USE OF DDT FOR THE CONTROL OF

CYCLOPS BREEDING AND AS AN ANT1-

DRACONTIASIS MEASURE

By N. R. RAMAKRISHNAN, n,v, m.b.b.s., d.p.H.

Research Health Officer and

G. K. RATHN"ASWAMY, b.sc.,

Entomological Assistant, Research Section

(Office oj the Director of Public Health, Madras State)

Introduction

About half a dozen species of cvclops have been declared to be effective carriers of embryos of guinea-worm disease. In many villages of Ceded districts, North Arcot and some other districts in Madras State the main drinking water sources are the ponds, stepwells and the

like, mostly infested with some species of cyclops or other responsible for the spread of dracontiasis.

Till now for control of dracontiasis, the drink- ing water sources showing prolific breeding of c;/clops in endemic areas were either super' chlorinated or the biological method of control by introduction of cyclopscidal fishes like

Ambassis, Etroplus, Barbus etc., was resorted to after the removal of the predatory fishes.

Super-chlorination, if done regularly, gives fairly good results but social obstacles have to be overcome. Also super-chlorination will not be

practicable where large volumes of water as i11

big tanks, large stepwells are involved. I*1

places where biological method is resorted to

though control of cyclops breeding could be

checked to a great extent, yet it must be said ' that the fish control has its own limitations. The infected cyclops is said to remain almost all the time at the bottom of wells or ponds exhibiting sluggish movement and very rarely coming to the surface of water. Hence it be' comes necessary to use such fishes mostly that arc also bottom feeders, in the biological control to ensure the elimination of infected cyclops- However, it would seem difficult for any variety of fish that may be used to have access to the bottom portion and eat the infected cyclops

JuLY' l953] USE OF DDT... .MEASURE : RAMAKRISHNAN & RATHNASWAMY 387

,,lat sluggishly remain there. Further, there is 10 risk of these fishes being removed even if ley be of slight food value if no proper watch s exercised over such fish introduced wells or

Ponds.

^se 0/ DDT for Control oj Cyclops Breeding in

drinking Water sources

^ the above points in view, small scale ex- tents under laboratory conditions were

out to find out how far DDT could be

e ,ectlye against cyclops. DDT having been

u ^lished as a powerful insecticide and being extensively in modern times, it was decided

m aS^inst cyclops as an experimental f0^e. As the chemical must be used , drinking water sources, the toxic dose for

(pnitiU tolerance as determined by Dr. Boyce g-

r?*essor and Head of the Entomology Divi-

ttVir ^a^^ornia University) at 7 parts per

j 1

^ was taken into consideration in prepar- n ̂ "ie experimental trials. It is also said that

sv i ^10 ^^T that *s taken into the human

ystem gets absorbed into the system,

toxicity.?The following observations e relevant?

"

Smith and Stohlman studying the phar- macological action of DDT on rabbits and cats observed very low absorption of DDT in the system being rejected_through laecal contents and urine progressively." "

Stiff and Castillo believed that DDT Was probably transferred into other

organic chlorides in the alimentary sys- tem and that only these organic chlorides are absorbed." "

Woodward et al found storage of DDT in body fat when animals were fed on oil solutions of DDT than when fed on un- dissolved material."

f J^'oni these observations it is possible to in-

tit' while DDT is rejected in small quan- ts from the system either in urine or fa;cal

contents regularly, certain amount of it is ab- sorbed as organic chlorides. Oily solutions of DDT are absorbed by fatty tissues of the body fcher intake ceases. Accumulation of DDT in the fcher ntake ceases. Accumulation of DDT in the

body possibly never occurs if the interval of intake is sufficiently long and it is highly pro- bable that the human system is capable of re-

jecting the absorbed quantities of DDT much

quicker than expected as field experience would indicate

" (Buxton, 1945).

The solubility of DDT being less than one

part per million, DDT is practically insoluble

in water and therefore the possibility of render- ing water poisonous by contamination can be

completely ruled out. To quote Buxton, "My conclusion, given without reserve and in simple words, is that DDT used as an insecticide is

quite safe " and to this it may be added

" and

as a larvicide "

as well.

Also not all* the DDT used in a water source is going to be taken out in a bucket or a few buckets full of water baled out as the DDT will

get dispersed in the bulk of the volume of water contained in a pond or well. Hence the intake of DDT will be of very negligible proportion in the water potted.

Laboratory Trials with DDT against cy- clops.?Experiments were conducted by using glass jars of 8" by 5" by 5" size and only with well or pond water to avoid the effect of traces of chlorine on cyclops in case the tap water had been treated with bleaching powder. The jar was filled up to a capacity of 2000 cc. of well or pond water and a known number of cyclops was introduced. One jar was kept for contrast while the other was treated with DDT and observa- tions carried out a periodical intervals.

(a) 0.5 per cent DDT-Kerosene-Soap water emulsion.?In the first set of experiments a 0.5 per cent. DDT-Kerosene-Soap water emulsion was used at a dosage of 2.0 cc. for 2000 cc.

of water giving 5.0 parts per million with 100

cyclops each in the treated and contrast jars. The result of the observation is given in a

tabular statement.

L

Serial Volume Number Number 0f Parts per

dumber 9 c?' 0.5% million water cyclops strength

3 *

2,000 4 2,000 5 2,000 0 2,000

suspension Used

1 2,000 cc, 100 2.0 cc. 5.0 2 2,000 ? 260 3.0

500 5.0 1,000 2.5

500 1.5

1,000 1.5

7.5 12.5 6.25 3.75 3.75

388 THE INDIAN MEDICAL GAZETTE [July, 195$

From the above observation it could be seen that the emulsion did not produce the desired effect as in the case of A. stephensi mosquito larval control in wells where these were surface feeders and are highly susceptible, to obtain con- tact with DDT contained in the floating oil

layer of the emulsion on the water suriace.

After 43 hours only 30 per cent mortality was noticed in case of cyclops. Since cyclops are solely bottom feeders, the fine layer of oil film

with the dissolved DDT had not much action 011 them and they were found actively moving below the water surface. Hence the experiment with the DDT emulsion was given up after the first trial.

(b) 0.5 per cent strength DDT suspension.? This was prepared in the following manner out of 50 per cent water wettable DDT powder. 8 ozs. Geigy's Product of the 50 per cent water wettable DDT (Geigy's) was used to get 0.5 per cent strength technical DDT. ,

In the subsequent trials 50 per cent water

wettable DT (Geigy's) was used in the follow- ing dosages with tiie same glass container and 2000 cc. of water, but with varying number ol cyclops and varying dosages in each trial as

given below:?

With 5.0 cc. dosage the experiment was repeated without adding fresh DDT suspension to study the effect of residual toxicity oi DDT. The re-

sults of six trials are given in the tabular state- ment.

From the observations, it can be seen that there is a marked variation in the mode of ac-

tion of DDT used as a suspension as compared with that used as an emulsion. Even with lower

dosage of 2.0 cc. used, a mortality of about

90 per cent was obtained in 24 hours and 100

per cent mortality after 48 hours. With a

dosage of 5.0 cc. the effect was very spectacular but it was felt that this dosage was fairly high giving 12.5 parts per million. The use of sus-

pension produces a high percentage of mortality on adult cyclops as well as its larval stages, viz., the

'

nauplius ' and '

metanauplius '

stages. The larval stages readily succumb to the effect of

DDT, much more quickly than the adults, and seem to be highly vulnerable-to DDT used in the form of suspension.

Advantage and mode of action of DDT on

cyclops as a suspension

The advantage of using DDT as a suspension is that the majority of the DDT particles con- tained in the suspension sediment down to i -J

bottom within an hour or two after treatment, thus leaving the top layer or water mostly free lrom DDT and consequently harmless to humans who use such water for drinking purposes. And, the cyclops being bottom feeders died more by contact than by ingestion of DDT particles as it is presumed that DDT particles must be too big to enter the very small mouth of such a tiny creature. As the DDT remains in a

state of suspension m all the layers of water for at least an hour or two, the cyclops must necessarily come into contact with the suspended particles at some time or other and particularly ior those infected cyclops that remain sluggishly almost always at the bottom, the DDT particles are sure to come into contact with them when the same sediments down to the bottom after a short interval.

Further, there is also the residual effect of DDT. Hence the use of DDT suspension in

prescribed dosage and limited to well below the limit of tolerance to humans is worth a field trial in a guinea-worm endemic area where wells and ponds infested with cyclops are met with.

Summary and Conclusion 1. The super-chlorination and the biological

method for control of cyclops and the limita- tions of such methods tiiat are in vogue have been discussed briefly.

2. DDT when applied for drinking water sources must be well within the limit for human tolerance. A lew citations to indicate the liarin- lessness of DDT in low prescribed doses to humans have been given.

3. Use of 0.5 per cent DDT-Kerosene-Soap- water emulsion did not give encouraging results against cyclops.

4. Use of G.5 per cent strength DDT suspen- sion prepared out of 50 per cent water wettable DDI' did give excellent results in the laboratory trial.

Date of Number of Quantity of I>ate and time of Mortality ? cyclops water in Dosage observation rate, Remarks

experiment the jar introduced From To

20-12-51 100 2,000 cc. 2.0 cc. of 20-12-51 21-12-51 No mor-

0.5 per cent 11 a.m. 11 a.m. tality. After 24 hours,

emulsion.

21-12-51 22-12-51 30 per cent After 48 hours. 11 a.m. 11 a.m.

July, 1953] USE OF DDT... .MEASURE : RAMAKRISHNAN & RATHNASWAMY 389

pv Dosage of Date and time of

ate of Number of Quantity of suspension observation Periment cyclops water in at 0.5% Mortality Remarks

introduced the jar strength From. To rate

(a)

22-12-51 100 2,000 cc. 2.0 co. 22-12-51 23-12-51 ^ ^ ̂

11 p.m. 11 a.m.

23-12-51 24-12-51

11 a.m. .10-30 a.m. 100.0 Nearly 48 hours.

200 2,000 cc. 3.0 cc. 24-12-51 25-12-51 ~ 95.0 Nearly 48 hours. 11 p.m. 11 a.m.

^

25-12-51 26-12-51

~Tt 77. 99.0 All except two cyclops 11 a.m. 12 noon. dead in about 4g hours

26-12-51 27-12-51 ^hoSf01* ^ ̂ 12 noon. 12 noon. ? ? 1 c.ycloPs alive but not

active. 96 hours.

27-12-51 28-12-51

12 noon. 11 a.m.

28-12-51 29-12-51

11 a.m. 12 noon. 100.0 120 hours.

500 2,000 cc. 5.0 cc. 3-1-52 3-1-52

7 1 ern a Ar A Ad " alive

0-1-52 4-45 p.m. 4-45 p.m. 4 hours.

3-1-52 4-1-52

4-45 p.m. 12 noon.

94.0 28 alive but not active, 4 hours.

100.0 Nearly 24 hours.

111 500 2,000 cc. 2.5 cc.

5-i-52 -

.A a_b 1-15 P.m. 35.0 3 hours. H-2is

~1"52 . ^ 1J Overnight 11-30 a.m. 98.6 Nearly 22 hours. 7 alive

7-1 ko , but not active.

^ Overnight 10 a.m. 99.8 1 alive but not active.

8-1 no 45 hours nearly.

52 Overnight 11 a.m. 100.0 70 hours. d

go o o .y ̂

?-rt O

?-i O

IV

10-1-52 1,000 2,000 cc. 1.5 cc. 1 p.m. 3 p.m. 50.0 2 hours.

11-1-52 3 p.m. 5 p.m. 70.0 to 4 hours. Nearly 21 hours. 1 cy-

U-1.52 Overnight 10-30 a.m. .. clops alive but not ac- tive.

10-30 a.m. 2 p.m. 100.0 25 hours. All dead.

390 THE INDIAN MEDICAL GAZETTE [July, 1953

Date and time of

Dosage of Number of Quantity of observation

suspension cyclops water in Mortality introduced the jar strength From To rate

V

22-1-52 500 2,000 cc. 1.5 cc. 22-1-52 23-1-52

i^o^r 810 80 alive after 19 hours-

23-1-52 23-1-52

94.0 28 alive after 21 hours. 12 noon. 2 p.m.

23-1-52 23-1-52

2 p m. 5 p m 96.6 17 alive after 24 hours.

Overnight 24-1-52 97.8 11 alive after 42 hours.

24-1-52

-

p m 99.0 5 alive after 48 hours.

Overnight 25-1-32

5 p,m. 99.4 3 alive after 72 hours.

Overnight 26-1-32

10 a.m. 100.0 99 hours.

VI

28-1-52 1,000 2,000 cc. 75.0 28-1-52 29-1-52

3-30 p.m.

29-1-52 29-1-52

11-30 p.m. 5 p.m.

Overnight 30-1-52

96.8 32 alive after 20 hours.

99.4 6 alive after 25J hours.

11 nm 99-7 3 alive but not active

after 43J hours.

30-1-52

5 p.m. after 49! hours.

Overnight 31-1-52

11 p.m.

31-1-52

99.9 1 alive and not active after 49! hours.

99.9 1 'alive after 67! hours.

3-30 p.m. After 72 hours.

(In all the experiments there was no mortality in the contrast jar.)

5. The advantage and the mode of action of

DDT on cyclops as a contact poison are briefly discussed. The larval stages of cyclops are

highly vulnerable to DDT suspension. There

is residual toxicity of DDT on cyclops as well.

6. DDT as a suspension if proves successful under field conditions, a new field for controlling Dracontiasis is in prospect for the future.

REFERENCE Buxton, P. A. (1945) .. Roy. Soc. Trop. Med. and

Hyg., 38, 367.

Manson-Bahr, P. (1951). Manson's Tropical Diseases< Cassell and Co., Ltd., London.

Napier, L. E. (1943) .. Principles and Practice of Tropical M edicine. Thacker, Spink and Co.

(1933), Ltd., Calcutta.

West, T. F., and Camp- DDT and Newer Persistant

BELL, G. A. (1950). Insecticides. Chapman and ... Hall Ltd., London.