BIORESMETHRIN          JMPR 1975


    Chemical name



         propenyl) cyclopropane carboxylate

         5-benzyl-3-furylmethyl(+)-trans-chrysanthemum monocarboxylate


         NRDC 107; Bio NRDC 104; Biorestrin; Biobenzyl furoline, 95H66; RU
         1.484; SBP 1390. (Resmethrin is the name applied to the racemic
         (+)-cis,trans-mixture. Also known as NRDC 104, SEP 1384).

    Structural formula


         Molecular formula C22H26O3

         Molecular weight 338.45

    Other information on identity and properties

         Description :       A viscous yellow liquid which on
                             crystallization forms an off-white solid

         Specific gravity:   1.050 at 20°C

         Flash point :       125°C (open cup)

         Optical rotation:   D20-5 to -8° : measurement on a 10% solution
                                            in ethanol

         Solubility :        Soluble in most organic solvents but
                             substantially insoluble in water

         value :             160-175 mg KOH/gm

         Stability :         Bioresmethrin is sensitive to light but its
                             photo stability is greater than that of
                             pyrethrins. Bioresmethrin is stable to
                             temperatures met under most normal storage

                             Bioresmethrin spray deposits appear subject
                             to atmospheric oxidation but any adverse
                             effect appears to be reduced by the
                             introduction of antioxidants including
                             piperonyl butoxide and butylated



         Bioresmethrin is one of the most effective broad spectrum
    insecticides currently available. It exhibits a high order of
    insecticidal activity, which when coupled with its excellent
    toxicological properties, makes it potentially one of the safest and
    most useful insecticides now being produced.

         In addition to its insecticidal properties, bioresmethrin has a
    good knock-down performance against flying insects, particularly when
    this is compared with the organochlorine or organophosphorus

         Bioresmethrin, at low concentrations, is an effective killing
    agent against most insect pests affecting households, industrial
    premises, public health, food storage and livestock production.
    Efficacy against many insect pests of food crops and ornamentals has
    been demonstrated.

         The principal uses to which bioresmethrin is currently being put

         (a)  in household aerosols and sprays formulated in combination
              with pyrethrum, bioallethrin, tetramethrin and piperonyl

         (b)  as an insecticide for the control of pests in food premises;

         (c)  as a general purpose broad spectrum insecticide; and

         (d)  in grain disinfestation and protection.

         Bioresmethrin has been tested in conjunction with a number of
    well established synergists. Unlike natural pyrethrum, there is only a
    minimal increase in performance against flies, mosquitos and
    cockroaches when piperonyl butoxide is added to bioresmethrin.
    However, in the case of a number of the more important insect pests of
    stored products, bioresmethrin is synergized to a significant extent
    with piperonyl butoxide, the factor of synergism ranging from four- to

         Bioresmethrin shows good promise of becoming a major insecticide
    for use in the control of stored product pests. It combines a high
    potency, good persistence, and excellent safety features.

    Treatment of plants

         Although a number of trials have been reported where
    bioresmethrin has given satisfactory results against a wide variety of
    insect and mite pests of crops and ornamentals (Cooper McDougall and
    Robertson, 1971, 1975; Cantu et al., 1970) there appears as yet only
    limited commercial acceptance of bioresmethrin as a horticultural
    insecticide. This reflects not only the state of development, but the
    comparatively high cost and the relatively short residual life of
    bioresmethrin spray deposits. There are however, many obvious
    applications which will no doubt reach commercial development within
    the next two to three years.

    Non-crop situations

         Many commercial uses have been developed for bioresmethrin in
    non-crop situations including the control of flies, mosquitos and
    other flying pests in households, pests of institutions and food
    storage, aircraft disinfestation, animal-house treatments and similar
    situations where aerosols, knockdown sprays and residual sprays are
    conventionally used. In addition, bioresmethrin has been used in
    thermal fog generators and in mosquito coils. None of these uses are
    likely to give rise to significant residues in food or water, or to
    cause significant intake by the general public.

    Post-harvest application

         Following the demonstration of outstanding activity against many
    insect pests of stored products, numerous authors have reported
    studies on the effect and usefulness of bioresmethrin for the control
    of stored product pests and as a grain protectant (Ardley, 1973 and
    1975; Ardley and Desmarchelier, 1974; Cooper McDougall and Robertson,
    1971; Lloyd, 1973; Rowlands, 1975; Bengston et al., 1975a, 1975b).

         Ardley (1975) showed that of many pyrethroid and organophosphorus
    insecticides and insecticide combinations evaluated in silo trials,
    the best product on a cost/efficiency basis was 4 ppm bioresmethrin
    plus 20 ppm piperonyl butoxide. After 12 months, the treated grain
    controlled all species and strains exposed in bioassay. A lower
    efficiency was observed in the control of confused flour beetle
    (Tribolium confusum). 

         The problem of resistance to malathion, dichlorvos and lindane
    which is developing in stored product insects in almost all countries
    has caused intensive examination of alternative protectant chemicals,

         Lloyd (1973) in examining the toxicity of pyrethrins and five
    synthetic pyrethroids to susceptible and pyrethrin-resistant strains
    of stored product pests reported bioresmethrin to have up to 16 times
    more toxicity than that of pyrethrins. He showed that piperonyl
    butoxide synergized all the compounds against the various strains.
    When synergized, bioresmethrin was again the most potent of the
    synthetic compounds. L'Hoste et al. (1969) showed that bioresmethrin
    deteriorated less rapidly than malathion when admixed with grain.

         In Australia, the occurrence of malathion-resistant strains of
    Rhyzopertha dominica is a severe threat to the grain export
    industry. Malathion was never entirely satisfactory for the control of
    this species, which shows a high degree of tolerance to all
    organophosphorus materials that could possibly be used for the
    protection of stored grains. The efficiency of bioresmethrin or
    bioresmethrin/piperonyl butoxide combinations in controlling this
    species is therefore important.

         Bengston et al. (1975b) have shown clearly the high potency of
    bioresmethrin against Rhyzopertha dominica which makes it an ideal
    insecticide to complement such organophosphorus grain protectants as
    malathion, pirimiphos-methyl and chlorpyrifos-methyl.

         Table 1, from the work of Ardley and Desmarchelier (1974), shows
    the efficiency of bioresmethrin/piperonyl butoxide combinations
    against both susceptible and resistant strains of the more important
    grain pests.

    TABLE 1. Summary of Grain Protectant Trials, 1967-1974

                                          Storage details                              Final laboratory assay1
                           holding     Grain          Grain                 Bioassay3            F1 generation             (actual numbers)3
    Protectant2            period      moisture       temperature           %mortality           Dead                      Live
    treatment              (months)    (% average)    (°C average)       Sgs    Rds    Tcs       Sgs    Rds    Tcs         Sgs    Rds     Tcs

    1967 2 ppm             11-1/4      11.4           20.6               100    100              0      0      -           0      0       -
    resmethrin + 20 ppm
    pbo;2 2 ppm
    pyrethrins + 20        10          11.5           20.7               85     100              1      0      -           0      0       -
    ppm pbo

    1968 1 ppm             4  approx.  <10.0          29.0               99     100    0         1      0      0           0      0       0
    bio-resmethrin + 10       or 
    ppm pbo; 0.5 ppm          equal
    bioresmethrin +        4  "        <10.0          28.4               100    100    40        1      0      0           4      0       0
    5 ppm pbo; 2 ppm
    pyrethrins             3  "        <10.0          20.6               95     100    20        0      0      2           10     10      1
    +20 ppm pbo

    1969 2 ppm             8           10.9           19.2               75     100    40        0      0      0           50     10      9
    bio-resmethrin + 0.2
    ppm antioxidant;
    12 ppm malathion       8           10.8           20.7               100    80     90        23     0      0           0      1       0
                                                                         *             **
    1973 4 ppm 
    bio-resmethrin         12          10.2           23.9               5      100    <8        -      0      0           63     0       -

    8 ppm 
    bio-resmethrin         12          10.7           24.0               40     100    <15       -      0      0           3      1       -

    12 ppm 
    bio-resmethrin         12          10.5           24.4               95     100    <38       -      2      0           0      0       -

    TABLE 1. (cont'd)


                                          Storage details                              Final laboratory assay1
                           holding     Grain          Grain                 Bioassay3            F1 generation             (actual numbers)3
    Protectant2            period      moisture       temperature           %mortality           Dead                      Live
    treatment              (months)    (% average)    (°C average)       Sgs    Rds    Tcs       Sgs    Rds    Tcs         Sgs    Rds     Tcs

    4 ppm 
    bio-resmethrin +
    20 ppm pbo             12          10.5           23.5               100    100    <10       -      1      0           0      0       -

    8 ppm 
    bio-resmethrin + 20
    ppm pbo                12          10.5           23.6               100    100    <9        -      0      0           1      1       -

    12 ppm malathion       12          10.4           23.9               95     0      <8        -      3      1           0      6       -

    control, on
    clean wheat            12          10.5           23.5               4      5      -         -      0      4           376    0       -

    1 14 day period.

    2 pbo  =   piperonyl butoxide.

    3 Sgs  =   Sitophilus granarius   )malathion
      Rds  =   Rhyzopertha dominica   )susceptible
      Tcs  =   Tribolium castaneum )  strains.

    *S. oryzae in all 1973/74 trials.

    **T. castaneum assays discontinued after nine months.

         Carter et al. (1975) have evaluated a range of synthetic
    pyrethroid insecticides against susceptible and resistant strains of
    stored product pests and have concluded that synergized bioresmethrin
    was the most suitable pyrethroid and that it was of value in
    controlling organophosphorus resistant beetles.

         For reasons of economy, to increase the spectrum of effect
    against the many different pests encountered in stored products and to
    reduce the possibility of selecting resistant strains, it is proposed
    that bioresmethrin be combined with one of the organophosphorus grain
    protectants. There is already a good deal of evidence (Abernathy et
    al., 1973; Jao and Casida, 1974) that organophosphorus compounds
    inhibit the esterases responsible for the hydrolysis of bioresmethrin
    in living systems.

         When used for grain protection, bioresmethrin is applied with
    piperonyl butoxide in the form of an emulsion which has been diluted
    with water to a concentration which, when applied to bulk grain at the
    rate of 1 litre per tonne, will deposit a known amount of
    bioresmethrin evenly on the grain. The amount applied ranges from 1 to
    4 ppm. The amount of piperonyl butoxide applied concurrently would
    range from 5 to 20 mg/kg.

    Treatment of animals

         Bioresmethrin is suitable for the control of flies on cattle and
    pigs but no information was available to indicate whether such uses
    had yet been approved by registration authorities.


    Fruit and vegetable crops

         Only preliminary results are available to show the fate of
    bioresmethrin on tomatoes (Buick and Flanagan, 1973) and on cucumbers
    (Buick and Flanagan, 1974; Cooper McDougall and Robertson, 1975).

         In these studies, radio-labelled bioresmethrin emulsified in
    water was applied to tomato fruits (growing in a laboratory) at a rate
    sufficient to deposit 1.25 mg/kg of bioresmethrin on the tomatoes. The
    deposit applied to the growing tomatoes was estimated by determining
    the total radioactivity after allowing the deposit to dry for one
    hour. The fruit was harvested at 6, 12, 24, 48 and 72 hours after
    application and the amount of bioresmethrin in the flesh, skin and on
    the skin surface was measured after washing the fruit for two minutes
    in benzene. The degradation products were removed from the benzene
    solution by passing through alumina. The distribution of bioresmethrin
    in and on tomatoes is shown in Table 2. The results are expressed as a
    percentage of the total radioactivity applied.

    TABLE 2.  Distribution of bioresmethrin in tomatoes


    Hours           1       6        12      24       48       72

    Flesh           0.2     0.2      0.2     0.2      0.2      0.2

    Skin            1.75    2.45     3.2     1.95     4.65     4.65

    Benzene wash    92.5    39.0     50.0    54.5     22.5     15.5

    TOTAL           94.25   41.45    53.2    56.45    27.15    20.15

         From the table, it is evident that over 90% of the bioresmethrin
    will be recovered by simply washing with benzene if the fruit is
    harvested within 24 hours of spraying. If harvested later than this,
    then up to 25% of the remaining insecticide may be held in the skin
    three days after treatment but this will represent less than 5% of
    that originally applied. The amount of bioresmethrin found in the
    flesh is insignificant.

         In the case of cucumbers (Buick and Flanagan, 1974) bioresmethrin
    was applied as an emulsion to the surface of cucumbers growing in a
    darkened laboratory equivalent to approximately 1 mg/kg of fruit. The
    total radioactivity and radioactivity due to intact bioresmethrin was
    determined on the surface, in the skin and in the flesh of cucumbers
    harvested 1, 6, 12, 24, 48 and 72 hours after application.

         The results indicate that although most of the radioactivity
    applied is retained, the bioresmethrin is substantially degraded
    within an hour of application and more slowly thereafter (24% survival
    after one hour, 10% after 72 hours). This contrasts with the results
    of the tomato experiments in which the bioresmethrin was found to
    degrade more slowly. A simple washing of the intact fruit with benzene
    removes at least 85% of the surviving bioresmethrin at any time up to
    three days after treatment, whether or not the fruit is stored in the
    dark before analysis. The results of this work are summarized in Table

    TABLE 3. Distribution of undegraded bioresmethrin in cucumbers


    Bioresmethrin, mean of four results (from stored and unstored vegetables)
    shown as % of "concentration applied", after interval (hours)


        Fraction     1         6         12        24        48        72

        Flesh        <0.1      <0.1      <0.1      <0.1      <0.1      <0.1

        Skin         0.8       1.6       0.7       1.4       0.8       1.2

        Wash         23.3      14.7      8.1       9.8       7.0       8.8

        TOTAL        24.1      16.3      8.8       11.2      7.8       10.0


    On plants

         Rosen (1972) showed that resmethrin and its alcohol moiety
    photodecompose to many unidentified products at a rate which varies
    with the supporting surface. Residues exposed to sunlight on silica
    gel degrade more rapidly than residues on glass and different products
    are formed. The author postulates that plant and soil surfaces will
    show greater differences. Photodecomposition of bioresmethrin was
    studied intensively, although under limited experimental conditions,
    by using phenyl-14C alcohol and carboxy-14C acid preparations (Ueda
    et al., 1974). After irradiation of the radioactive resmethrin on a
    silica gel plate with a sunlamp for seven hours, 88% of the
    radioactivity was recovered, 5% of which was the intact resmethrin.
    Forty-three per cent. of the recovered radioactivity was identified
    and of this 33% and 10% respectively were ester and non-ester
    products. Figure 1 illustrates the proposed, although somewhat
    speculative, photodecomposition pathways. The photodecomposition
    product in largest amount (approximately one-fifth of the applied
    radioactivity) was 5-hydroxy-3-oxo-4-phenyl-1-cyclopentenylmethyl
    trans-chrysanthemate (II in Figure 1), followed by
    trans-chrysanthemic acid and an unidentified ester (about 5% of
    each). Four other oxidized esters with a modified alcohol moiety
    accumulated slowly, but not to a high level (less than 3%). They are
    the R and S isomers of 5-hydroxy-3-oxo-4-phenyl-1-cyclopentenylmethyl
    trans-epoxychrysanthemate (III),
    2-benzyloxy-5-oxo-2,5-dihydro-3-furylmethyl trans-chrysanthemic acid (V).
    A minute amount of 2-benzyloxy-5-oxo- 2,5-dihydro-3-furylmethyl
    trans-chrysanthemate (IV) was also detected. The R and S isomers
    of trans-epoxyresmethrin (I) were minor products and did not

         Thus, the initial pathways are of three types:

         (1)  oxidation of the furan ring to give a cyclic ozonide-type
              peroxide intermediate (II);

         (2)  epoxidation of the isobutenyl double bond; and

         (3)  cleavage at the ester linkage to give chrysanthemic acid.

         Ester bond cleavage would yield 5-benzyl-3-furylmethanol, but
    none was found. 5-benzyl-3-furoic acid, alpha-(4-carboxyl-2-furyl)
    benzyl alcohol and 5-benzoyl-3-furoic acid were not detected either.
    This indicates that a more complex cleavage mechanism is involved or
    that 5-benzyl-3-furylmethanol is not sufficiently stable to
    accumulate. Benzyl alcohol, benzoic acid and phenylacetic acid (less
    than 2% of each) were formed and tended to increase by extensive
    oxidation. The unpleasant odour of photodecomposed bioresmethrin
    appears to be due, at least in part, to the photochemical formation of
    phenylacetic acid.

         Following irradiation by sunlight, no appreciable changes in the
    deco position pattern were observed except an increase of compound V.
    A 0.14 mg/l aqueous solution of bioresmethrin irradiated with a
    sunlamp yielded a larger amount of the R isomer of
    trans-epoxyresmethrin (5.2% of the total radioactivity following 60
    minutes' irradiation) and trans-chrysanthemic acid (11%). No
    information was available on degradation studies carried out under
    other conditions.

         Andrews (1974) reports studies which indicate that when
    bioresmethrin is applied to a forest environment by helicopter in the
    form of an oil solution, there is a rapid disappearance of residues
    from forest foliage and the surface of ponds. When 50 and 150 grams of
    bioresmethrin in five litres of mineral oil was applied, it was
    possible to determine residues of even the lower rate on foliage of
    several forest species. Following application of the higher rate,
    approximately 1 ppm of bioresmethrin was deposited on the foliage of
    trees. Three days after application, approximately 0.3 mg/kg of
    bioresmethrin could be detected on the foliage of willows but not on
    other species. After seven days the deposit on willow foliage was at
    the limit of determination (0.05 mg/kg). Although bioresmethrin
    applied at the rate of 50 g/ha was toxic to most of the aquatic
    insects in the first hour after application, no trace of bioresmethrin
    could be found in any samples of pond water. Bioresmethrin was
    detected in control samples containing 10 micrograms of bioresmethrin
    per 100 ml of tap water.
    FIGURE 1

         Extensive studies now in progress in Australia are designed to
    determine the effective life of bioresmethrin deposits on grain stored
    under a wide variety of conditions of temperature, moisture and
    aeration. Preliminary results indicate that temperature has a distinct
    bearing on the residual life of the treatment and that grain
    temperatures of 30-35°C reduce the half-life to approximately 8-10

         Desmarchelier (1975b) has found that grain treated with
    bioresmethrin and subjected to bioassay with Rhyzopertha dominica,
    shows a consistent loss of insecticidal effect which is directly
    dependent on temperature. The "half-life" shown by these studies is as


         Storage temperature           Half-life

              20°C                     >20 weeks

              25°C                     12 weeks

              30°C                     10 weeks

              35°C                     8 weeks

         These studies are being confirmed by chemical analysis.

         Desmarchelier (1975a) who is studying the fate of bioresmethrin
    in various grains stored under a range of temperature and moisture
    conditions reports preliminary results after seven weeks of a 12-month
    storage programme. The results in Table 4 indicate that piperonyl
    butoxide has a pronounced influence on stability even at 35°C.
    Preliminary calculations indicate a half-life of 30 weeks at 30°C in
    the presence of 10 times the amount of piperonyl butoxide.

         Studies currently in progress in Australia (Bengston et al.,
    1975) in which bioresmethrin has been used with primiphos-methyl to
    treat bulk wheat held in commercial silos, both aerated and
    non-aerated, indicate that the bioresmethrin deposit remains stable
    for long periods. Wheat treated with a nominal 4 mg/kg bioresmethrin
    was found to contain 3.1 mg/kg when analysed a few days later. This
    wheat was maintained in an unaerated silo at 24°C and in an aerated
    silo at 14°C (lower temperature due to aeration). Six weeks after
    treatment the residue level was found to be 2.2 mg/kg (unaerated) and
    2.4 mg/kg (aerated) At the end of six months, the bioresmethrin
    residue had declined in only 1.1 mg/kg (unaerated) and 1.9 mg/kg


    In animals

         Extensive studies of the metabolism of bioresmethrin in animals
    have been carried out by many authors including the following:
    Abernathy and Casida (1973); Abernathy et al. (1973a); Farebrother
    (1973); Foote et al. (1967); Jao and Casida (1974); Miyamoto (1975);
    Miyamoto et al. (1971); Miyamoto et al. (1974); Suzuki and Miyamoto
    (1974); Ueda et al. (1975a,b); Weeks et al. (1972).

         Most of these studies have been carried out on laboratory
    animals, mainly rats. Radioactivity measurements and radioautographs
    indicate that the compound is rapidly absorbed from the intestinal
    tract and distributed into various tissues where only a negligible
    amount of intact bioresmethrin was found. However, the radioactivity
    was excreted rather slowly and it took three weeks to recover all the
    radioactivity in the excrete (36% in urine and 64% in faeces).

         Neither urine nor faeces contained intact bioresmethrin or the
    ester metabolites. The predominant urinary metabolite being
    5-benzyl-3-furoic acid amounting to approximately one-third of the
    radiocarbon recovered. A proposed metabolic pathway of bioresmethrin
    is shown in Figure 2.

        TABLE 4. Bioresmethrin residues in wheat stored at various temperatures


                              Moisture                            Bioresmethrin residue, mg/kg, after
                              content       Initial                           storage at:
                              of grain      bioresmethrin
      Treatment               %             level                 10°C    20°C    25°C    30°C    35°C
    Bioresmethrin on
    wheat                      11.9            3.3                 2.7    2.4     2.1     1.9     1.9

    Bioresmethrin +
      butoxide +
      1/10/1 on wheat          11.9            3.3                 -      -       -       2.9     -

    Bioresmethrin on
      wheat                    10.2            2.8                 -      -       2.3     -       2.2

    Bioresmethrin on
      husked rice              12.0            3.3                 2.9    2.3     -       1.5     -

    Bioresmethrin +
      butoxide (1/10)
      on husked rice           12.0            3.3                 -      3.1     -       2.9     -

    Bioresmethrin on
      polished rice            13.0            2.8                 -      -       0.8     -       0.8

    Bioresmethrin +
      butoxide (1/10)
      on polished rice         13.0            2.8                 -      -       1.7     -       1.4

    FIGURE 2

         Farebrother (1973) in a whole body autoradiographical study in
    rats showed that bioresmethrin was absorbed through the gut and widely
    distributed in the body two hours after dosing. At six hours the
    distribution was similar but the concentrations were increased,
    particularly in fatty tissues. At 24 hours most tissues showed greatly
    reduced activity but the concentration in fatty tissue remained high.

         No studies appear to have been carried out to determine the level
    or nature of the metabolites in animal fat or other tissues. No
    studies are yet available to show the fate of bioresmethrin when fed
    to livestock or poultry.


         Ardley (1975) reports trials in which wheat treated with
    bioresmethrin at varying rates with and without piperonyl butoxide,
    was subjected to standard milling and baking tests.

         The grain, when milled gave 25% bran, 7% pollard (shorts) and 68%
    flour. The flour was converted into bread. All loaves were
    satisfactory. No taint or odour was evident during dough processing or
    in the loaves fresh from the oven.

         The milling fractions and the bread were analysed. The nature of
    the chemical treatment and the results of analysis are provided in the
    following table. Analyses were carried out by two laboratories and the
    results were in good agreement.

        TABLE 5.  Residues of bioresmethrin and piperonyl butoxide in milling
              fractions and bread

              Recovered residue (i) bioresmethrin (ii) piperonyl butoxide (ppm)


                                (i)                                 (ii)
      treatment   bran   pollard   flour   bread      bran   pollard   flour   bread
         a         0.3     4.0      4.0     nil       21.0    10.0      2.0     2.0
         b         0.3     1.0      1.4     nil        0.5     0.3      nil     nil
         c         0.5     1.0      0.5     nil       11.0     8.0     10.0     nil
         d         1.1     1.2      0.5     nil        2.0     2.0      2.0     nil
         e         nil     nil      nil     nil        nil     nil      nil     nil

    1 a  =  4 mg/kg bioresmethrin + 20 mg/kg piperonyl butoxide
      b  =  2   "        "         alone
      c  =  4   "        "         + 10 mg/kg piperonyl butoxide +
                                     4 mg/kg anti-oxidant
      d  =  2   "        "         + 2 mg/kg piperonyl butoxide +
                                     10 mg/kg anti-oxidant + 4 mg/kg
             In a subsequent study Desmarchelier ( 1975b) took wheat which had
    been treated six weeks (A) and seven months (B) previously and
    subjected it to standard milling procedures for the preparation of
    wholemeal and white flour. The following results indicate the
    distribution and fate of the bioresmethrin:


         Sample                         A              B

    Interval since treated             6 weeks        7 months

    Residue in wheat                   2.9 mg/kg      1.9 mg/kg

         bran                          5.2 "          1.7 "

         pollard (shorts)              0.7 "          -

         white flour                   *               *

    wholemeal bread                    1.0 "          0.6 "

    white bread                        ND              ND

    limit of determination = 0.05 mg/kg

    * Interference led to poor recoveries during assay of flour.


         Bioresmethrin has not yet been widely used on food crops or for
    the treatment of stored grain and therefore no information is
    available on residues in food moving in commerce.


         The analytical methods for resmethrin have been reviewed by Brown
    (1973) and also by Murano et al. (1971), Murano (1972) and
    Desmarchelier (1975). The methods include ultra-violet absorption
    spectrophotometry, colorimetry, TLC and GLC. SE-30, DC200 ‰ QFI and DEGS
    have been used as stationary phases for the GLC determination of
    resmethrin in crops after suitable clean-up procedures. Brown (1973)
    proposes a residue analytical method for wheat, wheat flour and corn
    meal in which resmethrin is extracted with hexane, partitioned between
    hexane and acetonitrile, cleaned up on an Alumina column, and
    determined by GLC.

         The difficulty in the residue analysis of resmethrin, which would
    apply equally to the optical isomer bioresmethrin, seems to lie in the
    intrinsically low sensitivity to the compound of electron capture or
    flame ionization detectors. The limit of detection ranges at best from
    0.1 to 0.05 µg, equivalent in practice to a residue level of about
    0.1 mg/kg.

         To overcome the drawback, the component chrysanthemic acid is
    quantitatively condensed with 2,4-dichlorobenzyl chloride to yield
    2,4-dichlorobenzyl chrysanthemate, which can be determined by electron
    capture (Miyamoto, 1975), It is reported that this modification allows
    as little as 0.01 ng of the derivative or approximately 0.01 ng of
    bioresmethrin to be analysed. Up to 100 µg of bioresmethrin is
    hydrolyzed in 10% methanolic potassium hydroxide for one hour at 60°C.
    Chrysanthemic acid is extracted with chloroform at pH2. The chloroform
    is evaporated in vacuo and the residue dissolved in 5 ml acetone and
    warmed at 60°C for 120 min with the addition of 0.1 ml of
    N,N-dimethylformamide and one drop each of triethylamine and
    2,4-dichlorobenzyl chloride. The reaction mixture is passed through a
    Florisil column and eluted with benzene. 2,4-dichlorobenzyl
    chrysanthemate is chromatographed under the following conditions.
    Liquid phase Epon-1001 (1%) and QF-1 (1%) on Chromosorb B (100 to 120
    mesh); temperature of oven and detector, 200°C and of injection port,
    240°C; carrier nitrogen, 1.0 kg/cm›. Retention time of
    2,4-dichlorobenzyl chrysanthemate about 4-1/2 min. The overall
    recovery in the range 1 to 100 ng of resmethrin is at least 80%, often
    more than 90%. Resmethrin residues of the order of 1 µg/kg can
    therefore be determined.

         Desmarchelier (1975a,b) reports a colorimetric method based an
    the procedure of Screiber and McClellan (1954) and McClellan (1964)
    originally designed for the analysis of pyrethrum and based on the
    analysis of chrysanthemic acid. The author examines the applicability
    of this procedure to residue analysis of five pyrethroid derivatives
    of chrysanthemic acid on six commodities and extends it to derivatives
    of pyrethric acid, for example pyrethrin II. In addition, a TLC
    procedure is described that allows positive identification of
    derivatives of chrysanthemic acid in a one-step process. In the case
    of bioresmethrin, results obtained by these two procedures on aged
    residues on wheat were compared with results obtained by two
    procedures specific to bioresmethrin. Appreciable differences between
    results occurred only at the limit of determination. In the method of
    Desmarchelier, petroleum spirit (b.p. 30-40°C) was added to whole
    grain (100 g) and left overnight. The supernatant was decanted, the
    grain covered with solvent and extracted for a further hour and this
    procedure repeated once more. Methanol, acetone and 10% acetone in
    petroleum spirit appear equally suitable as solvents.

         Although none of the metabolites or photo-products have been
    reported to be analysed in the actual samples, various techniques and
    procedures for separation as well as identification of the possible
    terminal residues of bioresmethrin are described in a number of papers
    including those of Miyamoto et al. (1971); Ueda et al. (1974, 1975a
    and b); Abernathy (1973); Brown (1973) and Murano (1972).

         Simonartis and Coil (1975) have developed a GLC method for the
    determination of resmethrin in corn, corn meal, flour and wheat. it
    involves extraction with pentane, transfer to acetonitrile, Florisil
    clean-up using 3% ethyl acetate in perthane followed by GLC using
    flame conization detector. The method is sensitive to 0.2 ppm with
    better than 85% recovery and good reproductivity.


         The information available to the Meeting suggests that no
    national tolerances have yet been established.


         Bioresmethrin is a broad spectrum pyrethroid insecticide with
    contact action and pronounced knockdown effect. It shows only limited
    biological persistence on plant surfaces and is readily degraded by
    sunlight but gives long-lasting control of insect pests on inert
    surfaces and retains its biological activity when applied to stored
    agricultural commodities, including raw grain and nuts.

         The Meeting had only limited information concerning the use and
    performance of this material on crops pre-harvest but extensive data
    were available on the use, performance and fate of bioresmethrin on a
    variety of grains. The recommended rate of application to raw cereals
    is 1 to 4 mg/kg. The biological half-life on grain ranges from eight
    weeks at 35°C to more than 20 weeks at 20°C. 

         Data available suggest that when bioresmethrin is applied to
    wheat, the deposit is not confined to the seed coat but penetrates to
    the endosperm so that a substantial proportion of the amount applied
    is found in flour. Standard milling techniques which remove most of
    the seed coat, produce a bran which contains considerably less
    bioresmethrin than does the whole grain or the flour. Virtually all of
    the bioresmethrin is destroyed when bread prepared from such flour is

         Extensive information is available on the biological degradation
    and metabolism of bioresmethrin including the nature of the
    metabolites formed under a wide variety of conditions. The initial
    step in the metabolism of bioresmethrin is hydrolysis at the ester
    linkage, yielding 5-benzyl-3-furylmethanol and chrysanthemic acid.

         Several GLC methods of analysis suitable for the determination of
    residues of bioresmethrin and metabolites containing chrysanthemic
    acid in plant materials are available. The limit of determination
    ranges from 0.1 to 0.001 mg/kg. In addition there are several
    colorimetric methods based an the determination of chrysanthemic acid
    which can be used in conjunction with a TLC procedure for identifying
    the pyrethroid residue involved. No national tolerances have yet been

         In proposing maximum residue limits for bioresmethrin on raw
    grain, milled cereal products and foods prepared therefrom, careful
    consideration has been given to the fact that this insecticide is to
    be used as a grain protectant, that a certain concentration must be
    present in the grain to control infestations and prevent damage to
    stored products and that the compound is moderately stable under
    storage conditions. Under practical conditions of grain handling and
    storage, there will always be a natural variation in the level of the
    deposit resulting from a fluctuation in the flow of grain and
    insecticide. it is therefore not possible to fix the maximum limit on
    the minimum necessary to control insect pests. At the present time, it
    is anticipated that bioresmethrin will be used in conjunction with one
    or more of the organophosphorus grain protectants whose effect is
    complementary and possibly synergistic. Under such conditions the
    amount of bioresmethrin used will be at the lower range of the
    proposed rates. However, there will be situations where bioresmethrin
    must be used alone at the maximum of the proposed rate and due
    allowance must be made for the amplitude of the variations in
    concentration which are inevitable and the problems of sampling and
    analysis involved.


         The following guideline levels are recommended as limits which
    need not be exceeded when bioresmethrin is used according to good
    agricultural practices in the following commodities:


    Commodity                               Maximum residue limit, mg/kg

    Raw grain                                            5

    Milled products from grain                           5

    Cooked cereal products, including                    0.05*

    *  At or about the limit of determination.


    REQUIRED (before an acceptable daily intake can be allocated)

         1. Full toxicological data.


         1.   Further information on the level and fate of bioresmethrin
              on different classes of raw grains.

         2.   Information on residues from supervised trials on other
              stored commodities, including nuts, peanuts, lentils, dried
              fruit and dried vegetables,

         3.   Information on residues in fruit and vegetables following
              approved uses.

         4.   Further information on the level and fate of residues in
              food at the point of consumption following the use of
              bioresmethrin for the control of various stored-product

         5.   Improved procedures for the determination of bioresmethrin
              residues in fruit and vegetables as well as stored products.


    Abernathy, C. O. and Casida, J. E. (1973) Pyrethroid insecticides:
    esterase cleavage in relation to selective toxicity. Science, 179:

    Abernathy, C. O., Ueda, K., Engel, J. L., Gaughan, L. C. and Casida,
    J. E. (1973a) Substrate specificity and toxicological significance of
    pyrethroid hydrolyzing esterases of mouse liver microsomes. Pesticide
    Biochemistry and Physiology, 3: 300-311.

    Andrews, T. L. (1974) Resmethrin Residues in foliage after aerial
    application. Pesticide Monitoring Journal, 8(1):50-52.

    Ardley, J. H. (1973) Further field evaluation of bioresmethrin as a
    potential replacement for malathion in grain protection. Wellcome
    Australia Ltd Report TD/5/73/Kl-36.

    Ardley, J. H. (1975) Use and application of resmethrin and
    bioresmethrin as potential grain protectants. Paper submitted to
    Journal of Stored Products Research (May 1975)

    Ardley, J. H. and Desmarchelier, J. M. (1974) Investigations into the
    use of resmethrin and bioresmethrin as potential grain protectants.
    Proceedings of the First International Working Conference on Stored
    Product Entomology, Savannah, Georgia, USA.

    Ardley, J. H. (1975) Report of milling and baking trials with
    bioresmethrin treated wheat. Report of Wellcome Australia Ltd, 27
    August 1975.

    Bengston, M., Cooper, L. M. and Holton, F. J. (1975b) A comparison of
    bioresmethrin, chlorpyrifos-methyl and pirimiphos-methyl as grain
    protectants against malathion-resistant insects in wheat. Submitted
    for publication, Queensland Journal of Agricultural and Animal

    Bengston, M., Connell M., Desmarchelier, J., Snelson, J. and Sticka,
    R. (1975a) Report of field trials with grain protectants. To be

    Brooks, I. C., Hans, J., Blumenthal, R. R. and Davis, B. S. (1969) SBP
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    Brown, B. B. (1973) In "Analytical methods for pesticides and growth
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    Buick, A. R. and Flanagan, P. (1973) The fate of NRDC 107
    (bioresmethrin) on tomatoes. Wellcome Foundation Report HEGH 73/1.

    Buick, A. R. and Flanagan, P. (1974) The fate of bioresmethrin on
    cucumbers. Wellcome Foundation Report HEGH 74/1.

    Cantu, E. and Wolfenbarger, D. A. (1970) Toxicity tests of three
    pyrethroids to several insect pests of cotton. J. econ. Ent., 63(4):

    Carter, S. W., Chadwick, P. R. and Wickham, J. C. (1975) Comparative
    observations on the activity of pyrethroids against some susceptible
    and resistant stored products insects. Submitted for publication.

    Chesher, B. C. and Malone, J. C. (1970) Acute toxicity tests with NRDC
    107 in hens. Wellcome Foundation Report B 236-70.

    Chesher, B. C. and Malone, B. C. (1970) Sensitisation study with NRDC
    107 on guinea pigs. Wellcome Foundation Report B 198-70.

    Chesher, B. C. and Malone, J. C. (1970) Ocular irritancy of NRDC 107
    in rabbits. Wellcome Foundation Report B 217-70.

    Chesher, B. C. and Malone, J. C. (1971) Toxicity to dogs of NRDC 107
    (continuation). Wellcome Foundation Report No. B 27-71.

    Chesher, B. C. and Malone, J. C. (1971) Acute toxicity of NRDC 107 by
    the intravenous route. Wellcome Foundation Report B 329-71.

    Colas, R. (1970) Toxicité NRDC 107 et NRDC 104 sur poissons. Report
    from Procida, 9 September 1970.

    Cooper McDougall and Robertson. (1971) Bioresmethrin Technical Data
    BRM 1-8.

    Cooper McDougall and Robertson Ltd. (1975) Bioresmethrin for
    agricultural use. Technical Bulletin, 41 pages.

    Desmarchelier, J. M. (1975a) Analysis of pyrethroids on grains (In
    press). CSIRO Division of Entomology, P.O. Box 1700, Canberra City,

    Desmarchelier, J. M. (1975b) Results of studies to determine fate of
    bioresmethrin on stored grain. CSIRO Stored Grain Research Laboratory,
    Canberra, Australia (Personal communication).

    Elliott, M. (1969) Structural requirements for pyrethrum-like
    activity. Chemistry and Industry, 14 June 1969, 776-781.

    Elliott, M., Farnham, A. W., Janes, N. F., Needham, P. H. and Pearson,
    B. C. (1967) 5-benzyl-3-furfuryl methyl chrysanthemate - a new potent
    insecticide. Nature, 213(5075):493.

    Elliott, M., Janes, N. F. and Pearson, B. C. (1971) The pyrethrins and
    related compounds, Part XIII. Insecticidal methyl -, alkenyl- and
    benzyl-substituted furfuryl and furylmethyl chrysanthemates. Pestic.
    Sci., 2:243.

    Elliott, W., Janes, N. F. and Spanner, J. A. (1973) The pyrethrins and
    related compounds. Preparation of bioresmethrin, Pestic. Sci.,

    Fales, J. H., Bodensten, O. F., Waters, R. M., Fields, E. S. and Hall,
    R. P. (1971) Insecticidal Evaluation of SBP-1390 (bioresmethrin). Soap
    Chem. Spec., September 1971, pp. 54-62, 73.

    Farebrother, D. A. NRDC 107. (1973) Whole body radioautographal study
    in male albino rats. Wellcome Foundation Report HEFH 73-1.

    Flanagan, F. & Poll, G. S. (1970) Synthetic pyrethroids - estimation
    of cis and trans isomers. Cooper Technical Bureau Series B Report
    93/70, 21 May 1970.

    Foote, C. S., Wuesthoff, M. T., Wexler, S., Burnstain, I. G., Denny,
    R., Schenck, G. O. and Schulte-Elte, K.-H. (1967) Tetrahedron,

    Ford, M. G. and Pert, D. R. (1974) Time/Dose/Response relationships of
    pyrethroids insecticides with special reference to knockdown.
    Pesticide Science, 5:635-641

    Fujimoto, K., Itaya, N., Okuno, Y., Kadota, T. and Yamaguchi, T.
    (1973) A new insecticidal pyrethroid ester. Agri. Biol. Chem.,

    Glomot, R. (Undated) Etude de la toxicité chronique de 3 semaines chez
    le rat du RU11484 (NRDC 107) Roussel Uclaf Rapport.

    Glomot, R. and Chevalier, B. (1969) Etude de la Toxicité argue du
    RU11484 (NRDC 107) Roussel Uclaf Rapport Toxico 11386.

    Jao, L. T. and Casida, J. E. (1974) Pestic. Biochem. Physiol., 4:456

    L'Hoste, J., Balloy, J. and Rauch, F. (1969) La protection des blés
    contre Sitophilus granarius. Congr. Pl. Prot. Org. by CIA and CITA,
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    L'Hoste, J. and Rauch, F. (1969) Remarques sur quelques
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    L'Hoste, J. and Rauch, F. (1969) Sur les propriétés insecticides du
    d-trans ethanochrysanthémate de benzyl-5 furylméthyle-3. Conte
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    Lloyd, C. J. (1973) The toxicity of pyrethrins and five synthetic
    pyrethroids to Tribolium castaneum and susceptible and pyrethrins
    resistant Sitophilus granarius. J. Stored Prod. Res., 9:77-92

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    Malone, J. C. and Chesher, B. C. (1970) Toxicity of bioallethrin/NRDC
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    Malone, J. C. (1971) NRDC 107, 3 month oral toxicity study in beagle
    dogs. Wellcome Foundation Report No. B 109-71.

    Miyamoto, J. (1975) Terminal residues of bioresmethrin. Submission to
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    Miyamoto, J., Nishida, T. and Ueda , K. (1971) Metabolic fate of
    resmethrin, 5-benzyl-3-furyl methyl-dl-trans-chrysanthemate in the
    rat. Pesticide Biochemistry and Physiology, 1:293, 306.

    Miyamoto, J., Suzuki, T. and Nakae, C. (1974) Pestic. Biochem., 4:438

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    Noel, P. R. B., Rivett, K. F., Chesterman, H., Street, A. E. and
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    Rosen, J. D. (1972) In "Environmental Toxicology of Pesticides",
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    Simonartis, R. A. and Coil, R. S. (1975) Gas-liquid chromatographic
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    See Also:
       Toxicological Abbreviations
       Bioresmethrin (ICSC)
       Bioresmethrin (Pesticide residues in food: 1976 evaluations)
       Bioresmethrin (Pesticide residues in food: 1991 evaluations Part II Toxicology)
       Bioresmethrin (UKPID)