Journal of Helminthology (1992) 66, 255-259
The effects of crowding on adults of Philophthalmus nocturnus grown in domestic chicks V. G. M. SWARNAKUMARI and R. MADHAVI Department of Zoology, Andhra University, Visakhapatnam 530 003, India
ABSTRACT
The effects of crowding on growth, reproduction, rate of recovery and site of infection of Philophthalmus nocturnus were investigated by infecting various groups of day-old chicks with 25, 50, 75. or 100 excysted metacercariae and examining them at 10 or 25 days post-infection. Considerable reduction in the body length and the size of the gonads was noticed in flukes grown under crowded conditions. Crowding also caused some change in the habitat of flukes, but had no effect on their rate of recovery. Very few flukes reached the ovigerous stage under overcrowded conditions and none reached the embryonated larval stage. KEY WORDS: Philophthalmus nocturnus, crowding, chicken, Trematoda
INTRODUCTION
An earlier paper in this series (SWARNAKUMARI & MADHAVI, 1992) has dealt with the growth and development of Philophthalmus nocturnus in the eyes of chicks. The present paper deals with the effects of crowding on the growth, reproduction, rate of recovery and site of infection of P. nocturnus in the eyes of chicks. Only a few investigations have previously studied the effects of crowding on digenetic trematodes. WILLEY (1941), and FRIED & NELSON (1978) reported stunting of growth in the adults of Zygocotyle lunata under crowded conditions. NOLLEN (1983) studied the effects of crowding on the length of Philophthalmus gralli, its site of development in the host, rate of recovery and time required for the development of miracidia in the eggs. In the present study on P. nocturnus, the effect of crowding on the growth of the gonads has also been investigated. MATERIALS AND METHODS
Samples of the thiarid snail Thiara tuberculata were collected from Mehadrigedda reservoir situated about 15 kms from the Andhra University campus. Snails showing infections with cercariae of P. nocturnus were isolated. Cercariae were allowed to encyst on the bottom of petri-dishes and excystment was accomplished by pouring warm (40°C) saline solution (0-85%) over the cysts. Twenty, day-old white leghorn chicks obtained from a local poultry farm were separated into four groups (5 per group) and chicks in different groups were subjected to a different dosage of infection by inoculating each chick with 25 or 50 or 75 or 100 metacercariae in the right eye. The chicks were killed at 10 or 25 days post-infection and the numbers of flukes present in the right and left eyes recorded. The recovered flukes were relaxed in water, fixed in hot AFA solution, stained in alum carmine and mounted in balsam. Measurements of body size and gonads were taken. Drawings were made with the help of a camera lucida. The statistical tests employed were correlation coefficient, Student's t-test and ANOVA. OBSERVATIONS
All the chicks subjected to infection with P. nocturnus took the infection and
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V. G. M. SWARNAKUMARI and R. MADHAVI
the rate of recovery of flukes in the chicks examined 10 or 25 days post-infection varied from 85-100%. Among the flukes recovered 80-88% were found in the right eye and the rest in left eye. Thus, the numbers of flukes recovered from the right eye of chicks subjected to infection with dosages of 25, 50, 75 and 100 metacercariae were 17, 36, 60 and 75 respectively. The size of these flukes, site of development in the host, size of gonads, and time required for the development of oculate miracidia were used as parameters to study the effect of crowding on flukes. Length of flukes The length of the flukes was remarkably affected by crowding. At both the ages (10 and 25 days) pronounced differences were noted in the sizes of flukes
10:
FIGS. 1-3. Crowding effect on 25-day-old flukes recovered from the right eye of chicks harbouring: 1. 17 flukes; 2. 60 flukes; 3. 75 flukes.
Effect of crowding on Philophthalmus nocturnus TABLE I.
Effects of crowding on the body size and size of gonads of Philophthalmus nocturnus.
Dosage of infection (No. of metacercariae) 25 50 75 100
257
Body length (mm) Mean+S.D. Age ol? flukes 10 days 25 days 1-31 ±003 109±016 0-95±0-15 0-86±016
2-56±0-ll 2-24±0-17 l-92±0-09 1-45+0-13
Diameter of testis (fim) Mean±S.D. Age of flukes 10 days 25 days 161 + 8-48 139-2+20-62 100-4±7-92 41-2±2-28
425±15-77 385+11-71 304-4±78-01 174-4± 18-40
Diameter of ovary (fim) Mean + S.D. Age of flukes 10 days 25 days 97-6±16-14 91-2±24-19 71-0±7-55 33-2±4-82
232-2±7-70 223-2+14-83 191 ±78-49 70-8±7-43
recovered from different dosage of infection, the flukes recovered from the most crowded group being the smallest (Table I; Figs 1-3). Analysis of variance of sizes of flukes recovered from different levels of crowding at 25 days post-infection revealed highly significant differences (F=533-27; P
The effects of crowding on adults of Philophthalmus nocturnus grown in domestic chicks V. G. M. SWARNAKUMARI and R. MADHAVI Department of Zoology, Andhra University, Visakhapatnam 530 003, India
ABSTRACT
The effects of crowding on growth, reproduction, rate of recovery and site of infection of Philophthalmus nocturnus were investigated by infecting various groups of day-old chicks with 25, 50, 75. or 100 excysted metacercariae and examining them at 10 or 25 days post-infection. Considerable reduction in the body length and the size of the gonads was noticed in flukes grown under crowded conditions. Crowding also caused some change in the habitat of flukes, but had no effect on their rate of recovery. Very few flukes reached the ovigerous stage under overcrowded conditions and none reached the embryonated larval stage. KEY WORDS: Philophthalmus nocturnus, crowding, chicken, Trematoda
INTRODUCTION
An earlier paper in this series (SWARNAKUMARI & MADHAVI, 1992) has dealt with the growth and development of Philophthalmus nocturnus in the eyes of chicks. The present paper deals with the effects of crowding on the growth, reproduction, rate of recovery and site of infection of P. nocturnus in the eyes of chicks. Only a few investigations have previously studied the effects of crowding on digenetic trematodes. WILLEY (1941), and FRIED & NELSON (1978) reported stunting of growth in the adults of Zygocotyle lunata under crowded conditions. NOLLEN (1983) studied the effects of crowding on the length of Philophthalmus gralli, its site of development in the host, rate of recovery and time required for the development of miracidia in the eggs. In the present study on P. nocturnus, the effect of crowding on the growth of the gonads has also been investigated. MATERIALS AND METHODS
Samples of the thiarid snail Thiara tuberculata were collected from Mehadrigedda reservoir situated about 15 kms from the Andhra University campus. Snails showing infections with cercariae of P. nocturnus were isolated. Cercariae were allowed to encyst on the bottom of petri-dishes and excystment was accomplished by pouring warm (40°C) saline solution (0-85%) over the cysts. Twenty, day-old white leghorn chicks obtained from a local poultry farm were separated into four groups (5 per group) and chicks in different groups were subjected to a different dosage of infection by inoculating each chick with 25 or 50 or 75 or 100 metacercariae in the right eye. The chicks were killed at 10 or 25 days post-infection and the numbers of flukes present in the right and left eyes recorded. The recovered flukes were relaxed in water, fixed in hot AFA solution, stained in alum carmine and mounted in balsam. Measurements of body size and gonads were taken. Drawings were made with the help of a camera lucida. The statistical tests employed were correlation coefficient, Student's t-test and ANOVA. OBSERVATIONS
All the chicks subjected to infection with P. nocturnus took the infection and
256
V. G. M. SWARNAKUMARI and R. MADHAVI
the rate of recovery of flukes in the chicks examined 10 or 25 days post-infection varied from 85-100%. Among the flukes recovered 80-88% were found in the right eye and the rest in left eye. Thus, the numbers of flukes recovered from the right eye of chicks subjected to infection with dosages of 25, 50, 75 and 100 metacercariae were 17, 36, 60 and 75 respectively. The size of these flukes, site of development in the host, size of gonads, and time required for the development of oculate miracidia were used as parameters to study the effect of crowding on flukes. Length of flukes The length of the flukes was remarkably affected by crowding. At both the ages (10 and 25 days) pronounced differences were noted in the sizes of flukes
10:
FIGS. 1-3. Crowding effect on 25-day-old flukes recovered from the right eye of chicks harbouring: 1. 17 flukes; 2. 60 flukes; 3. 75 flukes.
Effect of crowding on Philophthalmus nocturnus TABLE I.
Effects of crowding on the body size and size of gonads of Philophthalmus nocturnus.
Dosage of infection (No. of metacercariae) 25 50 75 100
257
Body length (mm) Mean+S.D. Age ol? flukes 10 days 25 days 1-31 ±003 109±016 0-95±0-15 0-86±016
2-56±0-ll 2-24±0-17 l-92±0-09 1-45+0-13
Diameter of testis (fim) Mean±S.D. Age of flukes 10 days 25 days 161 + 8-48 139-2+20-62 100-4±7-92 41-2±2-28
425±15-77 385+11-71 304-4±78-01 174-4± 18-40
Diameter of ovary (fim) Mean + S.D. Age of flukes 10 days 25 days 97-6±16-14 91-2±24-19 71-0±7-55 33-2±4-82
232-2±7-70 223-2+14-83 191 ±78-49 70-8±7-43
recovered from different dosage of infection, the flukes recovered from the most crowded group being the smallest (Table I; Figs 1-3). Analysis of variance of sizes of flukes recovered from different levels of crowding at 25 days post-infection revealed highly significant differences (F=533-27; P
