Biology and feeding behaviour of Ischiodon aegyptius (Wied)
(Diptera: Syrphidae) and Coccinella undecimpunctata (L)
(Coleoptera: Coccinellidae) Under Laboratory condition
By
Sir Elkhatim Elbadwi Ismail Malik
B.Sc. (Honours) Agricultural Science
University of Gezira, 1999
A thesis submitted in partial fulfillment of the requirements
for the degree of M. Sc. in Crop Protection
Supervisor
Prof. Mohammed Saeed Elsarrag
Department of Crop Protection
Faculty of Agriculture
University of Khartoum
April - 2006
Dedication
To my Parents,
Brothers,
Sisters and my Friends.
With love ,,,,
ACKNOWLEDGMENTS
First, of all I am grateful to Allah for his great blessings.
My sincere thanks and gratitude to my supervisor
Professor Mohammed Saeed El Sarrag for his advice, interest, encouragement and leadership throughout this study.
I am indebted to my colleagues in the Department of Crop
Protection, Faculty of Agriculture, University of Khartoum.
My thanks are also due to the soul of El Zaki Elsamani and Abdelhamed Abdelrahim for their help in typing of this thesis.
More thanks to my relatives and friends for their support and encouragement.
Finally, my thanks are extended to El Suki Agricultural
Corporation.
LIST OF CONTENTS
Dedication …………………………………………………………………………………… i
Acknowledgements……………………………….……………………………………… ii
List of contents ……………………………………….…………………………………… iii
List of tables ………………………………………………………………………………… vii
List of figures …………………………………….………………………………………… viii
List of plates ………………………………………………………………………………… ix
Abstract …………………………………………...…………………………………………… x
Arabic Abstract …………………………………………….……………………………… xii
CHAPTER ONE: INTRODUCTION …………………………………… 1
CHAPTER TWO: LITERATURE REVIEW …………….………… 5
2.1 Geographical distribution……………………………………………………… 10
2.2 Morphology…………………………….……………………………………………… 10
2.3 Biology…………………………………………………………………………………… 13
2.4 Feeding behaviour………………………………………………………………… 15
2.5 Longevity of larvae and adult deprived of food…………………… 16
2.6 Cannibalism…………………………………….……………………………………… 17
CHAPTER THREE: MATERIALS AND METHODS ……… 18
3. Laboratory studies of Syrphid fly ………………………………………… 18
3.1 Stock culture………………………………..………………………………………… 18
3.2 Biology and data life table under laboratory condition…..…… 19
3.3 Food relations……………………………………………………….………………… 21
3.3.1 Feeding rates and behaviour……………………………………………… 21
3.4 Searching patterns………………..……….……………………………………… 21
3.4.1 Searching pattern and behaviour…………………..…………………… 21
3.4.2 Longevity of larvae deprived of food……………………………… 21
3.5 Laboratory studies of Coccinella undecimpunctata (L.)...…… 22
3.5.1 Stock culture……………………………………………………………………… 22
3.5.2 Biology and data life cycle under laboratory condition…… 22
3.6 Food relations…………………………………………….…………………………… 24
3.7 Longevity of adults and larvae deprived of food………….……… 25
3.8 Starvation test of adults………………………………………….……………… 25
3.8.1 Cannibalism………………………………………………………………………… 25
CHAPTER FOUR: RESULTS ……………………………………………… 26
4.1 Biological studies…………………………………………………………………… 26
4.1.1 Immature stages……………………………………………………………… 26
4.2.1 Duration of the immature stages………………………………………… 29
4.3 Adult fecundity, longevity and reproduction habits………..…… 29
4.4 Food relations………………………………………………….……………………… 31
4.4.1 Feeding rates and behaviour…………………...………………………… 31
4.5 Searching patterns ………………………………….……………………………… 31
4.5.1 Searching patterns and behaviour……………………………………… 31
4.5.2 Longevity of larvae deprived of food………………………………… 34
4.6 Coccinella undecimpunctata (L) …………………………………...……… 34
4.6.1 Immature stages……………………..…………………………………………… 34
4.6.2 Duration of the immature stages………………………………………… 35
4.6.3 Adult fecundity, longevity and reproduction habits……..…… 40
4.7 Food relations…………………………………………………………………….…… 40 4.7.1 Feeding rates and behaviour………………………………….…………… 40
4.7.2 Longevity of adults and larvae deprived of food…….………… 42
4.8 Starvations test of adults…………………………………...…………………… 42
CHAPTER FIVE: DISCUSSION……………….…………………………… 45
5.1 Biology of Syrphid fly ………………………………………………………… 45
5.2 Food relations……………………………………….………………………………… 47
5.3 Biology of Coccinella undecimpunctata (L.) ……………………… 48
5.4 Food relations……………………………………….………………………………… 50
REFERENCES …………………………………………..……………………………… 52
LIST OF TABLES Table Page 1. Duration of the immature stages of Ischiodon aegyptius (Wied) reared on Melanaphis sacchari (Zhnt) under
laboratory conditions………………..………………………………………… 30 2. Mean pre-oviposition period, oviposition period, postovio- sition period, longevity and fecundity of Ischiodon aegyptius (Wied) fed on sugar syrup under laboratory
conditions…………………...…………………………………….………………… 30 3. Mean feeding rates of the first, second and third instars larval of Ischiodon aegyptius (Wied) fed on Melanaphis
sacehari (Zhnt) under laboratory conditions……………………… 33 4. Mean longevity of the larval instars of Ischiodon aegyptius
(Wied) deprived of food under laboratory conditions….……… 36 5. Duration of the immature stages of Coccinella undecimpunctata (L) reared on Melanaphis sacchari (Zhnt)
under laboratory conditions………………………………………………… 39 6. Mean pre-oviposition period and longevity of Coccinella undecimpunctata (L) reared on Melanaphis sacchari (Zhnt)
under laboratory conditions………………………………………………… 41 7. Mean feeding rates of larval instars and adults of Coccinella undecimpunctata (L) fed on Melanaphis sacchari (Zhnt)
under laboratory condition…………..……………………………………… 43 8. Mean longevity of the larval instars and adults of Coccinella undecimpunctata (L) deprived of food under laboratory
conditions…………………………………….……..……………………………… 44 LIST OF FIGURES
Fig Page
st 1. Searching pattern for the 1 instar………………………………...… 32
rd 2. Searching pattern for the 3 instar………………………………..…… 32 LIST OF PLATES
Plate Page
1. Stock culture of Syrphid fly…………….………………………………… 20
2. Oviposition cage………………………………………………………………… 20
3. Egg laying of C. undecimpunctata…………………………………… 23
4. The eggs of Syrphid fly……………………………………………………… 28
st 5. 1 instar of Syrphid fly…………………….………………………………… 28
nd 6. 2 instar of Syrphid fly……………………………………………………… 28
rd 7. 3 instar of Syrphid fly……………………………………………………… 28
8. Pupa of Syrphid fly……………………………….…………………………… 28
9. Adult of Syrphid fly…………………………………………………………… 28
10. Eggs of C. undecimpunctata……..……………………………………… 37
11. Different stages of C. undecimpunctata…………………………… 38 ABSTRACT
The laboratory trials were carried out at Shambat area (20 km north of Khartoum) to study the biology and feeding behaviour of the predators Syrphid fly Ischiodon acgyptius (Wied) (Diptera, syrphidae), and the Ladybird beetle Conccinella undecimpunctata (L.). This was done during the period from January to March 2005, the mean temperature and mean relative humidity were (22.4 ± 1.4 – 29.2 ± 1.4°C and 41.3 ± 4.4 – 54.4 ± 3.4%).
Laboratory investigations on the biology of the predators Syrphid fly Ischiodon aegyptius (Wied) and Coccinella undecimpuncata (L.) reared on Melanaphis sacchari (Zhnt) showed that the duration from egg laying to adult emergence was 11.2, and 10.2 days for I. aegyptius
(Wied) and C. undecimpunctata (L), respectively (mean of two generations).
The egg incubation period was 1.2 ± 0.41 days, the larval period was 5 days, the pupal period was 5 days, for the Syrphid fly I. aegyptius
(Wied). The total average of Melanaphis sacchari (Zhnt) consumed per day for the different larval instars were, 13 ± 1.66, 40 ± 1.18 and 86 ± 1.41 aphid for the first, second and the third instar respectively and the percentage of hatchability was 61.2 ± 0.86%.
The egg incubation period was, 2.5 ± 0.80 days, the larval period was 4 days, the pre-pupal period was 1 day, the pupal period was 2.7 ±
0.45 days for the ladybird beetle C. undecimpunctata (L.) and the percentage of hatchability was 82.5 ± 2.5%. The total average of M. sacchari (Zhnt) consumed per day for the different larval instars, adult male and female of C. undecimpunctata (L.) were found to be 6.8 ± 0.87,
9.2 ± 74, 22.6 ± 2.90, 44.6 ± 2.48, 46.6 ± 2.83 and 49.4 ± 3.55 aphid for thr 1st, 2nd, 3rd, 4th, adult male and female respectively.
Cannibalism phenomenon was observed during the study on C. undecimpunctata (L.) in the larval stages particularly in the late instars and the adult females, the female was found to eat their own eggs under shortage of food, and the proportion of cannibalized eggs by adult female of C. unecimpunctata (L.) was 96%. ﺧﻼﺻﺔ اﻷﻃﺮوﺣﺔ
أﺟﺮﻳﺖ ﺗﺠﺎرب ﻣﻌﻤﻠﻴﺔ ﻓﻲ آﻠﻴﺔ اﻟﺰراﻋﺔ ﺷﻤﺒﺎت ﻟﺪراﺳﺔ اﻟﺒﻴﻮﻟﻮﺟﻴﺔ واﻟﺴﻠﻮك اﻟﻐﺬاﺋﻲ
ﻟﻠﻤﻔﺘﺮﺳﻴﻦ، اﻟﺬﺑﺎب اﻟﺤﺎﺋﻢ (Ischiodon aegyptius (Wied اﻟﺬي ﻳﺘﺒﻊ ﻟﺘﺮﺑﺔ ﺛﻨﺎﺋﻴﺔ اﻷﺟﻨﺤﺔ،
ﻋﺎﺋﻠﺔ اﻟﺬﺑﺎب اﻟﺤﺎﺋﻢ واﻟﻤﻔﺘﺮس ﺧﻨﻔﺴﺎء أﺑﻮ اﻟﻌﻴﺪ(Coccinella undecimpunctata (L ﻓﻲ
اﻟﻔﺘﺮة ﻣﻦ ﺷﻬﺮ ﻳﻨﺎﻳﺮ ﺣﺘﻰ ﻣﺎرس 2005م ﺣﻴﺚ آﺎن ﻣﺘﻮﺳﻂ درﺟﺎت اﻟﺤﺮارة واﻟﺮﻃﻮﺑﺔ اﻟﻨﺴﺒﺔ
آﺎﻵﺗﻲ: (22.4±1.4 – 29.2±1.4°م) واﻟﺮﻃﻮﺑﺔ اﻟﻨﺴﺒﻴﺔ (4.4±41.3 – %3.4±54.4).
أوﺿﺤﺖ اﻟﺪراﺳﺎت اﻟﻤﻌﻤﻠﻴﺔ ﻋﻠﻲ ﺑﻴﻮﻟﻮﺟﻴﺔ اﻟﻤﻔﺘﺮﺳﻴﻦ (اﻟﺬﺑﺎب اﻟﺤﺎﺋﻢ وﺧﻨﻔﺴﺎء أﺑﻮ
اﻟﻌﻴﺪ) اﻟﺬﻳﻦ ﺗﻤﺖ ﺗﺮﺑﻴﺘﻬﻤﺎ ﻋﻠﻲ ﺣﺸﺮة ﻣﻦ اﻟﺬرة (Melanophis sacchari (Zhnt أن ﻓﺘﺮة
اﻟﻨﻤﻮ ﻣﻦ ﻃﻮر اﻟﺒﻴﻀﺔ ﺣﺘﻰ ﺧﺮوج اﻟﺤﺸﺮة اﻟﻜﺎﻣﻠﺔ ﻗﺪ اﺳﺘﻐﺮﻗﺖ 0.4 ± 11.2 ﻳﻮم و 10.2 ﻳﻮم
ﺑﺎﻟﻨﺴﺒﺔ ﻟﻠﺬﺑﺎب اﻟﺤﺎﺋﻢ وﺧﻨﻔﺴﺎء أﺑﻮ اﻟﻌﻴﺪ ﻋﻠﻲ اﻟﺘﻮاﻟﻲ ﻟﺠﻴﻠﻴﻦ. آﻤﺎ أن ﻓﺘﺮة ﺣﻀﺎﻧﺔ اﻟﺒﻴﺾ ﻟﻤﻔﺘﺮس
اﻟﺬﺑﺎب اﻟﺤﺎﺋﻢ آﺎﻧﺖ 1.2 ﻳﻮم ﺑﻴﻨﻤﺎ اﻟﻄﻮر اﻟﻴﺮﻗﻲ ﻟﻬﺬا اﻟﻤﻔﺘﺮس ﻗﺪ اﺳﺘﻐﺮق 5 أﻳﺎم، وﻃﻮر اﻟﻌﺬراء
5 أﻳﺎم أﻳﻀﺎ، آﻤﺎ وﺟﺪ أن ﻣﺘﻮﺳﻂ اﻻﺳﺘﻬﻼك اﻟﻜﻠﻲ ﻟﻤﻔﺘﺮس اﻟﺬﺑﺎب اﻟﺤﺎﺋﻢ ﻣﻦ ﺣﺸﺮة ﻣﻦ اﻟﺬرة ﻓﻲ
اﻟﻴﻮم ﺑﺎﻟﻨﺴﺒﺔ ﻟﻸﻃﻮار اﻟﻴﺮﻗﻴﺔ اﻟﻤﺨﺘﻠﻔﺔ ﻋﻠﻲ اﻟﻨﺤﻮ اﻟﺘﺎﻟﻲ: 1.66 ± 13 – 1.18 ± 40 و 1.41 ±
86 ﺣﺸﺮة ﺑﺎﻟﻨﺴﺒﺔ ﻟﻠﻄﻮر اﻟﻴﺮﻗﻲ اﻷول واﻟﺜﺎﻧﻲ واﻟﺜﺎﻟﺚ ﻋﻠﻲ اﻟﺘﻮاﻟﻲ. آﻤﺎ وﺟﺪ أن اﻟﻨﺴﺒﺔ اﻟﻤﺌﻮﻳﺔ
ﻟﻔﻘﺲ اﻟﺒﻴﺾ 0.86 ± 61.2 ﺑﺎﻟﻨﺴﺒﺔ ﻟﺒﻴﺾ ﻣﻔﺘﺮس اﻟﺬﺑﺎب اﻟﺤﺎﺋﻢ.
آﻤﺎ وﺟﺪ أ ﻳ ﻀ ﺎً أن ﻓﺘﺮة ﺣﻀﺎﻧﺔ اﻟﺒﻴﺾ 0.80 ± 2.5 ﻳﻮم واﻟﻄﻮر اﻟﻴﺮﻗﻲ اﺳﺘﻐﺮق 4 أﻳﺎم
وﻃﻮر ﻗﺒﻞ اﻟﻌﺬراء اﺳﺘﻐﺮق ﻳﻮم واﺣﺪ ، وﻃﻮر اﻟﻌﺬراء اﺳﺘﻐﺮق0.45 ± 2.7 ﻳﻮم ﺑﺎﻟﻨﺴﺒﺔ
ﻟﻤﻔﺘﺮس ﺧﻨﻔﺴﺎء أﺑﻮ اﻟﻌﻴﺪ ، آﻤﺎ وﺟﺪ أن اﻟﻨﺴﺒﺔ اﻟﻤﺌﻮﻳﺔ ﻟﻔﻘﺲ اﻟﺒﻴﺾ هﻲ 2.5 ± 82.5. وﺟﺪ أن
ﻣﺘﻮﺳﻂ اﻻﺳﺘﻬﻼك اﻟﻜﻠﻲ ﺑﺎﻟﻨﺴﺒﺔ ﻟﻤﻔﺘﺮس ﺧﻨﻔﺴﺎء أﺑﻮ اﻟﻌﻴﺪ ﻣﻦ ﺣﺸﺮة ﻣﻦ اﻟﺬرة ﻓﻲ اﻟﻴﻮم ﻟﻸﻃﻮار اﻟﻴﺮﻗﻴﺔ اﻟﻤﺨﺘﻠﻔﺔ واﻷﻃﻮار اﻟﺒﺎﻟﻐﺔ، واﻟﺬآﺮ واﻷﻧﺜﻰ هﻲ 0.87 ± 6.8، 0.74 ± 9.2، ±2.90
22.6، 2.48 ± 44.6، 2.83 ± 46.6، 3.55 ± 49.4 ﺣﺸﺮة ﺑﺎﻟﻨﺴﺒﺔ ﻟﻠﻄﻮر اﻟﻴﺮﻗﻲ اﻷول
واﻟﺜﺎﻧﻲ واﻟﺜﺎﻟﺚ واﻟﺮاﺑﻊ واﻷﻃﻮار اﻟﻜﺎﻣﻠﺔ اﻟﺬآﺮ واﻷﻧﺜﻰ ﻋﻠﻲ اﻟﺘﻮاﻟﻲ.
آﻤﺎ ﻟﻮﺣﻈﺖ ﻇﺎهﺮة اﻻﻓﺘﺮاس أﺛﻨﺎء اﻟﺪراﺳﺔ ﻋﻠﻲ اﻷﻃﻮار اﻟﻴﺮﻗﻴﺔ ﻟﻠﻤﻔﺘﺮس أﺑﻮ اﻟﻌﻴﺪ
ﺧﺎﺻﺔ اﻷﻃﻮار اﻟﻴﺮﻗﻴﺔ اﻷﺧﻴﺮة واﻹﻧﺎث اﻟﺒﺎﻟﻐﺔ ، ﺣﻴﺚ وﺟﺪ أن اﻷﻧﺜﻰ اﻟﺒﺎﻟﻐﺔ ﻟﺨﻨﻔﺴﺎء أﺑﻮ اﻟﻌﻴﺪ
ﺗﺄآﻞ ﺑﻴﻀﻬﺎ ﻓﻲ ﺣﺎﻟﺔ ﻗﻠﺔ اﻟﻐﺬاء وأن اﻟﻨﺴﺒﺔ اﻟﻤﺌﻮﻳﺔ ﻟﻠﺒﻴﺾ اﻟﻤﻔﺘﺮس ﺑﻮاﺳﻄﺔ أﻧﺜﻲ أﺑﻮ اﻟﻌﻴﺪ هﻲ
.%96 CHAPTER ONE
INTRODUCTION
Dura (Sorghum vulgaris L) is a human and a staple food in Sudan.
It is infested by Dura aphid, Melanaphis sacchari (Zhnt) which influence sorghum yields.
The Dura aphid attacks many, if not all, varieties of sorghum in
Sudan. It forms its dense colonies on the lower surface of medium – aged and older leaves but was also found on young growth.
Heavy outbreaks occur mainly in late sown field after the rainy season especially under the conditions of the central rain lands in Sudan.
Direct injury to the plants, even with heavy infestations, is not obvious. However, the honey-dew produced by the pest in large quantities disturbs the assimilation and other physiological reactions of the host plant.
In general, M. sacchari (Zhnt) is probably a minor pest of sorghum, but its real economic status has not yet been investigated.
The species seems to be able to attain major economic importance under certain favourable conditions, (Schmutterer, 1969 ).
Chemical control was of no use in sorghum fields because of the high cost of the insecticide and the low value of the product and also the other side effects of the chemicals that render their use hazardous to man, wildlife and the environment. These effects include the poisoning of humans, animals, water and plant resources. Food contamination, environment pollution and an inhalation of non-target species, all are undesirable side effects of chemicals. Accordingly man thought for alternatives. One of these is to resort to the use of natural enemies.
Aphidophagous syrphids are high – performance insects, although strong flies, but relatively poor when weather is cold, wet, or windy
(Lewis, 1965).
According to Vockeroth and Thompson (1987) the family
Syrphidae (Diptera) comprises three sub-families, 180 genera, and about
6,000 described species. Adults of many Syrphid species resemble stinging bee and wasps. Larvae of some species are aphidophagous; these are in sub-family Syrphinae.
Adult aphidophagous syrphidae are frequent flower visitors, and the morphology of the mouthparts suggests that certain species are predominantly nectarivorous, where as others are pollinivorous (Gilbert,
1981). Adults require honey-dew or nectar and pollen to ensure reproduction, whereas larvae usually require aphids to complete development (Schneider, 1969). This seem to indicate that complementary foods are required for completion of the life cycle.
Aphid colonies are ephemeral resources: they can appear quickly and just as suddenly disappear due to the natural predation, parasitism, fungal development, declining host - plant quality, changes in weather, or dispersal. Therefore, it may be important to predators to locate aphid infestations quickly. Because of their strong flight and ability to hover and inspect foliage for aphid, syrphids may be especially adept at this.
Adult females of several syrphid species determine whether to oviposit based on the size of aphid colonies. several syrphid species discriminate against older, larger colonies in favor of smaller
“promising” colonies (Kan, 1988a, b, c).
Aphidophagous coccinellids are very polyphagous beetles with a wide range of accepted foods. They feed on small insects and eggs of insect specially the Aphididae, Chermidae, Coccidae and Aleyrodidae
(Sweet man, 1958 and Hodek, 1966).
Coccinella undecimpunctata (L) had been reported from different parts of the world feeding on many species of aphids (Smee, 1922;
Sacharov, 1915; Hawkes, 1927; Brog, 1931; Franklin and Cross, 1941 and Hassan, 1957). In the Sudan it was reported by Theobald (1904) feeding on Aphis sorghi ( Longiungius sacchari).
Adults and larvae were observed to seize the prey by any part of the host’s body. Early instars larvae mostly use fore legs together with the mandibles for holding the prey, while they suck the body fluids, and reject the shriveled cuticle. Third and fourth instars seem to have the habit of regurgitating the host fluid taken, and reabsorbing many times until the fluids of the host are imbibed. Older stages in addition to consuming body fluids of hosts, also feed on parts of the body or the entire host, (Bashir, 1968).
The main objective of this work was to study biology and feeding behaviour of the natural enemies: the Syrphid fly Ischiodon aegyptius
(Wied) and the beetle Coccinella undecimpunctata (L) associated with the sorghum aphids, Melanaphis sacchari (Zhnt) around Shambat area. CHAPTER TWO
LITERATURE REVIEW
A. Syrphid fly (Ischiodon aegyptius (Wied)):
The old name of the predator Ischiodon aegyptius (Wied) was
Syrphus clegyptius (ElAbjar 1996).
According to Drescher (2001) the hover flies (Syrphidae) were only second to the Hymenoptera as important pollinators. Further more approximately 40% of the 800 palearctic syrphid species, were aphidophagous. So they were classified as beneficial insects.
Mahr (1998) reported that the hover flies were by far the most important family of predatory flies. The adults are not predaceous, but the larvae of many species are. syrphid larvae tend to prey primarily on aphids, mealy bugs scale insects and related homoptera.
Mahr (1998) reported that adults which had a yellow and black striped abdomen and look superficially like a small bee, feed on the nectar and pollen from flowers. The adults seek colonies of aphids and laid their eggs near by. The headless, legless, maggot-like larvae tend to be pale yellow to light green in colour. The large species get to be slightly bigger than 1/4 inch long when fully grown. They often pupate right where they finish feeding. The life cycle, from egg to adult, usually takes two to four weeks. Several generations occur each year. Although normally though as aphid predators, many syrphids probably had a wider host range. In Europe, one species was known to commonly feed on small caterpillars.
In wisconsin, one very common species, generally considered an aphid predator, was also an important predator of cranberry tip worm, which was the larva of a small midge that attacks the cranberry plant.
(Mahr 1998).
Short and Bergh (2003) reported that, Syrphid flies. or hover flies, were very common and conspicuously coloured flies. Many adults appear as bee mimics and contribute to pollination in various cropping systems.
Adults feed on pollen, nectar and honey-dew of aphids. Family syrphidae can usually be identified by the spurious vein (false vein) that runs between the radial and medial veins and typically crosses the r-m cross vein (except-some exotic species where the spurious vein was very faint).
Short and Bergh (2003) said that, larvae of family Syrphidae can be phytophagous, saprophagous, or entomophagous. The aphidophagous (aphid eating) adults deposit their eggs directly next to, or in aphid colonies to limit searching by the blind larvae. The larvae search for prey by method known as "casting", where the front of the body was swung side-to-side until contacting prey. Oral hooks were then inserted into the body of an aphid and it was sucked dry.
Lanthier and Jensen (2001) stated that, adult Syrphid flies, also called "hover flies", resemble bees or wasps in their colour pattern but were usually smaller and had only one set of wings. The surname "hover fly" comes from their distinguished ability to hover in flight. The body length ranges from 8.0 to 15.0 mm. Hundreds species had been identified in U.S.A (Lantheir and Jensen 2001).
Lanthier and Jensen (2001) said that the white elongated eggs were normally laid singly among aphid colonies. The larvae are legless, had tapered flattened body 10 to 15mm in length, and exhibit varying colours of yellow, green and brown. These maggots sway their pointed head from side to side to search for prey or when disturbed.
The pupal stage was smooth cigar-shaped, light to dark brown in colour. Lanthier and Jensen (2001) reported that, syrphid adults feed strictly on pollen and nectar but the larvae were varacious aphid feeders.
Despite being legless, the larva is very efficient at finding its prey and consume 200 to 800 aphid in 10-day period (Lanthier and Jensen 2001).
When aphids are in short supply, some species can survive on flower pollen. The syrphid larvae can also feed on caterpillars, thrips and sawfly larvae (Lanthier and Jensen 2001).
In USA, Syrphid flies overwintered as mature larvae, pupae or adults. The adults can be seen as early as April and both adults and larvae were found in large numbers in May (Lanthier and Jensen 2001). The females require pollen to produce their eggs, which amounted to 400 to
1000 eggs over the life span. The eggs require only a few days to hatch, and larval stage lasts seven to ten days. Pupation occurs in a dark place such as a rolled leaf or in the soil litter and takes approximately one week. The total duration from egg to adult was two to four weeks with two to four generation occurring per year, (Lanthier and Jensen 2001).
Hassan and Mohamed (2003), reported averages of some biological aspects of Syrphid fly Ischiodon aegyptius (Wied) fed on
Aphis craccivoera: pre oviposition period 6.6±0.80 days (range 5-7 days), incubation period of eggs 2.2 ± 0.80 days (range 2-4 days), egg hatchability 60.2 ± 21.8% (range 29-100), total eggs per female 31.0 ±
21.8 (range 9-71), daily eggs per female 10.4 ±3.7 9 range 1-31) eggs, larval period 6.0 ± 0.5 days (range 5-7 days), pupation period 5.2±0.7 days (range 4-7) and the total duration from egg to adult was 13.3 ± 1.6 days (range 12-14) days.
El Abjer, (1996) reported that female of Syrphid fly lays an average of 25eggs per day with a maximum of 400 eggs through its life span. The larvae live as a predator on aphid and scale insects.
B. Lady bird beetle Coccinella undecimpunctata (L):
The beneficial work of the predaceous coccinellids has been common knowledge to man kind for centuries, thus they obtained in
France the name "Gods cows" and the "Virgin's" cattle and in England
"our lady's birds" Fitch (1856).
The predator Coccinella undecimpunctata (L) (Coleoptero,
Coccinellidae), was among the most important aphidophagous species in many countries.
2.1 Geographical distribution:
This predator had been reported from different parts of the world feeding on many species of aphids (Smee, 1922; Scharov, 1915; Hawkes,
1927; Brog, 1931; Franklin and cross, 1941; and Hassan, 1957).
2.2 Morphology:
Throught (1965) reported that adults of lady bird beetles hibernate in sheltered place and were seen in the first worm days of spring. The yellowish batches of eggs were laid in bunches on the underside of leaves generally in vicinity of aphid colonies. When they latched the grey or black larvae were very active and searched out and destroyed large number of aphids. The chrysalis stage was found attacked by its tail in sheltered places, sometime together in very large numbers. There may be two or three generations in a year said Trought (1965).
Skaife (1953) reported that female of the lady bird beetle lays her yellow eggs in clusters, generally on the under side of leaves, with twenty or thirty eggs in cluster, they were usually found on plants that were infested with aphids, the female leaves her eggs where the young's, when they hatch, will not have far to search for their prey, the eggs hatched in about a fortnight into small black larvae with six legs and three simple eyes on each side of the head. They feed on the aphids, spearing them with their sharp, sickle-shoped jaws and sucking their juices. The larvae casts its skin four times before it is fully grown.
In about 10 days the adult beetle emerges from the pupa (Skaife,
1953). Abdalla (1981) reported that the newly deposited eggs were orange in colour. Eggs were laid in clusters, ranging between 15-25 eggs per cluster, generally on the underside of leaves.
Four larval instars were observed under laboratory conditions.
Newly hatched larvae were yellowish in colour the late larval stage was grayish to black colour turned in to light orange in the fourth instars
(Abdalla, 1981).
Abdalla (1981) reported that pre-pupal stage was observed after the final larval moult and before changed to pupa. The pupa was yellowish at first, changed to grey later. The newly emerged adult was light yellow with faint spots, later as the elytra hardens it assumed a yellow red colour with 11 black spots. The head was black with two yellowish spots. The prothorax and suctelum were black. It measured
4.5-5mm. Bashir (1968) reported that, eggs were elongate orange laid in clusters ranged between 8-22 eggs per cluster, arranged closely.
Newly hatched larvae were yellowish in colour. They remain clining to their egg shells for some times, until they move away. Before the larvae start to disperse. The larvae very often feed on unhitched eggs and those hatched in cluster. Four larval instars were observed under laboratory condition. The late larval stages were grayish to black in colour, with prominent dorso-lateral tubercles, which were darker in the second and third instars, turned into light orange in the fourth instars
A pre-pupal stage was present, and after the final moult this changed to pupa, which was at first yellowish, later changed to deep grey
(Bashir, 1968).
Adam (1979) reported that the elongate orange eggs were laid in cluster ranged between 3-30 eggs per cluster, four larval instars were observed under laboratory conditions. A pre-pupal stage was present and after moulting this changed to pupal stage, adult emergence terminates the developmental stages of the beetle. 2.3 Biology:
Abdalla (1981) reported that under laboratory conditions, the mean incubation period of eggs obtained from females fed on Schizaphis graminum was 2.3 days in the first season of his study while it was 2.5 days in the second season. Egg hatchability 85% in the first season and
80% in the second season.
The total larval period 8.9 and 9.6 days in the first and second season respectively. The percent of mortality of different larval instars was 30-35% (Abdalla, 1981).
The duration of the pre-pupal stage was 1.5 and 1.4 days in the first and second season, respectively. The duration of the pupal stage 5.1-
5.3 days. The duration of development from egg to adult emergency was
18.3 - 18.8 days. The pre-oviposition period averaged 2.1 - 2.2 days
(Abdalla. 1981).
Abdalla (1981) reported that copulated females started to lay eggs in 24-48 hours after emergence. Egg laying was almost continuous and the mean number of eggs laid by female was 550.6 and 453.3 in the first and second season. The female longevity was 65.4 - 66.3 days, while the male longevity was 63.5 – 65.8 days. Bashir (1968) reported that the incubation period was 2 days , the larval period for the 1st, 2nd , 3rd, and the 4th instars, was 3.2, 1.8, 4 days respectively, and per-pupal period was 1.7 days, and pupal period was
5days. The total period from egg to adult emergence was 19.8 days.
Bashir (1968) mentioned that copulation started within 24 hours after emergence the act took along time, as observed in other lady bird beetles and it was frequently repeated during life, Unmated females usually laid very few eggs which do not hatched. The pre - oviposition period was 2days, and total number of eggs laid by female was on average 1028.25 and the female longevity was 68.25 days, while the male longevity was 68 days.
Adam (1979) reported the incubation period as 3 days. Pairs in cages started mating few hours after emergence, and the act lasted for along time and frequently repeated during life. Copulated females started to lay eggs after an average of 5.7 days from their emergence in the first generation and this preoviposition period decreased to 4.1 and 3.0 days in the second and third generations, respectively. Egg laying was almost continuous and the maximum number of eggs laid by a female was 113, recorded from the first generation. Fecundity was highest in the first generation but low in the proceeding ones. So, while the mean total number of eggs per female was
1701.1 eggs in the first generation, the number decreased to 965.4 and
525.4 eggs in the second and third generation, respectively (Adam
1979).
2.4 Feeding behaviour:
Abdalla (1981) explained that the feeding capacity of the larval instars and adult of Coccinella undecimpunctata (L) was determined under laboratory conditions and the data obtained indicated that the daily average consumption of aphid was 1.2, 13, 22 and 33 aphid for the first; second, third, fourth and the adult respectively, the average mortality of aphids per day was 3.6, 25, 36 and 31 for the first, second, third, fourth larval and the adult respectively.
Bashir (1968) reported that adults and larvae were observed to size the prey by any part of the host's body. Early instars larvae mostly use forelegs together with the mandibles for holding the prey, while they suck the body fluid, and reject the shriveled cuticle. Third and fourth instars seem to have the habit of regurgitating the host fluid taken, and reabsorbing many times until the fluids of the host are inhibit. Older stages in addition to consuming body fluids of hosts, also feed on parts of the body or the entire host. During the development of the larval stages, two periods of inactivity, one before and the other after each ecdysis, were evident and during this period no food was consumed.
The average number of aphids consumed per day by the 1st, 2nd, 3rd and 4th, instars were 0.7, 2.08, 15.85, 33.42 aphids per day respectively, and the feeding capacity of the predator as indicated by the amount of prey killed and consumed, increased as the development of larval stages progressed.
The adult feeding rates of Coccinella undecimpunctata (L) also reported by Bashir (1968), he said that the average number of aphids consumed per day by adult female was 42.15 aphids, while male consumed 41.07 aphids per day, female beetles, seem to attack and consume more aphids than the males. The feeding time of a single pair, was not generally affected by the frequent matings, when caged together.
2.5 Longevity of larvae and adult deprived of food:
Bashir (1968) reported that freshly moulted larvae of different stages when confined separately in cages and without food, were found to live for a few days. Generally the activity of these larvae stopped about 12 hours before they died. The longevity of larval stages under starvation was, 37.5, 45.33,
68.33s, and 95.26 hours in the first, second, third, and fourth instars respectively.
2.6 Cannibalism:
Bashir (1968) stated that cannibalism was observed to occur under scarcity of food or over crowding. Female beetles were noticed to feed on their own eggs but did not attack the larvae or pupae.
Newly hatched larvae usually fed on unhatched eggs and those hatching in the same cluster. Percentage of eggs destroyed by the newly hatched larvae was found to increase with the increase in the length of hatching period of the egg cluster (Bashir 1968). Advanced larval stages were also observed to attack each other under stress; the immobile stage before each ecdysis, when the larva was fixed by its caudal segment to the plant was easily attacked by individuals of the same species (Bashir,
1968). CHAPTER THREE
MATERIALS AND METHODS
3. Laboratory studies of Syrphid fly:
3.1 Stock culture:
Stock culture of Syrphid fly Ischiodon aegyptius (Zhnt) was established from eggs collected from Dura fields Sorghum vulgaris (L), in Shambat area .
The eggs were taken by cutting the leaves of sorghum which contain both eggs and colonies of Melanaphis sacchari (Zhnt) and placed on moistened filter paper in Petri - dish (plate 1).
The newly hatched larvae were taken and reared individually on
M. sacchari (Zhnt ) in Petri-dishes.
The emerged adults were paired and each pair was kept in oviposition cage. The cage consisted simply of lantern globe enclosing flowers of marigold (Tagets erecta) and part of sorghum leaves contained colonies of M. sacchari (Zhnt).
The lantern globe were covered with muslin cloth at their wider ends and standing on a jam bottle at the other ends. The flies were supplied with sugar syrup (5%) and strips of honey as food . The sugar syrup was kept in laboratory tubes hanged from the top, covered with cotton wigs and fixed with rubber bands, (Plate 2).
3.2 Biology and data life cycle under laboratory conditions:
Eggs of Ischiodon aegyptius (Wied) were taken by replaced leaves from each cage which contain eggs. Each leaf was divided into small parts containing eggs and placed on moistened filter paper in Petri- dishes.
The Petri-dishes were checked daily to determine the incubation period and hatchability of these eggs.
The newly hatched larvae were taken and reared individually on
M. sacchari (Zhnt) in Petri-dishes to determine the number and duration of the larval instars, their survival and mortality rates.
The rest of the larvae were reared together in Petri-dishes.
Adults resulting from individual or mass rearing were sexed soon after emergence.
Pairs of similar age were kept in oviposition cage for fecundity and longevity investigations. Eight replicates were reared.
The data obtained on cohorts of eggs, larvae and adults were used to calculate the life table parameters according to the method described by (Birch, 1948). Plate 1. Stock culture of Syrphid fly
Plate 2. Oviposition cage 3.3 Food relations:
3.3.1 Feeding rates and behaviour:
The feeding rates of the first, second and third instars larvae were assessed in Petri - dishes which were provided with known numbers of the 4th instar nymphs of M sacchari (Zhnt). After 24 hours the Petri- dishes were inspected and the killed aphids were counted.
3.4 Searching capacity:
3.4.1 Searching pattern and behaviour:
First and 3rd instar larvae were deprived of food for 24 hours. Each larva was then released on white sheet of paper placed in plastic Petri - dish and it’s searching pattern was closely followed by tracing it’s track with a pencil before and after it was fed on one aphid.
3.4.2 Longevity of larvae deprived of food:
Newly moulted larvae of different instars were kept each in a separate Petri-dish. The longevity of these larvae deprived of food was recorded . 3.5 Laboratory studies of Coccinella undecimpunctata (L):
3.5.1 Stock culture:
Stock culture of C undecimpunctata (L) was established from larvae collected from berseem fields in Shambat area, and reared on M sacchari (Zhnt ) in Petri-dishes.
The emerged adults were paired and each pair was kept in a glass
Petri-dish, provided with apart of sorghum leaf containing colonies of M sacchari (Zhnt) everyday the dishes were examined for feeding and egg laying. (Plate 3).
3.5.2 Biology and data life cycle under laboratory conditions:
Eggs of C. undecimpunctata (L) were carefully taken by a fine hairy brush, and placed on a moistened filter paper in Petri-dishes.
The Petri - dishes were checked daily to determine the incubation period and hatchability of these eggs.
The newly hatched larvae were taken and reared individually on
M. sacchari (Zhnt) in Petri-dishes to determine the number and duration of the larval instars, their survival and mortality rate. Plate 3. Egg laying of C. undecimpunctata Adults resulting from individual or mass reared larvae were sexed soon after emergence. Five pairs of equal age were kept each pair in Petri-dish for fecundity and longevity investigations.
The data obtained of eggs, larvae and adults were used to calculate the life table parameters.
3.6 Food relations:
The feeding rate of the first, second, third, four instar larvae and adults were assessed in Petri - dishes.
Each individual kept in a separate Petri-dish was provided with known numbers of the 4th instar nymphs of M. sacchari (Zhnt). After 24 hours the Petri-dishes were inspected and the killed aphids were counted and classified according to the method described by Kaddou (1960), namely.
1. Less than half the aphid consumed 1 food unit.
2. half consumed 2 food units.
3. More than half consumed 3 food units.
4. Entirely consumed 4 food unites. 3.7 Longevity of adults and larvae deprived of food:
Newly moulted larvae of different instars were kept each in a separate Petri – dish, also adult female and male were kept individually in a separate Petri–dish. The longevity of these larvae and adults deprived of food were recorded.
3.8 Starvation test of adults:
3.8.1 Cannibalism:
Ten female adults of C. undecimpunctata (L) were placed each in
Petri – dish after they have been deprived of food for 24 hours. Twenty eggs of C. undecimpunctata (L) were added to each Petri – dish containing the female. After 24 hours, the number of eggs eaten were recorded. The proportion of cannibalized eggs were computed accordingly. CHAPTER FOUR
RESULTS
4.1 Biological studies:
The biology of Syrphid fly Ischiodon aegyptius (Wied) and
Coccinella undecimpunctata (L) were studied under laboratory conditions during the period from January 2005 to March 2005
(temperature ranged from 22.4 ± 1.4 to 29.2 ± 1.4 with average 25.8 and
R.H 41.3 ± 4.4 to 54.4 ± 3.4% with an average 47.85).
Syrphid fly Ischiodon aegyptius (Wied):
4.1.1 Immature stages:
Eggs are oblong, chalky white in colour with an average length of
0.7 mm and width 0.3 mm. plate (4), females lay their eggs singly and attached to the plant in the middle of an aphid colony.
Three legless larval instars were observed. They can be pale yellowish with brown patterns yellowish to reddish in the first instar with an average length 5±0.31 mm and width 0.6 mm plate (5). The second instar can be pale green with white patterns or brown redish with an average length 7.2 ± 0.59mm and width 1.4 ± 0.2 mm plate (6). The third instar also green or brown in colour with an average length 8.7±0.24 mm and width 2mm.
The full grown larvae measures 1cm long. The dorsum is fully covered with stout sculptured spines. Plate (7).
The final instar larva before pupation excretes a large black mass of sludge material. The pupa is at first green. Rounded posteriorly, and tapering anteriorly. Later on it changes into brownish colour. The puparium is pear shaped with an average length of 6mm and width of
2mm. plate (8).
The adult female length with an average 8.80 ± 0.33 mm, and width 2 mm and male length with an average 7.4 ± 0.37 mm and width
2mm. They have a large black heads, large eyes, black thorax, and abdomen with prominent alternating bands of black and white, and have small or incomspicuous antennae (Plate 9). Their wings are transparent, and when flying they often appear almost to stand still in the mid-air with spread wings. The females were observed hovering near aphid colonies. Plate 4. The eggs of syrphid fly Plate 5. 1st instar larva of Syrphid fly
Plate 7. 3rd instar larva Plate 6. 2nd instar larva of Syrphid fly of Syrphid fly
Plate 8. Pupa of Syrphid fly Plate 9. Adult of Syrphid fly 4.2.1 Duration of the immature stages:
Table (1) shows the duration of the immature stages of the two generations of Ischiodon aegyptius (Wied) reared on M. sacchari (Zhnt) under laboratory conditions. The egg incubation period was 1.2 ± 0.4 days, the larval period was 5 days, the pupal period was 5 days and the whole life cycle was 1.2 ± 0.4, 5.5 and 11.2 days for both first and second generations.
4.3 Adult fecundity, longevity and reproduction habits:
Adult started to copulate 1-2 days after emergence. Mating lasted for a while and was repeated many time.
Table (2) shows the fecundity and longevity of one generation of
Ischiodon aegyptius (Wied) reared on M. sacchari (Zhnt) under laboratory conditions. Adult flies mainly feed on nectar and insect honey- dew. Under laboratory conditions flies were fed on sugar syrup and lived for an average of 12.25 ± 1.9 and 10 ± 0.8 days for the female and male respectively. The pre-oviposition period was 3 ± 0.5 days and post- oviposition period was 3.33 ± 0.47 days, the oviposition period was 10.5
± 1.11 days; the fecundity was 166 ± 7.63 eggs. Table (1): Duration of the immature stages of Ischiodon aegyptius (wied) reared on Melanaphis sacchari (Zhnt) under laboratory conditions: Egg Incubation Second instar Third instar Larval period Pupal period Duration egg to First instar (days) period (days) (days) (days) (days) (days) adult (days) ± SE.
1.2 2 1 2 5 5 11.2 ± 0.40
Table (2): Mean pre-oviposition period, oviposition period, post-oviosition period, longevity and fecundity of Ischiodon aegyptius (Wied) fed on sugar syrup under laboratory conditions: Female Male Pre-oviposition Oviposition Post-oviposition Mean eggs per female Generation longevity longevity period (day) period (day) period (day) (fecundity) ± SE (days) (days)
(1) 3 ± 0.50 10.5 ±1.11 3.33 ± 0.47 12.25 ± 1.90 10 ± 0.80 166 ± 7.63 4.4 Food relations:
4.4.1 Feeding rates and behaviour: Adult flies are mainly nectar feeders. In the laboratory, they were fed on sugar syrup, honey and flowers.
All larval stages of lschiodon aegyptius (Wied) were observed to feed by sucking the prey's body fluid and discarding the shrivelled skin. The sharp mandibles are thrust into the aphid body, when the pharyngeal pump was observed sucking, the prey was dry of its body fluids.
Table (3) shows the feeding rates of the larval stages of Ischiodon aegyptius (Wied). The mean number of aphids sucked per day was 13 ±
1.66, 40 ± 1.18, and 86 ± 1.41 for the first, second, and third instar larvae respectively. The number of aphid consumed during the whole larval stage was 238 aphid.
4.5 Searching capacity:
4.5.1 Searching patterns and behaviour:
The searching patterns of the first and third instar larvae before and after feeding on one aphid were shown in Figures (2) and (3). The searching pattern of starved larvae was random, overlapping and without a definite course, when food was given, the larva continued searching in the side where food was laid and its searching pattern became guided to the prey by swung the front of the body from side to side until contacting a prey. It was observed that the larvae before feeding move in circle patterns while after feeding it change its movement in the zigzaging pattern toward straight line.
Before feeding After feeding
Fig. (2): Searching capacity for the 1st instar
Before feeding After feeding
Fig. (3): Searching pattern for the 3rd instar
Table (3): Mean feeding rates of the first, second and third larval instars
Ischiodon aegyptius (wied) fed on Melanaphis sacehari (Zhnt) under laboratory conditions:
Feeding period Mean aphids Stage Number tested (hours) sucked
First instar 13 10 24 (1.66)
Second instar 40 10 24 (1.18)
Third instar 86 10 24 (1.41)
4.5.2 Longevity of larvae deprived of food:
Table (4) shows the longevity of the different larval instars of
Ischiodon aegyptius (Wied) confined without food under laboratory conditions. The mean longevity was 23.6 ± 1.11, 72.5 ± 1.02 and 92.7 ± 1.55 hours for the first, second and third instars, respectively.
4.6 Coccinella undecimpunctata (L):
4.6.1 Immature stages:
Eggs are elongate, yellowish in colour with an average length of 1m and width 0.5mm (plate 10). Females lay their eggs either singly or in clusters. The largest number of eggs per cluster was found to be 30 eggs ranging between (5-30) egg per cluster.
Four larval instars were observed which have an alligator –like shape.
At first they were black with short hairs and spines on their backs, and well- developed legs. The later instars were grey to blue–grey with orange markings. The average length was, 1.38 ± 0.09, 2, 3.6 ± 0.2, and 5.35 ± 0.39 mm for the first, second, third and fourth instars respectively. And the average width was, 0.47±0.04, 0.5, 1, and 1.1±0.2 mm for the 1st, 2nd, 3rd, and 4th instars respectively (Plate 11). Cannibalism was observed among the larvae. The newly hatched larvae tend to attack and feed on unhatched eggs and hatching larvae. Cannibalism was strong in the late larval stages, particularly the 4th instar which is more aggressive. Under food shortage it tended to feed on younger larvae and on older larvae during the process of moulting.
The pre-pupal stage was present which have short live, about one day.
The pupae were creamy to yellowish in colour with black spots. It measures
5 mm in length and 2 mm. width (plate 12). The male pupae were smaller than the female pupae.
Adults are oval, orange-red in colour and have eleven black spots.
Adult males and females measured 5, and 6.4 ± 0.48 mm in length, and 2.55
± 0.35, and 2.95 ± 0.15 mm in width respectively. The male is smaller than the female (Plate 13).
4.6.2 Duration of the immature stages:
Table (5) shows the duration of the immature stages of two generations of Coccinella undecimpunctata (L) reared on M. sacchari (Zhnt) under laboratory conditions. The egg incubation period, was 2.5±80 day, the larval period was 4 days. (The mortality rate of the different larval instars was 20-30%), the pre-pupal period was, 1 day, the pupal period was 2.7 ±
0.45 days. The whole life cycle 2.5 ± 0.80, 4, 1, 2.7 ± 0.45 and 10.2 days for both the first and second generations.
Table (4): Mean longevity of the larval instars of Ischiodon aegyptius
(Wied) deprived of food under laboratory conditions:
Feeding period Stage Number tested (hours) ± SE
First instar 10 23.6 ± 1.11
Second instar 10 72.5 ± 1.02
Third instar 10 92.7 ± 1.55
Plate 10. Eggs of C. undecimpunctata 1st instar larva 2nd instar larva
3rd instar larva 4th instar larva
Pupa Adult
Plate 11. Different stages of C. undecimpunctata
Table (5): Duration of the immature stages of Coccinella undecimpunctata (L) reared on Melanaphis sacchari
(Zhnt) under laboratory conditions:
Egg Per-Pupal Pupal Duration egg First instar Second Third instar Fourth instar Larval period incubation period period to adult (days) instar (days) (days) period (days) (days) period (days) (days) (days) (days) ± SE
2.5 ± 0.80 1 1 1 1 4 1 2.7 ± 0.45 10.2 4.6.3 Adult fecundity, longevity and reproduction habits:
Adults started to copulate 24 hours after emergence and repeated the act many times during their life span. Table (6) shows the fecundity and longevity of one generation of Coccinella undecimpunctata (L) reared on M. sacchari (Zhnt) under laboratory conditions. The adult males and females longevity were 65.7 ± 1.83, and 66.6 ± 1.18 days respectively, the pre- oviposition period was 3.2 ± 1.93 days. The hatchability was 82.5 ± 2.5%.
4.7 Food relations:
4.7.1 Feeding rates and behaviour:
All stages of Coccinella undecimpunctata (L) were capable of capturing, subduing and feeding on different stages of its aphids prey. The first and second instars larvae were observed to feed by sucking the prey's body fluid and discarding the shriveled skin. The 3rd, 4thinstar and the adults in addition to sucking the prey's body fluid were capable of consuming the whole prey body. The first attacked aphids were entirely consumed.
Table (6): Mean pre-oviposition period and longevity of Coccinella undecimpunctata (L) reared on Melanaphis sacchari (Zhnt) under laboratory conditions:
Pre-oviposition period Male longevity Female longevity
(day) (days) (days) ± SE
3.2 ± 1.93 65.7 ± 1.83 66.6 ± 1.18 Table (7) shows the feeding rates of the larval instars and adults of
Coccinella undecimpunctata (L). The mean number of aphids sucked per day was 6.8±0.87 and 9.2±0.74 aphid for the first and second instars, respectively, and the mean number of aphids killed per day was, 22.6±2.90,
44.6±48, 46.6±2.83 and 49.4±3.55; the average food units was, 44.6±5.62,
115.8±5.54, 119.6±11.68, and 127.6±8.61 for the 3rd, 4th, adults male and female respectively.
4.7.2 Longevity of adults and larvae deprived of food:
Table (8) shows the longevity of the different larval instars, adults male and female of Coccinella undecimpunctata (L) deprived of food under laboratory conditions. The mean longevity was, 23 ± 1, 24 ± 1.41, 46.6 ±
1.11 and 73.7 ± 1.26 hours for the 1st, 2nd, 3rd and 4th instars, respectively and the longevity of the adults were, 12.3 ± 0.9, and 13.8 ± 2.27 day for the male and female respectively.
4.8 Starvations test of adults:
Ten female adults of Coccinella undecimpunctata (L) were deprived of food for 24 hours and placed each in Petri-dish, then provided with 20 eggs. After 24 hours, consumed and unconsumed eggs were recorded, 96% of eggs were eaten by adult females.
Table (7): Mean feeding rates of larval instars and adults of Coccinella undecimpunctata (L) fed on Melanaphis sacchari (Zhnt) under laboratory condition:
Stage Number tested Mean aphids killed per day ± SE Mean food units ± SE
First instar 10 6.8 ± 0.87 -
Second instar 10 9.2 ± 0.74 -
Third instar 10 22.6 ± 2.90 44.6 ± 5.62
Fourth instar 10 44.6 ± 0.48 115.8 ± 5.50
Adult male 10 46.6 ± 2.83 119.6 ± 11.68
Adult female 10 49.4 ± 3.55 127.6 ± 8.61
Table (8): Mean longevity of the larval instars and adults of Coccinella undecimpunctata (L) deprived of food under laboratory conditions:
(Based on 10 individuals in each stage)
Stage Longevity ± SE
First instar 23 ± 1.0 hours
Second instar 24 ± 1.41 hours
Third instar 46.6 ± 1.11 hours
Fourth instar 73 ± 1.26 hours
Adult male 12.3 ± 0.90 days
Adult female 13.8 ± 2.27 days CHAPTER FIVE
DISCUSSION
Syrphid fly Ischiodon aegyptius (Wied):
5.1 Biology:
Laboratory studies on the biology of Ischiodon aegyptius (Wied) showed that the pre-oviposition period was 3 ± 0.5, while the post- oviposition period was 3.33 ± 0.47 days, and the oviposition period was 10.5
± 1.11 days. The eggs were oblong, chalky white in colour, and the mean number of eggs per female was 166±7.63 eggs with the maximum number laid in a day was 35 eggs. The incubation period was 1.2±0.4 days. Three legless larval instars were observed, the duration of the larval instars was 5 days, the pupal period was 5 days, and the total duration period from egg to adult was 11.2±0.4 days, this indicated that the life cycle of the predator is short and have many generation per year. This makes the species a very important predator.
The percentage of egg hatchability was 61.2±0.86; the longevity of the adult was 10±0.8 and 12.25±1.9 days for the male and female respectively. The biology of Ischiodon aegyptius (Wied) was studied under laboratory conditions by Hassan and Mohamed (2003). They found that, the pre-oviposition period was 6.6±0.80 days ranging between (2-7) days, eggs incubation period was 2.2±0.80 days ranging between (2-4) days, egg hatchability was 60.2±21.8% ranging between (29-100) days, the total egg per female was 31.0±21.8 egg, ranging between (9-7) egg, and the daily egg per female was 10.4±3.7 egg ranging between (1-31) egg, the larval period was 6.0±0.5 days ranging between (5-7) days, the pupation period was
5.2±0.7 days ranging between (4-7) days, the total duration from egg to adult was 13.3±1.6 days ranging between (12-14) days, the longevity was 7.5±5.0 days ranging between (2-15) days. These records are in agreement to some extent with the findings in the present study. The slight difference may be due to the different sources of feeding. In their study the predator was fed
Aphis craccivora, whereas in the present study the predator fed Melanaphis sacchari (Zhnt).
El Abjar (1996), reported that the female lays an a average of 25 eggs per day with maximum of 30 -400 eggs through it’s life span. This finding came in line with our findings. 5.2 Food relations:
Adult flies are mainly nectar feeders. In the laboratory they were fed sugar syrup, honey and pollen grains, and the larvae were aphidophagous, this observation was in agreement with Mahr (1998) and Lanthier and
Jensen, (2001).
Laboratory studies on the larval instars of Ischiodon aegyptius (Wied) showed that their feeding rates were quite high. The larval feeding increased progressively with development; all larval stages of Ischiodon aegyptius
(Wied) were observed to feed by sucking the prey’s body fluid and discarding the shriveled skin. The sharp mandibles are thrust into the aphid body, when the pharyngeal pump was noticed sucking the prey dry of its body fluids. The daily average consumption of aphids by the different instars larvae were 13±1.66, 40±1.18 and 86±1.41 aphids for the first, second, and the third instars respectively. This rate is very effective in reducing the number of aphids. The legless larvae search for the prey by swung the front of the body from side to side until contacting a prey, this indicated that the larvae are very active and efficient predator. This indicated that Ischiodon aegyptius (Wied) is an important biotic factor in the natural control. When the larvae of Ischiodon aegyptius (Wied) were deprived of food it showed mean longevities of the different larval instars as 23.6 ± 1.11, 7.5 ± 1.02, and 92.7 ± 1.55 hours for the first, second and third instars respectively. This result show the high ability of the predator in food searching, and this, indicates that Ischiodon aegyptius (Wied) is a promising predator and can contribute efficiently in biological control of insects.
Coccinella undecimpunctata (L):
5.3 Biology:
Laboratory studies on the biology of Coccinella undecimpunctata (L) showed that this predator was prolific. The pre-oviposition period was
3.2±1.93 days, eggs are elongate, yellowish in colour. Females lay their eggs either singly or in clusters, and the largest number of egg per cluster was found to be 30 eggs ranging between 5 and 30 eggs. The egg incubation period was 2.5±0.80 days, the larval period was 4 days, the mortality rate of different larval instars was 20-30%. The pre-pupal period was 1 day, the pupal period was 2.7±0.45 days, and the total duration from egg to adult was
10.2±1.25 days, the percentage of egg hatchability was 82.5±2.5%. This results indicate that, the predator was very fertile and a prolific and have ability to produce many generations per year, and these characteristics make it most important predators in biological control. However, the results disagree with Abdalla (1981) who found that the pre-oviposition period was
2.1 and 2.2 days in the first and second season respectively and fecundity was 550.6 and 453.3 eggs in the first and second seasons. The egg incubation period was 2.3 days in the first season, while it was 2.5 days in the second season, this results within agreement to the present study. Egg hatchability was 85% in the first season and 80% in the second season. It is probable that these variations are due to the difference in the pray species used or may be to some other factors, also he found that the durations from egg to adult were 18.3 and 18.8 days in the first and seasons respectively.
Laboratory studies showed that, the longevity of the adults of C. undecimpunctata (L) were 65.7±1.83 and 66.6±1.18 day for the male and female respectively. This result is in full agreement with the work of Abdalla
(1981) who reported that, the male longevity was 63.5 and 65.8 days in the first and second seasons respectively, while female longevity was 66.3 and
65.4 days in the first and second season respectively. Four larval instars were observed and pre-pupal stage was also present. These results came in the same line to Bashir (1968), and Abdalla (1981). They are all agree that
C. undecimpunctata (L) had four larval instars and the pre-pupal stage was present regardless of the differences in duration because there was a difference in the source of food i.e. the aphid species.
5.4 food relations: All stages of C. undecimpunctata (L) were capable of capturing, subduing and feeding on all stages of their aphid prey, the first and second instars larvae were observed to feed by sucking the prey’s body fluid and discarding the shriveled skin. The 3rd, 4th instars and the adults in addition to sucking the prey’s body were capable of consuming the whole body of the prey. The mean numbers of aphids sucked per day were 6.8 ± 0.87 and 9.2
± 0.74 aphids for the first and second instars, respectively, and the mean numbers of aphids killed per day were 22.6 ± 2.90, 44.6 ± 0.48, 46.6 ± 2.83 and 49.4 ± 3.55; the average food units were 44.6 ± 5.62, 115.8 ± 5.54,
119.6 ± 11.68 and 127.6 ± 8.61 units for the 3rd, 4th, adults male and female respectively (Table 7). These results may be comparable with similar results obtained by Bashir (1968) who reported that, the early instars larvae mostly use forelegs together with the mandibles for holding the prey, while they suck the body fluids, and reject the shriveled cuticle. The 3rd and 4th instars seem to have the habit of regurgitating the host fluid taken, and reabsorbing many times until the fluids of the host are imbibed. Older stages in addition to consuming body fluids of hosts, also feed on parts of the body or the entire host.
The laboratory studies on the longevity of adults and larvae of C. undecimpunctata (L) deprived of food showed that, the mean longevity of the different instars larvae deprived of food under laboratory conditions were 23 ± 1, 24 ± 1.41, 40.6 ± 1.11 and 73.7 ± 1.26 hours for the 1st, 2nd, 3rd, and 4th instars respectively, and the adults longevity were 12.3±0.9, and
13.8±2.27 days for the male and female respectively. This mean of duration suggest that this predator has a good chance for surviving adverse condition which adds to its role as a good biocontrol agent.
This confirmed the efficiency of Coccinella undecimpunctata (L) as a good and promising biotic factor in the natural control. This result may be comparable with the results of Bashir (1968) who stated that, cannibalism was observed to occur under scarcity of food or over-crowding. Female beetles were noticed to feed on their own eggs but did not attack the larvae or the pupae.
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