CA1048929A - Synergistic pesticidal mixtures of phosalone and malathion and process for controlling arthropods therewith - Google Patents

Abstract

SYNERGISTIC PESTICIDAL MIXTURES
OF PHOSALONE AND MALATHION AND
PROCESS FOR CONTROLLING ARTHROPODS
THEREWITH
ABSTRACT OF THE DISCLOSURE

Synergistic pesticidal mixtures are provided that are effective against arthropods such as insects and mites, comprising an O,O-dialkyl diphosphoryl methyl halo-6-benzoxazolone, such as phosalone, and an O,O-dialkyl-(1,2-dicarbalkoxylalkyl) diphosphate, such as malathion.

A process is also provided for control of arthropods, i.e., insects and mites, using a mixture of these two compounds.

Description

1~48929 O, O-dialkyl dithiophosphoryl methyl halo-6- benzoxazolones have been proposed as insecticides and miticides or acaricides in Fren.ch patent No. 1, 277, 401 and British patent No. 1, 005, 372 to Rhone-Poulenc.
Certain of these compounds also are indicated as possessing parasiticidal properties, in British patent No. 1,164, 028 and French patent No. 1, 482, 025 to Rhc-ne-Poulellc. It has nc,t howe-ver been suggested that mixtures of these compounds with other phosphate esters be employed or ha~e advantageous properties .
Phosphate esters such as S-(1, 2-dicarba~oxyalkyl) O, O-dia kyl dithiophosphates ha~Je also been known as insecticidal. Such compounds were develo~ed in Germany during World War II, and became available following the war upon release of previously secret German technology in this field. However, these have not been proposed for comblnation with other phosphate esters.
In accordance with the invention, it has been determined that a mixture of these two types of phosphate esters is synergistically more effecti~e than either ester taken alone, and that the mixture is particularly effective aga.inst arthropods, such as insects and mites.
These two types of compounds are sufficiently similar in structure, since both have a phosphate or thiophosphate nucleus witll two homologous alkoxy substituents al:tached thereto, that it is surprising tha'c one has a synergistic - or activity-enhancing effect on the other, when used in combination.
The O, O-dialkyl diphosphoryl methyl halo-6-benzoxazolones employed in the ~ynergistic mixtures of the invention have the structure:

~ ' 1~)48929 X ~ ~= o ~ ~
J_ N--CH~--X2--~ I

Y ~1 wherein X represents a hydrogen or halogen atom, such as fluorine, chlorine, bromine, or iodine; R and Rl represent alkyl groups containing from one to about four carbon atoms, Xland X2 represent an oxygen or sulphur atom, and Y represents an oxygen or sulphur atom. Xl X2 and Y can be the same or different.
Preferably, Xl is oxygen, X2 is sulfur and R and Rl are ethyl, in which case the compound is phosalone, O, O-diethyl dithiophosphoryl methyl-3-chloro-6-benæoxazolone. This compound has the structure:

- Cl ~ ~_ O
~1~ CH2--S--ll(OC2Hs)2 S

Also useful is 0, O-diethyl-dithiophosphoryl methyl-3-benzothiazolone .
Additional compounds which can be used include:

~0~8~Z9 N--CH2--S--11 --(OC2H~)2 S

Cl ~N--CH2S--P -- (OC H ) Cl ~56`~ =o ~ N--CH2--S--11 --(OCH3)2 Cl f ~ ~--~N ' CH2--S--11 --(OC3H7)2 Cl ~O~=o N--CH2--S--11 --(OC.4Hg)2 1~)489Z9 CL ~ H2--S--11 --(OC2Hs)2 C1 ~ r . CHZS--~ OC2H5)2 C1 _~ S ~ O
~.N--CH2--S--~ CH3)2 - - S

1~ Cl ~S ~=o ~N--CH2--S--11 --(OC3~7)2 ' C1 ~S~_O
N--C~I2--S ~ (0~4H9)2 3a 1~)4~929 Cl ~~
b~ N - CH2--O--11 --(OC2H5~2 o ' ~~=o Cl ~N--CH2-O-II --(OC2H5)2 O . .

Cl _~0 ~=o ~ N--CHz----11 --(C~3)2 Cl ~ ~--N--CH2--O--11 --(OC3~I7)2 C~ .

Cl--'~0~ o ~ N--CH2--O--11 --(OC4Hg)2 ~ 4 1~89Z9 Cl ~S ~=o ~_ N--CH2--O~ (OC2EIs)2 O

~S~_o Cl --:~,~N--CH2-O~ (OC2Hs)2 O

Cl r~S~=O
.N--CH2--O--11 --(OCH3)2 O

Cl ~=
~, N--CH2--O--11 --(OC3H7)2 Cl--~S~=o 1~ N--CH2--O--11 --(CgH9)2 1~)48929 Cl ~~0 1~ N--CH2--S--11--(C2H5)2 Cl ~X CH S--P--(OCzHs)2 o Cl ~s~~_o 1~~ N--CH2-- S--11 --(OCH3)2 o Cl ~jl'~=
N--CH2--S ~ (OC3H7)2 o Cl--~0~_ o ~ N--CH2--S--îl --~oc~H9~a 1~ 0 ~,CP 5 .

1~)489Z9 Cl ~`~S~=o ~ ~--CH2--S-- I--(OC2H5)2 ~S~=o Cl ~,L-_N--CH2S ~ (OC2H5)2 O

Cl ~S~ S~_o ~N--CH2--S--11 --(OCH3)2 O

Cl ~S~=o ' ' ~N--C~I2--S--11 --(OC3~I7)2 Cl ~S ~_ O

N--CH2--S--11 --(Oc4~s)2 5a 1~413929 Cl ~/ ~_o l~ N--CH2--O--11--(OC2H6)2 Cl ~N--CHA-O-P--(OC,Hs¦

Cl _~O~=o ~ __N--CH2--O--P--(OCH3):2 Cl ~~
~ N--CH2--O--11 --(OC3H7)2 Cl--~0~= o N--CH~--O--11 --(OC4Hg)2 ~ 6 1048~29 Cl ~S ~=O
N--CH2--O~ (OC2~I5)2 , ~S~_o Cl ~ T

Cl _~S~=o N--CH2--O--11 --(OCH3)2 . ~
Cl ~S~=o I~N--C~2--O--11 --(0C3H7)2 .

Cl ~S~--O
~ N--CH2--O--11 --(OC4Hg)2 S

6a 1(~48929 The O, O-dialkyl-(1, 2-dicarbalkoxy alkyl) diphosphates have the structure:

\ 113 11 . 5 R3--O/ ¦ e wherein X3 and X4 are oxygen or sul~ur, and can be the same or di~erent;
and R2, R3, R4 and R5 are alkyl groups having from one to about four carbon atoms, and can be the same or different.
Preferably, X3 and X4 are sulfur, R2 and R3 are methyl, 11) and R4 and R5 are ethyl, in which case the compound is malathion.
Other compounds in this class include:

1~48929 CH3--o ~ S O

CH3--O / ¦ O

C2H2--O~ S Oj CH3--O / ¦ O
Il C3H7--O~SI 1l C3H7 --O/ ¦ O
. CH2--C--O--C2H5 C4H~3--O~SI l P--S--CH--C--O--CgHg 15C4Hg--O/ ¦ O

CH3--~) S 1l CH3--O I I .

1~)489Z9 P--O--CH--C--O--C2H~
CH3--O/ ¦ O

C2H2--O~ O lî

l 11 C3H7--O~ O O
P--O--CH--C--O--C2H, C3H7--O/ ¦ O
CH2--C----C2~5 C4Hg--\ l C~H9--o/ ¦ O

CH3--o~ 11 1 CH3--O/ ¦ l CH3--O ~ S O
P--O--CH--C O--C2H, CH3--O ¦ O

C2~2 - \ 11 8 CH3--O/ ¦ ¦

C3H7--O~ 1 1 C3H7--O/ ¦ O

C~Hg--O~S
P--O--CH--C--O--C4Hg C~H5--O/ ¦ 1l CH2--C--O--C4Hg CH3--O~ 11 1 ~ P--O--CH--C--O--CH3 CH3--O/ ¦¦ .
C~2--C--O--CH3 1~48929 CH3--O~O
~P--S--CH--C--O--C2HD
CH3--O ¦ O

C2H2--~ O

CH3--O/ - ¦ 1l C3H7--O~ O 1 C3H7 --O ¦ O

C,~Hg--O~ f 11 ~
P--S--CH--C--O--C4Hg CgHg--O ¦ O
CHz--C--O--C,~H~
CH3--O~O I -CHz-- C--O--CH3 1~)48~29 The proportions of each phosphate ester can be widely varied, but in general a synergistically enhanced arthropodicidal, i. e., insecticidal and miticidal, effect is obtained at ratios of 0, O-dialkyl-diphosphoryl methyl-halo-6-benzothiazolone to 0, O-dia~kyl~ 2-dicarba~koxyalkyl) diphosphate within the range from 0.225:1 to 50:1; and preferably from 10:1 to 20:1.
The compositions of the invention show excellent pesticidal activity against all orders of harmful insects, and suborders of harmful mites and ticks.
Exemplary insects are Thysanura such as the silverfish Lepisma saccharina; Orthoptera such as the German cockroach Blattela germanica; Isoptera such as the termite Reticulitermes santoninsis;
Dermaptera such as the earwig Forficula auricularia; Anoplura such as the hog louse Haematopinus suis; Mallophaga such as the chicken body louse Menacantl us stramineus; Thysanoptera such as the citrus thrip Scirtothrips citri: Hemiptera such as the tarnished plant bug Lygus lineolaris; Homoptera such as the rosy apple aphid Dysaphis plantaginea and the pear psylla Psylla pyricola, Coleoptera such as the plum curculio Conotrachelus nenuphar and the striped cucumber beetle Acalymma vittata;
Lepidoptera such as the southern armywormSpodoptera eridania and the codling moth Laspeyresia pomonella; Diptera such as the apple maggot Rhagoletis pomonella and the cherry fruit fly Rhagoie~is cingulata;
Siphonaptera such as the dog flea Ctenocephalides canis; Hymenoptera such as the rose sawfly Caliroa aethiops and springtails (Collernbola).
The compositions according to the present invention are especlally effective when combating representatives of the order Acarina.
Exemplary suborders of mites and ticks are Mesostigmata such as the ~048929 chicken mite, Dermallyssus gallinae; Ixodides such as the ~merican dog tick, Dermacentor variabilis; Sarcoptiformes such as the itch mite Sarcoptes scabiei; Trombidiformes such as the maple bladdergall mite Vasates quadripedes, the twospotted spider mite Tetranychus urticae, and the -European red mite Panonychus ulmi.
The compositions of the invention are also very effective against member-s of the class Diplopoda (millipedes)and the orders Isopoda (sowbugs) and Araneida (spiders).
These compositions can include the two insecticides-acaracides and also if desired inert carriers and/or other additives known to be useful in insecticidal-acaricidal compositions.
These compositions can include the two arthropodicides and also if desired inert carriers and/or other additives known to be useful in insecticidal acaricidal compositions. The inert carriers and additives can be solid or liquid, and include mineral salts, solvents, diluents, dispersing agents, emulsifiers, wetting agents, adhesives, thickeners, binders and fertilizers. Biocidal compounds can also be added, such as the ureas, the saturated or unsaturate~ h~logen-fatty acids, halogenobenzonitriies, halogenobenzoic acids, phenoxyalkyl-carboxylic acids, triazines, nitroaLkylphenols, organic phosphoric acid compounds, quaternary ammonium salts, sulphamic acids, arsenatqs, arsenites, borates or chlorates.
The compositions can be in the form o~ solutions, emulsions, suspensions, granules or dusting agents, The forms of application depend on the end uses and ensure that the active substances are finely distr-ibuted.

1~8~29 The content of active arthropodicides according to the invention is withill the range from û. 1 and 95~C- For application from a.ircraft or other sultable forms, concentrations of up to 99. 50`/G or even pure active substance combinations can be employed.
Solutions are prepared using solvents for the arthropodicides such as aliphatic alcohols~ for example ethyl alcohol or isopropyl alcohol, aliphatic ketones, such as acetone or cyclohexanone, a.liphatic hydrocarbons, such as kerosene, and cyclic hydrocarbons, such as benzene, toluene, xylene, tetrahydronaphthalene, alkylated naphthalenes, chlorinated hydrocarbons, such as tetrachlorethane and ethylene chloride, and mineral a.nd vegetable oils or mixtures of the abo~e mentioned substances .
Aqueous preparations in the form of emulsions and dispersions are especially useful. The active arthropodicides according to the invention, suitably in solution in a solvent, are homogenized in water, preferably by means of wetting agents or dispersing agents; quaternary ammonium compounds may be mentioned as examples of cationic emulsifiers or dispersing agents; soaps, aliphatic long-chain sulphuric acid monoesters, aliphatic-aromatic sulphonic acids and lone-chain alkoxyacetic acids may be mentioned as examples of anionic agents; any polyglycol ethers of fatty alcohols or ethylene oxide condensation products with p-tert--alkylphenols may be mentioned annongst non-ionic agants.
It is also possible to formulate concentra$es of the active substance, emulsifier or dispersing agent, and optionally solvents. Such concentrates can be diluted before use, for example, with water.

1~)48929 Dusting ~gents can be made by mixing or grindin~ the active arthropodicides according to the invention with a solid carrier.
Solid carriers are, for example: talc, diaton~aceous earth, kaolin, bentonite, calcium carbonate, boric acid and tricalcium phosphate, 5 wood flour, cork powder, charcoal and other materials of vegetable origin. Alternatively, the substarlces can be absorbed on the carriers, using a volatile solvent. Pulverulent preparations and pastes can be made capable of suspension in water, and used as spraying agents, by adding wetting agents and protective colloids.
In many cases the use of granules for gradual release of the active substance combination over a prolonged period of time is of advantage. These can be manufactured by dissolving the active substances in an organic solvent, absorbing this solution by a granular material, for example attapulgite or SiO2, and removing the solvent.
15 They can also be manufactured by mixing the active substance combination with polymerisable compounds, after which polymerisation is carried out which leaves the active substances unaffected, the granulation being carried out whilst the polymerisation is still proceeding.
The following Examples in the opinion of the inventors 20 represent preferred embodiments of the invention.

.

1~489Z9 The toxicity response from Tetranychus urticae Koch treated with (1) Zolone 34. 8~c EC (phosalone), (2) Malathion 95~Zc Tech, and(3) combinations of Zolone EC and Malathion Tech, was studied in the following experiments:
Mites used in this study were obtained from a University of Kentucky greenhouse culture maintained free from phosphate ester acaricide contact (phosphate-susceptible strain), and a New Jersey culture maintained in contact with phosphate ester acaricide (phosphate-resistant strain).
Thirty 8 day old T. urticae ~ mites were dipped into the solutions noted in Table I below. Mortality data were ta~en 48 hours after treatment. The test was repeated providing about 300 mites per treatment.
A lO,Q00 PPM stock solution of Malathion in acetone was used, and all formulations were mixed with tap water containing 1 drop of TritonX-207 ~Registered Trademark) per 500 ml of water.
The synergism of Zolone and Malathion as compared with either alone is shown in Tables I and II against both phosphate-susceptible and phosphate-resistant mites:

.. . .

1~48929 TABLE I

Mortality of T. urticae (Ky.--strain) at various concentrations oE Zolone and Malathion and the __ _ synergistic activity of Zolone-Malathion mixture.
_ _ 5 Example No. Arthrvpodicide Conc. lbs ai/100 gal ~/cmortalitya;
Control A Zolone EC 0.188 (0. 5 pt) 23.9 (phosalone) 0.375 (1. 0 pt) 47.1 Q. 750 (1. 0 qt) 60.6 Control B Malathion 0.00835 (10 PPM) 1. 6 0.0835 (100 PPM) 5. 1 0.835 (1000 PPM) 62. 7 Example 1 ~olone EC+ 0.188: 0. 00835 65.4 Malathion 0.188: 0. 0835 79. 5 0. 188: 0. 835 100. 0 0.375: 0. 00835 98.3 0.375: 0. 0835 99. 6 0.375: 0. 835 100. 0 a Control corrected mortality by Abbot's Formula b A phosphate-susceptible strain of predacious mites commonly found in apple orchards.

~048929 TABLE II
_ ~ortality of T. urticaeNJb strain) at various concentrations of Zolone, Malathion, and Zolone-.. ..
Malathion mixture.
. _ 5Example No. Test material Conc. lbs. ai/100 gal. ~cmortality-Control A Zolone EC 0. 188 (O. 5 pt 18.9 (phosalone) 0.375 (l.Opt) 32.5 O. 750 (1. 0 qt) 63. 6 Control B Malathion 0.û0835 (10 PPM) O
O. 0835 (100 PP~) 2. 1 0.835 (lûOO PPM) 25.4 Example 1 Zolone EC ~ O. 188:0. 00835 32.2 Malathion 0.188: O. 0835 77.9 0.188: 0.835 100 0.375:0.00835 64.2 0.375: O. 0835 84.3 0.375: 0.835 100 a Control corrected mortality by ~bbot's formula -- A phosphate-resistant strain of predacious mites commonly found in apple orchards.

1-~

1~1489Z9 It is apparent from the above data that the mixture of malathion and phosalone in accordance with the invention is synergistically more effective than either alone against both phosphate-susceptible and phosphate-resistant mites. The degree of enhancement of miticidal activity is in fact remarkable, since it is several times that of either alone, in the same concentration, and is clearly far more than merely additive.

In these experiments, the relative toxicity of zolone EC, malathion,and Zolone EC plus malathion is measured by induced 72-hour mortality of southern armyworm larvae.
Zolone EC was diluted to desired concentrations in deionized water. Malathion (95~) was dissolved in 10% acetone emulsion base, and then diluted to desired concentrations in deionized water.
Individually potted horticultural bean (Phaeseolus vulgaris), Dwarf French cultivar, plants in fir~t true leaf growth stage, were used as host plants. Upper and lower surfaces of foliar portions were alternately sprayed at 20 psi to incipient run-oEf, allowed to air dry under laboratory conditions, and then removed to greenhouse holding racks provided with subterranean water source. Five third-instar larvae were caged on each plant for 72 hours. Ten test plants (replicates) were used for each test unit.
At the end of the 72-hour holding period, observations were made for insect mortality, any abnormal physiological responses and plant injury. Phytotoxicity is rated on a zero (no injury) to ten (death of the test plant) scale.

The to~icity data obtained appear in Table III below:
TABL E III
Toxicity of Zolone EC, Malathion and Zolone EC plus Malathion as measured by induced 72-hour mortality of Southern Armyworm larvae.
Spodoptera eridania, 3rd instar Example No. Treatment Applied Test Concentration AYe C/cMorta Lbs a. i. /100 gal72 hours Control A Zolone EC 0. 188 40 0.37~ 64 0. 750 90 Control B Malathion 0.00835 4 - 0. 0835 34 0.835 90 Example 2 Zolone EC ~ 0.188 + 0. 00835 92 Malathion 0.188 + 0.083596 0.188 + 0.835 100 0.375 + 0. 00835 94 0.375 + 0. 0835 88 0.375 + 0.8351002 0.375 + 0.08 80 Untreated controls 4

2 100~C mortality all replicates in 24 hours The data in Table III indicate quite clearly t~hat Zolone EC
in com~ination with malathion is more toxic to southern armyworm larvae as a stomach poison than either 2~lone EC or malathion alone.
N is significant to note that Zolone EC plus malathion (0.375 + 0. 835 lbs a. i./100 gal) induced 100~C mortality in 24 hours.

."~
~v Zolone EC plus malathion (0.188 ~ 0.835 l~s a.i./100 gal) induced 1O0~G control but was slower acting, requiring 72 hours to induce complete control.
The reason for the potentiation of malathion by phosalone and of phosalone by malathion is not understood, and has not been established. It is however suggested that one of the possible reasons for malathion resistance is some insects and mites is a high carboxylesterase level, which detoxifies malathion before it can kill them. Phosalone inhibits carboxylesterase, and it is therefore possible that the phosalone blocks carboxylesterase, and thereby makes it possible to kill certàin arthropods with malathion that were previously malathion-resistant. The result is a mixture which is capable of killing phosphate-resistant arthropods, i.e., insects and mites.

The toxicity response from Tetranychus urticae Koch treated with (1) Parathion - O, O- diethy~-o-p-nitrophenyl phosphorothioate (2) Phosdrin - dimethyl phosphate of methyl-3-hydroxy-cis-crotonate and (3) cornbinations of Parathion and Phosdrin is studied.
Thirty 8 day old T urticae + mites are dipped into solutions of the abo~e arthropodicides as noted in Tahle IV below.
Mortality data are taken 48 hours after treatment. The tests provide about 300 mïtes per treatment. . -All formulations are mixed with tap water containing 1 drop of Triton ~-207 per 500 ml of water.

~0489Z9 TABLE IV

Example No. Arthropodicide Conc. lbs ai/100 gal . _ Control C Parathion 0.188 (0.5 pt) 0.375 (1.0 pt) 0.750 (1.0 qt) 5Control D Phosdrin 0.00835 (10 PPM3 0.0835 (100 PPM) 0.835 (1000 PPM) Example 3 Parathion ~ 0.188:0.00835 Phosdrin 0.188:0.0835 0.188:0.835 0.375:0.00835 0.375:~.0835 0.375: 0.835 The mixture of parathion and phosdrin in accordance with the invention is synergistically more effective than either alone against both phosphate-susceptible and phosphate-resistant mites.

15 The toxicity response from Tet_nychus urticae Koch treated with (l) Ethion - (2- chloroethyl) phosphonic acid, (2) Malathion 95% Tech, and (3) combinations of Ethion and Malathion Tech, is studied.
Thirty 8 day old T. urticae ~ mites are dipped into the solutions noted in Table V below. Mortality data ar.e taken 48 hours 20 after treatment. The tests provide about 30~ mitesper treatment.

All formulations are mixed with tap water containing 1 drop of Triton X-207 per 500 rnl of water.

1~48~29 TABLE V

Example No. Arthropodicide Conc. lbs ai/100 gal Control E Ethion 0.188 (0.5 pt) 0.375 (1.0 pt) 0.750 (1. ~ qt) Control F Malathion 0.00835 (10 PPM) 0.0835 (100 PPM) 0.835 (1000 PPM) Example 4 - Ethion + 0.188:0.00835 Malathion 0.188:0.0835 0.188:0.835 0.375: 0.00835 0.375:0.0835 0.375: 0.835 The mixture of Ethion and Malathion in accordance with the invention is synergistically more effective than either alone against both phosphate-susceptible and phosphate-resistant mites.

E~AMPLE 5 The toxicity response from Tetranychus urticae Koch treated with (1) Trithion - S-( (p-chlorophenylthio) methyl) O,O-diethyl phosphorodithioate, (2) Phenthoate - O, O- dimethyl-S- ( a -ethoxycarbonyl-benzyl)-phosphorodithioate and (3) combinations of Trithion and Phenthoate is studied.

Thirty 8 day old T. urtlcae +o mites are dipped into the solutions noted in Table VI below. Mortality data are taken 48 hours after treatment. The tests provide about 300 mites per treatment.
All formulations are mixed with tap water containing 1 drop of Triton X-207 per 500 ml of water.

~)48929 TABLE VI
Example No. Arthrop i_de Conc. lbs ai/100 gal Control G Trithion 0.188 (0.5 pt) 0.375 (1.0 pt) 0.750 (1.0 qt) Control H Phenthoate 0.00835 (10 PPM) O,0835 (100 PPM) 0,835 (lOOOPPM) Example 5 Trithion ~ 0.188: 0.00835 Phenthoate 0~ 188:0.0835 0.188:0.835 0.375: 0.00835 0.375:0.0835 0.375: 0.835 The mixture of trithion and phenthoate in accordance with the in~ention is synergistically more effective than either alone against both phosphate-susceptible and phosphate-resistant mites.

The toxicity response from Tetranychus urticae Koch treated with (1) Guthion - O, O-Diethyl-S-(4-oxo-1,2,3-benzotriazin-3 (4H)-ylmethyl)-phosphorodithioate, (2) Malathion 95% Tech, and (3) combinations of Guthion and Malathion Tech, is studied.
Thirty 8 day old T. urticae t mites are dipped into the solutions noted in Table VII below. Mortality data are taken 48 hours after treatment. The tests provide about 300 mites per treatment.
All formulations are mixed with tap water containing 1 drop of Triton X-207 per 500 ml of water.

~)489Z9 Example No. Arthropodicide Conc. lbs ai/10û gal Control I Guthion 0.188 (0.5 pt) 0.375 (1.0 pt) 0.750 (1.0 qt) Control J Malathion 0.00835 (10 PPM) 0.0835 (100 PPM) 0.835 (1000 PP~) Example 6 Guthion+ 0.188:0.00835 Malathion 0.188: 0.0835 0.188:0.835 0.375:0.00835 0.375:0.0835 0.375: 0.835 The mixture of Guthion and Malathion in accordance with the invention is synergistically more effective than either alone against both phosphate~susceptible and phosphate-resistant mites.

The toxicity response from Tetranychus urticae Koch treated with (1) DDVP - 2t 2- dichlorovinyl dimethyl phosphate (2) Phosdrin - dimethyl phosphate of methyl -3-hydroxy-cis-crotonate and

(3) combinations of DDVP and Phosdrin is studied.
Thirty 8 day old T. urticae + mites are dipped into the solutions noted in Table VIII below. Mortality data are taken 48 hours after treatment. The tests provide about 300 miteæ per treatment.
All formations are rnixed with tap water containing 1 drop of Triton X-207 per 500 ml of water.

2~

1~3489Z9 TABLE VIII
Example No. Arthropodicide Conc. lbs ai/100 gal Control K DDVP 0.188 (0.5 pt~
0.375 (1.0 pt) 0.750 (1.0 qt) Control L Phosdrin 0.00835 (10 PPM) 0.0835 (100 PPM) 0.835 (1000 PPM) Example 7 DDVP ~ 0.188:0.00835 Phosdrin 0.188: 0.0835 0.188: 0.835 0.375:0.00835 0.375: 0.0835 0.375:0.835 The mixture of DDVP and Phosdrin in accordance with the invention is synergistically more effective than either alone against both phosphate-susceptible and phosphate-resistant mites.

The toxicity response from Tetranychus urticae Koch treated with (1) Dimethoate -O, O - dimethyl S-(N-methylcarbamoyl-methyl) phosphorodithioate, (2) F~enthoate - O,O-dimethyl S-(~-etho~carbonyl-benzyl)-phosphorodithioate, and (3) combinations of I)imethoate and Phenthoate is studied.
Thirty 8 day old T. urticae + mites are dipped into the solutions noted in Table ~ below. Mortality data are-taken 48 hours after treatment. The tests provide about 300 mites per treatment.
All formulations are mixed with tap water containing 1 drop of Triton X-20~ per 500 ml of water.

1~489~:9 TABLE IX
Example No. Arthropodicide Conc. lbs ai/100 gal Control M Dimethoate 0.188 (0.5 pt) 0.375 (1.0 pt) 0.75~ (1.0 qt) Control N Phenthoate 0.00835 (10 PPM~
0.0835 (100 PPM) 0.835 (1000 PPM) Example 8 Dimethoate + 0.188:0.00835 Phenthoate 0.188: 0.0835 0.188:0.835 0.375: 0.00835 0.375:0.0835 0.375:0.835 The mixture of dimethoa.te and phenthoate in accordance with the invention is synergistically more effective than either alone against both phosphate-susceptible and phosphate-resistant mites.

Claims (7)

Having regard to the foregoing disclosure, the following is claimed as inventive and patentable embodiments thereof:

1. An arthropodicidal composition having an enhanced effective-ness against phosphate-resistant arthropods comprising O,O-diethyl-dithiophosphoryl-methyl-3-chloro-6-benzoxazolone and O,O-dimethyl-S-(1,2-dicarbethoxyethyl), dithiophosphate, each in an amount to enhance the effectiveness of the other, the weight ratio of O,O-diethyl-dithiophosphoryl methyl-3-chloro-6-benzoxazolone to O,O-dimethyl-S-(1,2-dicarbethoxy ethyl) dithiophosphate being within the range from about 0.225:1 to about 50:1.

2. A composition according to claim 1, in which the ratio is within the range from 10:1 to 20:1.

3. A composition according to claim 1, comprising an inert carrier and a content of active arthropodicide within the range from about 0.1 to about 95%.

4. A composition according to claim 3, in the form of a solution of active anthropodicides in a solvent therefor as the inert carrier.

5. A composition according to claim 4, in the form of an aqueous emulsion of the solution of the active arthropodicides in a solvent and compris-ing a wetting agent or dispersing agent.

6. A composition according to claim 4, in which the carrier is a solid and the composition is in particulate form.

7. A process for control of arthropods, which comprises applying to the arthropod a toxic amount of a composition according to claim 1.