مجلة جامعة الفاشر للعلوم التطبيقية - العدد الاول

1. Jfuas No.1 June 2013
17
A preliminary Study on the Toxicity of Aqueous Extracts of
Some Plants from Darfur against Bulinus Truncatus Snails.
Mohammed yousif Adam1
’*, Faysal Sawi Ali’2
* , Abd-El-Gabar Nasir Gumma,3
*
.1 Department of Science, Faculty of Education for Basic Teachers, University of Alfashir,
Sudan.
.2 Department of Biology, Faculty of Education, University of Khartoum, Sudan.
.3 Department of Biology, Faculty of Education, University of Khartoum, Sudan.
*Corresponding author:mhdyousif@yahoo.com
ª ­Ø
KË27
ª F 24E
Kª Ù ª Ì ª
ª
WØFEÙFE
FĞEFE
FKE
Abstract
In this study, some folk-medicinal used plants from Darfur region
of the Sudan were hypothesized to contain ingredients useful in
control of schistosomiasis intermediate host snails. Twenty seven
plant species were tested for their aqueous extracts molluscicidal
activity against Bulinus truncatus adult snails. The primary screening

2. ‫اﻟﻔﺎﴍ‬ ‫ﺟﺎﻣﻌﺔ‬–‫ﻣﺠﻠﺔ‬‫اﻟﻌﻠﻮم‬‫اﻟﺘﻄﺒﻴﻘﻴﺔ‬-‫اﻷول‬ ‫اﻟﻌﺪد‬–‫ﻳﻮﻧﻴﻮ‬2013‫م‬
18
technique was used. Eight species produced extracts that showed some
degree of molluscicidal activity in bioassays.The molluscicidal
activity of five of them were recorded for the first time in the Sudan.
These were: Alternanthera nodiflora (Amaranthaceae); Amaranthus
viridis (Amaranthaceae); Glinus lotoides (Molluginaceae); Khaya
senegalensis (Meliaceae) and Rorippa indica (Bassiaceae).
KEY WORDS: Schistosomiasis, Aqueous extract, plant molluscicde,
Bulinus truncatus
Introduction
Schistosomiasis (Bilharziasis) is a disease infecting various
mammals including man and domestic livestock. It is caused by blood
flukes of the genus Schistosoma (Brown, 1980). The disease endemic
in seventy four countries (WHO, 1985). In the Sudan schistosomiasis
comes after malaria as one of the most important public health
problems (Bella etal., 1980). In Sudan, El –Kheir and El-Tohami
(1979) screened seventy eight plants used in folk –medicines that were
collected from the Nuba Mountains, the Blue Nile Province and
Khartoum Province for molluscicidal activity. Eighteen plants proved
to possess molluscicidal activity. They were active against Bulinus
truncatus and seven of them were also found to be active against
Biomphalaria pfeifferi. Elamin et al., (2005) evaluated the toxic dose
of Balanites aegyptiaca fruit extract when applied naturally against
both Bulinus truncatus and Biomphalaria pfeifferi. LC90 of both types
of the snail was 9 ppm. Howida (2005) screened seeds, stems, and

3. Jfuas No.1 June 2013
19
leaves of Jatropha aceroides (Euphorbiaceae) plant for their
molluscicidal activity against Bulinus truncatus. The results of the
aqueous extracts revealed that the seeds, were the most active part,
have an LC100 of 100 ppm, while the same concentration of the leaf
killed 80% of the snails. On the other hand, the stem extract showed
LC50 of 100ppm (24h exposure). Molluscicidal properties of
Pulicaria crispa (Forssk.) Oliv. (Asteraceae) have already been
studied in the Sudan. Ali (1997) investigated the potency of aqueous,
as well as acetone, and ethanol extracts of leaves, stem, and flowers
against B. pfeifferi snails. Salha (1999) investigated toxicity of
aqueous and ethanol extracts of leaves, stem, and flowers on Bulinus
truncatus. Somia (1999) reported the activity of P. crispa leaves
aqueous extracts on Lymnaea cailludi snails and anophline larvae with
LC50 and LC100 on concentrations of 1086.4 ppm .Thus
investigation of molluscicidal activity of indigenous plants in the
control of the snail intermediate host of schistosomiasis in the Sudan
is needed, Darfur has a very rich and varied flora, which has been little
studied. This flora represents an enormous reservoir of potential
molluscicidal activity which is waiting to be discovered. Many of
these plants are used in folk medicine by the people of Darfur to treat
several tropical diseases including schistosomiasis, especially in rural
areas and 1500 ppm of aqueous extracts of leaves respectively. Somia
(2003) also found that juveniles of B. pfeifferi snails were more
susceptible to aqueous extract than adult snails. Atta El Mannan
(2001) showed molluscicidal activity of P. crispa whole plant against

4. ‫اﻟﻔﺎﴍ‬ ‫ﺟﺎﻣﻌﺔ‬–‫ﻣﺠﻠﺔ‬‫اﻟﻌﻠﻮم‬‫اﻟﺘﻄﺒﻴﻘﻴﺔ‬-‫اﻷول‬ ‫اﻟﻌﺪد‬–‫ﻳﻮﻧﻴﻮ‬2013‫م‬
20
L. natalensis in the field. Amna (2001) studied the effects of leaves
maturity and storage on the toxicity of P. crispa against Lymnaea
natalensis snails
The objectives of this study is to screen the potentiality of some
plant extracts which may have molluscicidal activities against the
snail Bulinus truncatus intermediate host of schistosmiasis in Darfur.
Materials and Methods
2-1 The Study Area
Alfashir city is the capital of North Darfur State, Western Sudan. It
is situated at latitude ˚13 37 N and longitude ˚25 22 E. It is about 800
Km south west of Khartoum and at an altitude of approximately 740
m above the sea level. The climate is semi-arid with an annual rainfall,
between 100-500 mm. The study was carried out from August 2006 to
September2007.
2-2 Collection and Preparation of Plant Samples
Selection of the plant samples used in this study was based on data
collected from the folk-medicine in Darfur area, assuming that it can
also lead to the discovery of promising new plant molluscicides.
Accordingly, tewenty seven of folk-medicinal plant samples were
collected from Valleys and Goz lands around Alfashir city during the
rainy season (from August-September 2006), when the plants were
flowering and fruiting. The local names, the habitat, methods of
preparation, application and the disease they are claimed to cure were
obtained from local herbalist and recorded (Table 1). The collected

5. Jfuas No.1 June 2013
21
plants were protected from direct sunlight by covering with wet sacks,
and then transported to the laboratory in University of Alfashir, where,
the collected plants were put separately. Each plant was assorted by
part (leaves, stem, roots, flowers and fruits). Every plant part was air
dried under shade in the laboratory for three to four days. Thereafter,
the plant parts were ground in a wooden mortar with a pestle. The
powdered plant material was then put in labeled air tight plastic bags
and kept in desiccators for further use.
Herbarium specimens of these herbs were kept and transported to
Khartoum for identification. The plant specimens used in this study
were identified by Dr. Abd-El-Gabar Nasir Gumma, a taxonomist
from Biology Department, Faculty of Education, University of
Khartoum and deposited in the laboratory of Faculty of Education for
basic level teachers, University of Alfashir.
2-3 Collection and Maintenance of Snail Samples
Snails were collected from Golo reservoir. The snails were
collected in the early morning (at 8.00-10.00 a.m.) using a flat dip-net
scoop (Demian and Kamel, 1972; Richie etal., 1962). The collected
snails were put in a plastic bucket containing some dam water with
few leaves. The snails were then transported to the laboratory for
identification and maintenance. The snails used in this study were
Bulinus truncatus. In the laboratory, snails were identified to the
species level using the snail identification key published by Danish
Bilharzias Laboratory (DBL, 1983), and were confirmed by National
Research Centre of Khartoum (Plate1). Healthy snails were

6. ‫اﻟﻔﺎﴍ‬ ‫ﺟﺎﻣﻌﺔ‬–‫ﻣﺠﻠﺔ‬‫اﻟﻌﻠﻮم‬‫اﻟﺘﻄﺒﻴﻘﻴﺔ‬-‫اﻷول‬ ‫اﻟﻌﺪد‬–‫ﻳﻮﻧﻴﻮ‬2013‫م‬
22
maintained in plastic troughs (12cm depth×30cm diameter) with a
capacity of about 6 liters (Plate2). The trough bottoms were covered
with a layer of clay and some gravel, had been sterilized by heating to
150˚C for at least 18 hours. Tap water used was strongly aerated for
about three days to allow evaporation of chlorine and then, the troughs
filled up to two thirds. Green Eruka sativa(Girgeer) leaves were
immersed in boiling water for about one minute and then cooled in tap
water. After the removal of the mid-rib, leaves were dried and ground.
The powdered dry Girgeer was used for feeding the snails three times
a week. It should be noted that the soft part of the Girgeer leaves were
the most suitable material for feeding the snail. Snails fed on dry ribs
of the leaves did not survive. The aquaria were maintained at
temperature between 25-30˚C. Water was changed twice a month or
when necessary. The dead snails were removed as soon as possible
from the troughs to prevent water fouling.
Plate (1): Bulinus truncatus adult snail Plate (2): B.
truncatus breeding aquarium

7. Jfuas No.1 June 2013
23
2-4 Preparation of the Aqueous Extracts
Five grams of each powdered dry plant part material (leaves, stem,
roots, flowers, fruits and seeds) of the twenty seven plant species used
in the screening tests were weighted using an electric balance. The
weighted powdered dry parts were soaked in 150 ml of distilled water
for 24 hours with occasional vigorous shaking, using a magnetic
stirrer during the first six hours. Then, the suspension was filtered
using (Whatman No.1) filter paper.The marc was washed with several
portions of distilled water to adjust the volume of the stock solution,
using volumetric flasks to 200 ml (25000ppm).The plant extracts were
used immediately after the extraction to gurantee their freshness.
2-5 Primary Screening Technique
Different stock solutions (5gm/200ml) of the aqueous extracts for
the different parts of the twenty seven plant species were tested
against adult Bulinus truncatus snails according to the method
recommended by WHO (1961). The working solutions were prepared
by using the simple dilution procedure, by adding 1, 3, 5, 7, 9, 11, 13,
15, 17, 19 and 21ml of stock solution to dechlorinated tap water in
containers (10cm depth×25cm diameter) and the total volume adjusted
to 500ml to give concentrations of 50, 150, 250, 350, 450, 550, 650,
750, 850, 950 and 1050 ppm respectively.
Ten healthy, uniform sized adult snails of B. truncatus were put in
each container. The exposure period was 24 hours followed with the
recovery period of 24 hours. For the recovery period, snails were
transferred to other containers with 500ml of dechlorinated tap water

8. ‫اﻟﻔﺎﴍ‬ ‫ﺟﺎﻣﻌﺔ‬–‫ﻣﺠﻠﺔ‬‫اﻟﻌﻠﻮم‬‫اﻟﺘﻄﺒﻴﻘﻴﺔ‬-‫اﻷول‬ ‫اﻟﻌﺪد‬–‫ﻳﻮﻧﻴﻮ‬2013‫م‬
24
and fed with powdered dry Girgeer. Dead snails were counted. All the
snails which at the end of the recovery period remained completely
within their shells, floated upside -down on the surface of the solution
or settled at the bottom without response to mechanical prodding were
considered dead. When all the snails were killed, further dilutions
were prepared to determine the least lethal concentration that killed
100% of the snails (LC100), using the simple dilution procedure.
Control tests were reared in similar conditions without treatment. All
treated and control groups were put under artificial light for about
eight hours daily. The surviving snails were removed to other
containers with 500ml of dechlorinated tap water, fed on Girgeer and
observed for three days.
Results
Aqueous Extracts of different parts (leaves, stem, flowers, seeds
and fruits) of twenty seven plant species suggested as medicinal plants
by the local people in Darfur region were screened for their
molluscicidal activity against the snail Bulinus truncatus. They
classified into eighteen families, with Amaranthaceae and
Caesalpiniaceae being the most represented families within the
collection. Out of the tested plant samples eight species were active
against B. truncatus snails as listed in Table (1). Table (2) summarizes
the results of the bioassays, listing only the species that showed some
molluscicidal activity in at least one bioassay.
The lethal doses that caused 100% mortality (LC100) of the adult
B. truncatus snails, when 5gm of the powdered plant species parts

9. Jfuas No.1 June 2013
25
were soaked in 200 ml of distilled water for 24 hours were:
Alternanthera nodiflora (Amaranthaceae) (leaves 187.36 ppm and
196.22 ppm for the flowers); Glinus lotoides (Molluginaceae) (leaves
736.24 ppm and 684.11 ppm for the fruits); Khaya senegalensis
(Meliaceae) stem bark 531.21 ppm; Rorippa indica (Bassicaceae)
stem 946.16ppm; Amaranthus viridis (Amaranthaceae) leaves 1032.08
ppm; Blanites aegyptiaca (Balanitaceae) fruits 9.42 ppm; Acacia
nilotica (Mimosaceae) fruits 112.50 ppm and Pulicaria crispa
(Asteraceae) leaves 1378.60 ppm.
Table (1): Screened plant species and their local uses
Scientific Name
(Species)
Family Local Name
Active
Morphologi
cal Part
Folk-medicine
Uses
1 Conyza
aegyptiaca
Asteraceae Raihan
Elgrouf
Leaves
stem
Smoke was used as
insects repellant
2 Pulicaria
crispa
Asteraceae Altagar(Rab
oul)
Leaves Hypertension
3 Glinus
lotoides
Molluginaceae Remta
ghabsha
Leaves
seeds
Drop tape worms
treating dysuria
4 Alternanther
a nodiflora
Amaranthaceae Gebbis
(Abu-Tagia)
Leaves
flowers
Treating dysuria
schistosomiasis
5 Amarathus
spinosa
Amaranthaceae Khadiga
kroa
Leaves Swallows
treating tonsillitis
6 Amaranthus
viridis
Amaranthaceae Lisan Eltair
Kabeer
Leaves Swallows
treating tonsillitis
7 Aerua
javanica
Amaranthaceae Ras –Al-
shaeb
Flowers Treating swallows
8 Cassia
obtusifolia
Caesalpiniaceae Kaual Seeds Treating hepatic
infections(speciall
y bile)
9 Senna italica Caesalpiniaceae Sana Kalib Fruits
roots
Laxative dermal
diseases treating
10 Cassia
occidentalio
Caesalpiniaceae Sim-
Eldabeib
Stem
roots
Anti-toxic
11 Senna
alexandrina
Caesalpiniaceae Sanamakka Fruits
roots
Laxative and
treating hepatic
diseases

10. ‫اﻟﻔﺎﴍ‬ ‫ﺟﺎﻣﻌﺔ‬–‫ﻣﺠﻠﺔ‬‫اﻟﻌﻠﻮم‬‫اﻟﺘﻄﺒﻴﻘﻴﺔ‬-‫اﻷول‬ ‫اﻟﻌﺪد‬–‫ﻳﻮﻧﻴﻮ‬2013‫م‬
26
12 Euphorbia
egyptiaca
Euphorbiaceae Um-Libaina
Masrea
Stem the
milky juice
Treating wounds
13 Euphorbia
hirta
Euphorbiaceae Um-
libaina(Tam
r Elghanam)
Roots Anti toxics
especially of the
scorpion
14 Rorippa
indica
Bassicaceae Hussain
Sakaran
(kamoun
Elgobn)
Stem Analgesic killing
tape worms
15 Geigaria
alata
Cruciferae Gadgad Stem roots Treating of
diabetus mellitus
stomachaches
16 Indigofera
arrecta
Papilionaceae Remta
Hamraa
Stem roots Dysuria
17 Rogera
adenophylla
Pedaliaceae Teber
Elgadaul
(Um –
ganato)
Stem
seeds
Pertusis
18 Indigofera
hochstetteri
Papilionaceae Dahaseer Stem Toxic
19 Ipomoea
cordofana
Convalvulaceae Ladouk Stem Toxic
20 Zizyphus
spina-christi
Rhamnaceae Sedder Leaves
Fruits
Laxative, drop
worms
21 Aristolochia
bracteolata
Aristolochiaceae Um-Galagil
(Errg
Elagrab)
Stem roots Anti Malaria,
dysentery
hepatic diseases
22 Solanum
dubium
Solanaceae Gibbain Fruits Guardiasis
making yogurt
23 Trianthema
pentandra
Ficoidaceae Rabaa Stem Anti scorpion
venom
24 Heliotropiu
m
aegyptium
Boranginaceae Danab
Elagrab
roots Treating wounds
25 Khaya
senegalensis
Meliaceae Mahogany Stem bark Treating jaundice,
hook worms
dermatomes
26 Accacia
nilotica
Mimosaceae Garadh Fruits Stomach aches,
colds
rheumatism
27 Balanites
aegyptiaca
Balanitaceae Heglieg Fruits Anathematic
against hepatitis

11. Jfuas No.1 June 2013
27
Table (2): Plants that Showed Molluscicidal Activity in the Screening
Tests.
No. Plant species Family Active Part LC100 (ppm)
1 Acacia nilotica Mimosaceae - Fruits 112.50
2 Alternanthera
nodiflora
Amaranthaceae -Leaves
-Flowers
187.36
196.22
3 Amaranthus viridis Amaranthaceae - Leaves 1032.08
4 Balanites aegyptiaca Balanitaceae -Fruits 9.42
5 Glinus lotoides Molluginaceae -Leaves
-Fruits
736.24
684.11
6 Khaya senegalensis Meliaceae - Stem Bark 531.21
7 Pulicaria crispa Asteraceae - Leaves 1378.60
8 Rorippa indica Bassicaceae - Stem 946.16
Discussion
The deciding factor in schistosomiasis control programmes using
molluscicides is the cost. Synthetic molluscicides are expensive and in
addition, may lead to problems of toxicity to non-target organisms and
deleterious long-term effects on the environment. The possible
development of resistance in schistosomiasis transmitting snails is
another important factor. Other methods of snails control such as
biological methods or drying of the canals also proved unsatisfactory.
Therefore, these considerations urge the use molluscicides of plant
origin that are selectively active, easily biodegradable, inexpensive
and available in endemic areas (WHO, 1983). The success of plant
molluscicidal plans may become in the near future a useful
complement for the control of schistosomiasis.
In the present study, twenty seven folk-medicinal plant species
from Darfur were preliminary screened by part for their molluscicidal
activity against B. truncatus adult snails using the aqueous extract

12. ‫اﻟﻔﺎﴍ‬ ‫ﺟﺎﻣﻌﺔ‬–‫ﻣﺠﻠﺔ‬‫اﻟﻌﻠﻮم‬‫اﻟﺘﻄﺒﻴﻘﻴﺔ‬-‫اﻷول‬ ‫اﻟﻌﺪد‬–‫ﻳﻮﻧﻴﻮ‬2013‫م‬
28
method. Eight of them (29.60%) caused a significant death of B.
truncatus adult snails after 24 hours of exposure. This is considered a
good rate, reinforcing the importance of ethno- medical information in
the search of bioactive extracts. Among the eight plant species that
showed molluscicidal activity three have been tested for their
mollscicidal activities by other researchers. Accacia nilotica
(Mimosaceae) was reported by Mardufa and Ouma, (1977); El Kheir
and El Tohami, (1979); Ayoub, (1985). Balanites aegyptiaca
(Balanitaceae) was reported by Archibald, (1933); Wagner, (1936);
Bashir et al., (1984); Elamin et al., (2005). Pulicaria crispa
(Asteraceae) was studied by many researchers (Ali, 1997; Somia,
1999 and 2003; Salha, 1999; Atta El Mannan, 2001; Amna, 2001 and
Ali, 2007). In the present study P. crispa showed less activity against
B. truncatus adult snails in the screening tests than mentioned in
previous studies. These differences may be due to the extraction
methods or to seasonal and geographical variations of the plant.
The molluscicidal activity of Alternanthera nodiflora
(Amaranthaceae); Amaranthus viridis (Amaranthaceae); Glinus
lotoides (Molluginaceae); Khaya senegalensis (Meliaceae) and
Rorippa indica (Bassicaceae) were reported for the first time in the
Sudan (Table1). Further studies are needed to test the potency of
solvent extracts on adult, one day old juveniles, and one day old egg
masses of B. truncatus and other intermediate snail hosts of
schistosomiasis.

13. Jfuas No.1 June 2013
29
On conclusion, according to the results obtained above, some of
the active species mentioned in this study were considered promising
molluscicides, in control of schistosomiasis. These results need to be
followed by further investigations for comprehensive evaluation and
possible use of the active species in schistosomiasis control
programmes.
Acknowledgement
The authors thanks and appreciation is to Dr. Abdelazziz Abd-
El-Rahim, Director of Schistosomiasis Research Laboratory,
University of Khartoum for his help and advice.
References
Ali, A. E. (1997). Investigation into the molluscicidal activity of
Pulicaria crispa (Forssk.) Oliv. (Compositae) on Biomphalaria
pfeifferi snail vectors of schistosoma mansoni in the Sudan. M. Sc.
Thesis. Faculty of Veterinary Sciences, University of Khartoum,
Sudan.
Amna, H.I. (2001). The Effect of Leaves Maturity and Storage on the
Toxicity of Pulicaria crispa (Forssk.) Oliv. (Compositae) on Lymnaea
natalensis snails. M. Sc. Thesis. Faculty of Education, U. of K.,
Sudan.
Archibald, R. G. (1933). The endemiology and epidemiology of
schistosomiasis in the Sudan. Journal of Tropical Medicine and
Hygiene, 36: 345-348.

14. ‫اﻟﻔﺎﴍ‬ ‫ﺟﺎﻣﻌﺔ‬–‫ﻣﺠﻠﺔ‬‫اﻟﻌﻠﻮم‬‫اﻟﺘﻄﺒﻴﻘﻴﺔ‬-‫اﻷول‬ ‫اﻟﻌﺪد‬–‫ﻳﻮﻧﻴﻮ‬2013‫م‬
30
Ayad, N. (1956). Bilharziasis survey in British Somalia, Eriteria,
Sudan and Yemen, Bulletin of World Health Organization, 14: 1-117.
Atta El-Mannan, A. M. (2001) . Studies on biological control of
Lymnaea natalensis snails using a molluscicidal indigenous plant
Pulicaria crispa (Forssk.) Oliv. (Compositae). Ph. D. Thesis. Faculty
of Veterinary Sciences, University of Khartoum, Sudan
Ayoub, S. M. (1985). Molluscicidal Properties of Acacia nilotica.
Medica, 46: 181-183.
Bashir, A. K. ; Ahmed, G. H. M. ; Suliaman, S. M. and El-Kheir,
Y. M. (1984). Molluscicidal and other biological activities of
Balanites aegyptiaca. The First Arab Conference on Medicinal Plants.
Cairo, Egypt.
Bella, H.; Marschall, T. E. Dec.; A. H. S. and Vaughan, J. P.
(1980). Migrant workers and schistosomiasis in the Gezira,Sudan.
Transactions of Royal Society of Tropical Medicine and Hygiene, 74:
36-39.
Brown, D. S. (1980). Freshwater snails in Africa and their medical
importance. Taylor and Francis Ltd., London.
Danish Biharziasis Laboratory (1983). A field guide to freshwater
snails in countries of the WHO Eastern Mediterranean Region. WHO
Collaborating Centre for Applied Malacology, Copenhagen
Demian, E. S. Kamel, E. G. (1972). Growth and population
dynamics of Bulinus truncatus under semi –field conditions in Egypt.
Proceeding of Egyptian Academy of Science, 25: 37-60.

15. Jfuas No.1 June 2013
31
Elamin, E.; Subki, H. and Koko, W. S. (2005). Utilization of
Balanites aegyptiaca fruit extract in the eradication of schistosomiasis
transmitting snails in Sudan (Primary investigation). Albuhuth Sudan
Journal of Scientific Research 8(2): 112-119.
El- Khier, Y. M. and El- Tohami, M. S. (1979). Investigation of
Molluscicidal Activity of Certain Sudanese plants Used in Folk-
Medicine 1, ll. The London School of Hygiene and Tropical Medicine.
82 (11/12): 237-241.
Howida, A. H. (2005). Investigation on the molluscicidal activity of
Jatropha aceroides against Bulinus truncatus. Albuhuth- Sudan
Journal of Scientific Research, 9 (12): 33-40.
Jurberg, P.; Vasconcellos M. C. and Mendes, N. M. (1989). Plants
empregadas como moluscicidas: Uma vis o critica. Mem. Inst.
Oswaldo Cruz. 84: 76-83.
Kloos, H. and McCullough, F. S. (1987). Plants with recognized
molluscicidal activity. In Mott, K. E. ed. Plant Molluscicides.
Kuo, Y. H. (1987). Plant molluscicidal Studies in the Peoples
Republic of China. In : Mott, K.E. ed. Plant Molluscicides. New York.
UNDP/World Bank/WHO, p.229-298.
Mardufa, A. and Ouma, J. H. (1977). A new Chalcone as a natural
product from Polygonum senegalensis. Phytochemistry, 17: 823-824.
Molgaad, P.; Chihaka, A.; Furu, P.; Ndekha, A. and Nyazema, N.
(1999). Community based schistosomiasis control in Zimbabwe using
the molluscicidal berries of Pytolacca dodencandra AETFAT
conference in Harare, Zimbabwe.

16. ‫اﻟﻔﺎﴍ‬ ‫ﺟﺎﻣﻌﺔ‬–‫ﻣﺠﻠﺔ‬‫اﻟﻌﻠﻮم‬‫اﻟﺘﻄﺒﻴﻘﻴﺔ‬-‫اﻷول‬ ‫اﻟﻌﺪد‬–‫ﻳﻮﻧﻴﻮ‬2013‫م‬
32
Richie, L. S.; Radke, M. E. and Ferguson, F. F. (1962). Population
dynamics of Australorbis glabratus in Puerto Rico. (bid, 11): 171.
Salha, B. F. (1999). The effect of Pulicaria crispa (Forssk). Oliv.
(Compositae) on Bulinus truncatus snail vector of Schistosoma
haematobium in the Sudan. M. Sc. Thesis. Faculty of Education,
University of Khartoum, Sudan.
Somia, A. M. (1999). The effect of Pulicaria crispa (Forssk). Oliv.
(Compositae) on Lymnaea cailludi snails and other aquatic lives. M.
Sc. Thesis. Faculty of Education, University of Khartoum, Sudan.
Somia, A. M. (2003). Ovicidal and Molluscicidal Potency of
Pulicaria crispa (Forssk). Oliv. on Biomphalaria pfeifferi egg-masses,
juveniles and adults. Ph. D. Thesis. Faculty of Education, University
of Khartoum, Sudan.
Wagner, V. A. (1936). The possibility of eradicating bilharzia by
intensive planting of the tree Balanities. South Africa Med. J. 10: 10-
11.
World Health Organization (WHO) (1961). Molluscicides: second
report of expert committee on Bilhaziasis. WHO Technical Report,
Series No. 214
‫ـ‬ ‫ــــــــــــــــــ‬ (1983). Report of scientific working group on plant
molluscicide and guidelines for evaluation of plant molluscicide.
Geneva, (TDR/SCH- SWE (4)/ 83.3).
‫ـ‬‫ــــــــــــــــــ‬ (1985). The control of schistosomiasis. WHO Technical
Report, Series No. 728, Geneva.