Hollow Fibers as Controlled Vapor Release Devices - ACS Publications

7 Hollow Fibers as Controlled Vapor Release Devices T. W. BROOKS, E. ASHARE, and D. W. SWENSON

Downloaded by CORNELL UNIV on October 12, 2016 | http://pubs.acs.org Publication Date: June 1, 1977 | doi: 10.1021/bk-1977-0049.ch007

Conrel, An Albany International Co., 735 Providence Highway, Norwood, MA 02062

In recent years controlled release of active materials has emerged as a distinct technology in answer to a great many end-use needs in medicine, agriculture, forestry and the home. The subject has gained enough prominence to deserve a book (1), two international symposia (2), and a symposium scheduled for this centennial meeting of the A m e r i c a n Chemical Society. A growing number of c o m m e r c i a l products are based on controlled release formulations including such familiar items as time release oral medications, fragrance dispensing wicks and gels, and impregnated plastic pesticide strips or animal collars. Modern controlled release devices and systems such as impregnated plastic or rubber matrices, membrane envelopes, laminated poromerics and microcapsules testify to the growing level of sophistication being demanded of this technology to satisfy increasingly complex end-use requirements. This paper w i l l deal with the use of hollow polymeric synthetic fibers as a controlled release medium for dispensing vaporizable materials. The underlying principles of the h o l low fiber approach to controlled release vapor dispensing w i l l be discussed along with examples of how these principles can be applied to specific controlled release formulation needs and some results f r o m actual field testing of hollow fiber dispensers for insect pheromones. In keeping with the spirit and i n tent of the symposium this paper provides an example of how man-made fiber technology is being wedded with other seemingly unreleated technologies to obtain products which hold promise in helping us manage our environment more responsibly.

Ill

Arthur; Textile and Paper Chemistry and Technology ACS Symposium Series; American Chemical Society: Washington, DC, 1977.

112

TEXTILE AND PAPER CHEMISTRY AND TECHNOLOGY


Objectives of Controlled Release Some of the more important objectives in developing con trolled release product forms are (1) an extended period of activity for the released material, (2) longer use life for n o r mally nonpersistent (unstable) active materials, (3) more ef ficient utilization of active materials, e . g . , lower total dos ages, (4) reduced environmental contamination, and (5) greater safety for the users of hazardous materials. C o n trolled release product forms meeting these objectives are becoming especially important in the pesticide field (2) where ecological considerations are dictating the abandonment of per sistent materials, like the chlorinated hydrocarbons, in favor of less stable materials such as the οrganophosphate and c a r bamate insecticides. Other potential benefits of controlled release product forms include improved specificity of action on target organisms and enhanced economics of application. Thus, whatever the field of application, be it economic ento mology, preventive and therapeutic medicine, or consumer products, the broad objective of controlled release is to i m prove the technical performance of an active material in an economical way. Controlled Vapor Release F r o m Hollow Fibers Hollow fibers have been found to be a useful means of con fining and mediating the controlled release of a variety of v a porizable materials. If a material is allowed to evaporate from the lumen of a hollow fiber sealed at one end and open at the other, the release curve, obtained by plotting mass r e leased versus time, is characterized by an initial steep slope followed by an extended lower slope flat portion which approx imates zero order release kinetics. This release behavior follows form with a l l vaporizable materials as long as they are single component or comprised of mixtures of components with comparable volatilities. T y p i c a l release curves are shown in Figure 1 for two insect pheromones and the insec ticide D D V P (2, 2-dichlorovinyl-O, O-dimethyl phosphate). The absolute rate of release for any given material is directly pro portional to fiber internal diameter. At a given temperature release rates can be manipulated by adjustments in fiber i n ternal diameter and the number of fibers employed. The active life for dispensing is a function of hollow fiber length, i . e. , the length of the column of active material.



7.

BROOKS ET AL.

113

Controlled Vapor Release Devices

For design purposes only the flat portion of the release curve is used. The initial high rate or "burst effect" portion of the curve can usually be ignored since it represents only a s m a l l percentage of the total lumen charge and a relatively short period of the total dispensing life. The "burst effect" portion of the release curve for an active material can some times be eliminated by diluting the lumen charge with a high volatility inert. This ploy is frequently useful in dispenser designs where one wishes to dispense vapor mixtures having individual components with substantially different volatilities. Dilution can also be used to make short lived dispensers which otherwise would have to be made up in inconveniently short lengths. Thus, for a given vaporizable material, hollow fiber con trolled release dispensers can be formulated knowing only the release curve obtained with a particular fiber material and size at some specified temperature. Designing the dispenser to a specific release rate and lifetime is a simple matter of calculating the number of fiber ends needed to give the desired dose rate and the fiber length needed to achieve a prescribed life span. The need to know the fiber material and internal diameter used in obtaining release curves deserves some explanation. It turns out that evaporation rates for many materials are sensitive to the diameter of the fiber lumen or capillary r e s e r v o i r . That i s , the vapor flux is not directly proportional to the square of the capillary radius for a l l liquid and fiber m a t e r i a l combinations, as one might naively expect. In Table I are shown data which illustrate this phenomenon. Steady state release rates were measured on four different materials using 200 and 500 m i c r o n I. D. hollow fibers. Neutroleumalpha is a commercial general purpose deodorizer formulation, while 4-methyl-3 -heptanol (_1), multistriatin (2), and acubebene (3) are compounds which comprise the three-com-

Φ

4-methyl-3-heptanol

(2) multistriatin

a-cubebene



114


0

10

20

30

40

50

60

70

80

90

DAYS

Figure 1.

Release of various

materials

Table I Comparison of Fluxes for Selected Materials from Two Different Hollow Tiber Sizes*' 1

Material

Flux, em/day^ 500μ 1.1). 200μ I.D.

Neutroleum-alpha

1.8x10

eubeb oil**

5.8x10

multistriatin

2.1x10

4-methyl-3-heptanol

2.2x15

-2 -3 -2 -2

1.8x10

-2

-2 1.5x10 -2 3.4x10 -2 3.16x10

Flux Ratio 200μ:50Ομ

Absolute Release lia to μ^/day/cnd 500μ 200μ

1

5.9

37.4

2.G

1.9

30.5

1.6

6.8

69.6

1.4

7.2

64.1

Fiber material is undrawn polyester (polyethylene terephthalatc). All release measurements were made at 21 ± 1°C and 65 ± 5", relative humidity. 3

The 200μ and 500μ fiber I.D.'s correspond to lumen cross-sectional areas of 3.24x10~ and 2.03x10~ cm respectively. This corresponds to a ratio of the larger to the smaller cross-sectional area of 6.3. 4

3

2

Ά proprietary general purpose deodorizer formulation comprised of a blend of essential oils and aromatic chemicals. Marketed by Fritzsche Bros., Inc., New York. α-cubebene is a constituent which is extracted from the berry of the Java pepper plant.


I

BROOKS ET AL.

115


ponent a g g r e g a t i o n p h e r o m o n e of the s m a l l e r E u r o p e a n

elm

b a r k beetle, S c o l y t u s m u l t i s t r i a t u s ( M a r s h a m ) (4). C o m p a r i s o n of f l u x e s of t h e s e m a t e r i a l s f r o m the two

different sized fiber

l u m i n a r e v e a l s that r e l e a s e r a t e v a r i e s u n p r e d i c t a b l y capillary diameter.

m a i n e q u a l f o r the two r i a l s f l u x r a t i o s f o r 200 to 2.6.

with

O n l y w i t h neutr o l e u m - a l p h a did f l u x r e diameters. and

W i t h the t h r e e other

mate

500p d i a m e t e r s r a n g e d f r o m

1.4

T h u s i n going f r o m the s m a l l e r to the l a r g e r d i a m e t e r ,

r e l e a s e r a t e i n c r e a s e d by m o r e than the r a t i o of c r o s s -


sectional An

areas. e x p l a n a t i o n f o r this p h e n o m e n o n p r o b a b l y l i e s i n the

s u r f a c e e n e r g y r e l a t i o n s h i p s between the l i q u i d c h a r g e and fiber wall.

the

It i s known f r o m c l a s s i c a l p h y s i c a l c h e m i s t r y that

the v a p o r p r e s s u r e above a l i q u i d s u r f a c e i s dependent upon the r a d i u s of c u r v a t u r e

of that s u r f a c e .

F o r different liquid-fiber

m a t e r i a l c o m b i n a t i o n s the l i q u i d m e n i s c u s - f i b e r

wall

contact

angles w i l l be d i f f e r e n t , and t h e r e f o r e the r a d i i of c u r v a t u r e the m e n i s c i w i l l a l s o d i f f e r .

It i s i m p o r t a n t to r e c o g n i z e

e x i s t e n c e of this p h e n o m e n o n w h e n c o n s i d e r i n g the d e s i g n hollow fiber c o n t r o l l e d r e l e a s e f o r m u l a t i o n s . subtle c o m p l i c a t i o n

of

the of

In p r a c t i c e this

i s a v o i d e d by m e a s u r i n g r e l e a s e c u r v e s

w i t h the f i b e r m a t e r i a l and

fiber internal diameter which w i l l

be u s e d f o r a s p e c i f i c f o r m u l a t i o n .

T h i s is e s p e c i a l l y i m p o r

tant w i t h i n s e c t p h e r o m o n e s w h e r e b i o l o g i c a l d o s e - r e s p o n s e r e l a t i o n s h i p s often d i c t a t e a v e r y p r e c i s e and

constant r e l e a s e

r a t e i n o r d e r to m a k e i n s e c t m o n i t o r i n g t r a p s f u n c t i o n M e c h a n i s m of V a p o r R e l e a s e f r o m H o l l o w The

properly

Fiber

m e c h a n i s m of v a p o r r e l e a s e f r o m hollow f i b e r s , i f

t r a n s - w a l l permeation is excluded, is a simple

three-step

process. 1.

E v a p o r a t i o n at the l i q u i d - v a p o r i n t e r f a c e .

2.

D i f f u s i o n f r o m the l i q u i d - v a p o r i n t e r f a c e to the

3.

C o n v e c t i o n away f r o m the open

open end of the h o l l o w f i b e r . end.

A d e t a i l e d d i s c u s s i o n of the m a s s t r a n s p o r t t h e o r y i n v o l v e d i n this p r o c e s s is g i v e n e l s e w h e r e (3^,_5). t i o n d e r i v e d f r o m the t h e o r y i s

v a

p

The

r e l e a s e r a t e equa

γ/2


116


w h e r e d l / d t , the change i n m e n i s c u s l e v e l w i t h t i m e , i s d i r e c t l y p r o p o r t i o n a l to the d i s p e n s i n g r a t e , M i s the m o l e c u l a r weight of the d i s p e n s e d m a t e r i a l , c i s its m o l a r density, D i s the d i f f u s i o n c o e f f i c i e n t ^ / i s the l i q u i d density, P ^ the v a p o r p r e s s u r e of the v o l a t i l e m a t e r i a l , and Ρ i s the p r e v a i l ing a t m o s p h e r i c p r e s s u r e . T h e v a l i d i t y of the equation w a s e x a m i n e d u s i n g c a r b o n t e t r a c h l o r i d e as a m o d e l m a t e r i a l . F i g u r e 2 shows a l o g a r i t h m i c plot o f e v a p o r a t i o n r a t e v e r s u s t i m e i n w h i c h c a l c u l a t e d and e x p e r i m e n t a l l y o b s e r v e d c u r v e s a r e d i s p l a y e d . T h e a g r e e m e n t between e x p e r i m e n t and t h e o r y t e s t i f i e s quite w e l l f o r the v a l i d i t y of the r a t e e x p r e s s i o n . 7

V a

I

S


a

R e l e a s e of m a t e r i a l by p e r m e a t i o n t h r o u g h the f i b e r w a l l is e x c l u d e d f r o m c o n s i d e r a t i o n f o r p r a c t i c a l as w e l l as t h e o r e t i c a l r e a s o n s . In p r a c t i c e f i b e r m a t e r i a l s a r e s e l e c t e d w h i c h a r e i m p e r m e a b l e to the a c t i v e m a t e r i a l to be d i s p e n s e d . T h i s i s n e c e s s a r y s i n c e the f i b e r m u s t confine the a c t i v e m a t e r i a l d u r i n g s t o r a g e p r i o r to a c t i v a t i n g r e l e a s e by opening the f i b e r end. Hollow F i b e r Controlled Release Product F o r m s C o n t r o l l e d r e l e a s e v a p o r d i s p e n s e r s have been f a s h i o n e d b a s i c a l l y i n two f o r m s . In the f i r s t a p a r a l l e l a r r a y of f i b e r s is f i x e d to an a d h e s i v e tape. A f t e r p r e s s u r e f i l l i n g the a c t i v e m a t e r i a l into the f i b e r s , the f i b e r s a r e s e a l e d u l t r a s o n i c a l l y at r e g u l a r i n t e r v a l s along the tape. T h e a c t i v e m a t e r i a l m u s t be i n l i q u i d f o r m f o r the f i l l i n g o p e r a t i o n . R e l e a s e i s a c t i v a t e d by cutting the tape at a point adjacent to the s e a l s t h e r e b y op ening f i b e r ends. A g r a p h i c a l i l l u s t r a t i o n of this d i s p e n s e r f o r m i s shown i n F i g u r e 3. T h i s k i n d of d i s p e n s e r is u s e f u l for the exact p o s i t i o n i n g of v a p o r point s o u r c e s . Example u s e s m i g h t i n c l u d e the b a i t i n g of i n s e c t t r a p s w i t h a n a t t r a c tant, d i s p e n s i n g a v a p o r a c t i o n i n s e c t i c i d e to p a c k a g e s o r c o n t a i n e r s of s t o r e d goods s u s c e p t i b l e to i n s e c t attack, and deodorizing enclosed areas with air freshening fragrances or masking chemicals. A s e c o n d f o r m of d i s p e n s e r i s m a d e by s e a l i n g i n d i v i d u a l f i b e r s at r e g u l a r i n t e r v a l s a n d t h e n c h o p p i n g at a p r e d e t e r m i n e d d i s t a n c e f r o m the s e a l . T h i s c h o p p e d f i b e r f o r m is d e s i g n e d p r i m a r i l y f o r b r o a d c a s t i n g v a p o r point s o u r c e s over large areas. C h a r g i n g chopped f i b e r s with an active m a t e r i a l i s a c c o m p l i s h e d by i m m e r s i n g the f i b e r s i n the m a t e r i a l , d r a w i n g a v a c u u m to r e m o v e a i r a n d other g a s e s f r o m the l u m e n , a n d then r e l e a s i n g the v a c u u m . A g a i n , the


7.

BROOKS ET AL. -4 I0

4

117


r

THEORETICAL


Ο

EXPERIMENTAL

Figure

2.

Rate of release of

TIME (hrs.)

tetrachloride

Continuous Tape

Single Dispenser Figure 3.

Tape form hollow fiber vapor

dispenser


carbon


118


active material must be in a liquid f o r m at the time of filling. Chopped fibers charged with active material are stored in hermetically sealed containers. Release is activated when the container is opened. Example uses for the chopped fiber form of hollow fiber dispenser would include broadcast dissemination of insect sex attractant pheromones for mating disruption of agricultural or forest insect pests (pheromones and pheromone dispensing applications are discussed further below), insecticide dispensing, and possibly soil fumigation. In both product forms, release rates are governed by fiber size and the number of fiber ends while active life is governed by fiber length. Which product form is preferred for a given application is generally determined by the purpose and the economics of the application. The Application of Hollow Fiber Vapor Dispensing to Insect Pheromones Insect pheromones are volatile organic compounds produced by insects for purposes of communication through their highly developed olfactory sensory systems (6). These highly specific chemical messengers serve to influence insect behavior in a variety of ways. Pheromones may function to signal alarm, mating conduct, t r a i l marks, oviposit, aggregation and specialized behavior in the regulation of social i n sect colonies. Sex attractant insect pheromones have been of particular interest to entomologists since they raise the possibility of controlling pest insects by interdicting the sexual communication which leads to mating and proliferation of populations f7, 8_). If population suppression could be accomplished with pheromones, of course, many of the environmental hazards associated with chemical insecticide control measures might be avoided. Indeed environmental considerations have been a motivating influence behind much of the research on i n sect pheromones. Three basic strategies are being developed for the use of pheromones in insect pest management. These are (1) m o n i toring and survey trapping, (2) mass trapping and (3) mating disruption (8). In the first case pheromone baited traps are employed to assist in the detection and location of infestations, timing of insecticide applications, and monitoring of the effectiveness of control measures. The mass trapping stratagem is designed to achieve pest population suppression by physically removing insects f r o m the environment, a novel refine-



7.

BROOKS E T A L .


119

ment of the flypaper approach. In the mating disruption approach an area is permeated with sex pheromone in order to interfere with the insect's olfactory inter-sexual communication system. By thus subverting the mating and reproduction process it is hoped that population suppression can be achieved without resort to lethal agents. The application of these pheromone use strategies is made a challenging task by two important factors. First, pheromones are frequently very expensive chemicals to synthesize. Those which are commercially available may cost anywhere from several hundred to several thousand dollars per pound. Second, pheromones typically possess a high order of biological activity and therefore are used in extremely m i n ute quantities as compared, say, to conventional chemical i n secticides. Application rates for mating disruption of lepidopterous species, for example, are on the order of grams per acre-season. For successful pheromone trapping the lure frequently must be metered out at a very precise rate. It is not uncommon for the optimum dose rate of a pheromone trap bait to be on the order of micrograms per day. An underdose can cause the trap to fail for lack of attractiveness while an overdose can lead to disorientation of an insect attracted to the vicinity of the trap so that he fails to find his way i n . These factors necessitate a controlled release method of pheromone dispensing which is precise, reliable, and efficient. In many instances the development of pheromone technology for insect control and the development of controlled release technology have gone hand in hand. Without an adequate controlled r e lease system it is doubtful that pheromones could ever be made sufficiently practical and economical for pest control use on a commercial scale. Our investigations into insect pheromone dispensing with hollow fibers have involved work with more than twenty different insects. Out of this number three have been selected as illustrative examples of how the principles of hollow fiber vapor dispensing can be applied in various ways to the controlled release of pheromones. Hollow fiber pheromone dispensers have been prepared and field tested for the trapping of the smaller European elm bark beetle, Scolytus multistriatus (Marsham), principle vector for the Dutch elm disease pathogen Ceratocystis ulni. The aggregation pheromone of the elm bark beetle is a mixture comprised of at least three compounds, 4-methyl-3-heptanol (_1), 2, 4-dimethyl-5-ethyl-6, 8-dioxabicyclo (3. 2. 1 ) ocatane(2),



120


and a-cubebene (a constituent of cubeb oil) (3). Compound (2) has been given the t r i v i a l name, multistriatin. The alcohol and multistriatin are beetle-produced while the a-cubebene is a host-produced synergist (4). Release curves for the elm bark beetle pheromone constituents are shown in Figure 4. Note that release rates at steady state are nearly equal for the alcohol and multistriatin while the steady state release rate for cubeb o i l , a much less volatile material, is significantly lower. At the time these experiments were conducted, the optimum release ratio for trapping baits was thought to be: Cubeb o i l 200pg/day multistriatin 40jig/day 4-methyl-3-heptanol 40jig/day F r o m these specifications and the respective release curves dispensers were prepared with the following design features: Cubeb o i l 115 fiber ends multistriatin 5 fiber ends 4-methyl-3-heptanol 5 fiber ends A i l fibers were 3 c m in length which corresponds to a design life of 3 months using an overdesign factor of fifty percent. Overdesign of dispenser life is frequently practiced to guard against premature exhaustion in the field owing to unanticipated periods of exceptionally w a r m weather. Dispensers with the above design were field tested in traps set out in Australia in early 1975 when U . S . beetle populations were dormant. The results of these trapping experiments are presented in Table II. The hollow fiber dispensers consistently out-captured beetles when compared to a polyethylene v i a l type of dispenser which is frequently employed by experimenters. Further, as the season progressed the hollow fiber dispensers improved in performance relative to the plastic v i a l s . Since no data were collected after the fifth week, no comment can be made on total performance. The data do suggest however, that the hollow fiber dispensers adhered more closely to release design specifications than did the plastic v i a l s . T h i s , in turn, demonstrates the greater potential hollow fibers offer in designing dispensers for multicomponent pheromones. Most other controlled release devices lack the design flexibility afforded by the hollow fiber approach. Experiments with elm bark beetle pheromone dispensers are continuing in the U . S . where it is hoped that spread of Dutch E l m disease can eventually be arrested by mass trapping of the beetle vector. The results of this work, including eval-


BROOKS ET AL.



CUBEB OIL MULTISTRIATIN 4- METHYL- 3- HEPTANOL

I Ο

L

I

I

I

1

1

4

8

12

16

20

24

1

28

TIME(DAYS)

Figure 4.

Release rate of elm bark beetle pheromone

components

Flm lliii'k Heotlc Trapping Results wit!) Hollow Fiber Pheromone Dispensers Trnp No. 1 3" 4 5 7 8 9 11 12 13 14 1G 17 19 2i 22 23* a

n

a

Trap Installed On Tree Species Eucalyptus saligna Archontophoenix cunningham inna Ditto Nothofagus solandori Ulmus procera Ditto Prumus spp. Ulmus procera Quercus spp. Eucalyptus calopliylla Ulmus uroccra Çcdrus doodara Ulmus procera Pinus radiata Pinus ponderosa Ulmus procera Ditto Total Catches

Dispenser Type" PV

I IF PV IIF PV IIF

—

PV III' PV IIF PV

— —

HF

1 of Total with I IF Dispensers

Meet Jo C'iitch on Dittos (197 2/6 2/2(1 31 0

175

13

54

I)

0

0

15 .6 3 17 ϋ IB 0 4 1G 23 210 33 0 54 0

37 15 35 99 0 144 0 5 302 75 78(i 70 0 235 J)

43(1

1978

15 5 53 35 0 8 0 1 130 4 209 1G 0 31 0 497

143 7 112 193 0 220 0 9 200 7 990 32 0 lfiO 0 2127

73

78

90

8G

"Control trees, traps installed without baits ^PV = polyethylene vials IIF - hollow fiber dispenser



122


uations of controlled release formulations w i l l be reported byother investigators (9). A second insect pheromone chemical to which hollow fiber dispensing has been applied is gossyplure, the sex attractant of the pink bollworm, Pectinophora gossypiella (Saunders). The pink bollworm is a major cotton pest in the U . S. Desert Southwest and in a number of Latin A m e r i c a n countries where cotton is grown. The use of pheromone baited traps to monitor for this insect is becoming a common practice in cotton pest management programs. Gossyplure is a 1:1 mixture of ( Z , Z ) - a n d ( Z , E ) - 7 , 11hexadecadienyl acetates (10). Its attracting power for male moths is remarkable. The optimum dose rate for attraction of pink bollworm males to a standard commercial trap is in the range of 2.4 to 4. 0 jig/day. Gossyplure is one pheromone which must be metered out carefully when used as a trap lure for monitoring purposes. This point is illustrated in Figure 5. The dose-response data were taken by field bioassay in a cotton field near Buckeye, A r i z o n a , late in the 1974 growing season. Captured insects were a l l from the local wild population. The plot of number of moths captured versus number of fibers per trap bait shows an optimum dose rate of about 3.2 jig/day, i . e. , eight fibers of 8 m i l I. D . (200p) (see Figure 1). As the number of fibers is increased beyond the optimum, trap catches drop off and tend to become erratic. This response pattern makes it imperative that traps be baited with a pheromone dispenser that gives off a well-defined and constant dose of the attractant. This is crucially important if the trapping results are used for monitoring control programs. The gossyplure experiment illustrates another useful feature of hollow fiber controlled release devices. When a new pheromone is isolated the entomologist often cannot specify an optimum release rate for trap baiting since he lacks doseresponse data of the kind in Figure 5. Hollow fiber dispensers make it convenient to obtain such data by field or laboratory experimentation in which release rates are manipulated simply by varying the number of fiber ends. This technique for obtaining dose-response data with pheromones promises to make the whole process of developing such information a much easier task. A third example of a promising use for hollow fiber pheromone dispensers can be drawn from a recent experiment on disruption of the grape berry moth Paralobesia viteana (Clemons). This insect is a very serious vineyard pest in many


7.

BROOKS ET AL.

Controlled

Vapor

Release

Devices

of the Eastern U . S . grape growing areas. The sex pheromone of the grape berry moth is (Z)-9-dodeceny1 acetate (11). Multifiber dispensers of the pheromone were placed in a New York vineyard test plot, one per vine and 604 dispensers per acre. Individual dispensers each had nine fiber ends giving a total of 5445 fiber ends per acre. The design release rate was 3. 5x10-7 cm.3 per day giving each point source an output of about 3.2x10-6 m? per day. F o r 605 point sources and a 150-day season the nominal rate of application was 0. 286g per acre-season. The true rate of application was 1. 85 g per acre-season because it was necessary to make the fibers one cm in length. This length was arbitrarily chosen to make it convenient to handle dispensers in the field. The results of the grape berry moth disruption experiment are summarized in Table III. Note that orientation on pheromone baited traps was disrupted for a period of two and one-half months, after which the experiment was terminated. Disruption of E . argutanus was also observed for the same period of time. The latter i n sect is a local species of no economic consequence. The r e c ord of its disruption serves only as additional evidence that the technique is working. The grape berry moths in this test were lab-reared insects while E . argutanus were f r o m the local wild population. This is the first time, to our knowledge, that orientation disruption of a pest insect was achieved for a two and one-half month periodwith a single pheromone treatment. This fact, coupled with the very modest rate of application, clearly i n dicates that pheromone treatment with a reliable and economical controlled release system has c o m m e r c i a l potential in a g r i culture. Tests planned for the 1976 season w i l l be designed to ascertain whether disruption of the grape berry moth also protects the crop against insect-caused damage. Successful crop protection is the ultimate measure of economic value for any treatment method. A more complete disclosure of the 1975 grape berry moth disruption experiments w i l l be made in a separate publication by Taschenberg and Roe lofs .(12). These investigators conducted the disruption experiment and graciously provided us with the data in Table III, along with other background information. C


123

Conclusion The principles of controlled vapor release with hollow fibers have been demonstrated in a variety of ways. The con-


124



60H

III

10 NO.

Figure

5.

Dose-response

40

20

30

OF FIBERS

PER DISPENSER

data for pheromone

trapping

of pink

5C

bollworm

moths

bioassay)

Tabic III Grape Merry Moth Orientation Disruption Tests with Hollow Fiber Phoronione Dispensers - 11)7Γι' Number of Males Captured in 6 Traps

Date

Totals

G RM

Treated Plot 1Î. Argutanus

b

Untr ont (id Cheek Plot I.. Argutanus GUM

Jul

15 20 25 30

0 0 0 0

0 0 0 0

2 1!) 14 7

2 45 65 39

Aug

6 16 26

2 0 0

2 0 1

28 9 11

199 4!) 26

Sept

5 15 25

0 0 0

0 0 0

15 7 11

2

3

123

8 0 0 433

These data were gathered by D r . E . F . Tnschcnborg, Vineyard Laboratory New York State Agricultural Experiment Station, Fredonia, New Y o r k . ^E. argutanus is a non-pest insect attracted by (Z) 9-dodeconyl acetate.


(field

7. BROOKS ET AL.


125

cept has been shown to have potential in specific applications involving the use of insect pheromone for pest management purposes. Based on the test results disclosed in this paper, it is reasonable to expect that hollow fiber vapor dispensing will find a number of commercial applications, some of which will represent a substantial contribution to a safer and better envi ronment.


Acknowledgements The technical assistance of JoanEllen Hoar and Roger Kitterman in preparing formulations and obtaining field test data is gratefully acknowledged. We wish also to acknowledge the invaluable contributions of E. F. Taschenberg and W. Roelofs of the New York State Agricultural Experiment Station who conducted the grape berry moth experiment, and J. W. Peacock and R. A. Cuthbert of the U. S. Department of Agri culture Northeast Forest Experiment Station who arranged for the elm bark beetle tests. Literature Cited (1) Tanquary, A. C., and Lacey, R. Ε., (eds.), "Con trolled Release of Biologically Active Agents," Plenum Press, New York (1974c). (2) Cardarelli, N . F . (ed.), "Proceedings of the 1974 Controlled Release Pesticide Symposium," University of Akron, Akron, Ohio, September 16-18, 1974; Harris, F. W., (ed.), "Proceedings of the 1975 Controlled Release Pesticide Symposium, "Wright State University, Dayton, Ohio, Septem ber 8-10, 1975. (3) Ashare, Ε., Brooks, T . W . , and Swenson, D.W., "Controlled Release from Hollow Fibers," Ibid., p. 42. (4) Pearce, G. Τ . , Gore, W. E., Silverstein, R . M . , Peacock, J. W., Cuthbert, R. A . , Lanier, G . N . , and Simeone, J. B., J. Chem Ecol., 1, 115 (1975). (5) Ashare, Ε . , Brooks, T . W . , and Swenson, D. W., Paper presented at the American Chemical Society Centennial Meeting, Joint Symposium on "Controlled Release Polymeric Formulations," sponsored by Divisions of Polymer Chemistry and Organic Coatings and Plastics Chemistry, New York, April 19, 1976. (6) Birch, M . C . , E d . , Pheromones, Elsevier Pub. Co., New York (1974c).



126


(7) Jacobson, Μ . , Insect Sex Pheromones, Academic Press, New York (1972c). (8) Roelofs, W., "Manipulating Sex Pheromones for Insect Suppression" in Insecticides of the Future, Jacobsen, M . , E d . , Marcel Dekker, Inc., New York (1975c) p. 41. (9) Peacock, J.W. and Cuthbert, R . A . , private com munications. (10) Hummel, Η. E., Gaston, L. Κ., Shorey, H . H . , Kaae, R.S., Byrne, K . J . and Silverstein, R. Μ., Science, 181 873 (1973). (11) Roelofs, W . L . , Tette, J. T., Taschenberg, E. F. and Comeau, Α . , J. Insect Physiol., 17, 2235 (1971). (12) Taschenberg, E. F. and Roelofs, W. private com munications.


Hollow Fibers as Controlled Vapor Release Devices - ACS Publications

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