CA1097131A - Packaging material resistant to insect infestation - Google Patents

Abstract

ABSTRACT

A sealable packaging film impregnated with a pesticide or insecticide such as pyrethrin. Heat sealable packages of such film ensure that infestation is either contained within the package or ensures that external infestation cannot penetrate the package.

Description

1097~L3~1L
This invention relates to the control and prevention o~ infestation of packaged food products.
Infestation of packaged foods can occur during all stages of storage from the warehouse to the housewife's pantry, in both tropical and temperate climates. Various techniques have been developed to prevent infestation but such technique cannot deal with all types of infestation and some are generally expensive in their application.
Jute sacks have traditionally been used for the storage and transportation of foodstuffs but because of easy penetration by insects and insect larvae these have generally been replaced by multi-wall paper sacks~ With these sacks it was found that insects and larvae could still penetrate the sack through the stiched seams. One proposal to overcome this problem was to tape the stitching with an adhesive tape incorporating an insecticide in the adhesive layer.
In order to prevent insect and larvae infestation in boxed products it has been proposed to coat the box materials with a varnish layer incorporating a general insecticide.
However, although this treatment prevented insects boring through the box wall they were still able to penetrate the seams and closures. Barrier films although a partial solution do not prevent insects boring through the plastic film.
`- It is an object o~ this invention to provide a means which can be generally applied to prevent insect infestation in packaged food products. To this end there is provided a plastic wrapping film incorporating an insecticidal agent as a component of the film. Such a film can be used to fully envelop conventional food packages and by sealing the

- 2 -~1 :

: . :,:: :: :: : :: :: . . : :
. ; :: . :. -, : : -.

. ` 1097~31 seams an airtight package is ~ormed which provides no access for insects to penetrate the plastic envelope. Insects are repelled from boring through the film due to the presence of the insecticide. The sealable plastic film of this invention thus provides a simple means, for packaging food products.
Large conventional containers or a ~roup of conventional containers can be wrapped within this plastic film and the film heat sealed to provid an effective preventive covering.
: One insecticidal chemical currently approved for use on food packages by the Food and Drug Administration of the U.S.A. is pyrethrins or a combination of pyrethrums with the s~lergist piperonyl butoxide. Pyrethrins have been used in paper coatings for food products packaged in paper or card-board containers. However it has never been proposed to incorporate pyrethrins or pyrethrums and synergists into a plastic film.
~he present invention is not limited to using pyreth~
rins, and other insecticides can be used particularly where avoidance of contamination of the contents o~ the packages with the insecticide is not essential. Suitable insecticides include:
(i) Bioresmethrin (ii) Dichlorvas - (iii) Methylbromide (iv) D.M.P.
(v) Ethelyne Dibromide (vi) Ethelyne Dichloride (vii) Chlorophictrin (viii) Sulfuryl Fluoride - 30 (ix) Malathion ..
~ ,,,: : . .
: ~ , : ':
.

~L09713~
The incorporation of an insecticide into the pack-aging film ensures that insects cannot penetrate through the film. Thus, if the package is then carefully sealed insects cannot enter through the seal or through the film itself.
Prior art attempts to solve~the problem of infestation could not provide a complete solution in the manner that the present invention does.
The sealing of the package is preferably by heat sealing but any other means of sealing which prevents ready .
.~

~' , .. ` ~.

i .
.: ~

., . :
.~ :
, :

::

' - 3a -- . ,, ~. . .,; ' -.

971~
access to insects is acceptable. For example, where the film is formed into an open ended bag, the open end is folded about itself and stapled together the insects will need to pass between a large area of closely overlapping film and this will be almost as effec~tive a seal as heat sealing.
Numerous conditions have to be met for the develop-ment of an impregnation suitable for packaging materials.
1. The impregnant must be highly effective against all insects considered as insect pests, but must be harmless to humans and domestic animals at the level of concentration used.
2. The impregnation should be such that only tolerable levels of the impregnant will appear in the food stuff and the impregnant must have no deleterious effect on the packing material or any printing.

3. The impregnation should be preferably be sufficient to protect the foodstuf~ for the duration of its life prior to consumption.

4. Cost per unit must be minimal without, however, reducing the efficiency.
Previous proposals of :impregnantion have been successful in complying with the above requirements but have not been successul in preventing infestation because the packaging system as a whole has not prevented penetration by insects.
In a further aspect of this invention there is provided a method of incorporating insecticides into packag-ing film comprising mixing the active insecticidal composit-ion with the extrudable plastic mix and then extruding the combined mix to form a plastic wrapping film of this invention.
The films of the present invention can be either air ; :, ~ . , .
- , . ., ., .. - : :

: : . :. ~.: . : ~: ...
.: , . .... .. . . . . . . . .
. ~.. . : i ~0~7~l31 permeable or air impermeable. Where the film is air B dCf~
permeable the ~ct-we-insecticide is more likely to migrate from the film into the surrounding atmosphere or the product.
Where low contamination of the pack contents is desirable a laminated film can be used. Such a laminate can include a comparatively air impermeable film as the inner layer and an air permeable film in the outer layer. The presence of the insecticide in the outer air permeable layer will ensure that external infestation cannot penetrate the pack. ~ny infestation within the pack will be unable to spread from the pack because the presence oE the insecticide in the outer layer of the laminate will prevent the insects within the pack from boring through the filrn. A preferred laminate ,according to this invention is thus a laminate of ~2 p/~ yl~c~en e inyldlcn~ chloride and polyethylene in which the poly-ethylene film incorporates the preferred insecticide impreg-nant namely synergized pyrethrins. Other suitable laminates which may include the active insecticide in either one'or both films are cellophane/LDPE, Nylon/LDPE, PVDC control Nylon/
LDPE and PVDC/EVA.
The preferred insecticidal agents are pyrethrins which have low solubility in water and are generally available as oil solutions the solvent generally cornprising isoparaffins.
Care must be taken to ensure that the pyrethrins are retained within the film and are homogenously distributed within the film. By ensuring this, comp]iance with the conditions se-t out above can be ensured.
Difficulty can be encountered in obtaining homogen-ous retention of the pyrethrins in the film and the technique which is e~fective is to premix the pyrethrins with polymer . ~ ,- ... ...

, . 1~9~L3~L

granules and then to work the mixture in the screw compounder of the extruder followed by extrusion. Preferably low .' . : , - 5a -'; '. '' ' ''``'.'' ~ '. ' '' ,.' ' ' ~ Og713~
temperature a~iabatic extruders are used to maintain a short, low heat history for the material to prevent degradation of the pyrethrins.
In one practical example of this invention the following master batch was prepared.
10 kg low density polyethylene (LDPE) granules 250 gm pyrethrum (50% w/w) 500 gms piperonyl butoxide (synergist) stabilizer for film.
This master batch comprises approximately 6.25% by weight of active ingredient. ~y mixing one part of this master batch with 50 parts of LDPE granules and extruding under low temperature adiabatic conditions a polyethylene packaging film is obtained containing 0.125% of pyrethrum synergized insecticide.
Four pyrethrum containing films according to this inventio~ were prepared, using the above procedure, containing the following content of pyrethrins (PYR) and piperonyl butoxide (PB0).
20(i) 0.1% PYR and 0.4% PB0 ; film treatment 1 (ii) 0.2% PYR and 0.8% PB0 ; " " 2 (iii) 0.1% PYR and 1.0% PB0 ; " " 3 (iv) O.2% PYR and 2.0% PB0 ; " " 4 These four films were subjected to a series of tests as outlined below.
FILM REPELLANCY TEST.
A trial was set up to test repellancy of the various film treatments. Insects were placed on a watch glass covered with treated film, a control film or 50% control and treated - 30 film. However it appears from first results (see Table 1) .. . .

- .. :, , , . . :

10~7~31 that the film treatment levels are so high that nearly 100%
knock down and even significant kill of the insects was achieved.
Obviously the effect of the actives in the enclosed space above the films, even for the divided films, was sufficiently high to confuse the insects and prevent a determination of repellancy. Results of mortality and kill counts are recorded in table 1.
TABLE 1. FILM REPELLANCY TEST ... AFTER 28 HOURS

.. .. _ .. . .. _ FILM SAMPLE % KNOCKDOWN% KILL
ST LGB* RWST LBG RW

1. Film treatment 1.100 80 20 8 0 2. Film treatment 2~100 100 8 20 12 3. Film treatment 3.100 100 0 12 4 4. Film treatment 4.100 100 96 50 96 .. _ . .... . _

5. Control 0 - 0 0 8 0

6. Control/film 1 100 80 8 - 4

7. Control/film 2 100 100 88 68 36

8. Control/film 3 100 92 64 32 16

9. Control/film 4 100 100 16 32 24 ..... _ . ............ . _ . .
S.T. Sawtoothed grain beetle L.G.B. Lesser grain borer R.W. Rice Weevil * It was not possible to determine effective knowndown oE the lesser grain borer on file samples, as they are very unstable insects on smooth flat surfaces.

~i ., . ~ , ~

,: ~ . ..
.

~ 973L3~

.
A. EXTERNAL SOURCE OF INFESTATION.
Two packs each of Infest guard film control film and control film containing rice treated with 2 ppm pyrethrins (1:10 Pyr:P.B.O.) were rnade up containing 80g of brown rice.
The 6 packs were placed standing end on in jars containing 200 insects of a particular species. The insects were placed below a cardboard platform which supported the six packs.
The packs were inspected for insect penetration after 13 days storage at 30C and 70% RH. The following results were obtained:
TABLE 2(a) _ . _ _ _ JARS CONTAINING INSECT SPECIES IN JAR
_ _ _S.T. _ L.G.B. _ R.W._ Film treatment 1. Insects very Active Active active. All All packs All packs packs intact. intact. intact.
.. _ _. . . ~
Film treatment 2. Very active Partial knock- Active All packs down. All All packs 2Q intact. packs lntact. intact.

Film treatment 3. Active Majority of Same knock-All packs borers knock~ down. All intact. ed down. packs intact.
Pack contain-ing Pyb treated rice chewed into.
. _ _ . _ . _ . .. . _ . . _ .. _ F~lm treatment 4. Active though Majority of Many weevils some insects borers appear dead at base knocked down. knocked down. of treated All packs All packs packs. All intact. intact. packs intact.
.... _ . . . _ . _ _ .

. ~

~.. . ........ . . .. ~ ... .

.

7~31 Inspection after 37 days storage TABLE 2(b).

JARS CONTAINING INSECT SPECIES IN JAR -S.T. L.G.B. R.W.

Film treatment 1 Partial Complete Complete knockdown/ knockdown/ knockdown/
kill. All kill of kill. All packs intact. insects at packs intact.
base of jar.
One control pack penetrated.

Film treatment ~ Complete Majority Complete ~nockdown/ knockdown/ knockdown/
kill. All kill. All kill. Packs packs intact. packs intact. intact.

Film treatment 3 Partial Majority Majority knockdown/ knockdown/kill. knockdown and kill. Remain- Pack containing apparently ing insects PYB treatment dead. All active. penetrated,with packs intact.
healthy insects inside.

Film treatment 4 Generally Total Total knock-total knock- knockdown/kill. down/kill.
down/kill All Packs All packs except for 1 intact. intact.
pack contain-ing PYB rice with faulty seal. Saw-tooths inside pack active.
Following 50_~ys storage, insect counts were carried out for all storage jars. Packs infested during the storage period were also opened for insect counts. Following counting, all sound packs were returned to the jars and a further 200 adult insects and a teaspoon of brown rice feed added to the jars.

_~ ... .

'' '- '' ''` ' ~ ' ; ', : ' .'.

~)97~3 a TABLE 2(c).

JARS CONTAINING INSECT SPECIES IN JAR
L.G.B. R.W. S.T.

Film treatment 1 165 dead, 5 180 dead 0 212 dead 17 alive. Control alive. All alive~ All pack infested packs sound. packs sound.
with 100 alive, 6 dead and breeding.
Remaining packs sound.

Film treatment 2 186 dead, 0 230 dead, 0 210 dead, 7 alive. All Alive. All alive. All packs sound. packs sound. packs sound.

Film treatment 3 163 dead, 1 215 dead, 0 224 dead, 7 alive. Pybuthrin alive. All alive. All pack infested packs sound. packs sound.
with 18 alive, 15 dead and breeding.
Remaining packs sound.

Film treatment 4 200 dead, 1 200 dead, 0 167 dead, 28 alive. All alive. A11 alive. Pybu-packs sound. packs sound. thrin pack with faulty seal invested with 38 alive, 8 dead and breeding.
Remaining packs sound.
B. INTERNAL SOURCE OF INFESTATION.
One pack of each film treatment and the control film was made up containing 400 g of brown rice seeded wi-th 50 of each insect species~ A second control film pack was made up with 400 g of pyrethrin treated brown rice and 50 of each insect species. The treated rise is directly sprayed with a - pyrethrin solution which results in a content of 2ppm pyrethrin in the rice. The packs, placed in ventilated screw top ~ars, -. .: : : -~
, . . ........ . ~, ,. . . :

- . ::: .: : ,: ~ -~. :: :~:: :,, . : ;: : :.: :
.

1~97~3~

were inspected after 12 days storage at 30C and 70~ RH. The following points were noted:
TABL _3(a).
. . _ . . . _ . . _ _ .
PACK INSECT/PACK CONDITION
. ._ ... _ _ , _ ~
Control film Insects active. Control film chewed through.
. . _ . . _ _ .
; Control film con- Majority of insects knocked down. Some taining treated Active.
rice. (2ppm pyr.) Majority of insects knocked down. Some Film treatment 1. No visible effect on insects. Film intact.
- ---- ----- . .
Film treatment 2. Majority of insects knocked down. Some active. Film intact.

Film treatment 3. As for film treatment 2.

Film treatment 4. Total insect knockdown - many of the insects appear dead.

Inspection after 36 days storage TABLE 3(b).

PACK INSECT/PACK CONDITION
. _ Control film Insects very active. Considerable damage to rice. Pack chewed through.
. _ Control fiIm con- Pack chewed through. Live sawtooths and taining 2 ppm Pyr. weevils and two dead borers outside the treated rice. pack.
_ _ Film treatment 1 Complete knockdown/kill of all visible insects. Pack sound.

~ .

. ~

~9713i ... . _ . . :
ilm treatment 2 Complete knockdown/kill of borers. Some sawthooths and weevils active. Pack sound.
ilm treatment 3 As for 2.
ilm treatment 4 Only one sawtooth visibly alive, otherwise complete knockdown/kill. Pack sound.
_ _ _ . _ _ ................... . _ _ - ^ \

1~97~

O ~ In o . ~ ~ r~
.~ ~n ~ ~D O ~D O CO CO OO ~ O
O ,1 n ~D ~ OD
o ' a ~D I t` O ~ I ~ ~ O r~

co ~ I o o r~ I 1` o ~ ~ o a :~1 ~1 ~1 ~I N ~1 (~
O ~ h ~ ~ O CO O
m ~
,~
1~ :~ ~) 00 ~1 0 0 ¦ O N ~r N 1~ S~ U
~,1 U~ 1~ N I N 9 0 N C5~ ~rl 1;1 a) N N ~) N
S '~ ~, a) ~
h U ~ ,1 ~ ~1 ~ O ~ ~ O ~ ~ O
.YH 1~ O ~ l O

~U O
S
:~1 u~
40 ~ ~1 ~1 Z Z Z; Z;
~ ~O ~o tO ~æ ~ O ~ ~ o ~ ~1 U ,_~ N ~r)~r U~ ~ ~1 ~ O ' ~ S
C~ ~11 ~ 0 S O
Sl . a) ~ ~ E~ ~ ~; m ~ u o ~) 3 U
.~ U~ ~
3 ,_1 X h ~) E E E 3 m c~
o a) ~ ~ o ~ ~ rl O O a~
14 ~IE~ ~ C ) ~4 1:4 1:4 ~4 14 ~ ~ S I

: ~, : . , ,` , ~ ` ,.,,, , : :

,. , ,., . ~ ~. :
: :: :: : , , ~ . :` :
: . ~' ' . : '; ' ' :: `' `

~097:~L3~
SIMULATION OF RETAIL STORAGE CONDITIONS
SUBJECT TO HEAVY INFESTATION PRESSURE.
500 gram packs of milled and brown rice were made up in so~md (sealed) and unsound (unsealed) packs. The packs are stored randomly o~ shelves in infested with Lesser Gram borers and to a lesser extent with Rice weevils and Saw tooth bee-tles.
The results of a count of dead insects around each group of brown-rice packets is tabulated below. The co~mt was carried out after 15 days.

FILM PACK CONDITION INSECT MORTALITY
L.G.B. R.W. S.T.
. _ _ . . ~ _ . . _ _ _ . _ Control Sound O O O
" Unsound 2 0 0 Control-Pyb Sound 2 0 0 " Unsound 2 1 0 Film Treatment 1 Sound 34 1 0 " " Unsound 45 1 0 " " 2 Sound 48 0 0 " " Unsound 47 1 2 , " " 3 Sound 40 0 0 " " Unsound 33 0 0 " " 4 Sound 130 0 3 " " Unsound 65 0 3 Control=Pyb is control film containing pyrethrin sprayed rice containing 2ppm pyrethrins with synergist.
After 31 days the packs for each ~roup of sound and unsound packs of milled and brown rice were checked for infestation. The results are shown in Tables 5 to 8.

.. . . . . ~ . .. ... ~ .. ..... .... .. . . . . .. . . . , .. ~ . .. . . . . ..

,. , . ,, - . " . - / ,, .~.

: :: . .
- : - ;~
' . ~ . . , ' ' ' . ' 1, ,~ ` ' : ' :

~97131 TABLE 5 - Thirtyone days Pack Condition: Unsound Rice: Milled _ _ , PACK No. Insects Present L.G.B. RoW. S.T. TOTAL
Alive Dead Alive Dead Alive Dead Alive Dead Control 224664 42 8 42 714 42 211592 49 8 88 688 _ _ Total189213020 0170 0 2082 130 Ave.630 43 7 0 57 0 694 43 _ .
PYB. 543816 52 0 28 844 52 Treated Rice 244122 13 0 12 134 13 232156 34 0 _ 28 _ 18q 34 Total109499 0 0 68 0 1162 99 Ave~364 33 0 0 33 0 387 33 . _ Film 22 0 0 1 1 Treatment ` 1 25 0 0 4 4 21 0 0 _ 0 _ ~

Total0 0 0 0 5 0 5 0 Ave. 0 0 0 0 2 0 2 0 ~i : ~ : . : :

~0~7~L31 TABLE 5 - Thirtyone days, cont'd Film 92 0 _ 0 6 6 Treatment 100 O _O O 1 O

Total 0 0 0 0 6 1 6 Ave. 0 0 0 0 2 0 2 0 . _ _. _ Film 124 0 0 5 5 Treatment 3 ~ __ _ ~ 7 ~ 3 ~ 35 Total 40 2 8 3 45 0 93 . Age. 13 1 3 1 lS 0 31 2 TABLE 6 - Thirtyone days Pack Condition: Unsound Ri:ce: Brown PACK No. Insects Present : L.G.B. R.W. S.T. TOTAL
Alive Dead Alive Dead Alive Dead Alive Dead Control 377 504 24 12 0 60 0 576 24 :~ 357 151 11 3 ! 13 167 11 l ~ ~
Total744 44 17 0 95 0 856 44 : Ave. 248 15 6 0 31 0 285 15 " ` ' : ' . '' ' . : .

7~L31 TABLE 6 - Thirtyone days, cont'd PYB. 309 167 31 1 O17 1185 32 Treated .
rice 311 54 1 1 19 74 325 222 18 O _ 14 236 18 ; Total443 50 2 O50 1495 51 . Ave.148 17 1 O16 O165 17 _ _ _ : Film 421 1 1 5 1 7 Treatment _ Total 1 O 2 313 116 4 . .
Ave. O O 1 . 1 4 O 5 . _ Film 445 O O OO 3 1 3 Treatment _ _ .
Total 1 O 2 112 515 6 Ave. O O 1 O 4 2 5 2 __ Film 524 O O O 1 6 O 6 Treatment : 3 513 O O .9 9 O

~__ _ _ _ Total O O 1 1 18 319 4 Ave. O O O O 6 1 6 Film 530 O O O O O OO O
Treatment _ ~
Total O O O O O O . O O
__ Ave O O O O O O O

.. ~ ^j ., ,. , . :,. . , . :: . - ., . ,, . : . .. .

97~3~

TABLE 7 - Thirtyone days Pack Condition: Sound Rice: Milled PACK Item Insects Present No. L.G.B. R.W. S.T.TOTAL
Alive Dead Alive Dead Alive Dead Alive Dead _ Control 180 360 8 0 12 372 8 181 414 28 0 22 436 2g Total 1328 44 56 0 80 01464 44 Ave. 443 15 18 0 27 0488 15 . _ PYB. 261 27 1 0 0 3 0 30 Treated Rice 258 196 6 0 6 202 6 Total 231 8 0 0 9 0240 8 Ave. 77 3 0 0 3 0 80 3 Pilm _ ~ ~ _ Treatment .
Total !
Ave. 0 0 0 0 0 0 0 0 Film _ Treatment -~ Avtal 0 0 0 0 0 ~ 0 ~ 0 . ~ ~ ,~

~ 18 ~

. .

-:~97~3~

TABLE 7 - Thirtyone days, cont'd . _ ..
Film 477* 44 2 0 9 53 2 3rea~enl ~ ~ 1~L~

Total 44 2 0 0 9 0 53 2 Ave. 15 1 0 0 3 0 18 _ TABLE 8 - Thirtyone days Pack Condition: Sound Rice:Brown _ :
..__ PACK No. Insects Present L.G.B. R.W. S.T. TOTAL
Alive Dead Alive Dead Alive Dead Alive Dead Control 357 130 10 0 10 0 140 10 Total 449 43 6 2 67 0 552 45 Ave. 150 14 2 1 22 0 174 15 :
Treated 290 216 22 6 32 254 22 Rice 292 166 6 0 30 196 6 298 19 1 ~ 5 24 Total 40] 29 6 ¦0 67 0 474 29 Ave. 134 10 2 j 0 22 0 158 10 _ * 4 Holes chewed through pack .~ ' ~ ~j .

71:~3~

TABLE 8 - Thirtyone days, cont'd Treatmen~ ~ ~ ~ I ~ r Total 0 0 0 0 0 0 0 0 Film ~ve 0 0 0 0 0 0 0 0 Treatment Total 0 0 0 0 0 0 0 0 Ave. 0 0 0 0 0 0 0 0 Film 494* 0 3 59 5 62 5 Treatment __ Total 0 0 3 0 59 5 62 5 Ave. 0 0 l 0 20 2 21 2 Film _ _ Treatment _ _ Total 0 0 0 0 0 0 0 0 Ave. 0 0 ~ 0 0 0 n 0 The results of the Tables 1 to 8 shows that the impregnated fllms are a superior form of pest control to direct : insecticide spraying of the product to be packaged which to date has been the most successful conventional method of controlling investation.

* Pack Punctured i~l ~: , .. :
, 3t7~3~

Further tests have been carried out using low concen-trations of insecticide in the film.
As for the other tests the impregnated films were compared with a control and packs containing brown rice directly sprayed with insecticide.
The films were polyethylene made into bags containing 500 g of rice and containing -1) 0.015% pyrethrin 2) 0.030~ "
3) 0.060% "
4) 0.1 ~ "
film treatment 1 is equivalent to a direct rice treatment of lppm film treatment 2 is equivalent to a direct rice treatment of 2ppm film treatment 3 is equivalent to a direct rice treatment of 4ppm film treatment 4 is equivalent to a direct rice treatment of 6.6ppm.
Tables 9 and 10 set out the results.

Pack Condition: Unsound R _e: Brown PACK No. Insects Present L.G.B. R.W. S.T. TOTAL
Alive¦Dead Alive¦Dead Alive Dead Alive Dead ~ _ ` Control 77 12 12 28 2 72 28 112 42 '. g6 O O 1 O 10 O 11 O

Total 12 12 30 2 9429 136 43 Ave. 4 4 10 1 3110 45 14 ~ 21 ~
. `~ .

. . : : : .. ... ~. .. : :- .:
. . : . .. :-~- : , . : .:

97~L31 TABLE 9 - Lower Film Treatment Levels After 60 Days, cont'd PYB. 6 0 0 I 0103 8 104 8 (2ppm.Rice Treatment 14 0 0 0 0 58 2 58 2 _ _ Total 24 12 61 12197 26 282 50 Ave. 8 4 20 4 66 _ 94 17 (01015% 104 2 2 1 1 46 0 49 3 PYR_lppm) Total 2 2 5 1110 0 117 3 Ave. 1 1 2 0 37 O 39 _ (o2,o3% 190 0 0 0 0 0 0 0 0 PYR_2ppm) _ _ Total 0 0 0 0105 2 lG5 2 Ave. 0 0 0 0 35 1 1 L

(o3065% 206 0 0 1 0 q7 O 48 O
PYR_4ppm) 217 0 0 0 0 1 0 1 0 :
_ . _ Total 0 0 1 0 48 0 49 0 Ave. 0 0 0 0 16 0 16 0 .

- 2~ -.- ... . ..

~097~3~

TABLE 9 - Lower Film Treatment Levels A~ter 60 Days, cont'd 2g7 0 0 0 067 1 67 281 37 _ 37 0 Total 0 0 0 0127 1 127 Ave. 0 0 O 042 0 42 0 Pack Condition: Sound Rice: Brown PACK No. Insects Present L.G.B. R.W. S.T. TOTAL
Alive Dead Alive Dead Alive¦Dead AlivelDead .. I ......
Control 64 10 16 12 4324 24 346¦ 44 ` 69 0 0 5 0209 2 214 2 Total 21 32 21 4685 30 7271 66 Ave. 7 11 7 1228 10 242¦ 22 (2pFm Rice Treatment) _ Total ~6 4 4 041 6 51 10 Ave. 12 1 1 014 2 17 3 ~ _ I _ _ (0.015% 41 ; 2 0 61 1 63 ` PYR_lppm) , Total 0 0 2 061 1 63 Ave. _ _ 1 _20 _ 21 .
_ 23 --, .. ::
, . ~ ~ :. ,:. : i :.. ..

'~`, ,:, ,' : ' ~ :

3~

TABLE 10 - Lower Film Levels After 60 Days, cont'd PYR 2ppm) ; ~ _ _ .. ... _ (0.3055% 249 0 0 0 0 185 2 185 2 PYR-4ppm) .
Total 6 4 6 0263 3 275 7 PYR) ¦Ave. l 2 ~ 1 Total0 0 0 08 0 8 0 _ Ave._ _ _ _ _ 3 _ 3 These figures again show the superiority of sealed packs of impregnated film in preventing infestation.
The packaging film of this invention when used as an outer heat sealed wrapping or bag for food packages not only prevents insects from boring into or entering the plastic film envelope but also prevents any insect infestation from spreading should larvae or eggs be present in the food product prior to wrapping. The cost of providing such a film is only higher than that of existing film by the cost of incorporatin~ the pyrethrins and thus is less costly and more effective than conventional methods which require an additional manufacturing step and are not totally effective.

: -. .

: . ...... . .
- : . , : . . :

Claims (2)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A heat sealed package containing products subject to insecticidal or pesticidal infestation comprising a package con-taining said product wherein the package is formed of a heat sealable extruded polymeric film material and a pyrethrin com-pound or a synergized pyrethrin compound which has been homo-eeneously incorporated into the film forming material prior to extrusion of the material as a film and at least one seal causing a sealing of the package.

2. A method of storing products subject to insecticidal or pesticidal infestation which comprises enclosing said products within a package containing said products, wherein the package is formed of a heat sealed extruded polymeric film material and a pyrethrin compound or a synergized pyrethrin compound which has been incorporated into the film forming material prior to extrusion of the material as a film.