الفهرس 
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Abstract
Population fluctuations, annual generations, infestation rates, parasitoids and predators of the citrus flower moth, Prays citri Mill. (Lepidoptera: Hyponomeutidae) on lime flower buds, flowers and newly formed fruits were studied at ElKanater ElKhairia region in ElQalubia Governorate throughout two seasons (years) from Apr., 2015 to Mar., 2017. Trees were monthly sprayed with different insecticides to control insect pests for maintaining high fruit production.
1. Population fluctuations:
Mean numbers of immature stages of P. citri on flower buds showed six annual population peaks of 13.3, 1.2, 1.8, 6.2, 2.8 and 3.4 in mid-May, mid-Oct., mid-Nov., mid-Dec., mid-Feb. and mid-Mar., respectively during 2015/2016 season. Five peaks of 13.5, 14.5, 1.8, 5.8 and 5.0 immature stages were observed on flowers in mid-Apr., mid-June, mid-Oct., mid-Dec. and mid-Mar., respectively. On newly formed fruits, five peaks of 7.3, 0.4, 2.2, 1.8 and 2.4 immature stages were also recorded in the middle of June, Oct., Dec., Feb. and Mar., respectively. The highest mean numbers of immature stages occurred on flowers (5.4), followed by flower buds (4.6) then newly formed fruits (2.2). The general mean was the highest (11.3 immature stages) in June, while it was the lowest (0.0 immature stage) in Sep. The highest population density of P. citri was recorded in spring, followed by summer then winter and autumn. The seasonal mean was 4.1 immature stages in 2015/2016 season.
The same previous trend could be applied during 2016/2017 season. Six peaks of 12.8, 2.5, 4.0, 5.8, 3.3 and 4.6 immature stages were estimated on lime flower buds in mid-May, mid-Oct., mid-Nov., mid-Dec., mid-Feb. and mid-Mar., respectively. Mean numbers of P. citri immature stages on flowers also exhibited six peaks of 14.5, 2.8, 5.3, 7.2, 4.3 and 5.6 in mid-Apr., mid-Oct., mid-Nov., mid-Dec., mid-Feb. and
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Ahmed F. M. Badr (2019), M.Sc.; Fac. Agri., Ain Shams Univ.
mid-Mar., respectively. Six peaks of 5.8, 1.0, 1.8, 3.0, 1.5 and 2.4 immature stages were also found on newly formed fruits in the middle of May, Oct., Nov., Dec., Feb. and Mar., respectively. Immature stages showed the highest mean numbers on flowers (6.3), followed by flower buds (5.0) then newly formed fruits (2.3). The highest general mean was 10.8 immature stages in May, while the lowest was 0.0 immature stage in Sep. The highest population density of P. citri occurred in spring, followed by summer then winter and autumn. The seasonal mean was 4.6 immature stages in the second season.
2. Annual generations:
P. citri immature stages had nine, nine and eight annual field generations, which lasted 28-49, 22-57 and 22-69 days on flower buds, flowers and newly formed fruits, respectively during 2015/2016 season. P. citri eggs exhibited the shortest generation period (31.3 days) on flowers, followed by immature stages (32.0 days) then larvae (34.3 days) and pupae (50.0 days). The shortest generation duration of immature stages averaged 32.0 days on flowers, while the longest was 36.4 days on newly formed fruits.
The same previous trend could be applied during 2016/2017 season. The estimated number of annual generations slightly increased because the approximate duration obviously shortened. However, immature stages of P. citri showed the same estimated number and approximate duration of annual generations on the three tree parts. P. citri eggs showed the shortest generation period (31.3 days), which was followed by larvae (32.1 days) on newly formed fruits. Immature stages of P. citri exhibited the shortest generation duration (32.9 days), that was followed by pupae (42.0 days) on flowers. The shortest generation period of immature stages lasted 32.9 days on flowers, while the longest took 36.0 days on newly formed fruits.
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Ahmed F. M. Badr (2019), M.Sc.; Fac. Agri., Ain Shams Univ.
3. Infestation rates:
P. citri larvae caused four infestation peaks of 40.5, 3.6, 16.4 and 6.5% on flower buds in mid-May, mid-Oct., mid-Dec. and mid-Feb., respectively during 2015/2016 season. Four infestation peaks of 55.0, 4.6, 19.2 and 13.2 % were also recorded on flowers in mid-Apr., mid-Oct., mid-Dec. and mid-Mar., respectively. There were also four infestation peaks of 19.5, 21.0, 2.8 and 8.8 % on newly formed fruits in mid-Apr., mid-Jun., mid-Oct. and mid-Dec., respectively. The highest infestation mean (18.3%) occurred on flowers, followed by flower buds (14.0%) then newly formed fruits (7.6%). The monthly infestation mean was the highest (36%) in Apr., while it was the lowest (0.0%) in Sep. The highest infestation level took place in spring, followed by summer then winter and autumn. The seasonal infestation mean averaged 13.3%.
The same previous trend could be applied during 2016/2017 season. The larvae also exhibited four infestation peaks of 40.0, 6.5, 16.4 and 10.0% on flower buds in mid-May, mid-Oct., mid-Dec. and mid-Mar., respectively. There were also four infestation peaks of 47.5, 7.5, 19.2 and 13.2% on flowers in mid-Apr., mid-Oct., mid-Dec. and mid-Mar., respectively. Four infestation peaks of 18.0, 4.0, 7.2 and 7.2% were also recorded on newly formed fruits in mid-Jun., mid-Oct., mid-Dec. and mid-Mar., respectively. The infestation mean was also the highest (18.5%) on flowers, followed by flower buds (13.3%) then newly formed fruits (7.3%). The highest monthly infestation mean was 34.8% in May, while the lowest was 0.0% in Sep. The highest infestation percentage was also recorded in spring, followed by summer then winter and autumn. The seasonal infestation mean was also 13.3%.
4. Parasitoids:
Trichogramma evanescens Westw., Bracon brevicornis (Wesm.), Phanerotoma hendecasisella Cam. and Diadegma semiclausum (Hell.)
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were surveyed parasitizing P. citri on lime flower buds, flowers and newly formed fruits. These parasitic insects were descendingly arranged according to their numbers. T. evanescens may be a newly recorded parasitoid of P. citri in the world, while D. semiclausum is a novel record on this pest in Egypt. T. evanescens, P. hendecasisella and D. semiclausum are solitary endoparasitoids developing in host eggs, eggs-larvae and larvae, respectively. However, B. brevicornis is a gregarious ectoparasitoid on P. citri larvae.
4.1. T. evanescens:
The highest parasitism rate of P. citri eggs by T. evanescens occurred on flowers (7.68%), followed by newly formed fruits (6.33%) then flower buds (3.24%) during 2015/2016 season. Parasitism of host eggs by the parasitoid ranged from 0% to 10.56% during season months and the greatest rate was in Nov. T. evanescens showed the highest parasitism percentage of eggs in autumn (10.56%), followed by summer (3.45%) then spring (3.24%) and winter (0%). The seasonal general total of the parasitism rate of eggs by the parasitoid reached 17.25%. The sex ratio in T. evanescens was in favour of females (1:3).
T. evanescens revealed the highest parasitism percentage of P. citri eggs on flowers (11.19%), followed by flower buds (9.81%) then newly formed fruits (0%) during 2016/2017 season. The parasitism rate of host eggs by T. evanescens ranged between 0% and 7.54% during year months with the maximum percentage in May. The highest parasitism rate of eggs by the parasitoid was recorded in winter (13.46%), followed by spring (7.54%) then summer (0%) and autumn (0%). The seasonal general total of the parasitism percentage of eggs by T. evanescens was 21.00%. The sex ratio of males to females in the parasitoid was equal (1:1).
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Ahmed F. M. Badr (2019), M.Sc.; Fac. Agri., Ain Shams Univ.
4.2. B. brevicornis:
The parasitism rate of P. citri larvae by B. brevicornis was 13.16% on flowers, while no parasitism occurred on those infesting flower buds and newly formed fruits during 2015/2016 season. The parasitism percentage of host larvae by the parasitoid varied from 0% to 5.82% during season months and the highest level took place in Dec. B. brevicornis revealed the highest parasitism percentage of larvae in winter (5.82%), followed by summer (4.41%) then spring (2.93%) and autumn (0%). The seasonal general total of the parasitism rate of larvae by the parasitoid reached 13.16%. The sex ratio of males to females in B. brevicornis was equal (1:1).
The same previous trend could be applied during 2016/2017 season. The parasitoid only showed a parasitism percentage of 10.26% on larvae attacking flowers. The parasitism rate of larvae by B. brevicornis ranged between 0% and 6.65% during year months with the maximum percentage in Mar. The highest parasitism rate of larvae by the parasitoid was recorded in spring (6.65%), followed by summer (3.61%) then autumn (0%) and winter (0%). The seasonal general total of the parasitism rate of larvae by B. brevicornis was 10.26%. The sex ratio of males to females in the parasitoid was (1:0).
4.3. P. hendecasisella:
The parasitism rate of eggs-larvae of P. citri by P. hendecasisella was higher on newly formed fruits (7.14%) than on flowers (5.67%), while no parasitism took place regarding flower buds during 2015/2016 season. The total range of the parasitism percentage of eggs-larvae by the parasitoid was 0-7.14% during season months and the maximum level happened in Oct. The highest parasitism rate of eggs-larvae by P. hendecasisella occurred in autumn (7.14%), followed by spring (5.67%) then summer (0%) and winter (0%). The seasonal general total of the
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parasitism percentage of eggs-larvae by the parasitoid was 12.81%. The sex ratio of males to females in P. hendecasisella was equal (1:1).
P. hendecasisella only caused a parasitism percentage of 8.36% in P. citri eggs-larvae on flowers during 2016/2017 season. The total range of the parasitism rate of eggs-larvae by the parasitoid reached 0-8.36% during year months with the greatest percentage in Oct. The parasitism rate of eggs-larvae by P. hendecasisella was the highest (8.36%) in autumn, while it was the lowest (0%) in winter, spring and summer. The seasonal general total of the parasitism percentage of eggs-larvae by the parasitoid reached 8.36%. The sex ratio of males to females in P. hendecasisella was (1:0).
4.4. D. semiclausum:
D. semiclausum was not recorded from P. citri larvae during 2015/2016 season.
The parasitism rate of P. citri larvae by D. semiclausum only occurred on flowers (3.33%) in Apr. (spring) during 2016/2017 season. The sex ratio of males to females in D. semiclausum reached 0:1.
The parasitic complex achieved parasitism rates of 43.22 and 42.95 % on field populations of P. citri in the first and second seasons, respectively.
5. Predators:
Chrysoperla carnea (Steph.), Coccinella septempunctata L., Orius laevigatus (Fieb.), Orius albidipennis (Reut.) and Coccinella undecimpunctata L. were surveyed associating with P. citri immature stages on lime flower buds, flowers and newly formed fruits. These predaceous insects were descendingly arranged according to their numbers.
5.1. C. carnea:
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Ahmed F. M. Badr (2019), M.Sc.; Fac. Agri., Ain Shams Univ.
The general total number of C. carnea (35 individuals) represented 27.1% of the predatory complex during 2015/2016 season.
The total number of larvae (20) significantly differed than that of adults (15). There was a highly significant difference in the number of larvae among season months. C. carnea larvae showed the highest number in spring (12), followed by autumn (7) then summer (1) and winter (0). The correlation between the number of larvae or adults and the relative humidity was highly significantly negative.
The same previous trend could be applied during 2016/2017 season. The total number of C. carnea (32 individuals) constituted 27.6% of the predatory complex. There was a significant difference between the total number of larvae (19) and that of adults (13). The number of C. carnea adults showed a highly significant difference among season months. The highest number of adults was recorded in spring (6), followed by autumn (4) then winter (3) and summer (0). The correlation was highly significantly negative between the number of larvae or adults and the relative humidity. Noteworthy that this correlation result also occurred for other predaceous species, which differ in the predator immature stage (larvae or nymphs).
5.2. C. septempunctata:
C. septempunctata had a general total number of 33 individuals, which exhibited 25.6% of the predatory complex during 2015/2016 season. The number of adults revealed a highly significant difference among season months. C. septempunctata adults showed the highest number in spring (10), followed by autumn (5) then summer (2) and winter (1).
C. septempunctata exhibited a general total number of 27 individuals, which recorded 23.3% of the predatory complex during
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Ahmed F. M. Badr (2019), M.Sc.; Fac. Agri., Ain Shams Univ.
2016/2017 season. The total number of larvae (11) significantly differed than that of adults (16).
5.3. O. laevigatus:
The general total number of O. laevigatus (28 individuals) represented 21.7% of the predatory complex during 2015/2016 season. There was a highly significant difference between the total number of nymphs (9) and that of adults (19). The number of O. laevigatus adults showed a highly significant difference among season months. The highest number of adults was reported in spring (11), followed by autumn (5) then winter (3) and summer (0).
The same previous trend could be applied during 2016/2017 season. The general total number of O. laevigatus (24 individuals) constituted 20.7% of the predatory complex. The total number of nymphs (10) significantly differed than that of adults (14). There was a highly significant difference in the number of O. laevigatus adults among season months. The adults revealed the highest number in spring (11), followed by autumn (3) then winter (0) and summer (0).
5.4. O. albidipennis:
O. albidipennis showed a general total number of 21 individuals, which revealed 16.3% of the predatory complex during 2015/2016 season. There was a significant difference between the total number of nymphs (8) and that of adults (13).
O. albidipennis had a general total number of 19 individuals, which exhibited 16.4% of the predatory complex during 2016/2017 season. The number of nymphs revealed a significant difference among season months. O. albidipennis nymphs showed the highest number in spring (5), followed by autumn (3) then winter (1) and summer (0).
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Ahmed F. M. Badr (2019), M.Sc.; Fac. Agri., Ain Shams Univ.
5.5. C. undecimpunctata:
The general total number of C. undecimpunctata (12 individuals) expressed 9.3% of the predatory complex during 2015/2016 season. There was a highly significant difference between the total number of larvae (4) and that of adults (8).
The same previous trend could be applied during 2016/2017 season. C. undecimpunctata exhibited a general total number of 14 individuals, which constituted 12.1% of the predatory complex. The total number of larvae (6) significantly differed than that of adults (8).