United States

Department of

Agriculture

0

$$ Forest Service Research Note

Southern Forest SO-280

Experiment Station December, 1981

Termite Control Studies in Panama

Raymond H. Beal

SUMMARY

Subterranean termite control studies in a tropic area

(Panama) are described. Testing was first started in 1943

on Barro Colorado Island, which was formed when the

Panama Canal was completed in the early 1900’s.

Materials tested included DDT (various concentrations

and formulations), BHC, trichlorobenzene, sodium arsenite, pentachlorophenol, sodium flurosilicate, copper

ammonium fluoride, aldrin, chlordane, dieldrin, and heptachlor. Dieldrin (1.0 percent), applied to the soil as a

water emulsion, was still 100 percent effective after 27

years when the tests were terminated. Tests with aldrin,

chlordane, and heptachlor were initiated in 1963 and all

three chemicals were still 100 percent effective after 16

years.’

Additional keywords: Field studies, soil treatments,

test procedures, tropics.

INTRODUCTION

Since construction of the Panama Canal in the early

1900’s, subterranean termites have interfered with canal

operations by damaging its facilities. Nearby military installations have also suffered severe damage. To deter-

‘This publication reports research involving insecticides. It does not

contain recommendations for their use, nor does it imply that the uses

discussed here have been registered. All uses of pesticides must be

registered by appropriate State and Federal agencies before they can

be recommended.

CAUTION: Pesticides can be injurious to humans, domestic animals,

desirable plants, and fish or other wildlife-if they are not handled or

applied properly. Use all pesticides selectively and carefully. Follow

recommended practices for the disposal of surplus pesticides and

pesticide containers.

mine the effectiveness of treating the soil for the prevention of termite damage and to evaluate many soil treatment chemicals in a tropical environment, a series of

long-term field evaluations were conducted. Tests began

in 1943 on Barro Colorado Island, Panama where additional tests were installed in 1946. The island, formed by

canal construction, is about 18 miles from the Atlantic

outlet in the Canal, and since 1924 has been under the

jurisdiction of the Smithsonian Institute. During 1951-53,

termite control studies were considerably expanded in an

area known as the Curundu Jungle Test Site at Fort

Clayton on the Pacific side of the isthmus. In 1963, more

tests were installed on an adjacent jungle site.

The early work began when our Forest Insect Laboratory was part of the Division of Forest Insect Investigations, Bureau of Entomology and Plant Quarantine, with

funding stimulated by information requests from the

United States War and Navy Departments.

All these tests were closed in 1979 when jurisdiction of

the test areas reverted to the Republic of Panama.

Although many of the test chemicals did not perform

well enough to be recommended for termite control, significant results from all tests are reported and discussed to

provide a basis of comparison for results from future tests

in tropical environments.

MATERIALS AND METHODS

Although the procedural details varied slightly from test

to test and were modified and improved with experience,

essentially 2 standard field test procedures were used to

evaluate the effectiveness of various chemical treatments.

Standard Test Methods

The first standard method, the stake test (fig. l), consisted of digging a hole 38 cm in diameter and 48 cm

deep, removing approximately 0.057 m3 of soil, and then

Southern Forest Experiment Station/T-10210 U.S. Postal Services Bldg., 701 Loyola Avenue, New Orleans, La. 70113

Forest Service, U.S. Department of Agriculture.

Serving Alabama, Arkansas, Louisiana, Mississippi, Eastern Oklahoma, Tennessee, Eastern Texas.
-

38 cm

Figure 1 .-Stake test method for evaluating insecticides.

treating the soil before it was replaced. A wooden stake,

5x 10 x46 cm, was driven to a depth of 31 cm in the

center of this treated soil to serve as bait (food) for the

termites. This bait stake was either southern pine or some

other termite susceptible wood and served as an indicator at the annual inspections to determine if termites had

successfully penetrated the treated soil around the stake.

Each treatment was placed a minimum of 1.5 m away

from another treatment. Each concentration of each

chemical was replicated 10 times in a randomized complete block. When termites had penetrated the soil in 5 of

the 10 replicates, the treatment was considered a failure.

The 1943 Barro Colorado stake tests were the first

replicated termite studies installed under tropical conditions in which 39 different treatments were applied.

Treatments included sodium arsenite as a dry powder

and as a 10 percent solution in water; creosote in various

oils; 5 percent pentachlorophenol; orthodichlorobenzene

in oil, in creosote, and in creosote plus diesel oil; and

diesel oil controls.

The 1946 Barro Colorado stake tests included different

dosages of 16 chemicals and methods for a total of 54

treatments. Dosages were 1.69,3.38, and 6.76 liter/m3 of

soil for plots with the standard 38 cm diameter x 48-cm

deep hole (0.057 m3). Some of the more recognizable

formulations included 5.0 percent DDT in water; 5.0 percent DDT in acetylenetetrachloride; 0.8 percent benzene

hexachloride (BHC) in kerosene; copper naphthanate (2

percent copper in kerosene); lead arsenate, dry powder

at 227-g dosage and in water, 227 g in 0.94 liter at a

0.94-liter dosage only; 5 percent monochloronaphthalene in kerosene; kerosene controls; and untreated

controls.

A new series of standardized stake tests was installed

at Curundu in a new test area in 1952-53. The 1952 group

included the following emulsions and fuel oil solutions:

- 5.0 percent DDT in oil

- 5.0 percent DDT plus 2.0 percent chlordane in oil.

- 20.0 percent DDT in Xylene.

- 0.50, 1.0, and 2.0 percent dieldrin in water.

- 0.4 percent gamma BHC in oil.

- Trichlorobenzene in diesel oil (3 to 1 ratio).

- Untreated controls-both oil and water.

Dosages were 6.76 and 10.1 liters/m3 for the emulsions

and oils and 0.94 and 1.88 liters for the DDT concentrate.

The second standard method, the ground-board test

(fig. 2), was designed to protect wooden military equipment laid on the jungle floor. However, it is also a good

method for evaluating materials used underneath slabtype house construction. The method consisted of removing the duff and debris from a 43-cm* area of soil in

order to expose the mineral soil. The material to be evaluated was then sprinkled on the soil surface and a wooden

pine board 30 x 30 x 2.5 cm was placed in the center of

the treated area. A rock or brick was then laid on the

board to hold it in place. The board was examined annually for the presence of damage by termites, which, if found,

would indicate that termites had successfully penetrated

the treated soil. Ten replicates of the test variables were

also used in this method and randomization was complete within blocks. Again, when termites had penetrated

5 of the 10 replicates, the treatment was considered a

failure.

In 1946, a series of ground-board treatments were

established on Barro Colorado Island to determine not

only the chemical effectiveness in controlling termites but

also to make comparisons with the earlier described

stake test method. A set of 10 sample replicates were

installed on tilled and 10 on untilled soil in this heavily

shaded jungle area. The 43 treatments included 3 dosages each of 13 chemical formulations and 4 untreated

controls. The formulations consisted of the following:

- Acetylenetetrachloride.

- 5.0 percent DDT in diesel oil.

-

GROUND-LINE

TREATED SOIL - 43 cm

Figure 2.-Standard ground-board method for evaluating insecticides.

Raymond H. Beal is principal entomologist, Southern Forest Experiment Station, Forest Service-USDA at Forestry Sciences Laboratory, Gulfport,

Mississippi. Other people involved with establishing and examining some of these studies were H. C. Secrest, J. R. Kowal, R. C. Morris, H. R. Johnston

(deceased), and V. K. Smith, all retired and former employees of the Gulfport laboratory. Special thanks to Ft. E. Daniel, biological technician, who gave

invaluable aid in assisting in examining the studies since 1972 and has compiled and kept up-to-date records of these studies.

2
the soil surface. Forty-eight separate treatments which

included chlordane and dieldrin at 0.03,0.06,0.12,0.25,

0.50, 1 .O, and 2.0 percent; and a1dri.n and heptachlor at

0.06 and 0.25 percent were installed at 946 and 1892

ml/929 cm2. Aldrin, dieldrin, and heptachlor granules

were applied to the soil to give equivalencles of 0.12,

0.25, 0.50, and 1 .O percent applied at the rate of 10.12

liters/m2. Chlordane granules were applied at only 0.25

and 0.50 percent.

RESULTS AND DISCUSSION

Barro Coloradc+1943Stake Tests

By 1952 (9 years), all treatments except those which

included sodium arsenite had failed to prevent termites

from attacking wood bait stakes. At the time the test was

concluded in 1954, the arsenite treatments 810, 1620,

and 2430 g/m3 of dry chemical and 4.73 ml of 10 percent

solution in water/m3 were providing termite protection

under the severe tropical exposure.

Barro Colorado-1945-Stake Tests

By 1952 (6 years), all treatments except 2 DDT formulations, 2 BHC, 4 monochloronaphthalene, 4 copper

naphthanate, and 1 lead arsenate had failed to prevent

termite attack. The 1954 (8-year) inspection showed that

only the 8.0 percent DDT in acetylenetetrachloride treatment still had limited effectiveness. In the DDT treatment,

soil in only 6 of the 10 replicates was not penetrated by

termites-60 percent protection.

c

Barro Coloradc+l945-Ground-board Tests

When the test was closed in 1954 (8 years), only 2

formulations continued to provide control: 5.0 percent

DDT in diesel oil and 10 percent sodium arsenite in water.

They were giving 80 percent protection, which, by today’s

standards, would not be acceptable for recommendation

as subterranean termite control. The results of the new

technique were so similar to the “stake test” (a more

difficult and time-consuming study to install) that it has

been the test technique used in subsequent studies.

Curundu-1952-53-Stake Tests

BHC was less effective than DDT, chlordane, or dieldrin, and of the latter 3, DDT was the least effective (table

1). For example, in soil treated with BHC, attacks first

showed up at the end of the fifth year. By the end of the

ninth year, there were multiple attacks through the treated soil. The recorded attacks to the highest treatments

of dieldrin and chlordane during the second and third

years of the test may have been anomalies because little

or no further attacks occurred to these treatments.

Table P.-Evaluation of insecticides applied as soil treatments in ground-board tests in 1953 in the Panama Canal Zone

Treatment Rate of

designation application

and material liters/m”

% of ground boards undamaged by termites after exposure for indicated years

1 2 3 4 5 6 8 10 12 14 16 16 20 22 24 26

Richfield Oil Co.

Xl Lavacide Oil 5.06 100 50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Same as above plus

5% penta. 5.06 90 50 40 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Same as above plus

2% naphthanate copper 5.06 90 50 50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . .

Richfield Oil Co.

#4 Weedkiller “A” 5.06 100 70 60 60 50 . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . .

Same as above plus

5% penta 5.06 90 50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Same as above plus

2% naphthanate copper 5~06 90 60 50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1 .O% Dieidrin in water 5.06 100 100 100 100 100 100 100 100 100 89 89 89 89 89 75 75

1 .O% Dieidrin in water 7.59 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

2.0% Dieldrin in water 5.06 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

2.0% Dieidrin in water 7.59 100 100 100 100 100 100 100 100 89 89 89 89 89 89 89 89

0.5% Dieidrin in fuel oil 2.53 100 100 100 100 100 100 100 100 100 90 90 90 70 50’ . . . . . . .

0.5% Dieidrin in fuel oil 5.08 ~ 100 100 100 100 100 100 100 100 100 100 80 80 80 30’ . . . . . . .

1.0% Dieidrin in fuel oil 2.53 100 100 100 100 100 100 100 90 90 90 90 90 80 50’ . . . . . . .

1.0% Dieidrin in fuel oil 5.06 100 100 100 100 100 100 100 80 80 80 80 80 70’ 70 70 70

2.0% Dieidrin in fuel oil 2.53 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 75’

2.@% Dieidrin in fuel oil 5.06 100 100 100 100 100 100 100 100 100 100 100 100 89 89 89 89

Untreated control . . , . . . . . 50 60 50 70 50 50 40 50 50 70 70 30 20 40 40 40’

‘These attacks were made by Heterotermes sp.

4
Curundu-195%%-Ground-board Tests

Dieldrin was the only true insecticide evaluated in the

ground-board test in studies installed in 1951-53 (table

2). The other chemicals, mostly different oils, did not

prevent termite attack. Only a Richfield Oil Company2

weed killer gave 50 percent control for more than 4 years.

Dieldrin at both 0.5 percent and 1 .O percent at 5.06 liters/

m2 of soil surface area failed (less than 50 percent effective) at 22 years. Even though this is excellent long-term

- ’

2Mentionofacompanytradenamedoesnotnecessarilyimplyendorsement by the U.S. Department of Agriculture.

protection, it did not give protection as long as dieldrin

installed in tests in Mississippi. The only treatments which

remained 100 percent effective for the entire 26 years

was 1 .O percent dieldrin at 15.18 liters/m2 and 2.0 percent

dieldrin at 10.12 liters/m2. The 2.0 and 1 .O percent dieldrin

in fuel oil gave excellent protection but sustained some

attacks after 26 years and 20 years, respectively. Since

oil is no longer used as a carrier for termiticides except in

special cases, these formulations are not suggested for

use. Results of this test particularly apply to Heterofermes convexinotatus (Snyder) and Heterotermes

tenuis (Hagen) because these were the predominant

species found in the study areas.

Table 3.4nsecticide.s evaluated against subterranean termites (Coptotermes sp. and Heterotermes sp.) in the Panama Canal Zone in ‘1963

Formulation

(approx. %

by wt.)

Aldrin (actual)

0.067

0.25

Dieldrin (actual)

0.033

0.067

0.125

0.25

0.50

5%

1.0

Heptachlor (actual)

0.067

0.25

Chlordane (technical)

0.033

0.067

0.125

0.25

0.5

1.0

2.0

Untreated control 0 _

Rate of

application

liters/m2

5.06

10.12

5.06

10.12

5.06

10.12

5.06

10.12

5.06

10.12

5.06

10.12

5.06

10.12

5.06

10.12

5.06

10.12

5.06

10.12

5.06

10.12

5.06

10.12

5.06

10.12

5.06

10.12

5.06

10.12

5.06

10.12

5.06

10.12

% of ground boards undamaged by termites after exposure for indicated years

1 2 3 4 5 6 7 6 9 1011 1 2 1 3 1 4 1 5 1 6

100 100 100 100 100 100 100 100 9 0 8 0 8 0 7 0 6 0 6 0 3 0 . . . .

100 100 100 100 100 100 100 100 100 100 100 100 9 0 7 0 7 0 6 0

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100. 100

100 100 100 9 0 9 0 9 0 6 0 7 0 5 0 . . . . . . . . . . . . . . . . . . . .

100 100 9 0 9 0 6 0 80 8 0 8 0 5 0 . . . . . . . . . . . . . . . . . . . .

100 100 100 9 0 9 0 9 0 9 0 8 0 6 0 5 0 .a.. t... . . . . . . . .

100 100 100 100 100 100 9 0 8 0 8 0 8 0 5 0 . . . . . . . . . . . .

100 100 100 100 100 100 100 100 100 100 9 0 7 0 5 0 . . . .

100 100 100 100 100 100 100 100 100 100 100 100 100 7 0

100 100 100 100 100 100 100 100 100 100 100 100 100 100

100 100 100 100 100 100 100 100 100 100 100 100 100 100

100 100 100 100 100 100 100 100 100 100 100 100 100 100

100 100 100 100 100 100 100 100 100 100 100 100 100 100

100 100 100 100 100 100 100 100 100 100 100 100 100 100

100 100 100 100 100 100 100 100 100 100 100 100 100 100

. . . . . . . .

. , . . . . . .

.*.. ,I..’

. , . . . . . . 80 80

100 90

100 100

100 100

100 100

100 100

100 100

100 100 100 100 100 100 100 100 100 100 9 0 7 0 6 0 . . . . . . . . . . . .

100 100 100 100 100 100 100 100 100 100 100 100 8 0 8 0 5 0 . . . .

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 9 0

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

100 100 100 8 0 7 0 6 0 8 0 6 0 5 0 . . . . . . . . . . . . . . . . . . . . . . . . ..ti.

100 100 100 7 0 7 0 7 0 4 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

100 9 0 9 0 9 0 8 0 8 0 8 0 7 0 4 0 . . . . .,.. . . . . . . . . . . . . . . . . . . . .

100 100 100 100 100 9 0 9 0 8 0 7 0 7 0 5 0 . . . . . . . . . . . . .*.. . . . .

100 100 100 100 100 100 9 0 9 0 8 0 8 0 7 0 5 0 . . . . . . . . . . . . . . . .

100 100 106 100 100 9 0 9 0 9 0 8 0 8 0 8 0 7 0 5 0 . . . . . . . . . . . .

100 100 100 100 100 100 100 100 9 0 6 0 6 0 4 0 . . . . . . . . . . . . . . . .

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

100 100 100 100 100 100 100 100 100 9 0 8 0 8 0 8 0 8 0 8 0 8 0

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

100 100 100 100 100 100 100 100 9 0 9 0 9 0 9 0 9 0 9 0 9 0 9 0

100 100 100 106 100 100 100 100 100 100 100 100 100 100 100 100

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

5 0 5 0 7 0 4 0 6 0 5 0 4 0 5 0 1 0 0 1 0 0 0 4 0 1 0 1 0

5
Ground-board Series-1963

Aldrin- and heptachlor-treated soils were not penetrated by termites until the ninth and eleventh years,

respectively, when the 0.067 percent treatment of each

chemical sustained 1 penetration. By the thirteenth and

fifteenth year, respectively, they were both considered

failures because the bait wood had been attacked in over

50 percent of the replicates (table 3).

Chlordane and dieldrin, when applied at 0.067 percent,

were attacked by the second and fourth year, respectively, with total failure occurring at the ninth and tenth year,

respectively. Treatments with solutions higher than 0.067

percent were effective much longer: dosages higher than

0.25 percent were still 100 percent effective when the

tests were terminated.

Table 4 presents the results of the granular insecticides

applied directly to the soil. Only 5 treatments, 0.50 percent and 1 .O percent aldrin, 0.50 percent and 1 .O percent

dieldrin, and 1 .O percent heptachlor remained 100 percent effective for the duration (16 years) of the study. The

earliest attack was found on 0.125 percent and 0.25

percent heptachlor, which occurred during the fifth

annual inspection. Generally, these granular treatments

did not perform as well as the emulsions, but this was

expected because the granular materials were more subject to washing by rainfall than the emulsions.

The species of termites penetrating the soil (either

Coptotermes sp. or Heferotermes sp.) were recorded,

but in many cases, the wooden monitoring baits were

totally destroyed and no termites were present. Based on

the termites that could be identified, the predominant

termites in the study areas were Coptotermes niger

Snyder, H. convexinotarus and H. tenuis. NasutiteFmes

corniger Motsch. and Microcerotermes arboreus Emerson were also found in the area.

RECOMMENDATIONS

1. Aldrin is the best material to use based on the fact

that no attacks occurred on any soil treated with 0.25

percent solution or higher.

2. Heptachlor and dieldrin appear equal in effectiveness because both were 90 percent effective at 0.25

percent after 16 years, but it is suggested that heptachlor

be favored over dieldrin since 0.067 percent dieldrin was

attacked earlier than 0.067 heptachlor.

3. All granular materials at 0.50 percent appear approximately equal in effectiveness, however, since no-use

labels are available for granules, they are not recommended for use at this time.

Table 4.-Granular insecticides applied in ground-board tests in 1963 in the Panama Canal Zone

Formulation Weight of

(approx. % toxicant applied' % of ground boards undamaged by termites after indicated years

b y weight) (g/932cm2) 1 2 3 4 5 6 7 6 9 1 0 11 1 2 1 3 1 4 1 5 1 6

Aldrin (actual)

0.125

0.25

0.50

1.0

Dieldrin (actual)

0.125

0.25

0.50

1.0

Chlordane (technical)

0.25

0.50

Heptachlor (actual)

0.125

0.25

0.50

1.0

Untreated control

1.19

2.37

4.73

9.46

1.19

2.37

4.73

9.46

2.37

4.73

1.19

2.37

4.73

9.46

. . . . . .

100 100 100 100 100 9 0 9 0 9 0 9 0 9 0 9 0 8 0 7 0 7 0 3 0 . . . .

100 100 100 100 100 100 100 100 100 100 100 100 9 0 9 0 9 0 8 0

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

100 100 100 100 100 100 100 100 100 100 90 80 80 80 80 70

100 100 100 100 106 100 100 100 100 100 100 100 100 100 100 90

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

100 100 100 100 100 100 100 100 8 0 8 0 8 0 5 0 . . . . . . . . . . . . . . . .

100 100 100 100 100 100 100 100 100 100 100 100 100 9 0 9 0 9 0

100 100 100 100 9 0 9 0 9 0 9 0 8 0 8 0 7 0 6 0 8 0 4 0 . . . . . . . .

100 100 100 100 9 0 9 0 9 0 9 0 9 0 8 0 8 0 7 0 6 0 5 0 . . . . . . . .

100 100 100 9 0 9 0 9 0 9 0 9 0 9 0 9 0 9 0 9 0 9 0 9 0 9 0 9 0

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

5 0 5 0 7 0 4 0 6 0 5 0 4 0 5 0 1 0 0 1 0 0 0 4 0 1 0 1 0

'Theamountsshowninthiscolumn are equivalentto amountsoftoxicantthatareapplied for each percentageof ml/932 cm'in water emulsion.

6