- Email: [email protected]
The distribution and seasonal dynamics of Oestrus ovis linne infesting the nasal cavities and sinuses of sheep in egypt
Veterinary Parasitology, 4 (1978) 79--82 © Elsevier Scientific Publishing Company, Amsterdam -- Printed in The Netherlands
79
THE DISTRIBUTION AND SEASONAL DYNAMICS OF OESTRUS OVIS LINNE INFESTING THE NASAL CAVITIES AND SINUSES OF SHEEP IN EGYPT
I B R A H I M A. GAABOUB
Entomology Division, Faculty o f Agriculture, University of Alexandria, Alexandria (Egypt) (Received 27 April 1977}
ABSTRACT Gaaboub, I.A., 1978. The distribution and seasonal dynamics of Oestrus ovis Linn~ infesting the nasal cavities and sinuses o f sheep in Egypt Vet. Parasitol., 4 : 79--82. The distribution and seasonal dynamics of sheep bot fly, Oestrus ovis Linn~, infesting the nasal cavities and sinuses of sheep in the Egyptian Nile Delta and on its western and eastern perimeters were studied. Results indicate that O. ovis completed one generation during the year of study, 1976. The greatest infestation rate occurred from August to October, followed by a decrease in the rate which continued until February and a gradual increase during the subsequent months until July. No first instar larvae were recovered from August to October. The lowest prevalence of infestation was recorded in the eastern part of the Nile Delta. Higher prevalences were encountered in the delta and its western governorates.
INTRODUCTION
The sheep bot fly, Oestrus ovis Linn~, is encountered wherever sheep are found and may cause loss of production and sometimes death. The presence of larvae in the animals' nasal passages and frontal sinuses causes inflammation and a copious cattarhal discharge. This, coupled with dusty climatic conditions, causes giddiness or "blind staggers" (Metcalf and Flint, 1939; Herms and James, 1961; Leclereq, 1969). Abul-Hab (1970; in Iraq), Rogers and Knapp (1973; in Kentucky, U.S.A.) and Kettle (1973; in New Zealand) published useful papers on the seasonal occurrence and bionomics of this species. Their studies included information about the ecological conditions prevailing in the countries surveyed and notes on the geographical incidence of this insect. Sheep in Egypt are plagued by this infestation but no information on its distribution or seasonal prevalence is available. The present investigation is an attempt to define the distribution, seasonal dynamics and levels of O. ovis infestation in sheep in Egypt. During 1976, the heads of sheep
80
slaughtered in representative areas of the Nile Delta and its eastern and western perimeters were examined for the presence of O. ovis. METHODS AND TECHNIQUES
Seven slaughter-houses in seven governorates of the Nile Delta and on its western and eastern edges were chosen for the present study. There was one slaughter-house in each of Alexandria, Beheira, Kafr-E1-Sheikh, Gharbiya, Minufiya, Daqahliya and Damietta (Fig. 1). Throughout the year o f study (1976) 100 sheep heads were collected from each abattoir at m o n t h l y intervals and examined for the presence of larvae of O. ovis. Larvae were collected by running tap water under high pressure through the sheep's nasal cavities and sinuses. Remaining larvae were collected after cutting the heads into small pieces. Maggot indices (mean m o n t h l y number per 100 heads and percentage of total larvae from each region) were recorded. The three larval instars were identified and counted separately and their relative abundance was calculated for each m o n t h of the study. RESULTS AND DISCUSSION
A total of 1 200 heads was examined between January and December, 1976, for each of the seven governorates. The mean m o n t h l y numbers of l
I
ME
D
~
I
I
I
I
,3r30"
.31~:}0"
.3O'3O"
.30"00" ', l
29°/.,5 ' 30°00 ,
j
30'30"
I
0 'i
31"00
\ I
J
31°30 ,
I
32°00
3 -3o
Fig. 1. L o c a t i o n s o f O. ovis larvae c o l l e c t i o n in t h e Nile D e l t a a n d its w e s t e r n a n d eastern governorates.
81 first, second and third instars of larvae collected per 100 heads, and the percentage of total larvae found in each region total are presented in Figs 2 and 3. Results obtained indicated that all infested animals harboured larvae in the first and second instars from January to June, while all the animals infested in the period July--December harboured third instar larvae, though these were very few in number during December (Fig. 2). No first instar larva was collected during August, September or October. These results indicate that the sheep bot fly has one generation per year in the Nile Delta. It is thus most likely that the adults deposit first instar larvae during the a u t u m n and early winter. These larvae remain in the nasal cavities and sinuses until the next season. The greatest total numbers of larvae were recovered during August, September and October (Fig. 2). This was followed by a gradual decline in the degree of infestation during November and December and then a steep decrease during January and February. Thereafter, the mean m o n t h l y number of larvae per 100 heads increased gradually during the months March to July. The regional prevalence of infestation and mean m o n t h l y number of larvae per head for the various governorates are graphically illustrated in Fig. 3. The highest incidence of infestation was in Shibin E1-Kom -- 19.1% (Minufiya Governorate), followed by A l e x a n d r i a - 17.3%, D a m a n h o u r - 15.2% (Beheira Governorate), Tanta -- 14.6% (Gharbiya Governorate), Kafr ElSheikh - 14.1%, E1-Mansoura -- 12.8% (Daqahliya Governorate) and finally D a m i e t t a - - 6.9% (Fig. 3). The greater prevalence of infestation and higher larval totals in the governorates of the Nile Delta and its western perimeter in comparison to those on the eastern perimeter suggest that the former are I
I r~Tota!
ul
[]1st Instar m2nd InsMr ~3rd Instar
l
~.1100.
o,o o 80.
~ > 40.
.a ~ 2 0 . 10
.........................................
197
6
......................................
Fig. 2. Seasonal d y n a m i c s o f O. ovis larvae c o l l e c t e d f r o m s h e e p s l a u g h t e r e d in t h e Nile Delta o f E g y p t a n d its w e s t e r n a n d e a s t e r n b o u n d a r i e s in 1 9 7 6 , e x p r e s s e d as m e a n m o n t h l y n u m b e r s p e r 100 i n f e s t e d heads.
82
,
•
~ Reg#onal
total
F,0
[~Monthly mean number Per head 25-
.j 2 0 -
'~
Uj
5I
Alexndria Damanhour
Ii I°04
i Kafr Tanta Damletta Shlbm El_MansEl_Sheikh EI-Kom oura
I
Fig. 3. Percentage of total larvae found in each region and mean monthly number of O. ovis larvae per sheep head collected from different localities of the Nile Delta, Egypt,
and its western and eastern boundaries in 1976.
more suitable for the survival o f O. ovis. It is worth noting that the prevalence o f infestation seemed to be correlated with the n u m b e r of sheep f o u n d in the areas concerned; the Nile Delta and its western perimeter have more sheep per unit area than the eastern regions.
REFERENCES Abul-Hab, J., 1970. Seasonal occurrence of O. ovis in Iraq. J. Med. E n t o m o l . 7 : 111--115. Herms, W.B. and James, M.T., 1961. Medical Entomology. Macmillan, New York, N.Y., 5th edn, 616 pp. Kettle, P.R., 1973. O. ovis in New Zealand. N.Z. Entomol., 5: 185--191. Leclereq, M., 1969. Entomological Parasitology -- The Relations Between Entomology and the Medical Sciences. Pergamon Press, Oxford, London, New York, N.Y., 158 pp. Metcalf, C.L. and Flint, W.P., 1939. Destructive and Useful Insects, their Habits and Control. MacGraw-Hill, New York, N.Y., London, 2nd edn, 981 pp. Rogers, C.E. and Knapp, F.W., 1973. The bionomics of O. o v i s . Environ. Entomol., 2: 11--23.
79
THE DISTRIBUTION AND SEASONAL DYNAMICS OF OESTRUS OVIS LINNE INFESTING THE NASAL CAVITIES AND SINUSES OF SHEEP IN EGYPT
I B R A H I M A. GAABOUB
Entomology Division, Faculty o f Agriculture, University of Alexandria, Alexandria (Egypt) (Received 27 April 1977}
ABSTRACT Gaaboub, I.A., 1978. The distribution and seasonal dynamics of Oestrus ovis Linn~ infesting the nasal cavities and sinuses o f sheep in Egypt Vet. Parasitol., 4 : 79--82. The distribution and seasonal dynamics of sheep bot fly, Oestrus ovis Linn~, infesting the nasal cavities and sinuses of sheep in the Egyptian Nile Delta and on its western and eastern perimeters were studied. Results indicate that O. ovis completed one generation during the year of study, 1976. The greatest infestation rate occurred from August to October, followed by a decrease in the rate which continued until February and a gradual increase during the subsequent months until July. No first instar larvae were recovered from August to October. The lowest prevalence of infestation was recorded in the eastern part of the Nile Delta. Higher prevalences were encountered in the delta and its western governorates.
INTRODUCTION
The sheep bot fly, Oestrus ovis Linn~, is encountered wherever sheep are found and may cause loss of production and sometimes death. The presence of larvae in the animals' nasal passages and frontal sinuses causes inflammation and a copious cattarhal discharge. This, coupled with dusty climatic conditions, causes giddiness or "blind staggers" (Metcalf and Flint, 1939; Herms and James, 1961; Leclereq, 1969). Abul-Hab (1970; in Iraq), Rogers and Knapp (1973; in Kentucky, U.S.A.) and Kettle (1973; in New Zealand) published useful papers on the seasonal occurrence and bionomics of this species. Their studies included information about the ecological conditions prevailing in the countries surveyed and notes on the geographical incidence of this insect. Sheep in Egypt are plagued by this infestation but no information on its distribution or seasonal prevalence is available. The present investigation is an attempt to define the distribution, seasonal dynamics and levels of O. ovis infestation in sheep in Egypt. During 1976, the heads of sheep
80
slaughtered in representative areas of the Nile Delta and its eastern and western perimeters were examined for the presence of O. ovis. METHODS AND TECHNIQUES
Seven slaughter-houses in seven governorates of the Nile Delta and on its western and eastern edges were chosen for the present study. There was one slaughter-house in each of Alexandria, Beheira, Kafr-E1-Sheikh, Gharbiya, Minufiya, Daqahliya and Damietta (Fig. 1). Throughout the year o f study (1976) 100 sheep heads were collected from each abattoir at m o n t h l y intervals and examined for the presence of larvae of O. ovis. Larvae were collected by running tap water under high pressure through the sheep's nasal cavities and sinuses. Remaining larvae were collected after cutting the heads into small pieces. Maggot indices (mean m o n t h l y number per 100 heads and percentage of total larvae from each region) were recorded. The three larval instars were identified and counted separately and their relative abundance was calculated for each m o n t h of the study. RESULTS AND DISCUSSION
A total of 1 200 heads was examined between January and December, 1976, for each of the seven governorates. The mean m o n t h l y numbers of l
I
ME
D
~
I
I
I
I
,3r30"
.31~:}0"
.3O'3O"
.30"00" ', l
29°/.,5 ' 30°00 ,
j
30'30"
I
0 'i
31"00
\ I
J
31°30 ,
I
32°00
3 -3o
Fig. 1. L o c a t i o n s o f O. ovis larvae c o l l e c t i o n in t h e Nile D e l t a a n d its w e s t e r n a n d eastern governorates.
81 first, second and third instars of larvae collected per 100 heads, and the percentage of total larvae found in each region total are presented in Figs 2 and 3. Results obtained indicated that all infested animals harboured larvae in the first and second instars from January to June, while all the animals infested in the period July--December harboured third instar larvae, though these were very few in number during December (Fig. 2). No first instar larva was collected during August, September or October. These results indicate that the sheep bot fly has one generation per year in the Nile Delta. It is thus most likely that the adults deposit first instar larvae during the a u t u m n and early winter. These larvae remain in the nasal cavities and sinuses until the next season. The greatest total numbers of larvae were recovered during August, September and October (Fig. 2). This was followed by a gradual decline in the degree of infestation during November and December and then a steep decrease during January and February. Thereafter, the mean m o n t h l y number of larvae per 100 heads increased gradually during the months March to July. The regional prevalence of infestation and mean m o n t h l y number of larvae per head for the various governorates are graphically illustrated in Fig. 3. The highest incidence of infestation was in Shibin E1-Kom -- 19.1% (Minufiya Governorate), followed by A l e x a n d r i a - 17.3%, D a m a n h o u r - 15.2% (Beheira Governorate), Tanta -- 14.6% (Gharbiya Governorate), Kafr ElSheikh - 14.1%, E1-Mansoura -- 12.8% (Daqahliya Governorate) and finally D a m i e t t a - - 6.9% (Fig. 3). The greater prevalence of infestation and higher larval totals in the governorates of the Nile Delta and its western perimeter in comparison to those on the eastern perimeter suggest that the former are I
I r~Tota!
ul
[]1st Instar m2nd InsMr ~3rd Instar
l
~.1100.
o,o o 80.
~ > 40.
.a ~ 2 0 . 10
.........................................
197
6
......................................
Fig. 2. Seasonal d y n a m i c s o f O. ovis larvae c o l l e c t e d f r o m s h e e p s l a u g h t e r e d in t h e Nile Delta o f E g y p t a n d its w e s t e r n a n d e a s t e r n b o u n d a r i e s in 1 9 7 6 , e x p r e s s e d as m e a n m o n t h l y n u m b e r s p e r 100 i n f e s t e d heads.
82
,
•
~ Reg#onal
total
F,0
[~Monthly mean number Per head 25-
.j 2 0 -
'~
Uj
5I
Alexndria Damanhour
Ii I°04
i Kafr Tanta Damletta Shlbm El_MansEl_Sheikh EI-Kom oura
I
Fig. 3. Percentage of total larvae found in each region and mean monthly number of O. ovis larvae per sheep head collected from different localities of the Nile Delta, Egypt,
and its western and eastern boundaries in 1976.
more suitable for the survival o f O. ovis. It is worth noting that the prevalence o f infestation seemed to be correlated with the n u m b e r of sheep f o u n d in the areas concerned; the Nile Delta and its western perimeter have more sheep per unit area than the eastern regions.
REFERENCES Abul-Hab, J., 1970. Seasonal occurrence of O. ovis in Iraq. J. Med. E n t o m o l . 7 : 111--115. Herms, W.B. and James, M.T., 1961. Medical Entomology. Macmillan, New York, N.Y., 5th edn, 616 pp. Kettle, P.R., 1973. O. ovis in New Zealand. N.Z. Entomol., 5: 185--191. Leclereq, M., 1969. Entomological Parasitology -- The Relations Between Entomology and the Medical Sciences. Pergamon Press, Oxford, London, New York, N.Y., 158 pp. Metcalf, C.L. and Flint, W.P., 1939. Destructive and Useful Insects, their Habits and Control. MacGraw-Hill, New York, N.Y., London, 2nd edn, 981 pp. Rogers, C.E. and Knapp, F.W., 1973. The bionomics of O. o v i s . Environ. Entomol., 2: 11--23.