-dihalovinyl-3,3-dimethylcyclopropane carboxylic acids, the latter being 
pyrethroid insecticides related to chrysanthemum acid, and to the use of 
the compositions for controlling insects. 
2. Description of the Prior Art 
New pyrethroids, insecticidal 
2-(2,2-dihalovinyl)-3,3-dimethylcyclopropanecarboxylates [Elliott, et al., 
Nature, 246, 169(1973); British Patent No. 1,413,491], are of great 
interest currently because, unlike previous compounds of this type, such 
as natural pyrethrins and the older synthetic pyrethroids (for example, 
allethrin and tetramethrin) they have good photo-oxidative stability. 
However, the new pyrethroids are very costly, and ways to increase their 
cost effectiveness are actively being sought. 
Synergists have been used commercially in combination with pyrethrins and 
the older pyrethroid insecticides because they lessen the amount of 
insecticide required and thus reduce the cost at which insect control is 
achieved. Some of the most widely used synergists for pyrethrins and the 
older pyrethroids display little or no insecticidal activity in their own 
right; for example, the commercially important piperonyl butoxide [U.S. 
Pat. No. 2,550,737] and certain phosphonates such as mono(alkyl and 
alkenyl) mono-.omega.-alkynyl arylphosphonates [U.S. Pat. Nos. 3,885,031 
and 3,944,666]. 
Some of the compounds which produce synergistic combinations with the new 
pyrethroid, 3-phenoxybenzyl 
2-(2,2-dichlorovinyl)-3,3-dimethylcyclopropanecarboxylate, are themselves 
insecticides. It is known that combinations of 
2-allyl-3-methylcyclopent-2-en-1-one-4-yl 
2-(2,2-dimethylvinyl)-3,3-dimethylcyclopropanecarboxylate (allethrin) and 
N-(3,4,5,6-tetrahydrophthalimido)methyl 
2-(2,2-dimethylvinyl)-3,3-dimethylcyclopropanecarboxylate (tetramethrin) 
with the aforesaid insecticidal 
2-dihalovinyl-3,3-dimethylcyclopropanecarboxylate exhibit synergism when 
used to control several insect species, including insects of the order 
Diptera [U.S. Pat. No. 3,899,586]. O,O-Dimethyl 
O-(3-methyl-4-nitrophenyl)phosphorothioate (fenitrothion) and 1-naphthyl 
methylcarbamate (carbaryl), in combination with the aforesaid insecticidal 
2-dihalovinyl-3,3-dimethylcyclopropanecarboxylate, exhibit synergism when 
applied to Nephetettix cinctceps, a rice pest [Japan Kokai Nos. 75 58,237 
and 75 64,422, respectively]. 
Endosulfan, 
6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodi 
oxathiepin-3-oxide, is known to produce synergistic insecticidal 
combinations with O,O-dimethyl O-(4-nitrophenyl)phosphorothioate (methyl 
parathion) and methyl 3[(dimethoxyphosphinyl)oxy]-2-butenoate (mevinphos) 
when employed against Agrotis segetum [Chem. Abstr., 82, 39465y (1975)]. 
When used to control Musca domestica, compositions comprising endosulfan 
in combination with 3-methyl-5-(1-methylethyl)-phenyl methylcarbamate 
(promecarb) or 2-chlorophenyl methylcarbamate exhibit synergism [Chem. 
Abstr., 80, 56490d (1974) and ibid., 78, 39357g (1973), respectively]. 
SUMMARY OF THE INVENTION 
It has now been discovered that novel compositions of matter comprising 
endosulfan and at least one insecticidal 
2-dihalovinyl-3,3-dimethylcyclopropanecarboxylate, such as 3-phenoxybenzyl 
2-(2,2-dichlorovinyl)-3,3-dimethylcyclopropanecarboxylate, exhibit 
unexpectedly high insecticidal activity, 4-5 times higher than expected on 
the basis of simply additive activities. 
As will be evident to those skilled in the art, formulated insecticides 
incorporating the aforesaid compositions may also contain the solvents, 
dispersants, surfactants, carriers and other adjuvants commonly employed 
in pesticides. The compositions may be formulated in many different ways, 
including aerosol and space sprays, wettable powders, granules, dusts, and 
flowable formulations. 
Although the insecticidal activity of the aforesaid compositions may be 
enhanced if they contain as little as 10% endosulfan by weight, optimum 
synergism is obtained when the 
endosulfan/dihalovinylcyclopropanecarboxylate ratio is in the range 1/1 to 
20/1. 
Also within the contemplation of this invention is the use of the aforesaid 
novel compositions in a method for controlling insects. For example, the 
insecticidal compositions of this invention may be used to control insects 
of the order Diptera, exemplified by Musca domestica. 
In using the novel compositions for controlling insects, it is only 
necessary to contact said insects with an insecticidally effective amount 
of a composition of this invention, preferably between about 100 and 1000 
nanograms active ingredients per insect.