Population dynamics of Sand flies and Mosquitoes of Hanifa Valley
in Riyadh, Saudi Arabia
Aldawood, A. S., A. M. Alahmed, S. M. Kheir, and S. M. Hussein
Dept. of Plant Protection, College of Food Sciences and Agriculture,
King Saud Univ., Riyadh, Saudi Arabia.
Source:
Aldawood, A. S., A. M. Alahmed, S. M. Kheir, and S. M. Hussein. 2004.
Population dynamics of Sand flies (Diptera: Psychodidae) in Hanifah
Valley Riyadh, Saudi Arabia. P. J. Bio. Sci. 7(4):464-467.
Abstract
A survey of sand flies and mosquitoes was conducted in the Hanifa
valley, Riyadh, Saudi Arabia. Four species of sand flies were collected,
Phlebotomus papatasi, P. beregeroti, P. sergenti, and Sergentomiya
antennatus. P. papatasi accounted for 97% of the total catch. Mosquito
species found were mostly Culex spp. Few numbers of Aedes spp were
also found. Sand flies had two peaks, one in the middle of July and the
other in the middle of October. Where mosquitoes had the most activity
in the winter months. Light trap results for sand flies in this research
shows a biological meaning for the rise of cutaneous leishmaniasis in
Saudi Arabia, where population numbers of sand flies increase is
followed by an increase in reported cutaneous leishmaniasis cases in
hospitals.
Introduction
Insect victors play an important role in the transmission of many major
human diseases such as Malaria and leishmaniasis, which have a direct
impact on human health. Sand flies and mosquitoes are present in most
world regions especially Saudi Arabia where vast and diverse
geographical locations and environments within this big country are
present. A survey of mosquitoes in Saudi Arabia showed that more than
thirteen species were present belonging to three genera of Anopheles,
Culex and Aedes (Büttiker 1981). Species belonging to the genus
Anopheles were mostly found in the western and southern region of the
country while the genus Culex was present the central and eastern
regions, however, the genus Aedes was found in all regions but with
fewer species compared to the other two genera. In the same study, it was
1
found that house mosquito, Culex pipens, was the most abundant species
of all due to the easy of larval living requirements. Eight species of
Anopheles, a main vector of malaria, were recorded in the western and
southern region of Saudi Arabia (Badawi 1994).
Surveys of sand flies of Saudi Arabia showed the presence of twenty-five
species (Lewis and Büttiker 1980, 1982). The most abundant species in
these surveys and others (Al-Seghayer et al 1994) was Phlebotomus
papatasi, which is considered an important vector of Cutaneous
leishmaniasis in Saudi Arabia (Nadim et al. 1979, Lewis and Büttiker
1980, and Büttiker et al. 1980,1982). In Saudi Arabia, Cutaneous
leishmaniasis is reported in many cities including the capital of the
country, Riyadh (Morsy and Shoura 1975, Büttiker et al. 1980, and
anonymous 2001) and Riyadh reports the most cases for the years 19941996 (Al Amri et al. 1999).
No previous studies were done in Hanifa valley although it is considered
an important valley for Riyadh city. Hanifa valley is an important picnic
area. Furthermore, Hanifa valley is a valued natural passage of rain water
and leaking water coming from Riyadh city and leading to Hair region in
the south part of the city (anonymous 1995). The presence of such open
air water and farms on both sides of the valley impose a threat to the
medical health state of Riyadh inhabitants due to vectored diseases such
as Cutaneous leishmaniasis transmitted by sand flies.
The present study describes results of collection of population dynamics
of sand flies and mosquitoes from Hanifa valley, Riyadh city.
Material and Methods
Hasnifa valley was divided into two sections, a northern section in regard
to Riyadh city and a southern one (Fig 1). In Each section three sites were
used. Section one consists of three farms in Ammariyah, Diriyah, and
Irgah towns, about 15 km apart. Section two had two farms, one in
Almasanea part of Riyadh and one in Dar Albidhah town, while the third
site was an open area by the end of the valley in Hair town. Survey plots
within each site were selected according to the presence of favorable
breeding places for sand flies (Büttiker and Lewis 1983). Traps then were
randomly distributed in these plots.
In these sites sand flies were surveyed using two collection methods, light
traps and sticky paper traps. In the first method, battery operated
light/suction traps (CDC type) were used for collection of live specimens
2
of sand flies in the three sites of section one and in two sites of section
two. Alhair site did not have a light trap because of the difficulties of
leaving a light trap in such open site.
The light traps consisted of a source of light that attracts flies and a
rotating fan fixed to the trap drives sand flies towards a muslin bag. Light
traps were set before sun sit and collected the following morning. Traps
then were processed in King Saud Univ. Entomological labs, were sand
flies were sorted, identified, sexed, and counted.
Sticky traps were paper sheets 20*14 cm coated with castor oil on both
sides (Büttiker 1979). Rodent burrows were used as collecting sites when
present (Ba et al. 1999). Twenty sticky traps were sit in each site in the
afternoon time and collected the following morning. Same procedure
used with light trap specimens was done with sticky trap specimens. Data
were reported as sand fly index (flies per square meter) (Büttiker and
Lewis 1983).
Sand flies were picked from traps with entomological pins and mounted
in Puris medium on glass slides for identification and incubated at 38 c
for few days. Puris media was prepared according to Mahony (1999)
method.
Identification of sand flies:
Difficulty of identification of sand flies to species is due to the fact that
most of characters used for identification are internal like the shape and
structure of pharyngeal and buccal armature in both sexes. The shape and
segmentation of spermatheca of the female are the major characters for
female identification. Male genitalia, spines on the styles and their
orientation, size, number of soines of the lateral lobe, shape of penis and
sheath are the major characters used for identification of males. Length of
maxillary palps segments (palpal formula) is also used for identification.
Good preparation of specimens (cleaning and proper mounting) and use
of good powerful microscope are important for accurate identification of
specimens. Sand flies were identified using the key of Lewis and Büttiker
(1982).
Results
Sand fly collection - Light traps: The most northern site in the study
(site 1) had significantly lower number of sand flies compared to site 5,
the most southern site (Table 1). Sites within the same section were not
3
significantly different in the number of sand flies; furthermore, no
significant difference was shown between sections (Table 2).
Sand fly number is significantly higher in the month of October
compared to all months of the year in section 1 (Table 3). In Aug and
September, sand fly numbers were significantly higher than June and Jul.
months (Table 4).
Sand fly collection – Sticky traps: an increasing trend in sites, from
north to south, within sections is similar to that of light trap catches
although there are no significant difference (Table 5). Numbers are not
significantly different between sections similar to light catches though
section 1 had more numbers than section 2 which is reverse to that of the
light trap catches (Table 6).
In September, sand fly numbers were significantly higher than April and
December months (Table 7). The months of September, October,
November and February had the only presence of sand fly compared to
other months; however, September had the highest number (Table 8).
Mosquito collection - Light traps: The most northern site (site 1) has
significantly lower number of adult mosquitoes than site 4, in the
southern section (Table 9). However, sites within sections are not
significantly different. Between sections, numbers of sand flies were
significantly different (Table 10).
In December and February, mosquito numbers were significantly higher
than other months of the year (Table 11). In Jan and Oct, mosquito
numbers were significantly higher than other months of the year (Table
12).
Mosquito collection - Sticky traps: an increasing trend in sites, from
north to south, within sections is similar to that of light trap catches with
significantly lower number of sand flies in site 5, which had a trend in
light trap catches but was more evident when sticky traps were used
(Table 13). Same trend of light trap catches but with no significant
different detected (Table 14).
The highest peaks of mosquito numbers were in April and December,
which indicates the presence of a spring and fall activities (Table 15). The
highest peaks of mosquito numbers were in September followed by June
and December (Table 16).
4
Mosquito incomplete stages collection – water samples
The same trend from north to south is correlated with number of
mosquitoes larva collected by water samples (Table 17). The increasing
trend from north to south is evident which is correlated with number of
mosquitoes caught by light traps although not significantly different
(Table 18).
A similar increasing trend in pupa numbers from north to south is
correlated with number of mosquitoes caught by light traps (Table 19).
Mosquito Larval numbers were higher in April and November, and
lowest in February, where as pupal number were higher in April and
lowest in May (Table 23). In December, acidity level was significantly
higher than other months. Mosquito Larval numbers were higher in
February and lowest in October where as pupal numbers were higher in
September and lowest in March (Table 24). In November and December,
acidity level was significantly higher than other months.
Discussion
Results showed two peaks for sand flies (middle of July and middle of
October) which is similar to previous finding although numbers are lower
which might be related to the extensive urbanization of the studied
sections, hence, the increase use of insecticides (Büttiker et al. 1980,
Janini et al. 1995). Ground and Arial insecticide application affect the
population dynamics of sand flies drastically to the level of eradication
(Büttiker 1980). Also, habitat dgredation of sand fly populations is
another possible factor involved (Teodoro et al. 1999 and Travi et al.
2002).
P. papatasi is considered to be a vector of cutaneous leishmaniasis in
Riyadh region (Mustafa et al , 1994 ). In the present study P. papatasi
was the most dominant species, accounting for more than 97% of the total
catch. Other sand fly species, P. beregeroti, P. sergenti, and
Sergentomiya antennatus, were much less abundant. These finding are
similar to other research findings (Janini et al. 1995, Volf et al. 2002). It
was found that urban areas had only P. papatasi while peri-urban had P.
a. and S. t. (Büttiker et al. 1980). In valleys, 10 species of sand flies were
caught, where P. papatasi is the main insect vector for cutaneous
leishmaniasis (Lewis and Büttiker 1980). Results for population trend of
sand flies in this research is similar to population dynamic reported by
Büttiker et al. (1980).
5
Light trap results for sand flies in this research shows a biological
meaning for the rise of cutaneous leishmaniasis in Saudi Arabia, where
population numbers of sand flies increase is followed by an increase in
reported cutaneous leishmaniasis cases in hospitals (Büttiker et al. 1980,
Al Amri et al. 1999, anonymous 2001). An incubation period of about 412 weeks was reported (Büttiker et al. 1980) explaining the lag in time
between the increase of sand fly population and the incidence of
cutaneous leishmaniasis.
Rodents play an important role as reservoir for the protozoa of cutaneous
leishmaniasis and certain species of the genus Meriones are important
reservoir in Riyadh region (Büttiker et al. 1980, and Buttiker and
Harrison 1982). The presence of Meriones spp in Hanifa valley, Riyadh
(Alhmed and Aldawood 2001) represents a threat to the spread of
cutaneous leishmaniasis transmitted by P. papatasi.
Number of sand flies is increasing towards the southern part of the valley.
This might be related to the water stream escaping from underneath
Riyadh area, where it is a product of under ground water and sewage
runoff from water pipes and Riyadh houses sewage containers,
respectively. Southern sites (4,5,and 6) are located in a part that receives
that same stream and furthermore, the excess treated sewage water joins
this stream and continues towards the end of the valley in Hair area where
a farm receives that water and uses it for irrigation. However, site 1,2 and
3 are in an area without this running stream.
Horses seem to be attractive animals for sand fly populations followed by
cave sites (Melo Ximenes et al. 1999). In this research number of sand
flies were greater in site 3, though not statically different, where a horsebreeding farm is located.
Sand flies in less inhabited areas are better caught by light trap than by
sticky traps because they are more scattered. Mosquito did not show a
different trend for the two collection methods, though; light trap caught
more numbers than sticky traps. However, sticky traps for sand flies in
more inhabited areas are better catching traps than light trap because sand
flies are less scattered.
It was reported that CDC light trap was more effective in catching
members of the genus phlebotomus followed by sticky paper traps (Hilmy
et al. 1989), which is similar to the findings of this research. However,
sticky trap is less expensive and easier to handle. Also, sticky traps seem
6
to be more effective in low sand fly populations where light trap catch is
lower as shown in this study.
Mosquito species found were mostly Culex spp. Few numbers of Aedes
spp were found. Mosquito places of breeding include water tanks, drains
and desert coolers (Büttiker 1981). Mosquito numbers were greater on
site 4 because that site was near a sewage refinery place, which might
explain this increase despite the fact that pesticide application is done on
a daily bases. Furthermore, the southern section had more significant
numbers of mosquitoes due to the presence of the running water stream.
The higher number of mosquito adults in fall and winter months is due to
the intolerance to higher temperature of the summer. A temperature of
35-36˚c is considered lethal for mosquito development stages (Büttiker
1948).
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9
Table 1:
Site 1
Site 2
Site 3
Site 4
Site 5
Total
Table 2:
Mean
Total
Number of sand flies caught by light traps per sites
Mean
Total
0.33 a
1.08 ab
1.42 ab
1.75 ab
3.58 b
4
13
17
21
43
98
Number of sand flies caught by light traps per section
Section 1 Section 2 Total
0.94 a
34
2.67 a
64
98
Table 3:
Number of sand flies per month for section 1 collected by
light traps
Sand Fly
Date
Total Mean
0
2
3
4
3
6
11
3
0
0
0
2
34
10
0.00 c
29 April
0.67 bc
28 May
1.00 bc
25 June
1.33 bc
22 July
1.00 bc
19 Aug.
2.00 b
17 Sept.
3.67 a
15 Oct.
1.00 bc
12 Nov.
0.00 c
09 Dec.
0.00 c 06 Jan. 2001
0.00 c
05 Feb.
0.67 bc
12 Mar.
Table 4:
Number of sand flies per month for section 2 collected by
light traps
Sand Fly
Date
Total Mean
0
4
4
23
21
12
0
0
0
0
0
0
0.00 b
14 May
2.00 b
11 June
2.00 b
08 July
11.50 a
05 Aug.
10.50 a
03 Sept.
6.00 ab
01 Oct.
0.00 b
29 Oct.
0.00 b
26 Nov.
0.00 b
23 Dec.
0.00 b 22 Jan. 2001
0.00 b
17 Feb.
0.00 b
25 Mar.
64
Table 5:
Site 1
Site 2
Site 3
Site 4
Site 5
Site 6
Total
Table 6:
Mean
Total
11
Number of sand flies caught by sticky traps per sites
Mean Total
0.42 a
0.58 a
0.67 a
0.33 a
0.33 a
0.42 a
5
7
8
4
4
5
33
Number of sand flies caught by sticky traps per section
Section 1 Section 2 Total
0.56 a
20.0
0.36 a
13.0
33
Table 7:
Number of sand flies per month for section 1 collected by
sticky traps
Sand Fly
Total Mean
Date
1
0
3
4
2
5
2
0.33 bc
0.00 c
1.00 abc
1.33 ab
0.67 abc
1.67 a
0.67 abc
29 April
28 May
25 June
22 July
19 Aug.
17 Sept.
15 Oct.
2
1
0
0
0
0.67 abc
12 Nov.
0.33 bc
09 Dec.
0.00 c 06 Jan. 2001
0.00 c
05 Feb.
0.00 c
12 Mar.
20
Table 8:
Number of sand flies per month for section 2 collected by
sticky traps
Sand Fly
Total Mean
0
0
0
0
4
3
3
1
0
0.00 c
0.00 c
0.00 c
0.00 c
1.33 a
1.00 ab
1.00 ab
0.33 bc
0.00 c
0
2
0
0.00 c 22 Jan. 2001
0.67 abc
17 Feb.
0.00 c
25 Mar.
13
12
Date
14 May
11 June
08 July
05 Aug.
03 Sept.
01 Oct.
29 Oct.
26 Nov.
23 Dec.
Table 9:
Number of mosquitoes caught by light traps per sites
Mean Total
Site 1
Site 2
Site 3
Site 4
Site 5
Total
3.58 a
4.67 ab
4.25 ab
8.00 b
7.08 ab
331
Table 10:
Mean
Total
43
56
51
96
85
Number of mosquitoes caught by light traps per section
Section 1 Section 2 Total
4.17 a
150
7.54 b
181
331
Table 11: Number of mosquitoes per month for section 1 collected by
light traps
Mosquito
Date
Total Mean
7
2
10
9
7
18
3
6
34
18
31
5
150
13
2.33 c
29 April
0.67 c
28 May
3.33 bc
25 June
3.00 c
22 July
2.33 c
19 Aug.
6.00 b
17 Sept.
1.00 c
15 Oct.
2.00 c
12 Nov.
11.33 a
09 Dec.
6.00 b 06 Jan. 2001
10.33 a
05 Feb.
1.67 c
12 Mar.
Table 12: Number of mosquitoes per month for section 2 collected by
light traps
Mosquito
Date
Total Mean
4
7
4
7
10
22
24
20
25
44
1
13
2.00 d
14 May
3.50 d
11 June
2.00 d
08 July
3.50 d
05 Aug.
5.00 d
03 Sept.
11.00 bc
01 Oct.
12.00 b
29 Oct.
10.00 bc
26 Nov.
12.50 b
23 Dec.
22.00 a 22 Jan. 2001
0.50 d
17 Feb.
6.50 cbd
25 Mar.
181
Table 13:
Site 1
Site 2
Site 3
Site 4
Site 5
Site 6
Total
Table 14:
Mean
Total
14
Number of mosquitoes caught by sticky traps per sites
Mean Total
1.67 b
2.08 ab
2.50 ab
3.08 a
1.25 b
3.17 a
20
25
30
38
15
38
166
Number of mosquitoes caught by sticky traps per section
Section 1 Section 2 Total
2.08 a
75.0
2.50 a
91.0
166
Table 15: Number of mosquitoes per month for section 1 collected by
sticky traps
Mosquito
Total Mean
Date
13
2
10
9
6
7
0
4.33 a
0.67 ed
3.33 abc
3.00 abc
2.00 dc
2.33 bc
0.00 e
29 April
28 May
25 June
22 July
19 Aug.
17 Sept.
15 Oct.
7
11
2
8
0
2.33 bc
3.67 ab
0.67 ed
2.67 bc
0.00 e
12 Nov.
09 Dec.
06 Jan. 2001
05 Feb.
12 Mar.
75
Table 16: Number of mosquitoes per month for section 2 collected by
sticky traps
Mosquito
Total Mean
7
11
5
9
12
6
8
8
10
2.33 abc
3.67 ab
1.67 abc
3.00 abc
4.00 a
2.00 abc
2.67 abc
2.67 abc
3.33 abc
9
3
2
3.00 abc 22 Jan. 2001
1.00 bc
17 Feb.
0.67 bc
25 Mar.
90
15
Date
14 May
11 June
08 July
05 Aug.
03 Sept.
01 Oct.
29 Oct.
26 Nov.
23 Dec.
Table 17:
sites
Site 1
Site 2
Site 3
Site 4
Site 5
Site 6
Total
Table 18:
section
Mean
Total
Table 19:
sites
Site 1
Site 2
Site 3
Site 4
Site 5
Site 6
Total
Table 20:
section
Mean
Total
Table 21:
Site 1
Site 2
Site 3
Site 4
Site 5
Site 6
16
Number of mosquito Larva collected by water samples per
Mean
Total
2.75 a
3.75 a
3.00 a
3.83 a
4.50 a
3.33 a
33
45
36
46
54
40
254
Number of mosquito Larva collected by water samples per
Section 1
Section 2
Total
3.17 a
114
3.89 a
140
254
Number of mosquito pupa collected by water samples per
Mean
Total
1.33 a
1.67 a
1.42 a
1.08 a
1.33 a
1.25 a
16
20
17
13
16
15
97
Number of mosquito pupa collected by water samples per
Section 1
Section 2
Total
1.47 a
53
1.22 a
44
97
Average acidity per site collected by water samples
Mean
7.00 a
7.04 a
7.04 a
6.99 a
6.96 a
6.99 a
Table 22:
Mean
Average acidity per section collected by water samples
Section 1 Section 2
7.03 a
6.98 a
Table 23: Number of mosquito Larva, pupa, and average acidity per
month for section 1 collected by water samples
Larvae
Pupa
Total Mean Total Mean
Acidity
Date
18
4
7
6.00 a
1.33 bc
2.33 abc
10
2
6
3.33 a
0.67 cd
2.00 abcd
7.50 de
7.50 de
7.50 de
29 April
28 May
25 June
9
9
12
0
18
13
3
17
4
3.00 abc
3.00 abc
4.00 abc
0.00 c
6.00 a
4.33 ab
0.10 d
5.67 a
1.33 bc
7
6
4
0
3
6
0
9
0
2.33 abc
2.00 abcd
1.33 abcd
0.00 d
1.00 abc
2.00 abc
abcd
0.00 d
3.00 ab
0.00 d
7.26 f
7.39 ef
7.67 c
7.67 c
7.83 b
8.25 a
7.82 b
7.89 b
7.55 cd
22 July
19 Aug.
17 Sept.
15 Oct.
12 Nov.
09 Dec.
06 Jan.
2001
05 Feb.
12 Mar.
114
53
Table 24: Number of mosquito Larva, pupa, and average acidity per
month for section 2 collected by water samples
Larvae
Pupa
Total Mean Total Mean
Acidity
Date
6
13
6
8
13
16
2.00 b
4.33 ab
2.00 b
2.67 b
4.33 ab
5.33 ab
3
3
4
4
6
5
1.00 abc
1.00 abc
1.33 abc
1.33 abc
2.00 a
1.67 ab
7.28 f
7.28 f
7.31 f
7.34 f
7.41 ef
7.69 cd
14 May
11 June
08 July
05 Aug.
03 Sept.
01 Oct.
5
18
12
13
24
6
1.67 b
6.00 ab
4.00 ab
4.33 ab
8.00 a
2.00 b
0
5
4
4
5
1
0.00 c
1.67 ab
1.33 abc
1.33 abc
1.67 ab
0.33 bc
7.71 bcd
8.21 a
7.96 ab
7.81 bc
7.61 cd
7.47 def
29 Oct.
26 Nov.
23 Dec.
22 Jan.
2001
17 Feb.
25 Mar.
140
17
44