الفهرس 
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Abstract
Predators belonging to family Coccinellidae, comprise one of the most active groups of predatory species, that feed on different sucking insect pests including aphids, whiteflies, jassids and mites as well as other small insects attacking different crop plants.
Objectives of the present study were:
•Survey and study of seasonal fluctuations of aphids and their common predatory species in fields four economic crops; cotton, maize, faba bean and Egyptian clover, and determining the peaks and periods of highest abundance of aphids’ and their coccinellid predatory species.
•Determining the feeding capacity, longevity and fecundity of the two common coccinellid species; Coccinella undecimpunctata L and Hippoaamia convergens Guer. under laboratory conditions.
1-Field studies
Field studies were carried out at Kaha and Moshtohor districts in Qalubia Governorate, Egypt, during the two successive seasons 2002/03 — 2003/04. Two sampling methods were followed; direct counts of aphids and their associated predators / 50 plants of cotton, maize and faba bean and 50 double net strokes using a sweep net in case of the Egyptian clover.
2-Laboratory studies
Laboratory studies covered the main biological characters of the two most abundant coccinellid species C. undecimpunctata and H. convergens under the laboratory conditions [23 (21-25)C and 65 (60-70)% R.H.]. Obtained results could be summarized as follows:I- Field Studies: I-1- Cotton
1-1-1- Survey and seasonal abundance of aphids on cotton plants:
A. gossypii was the common aphid species recorded in cotton fields. The highest mean populations of the aphid (987.8±515.5 and 1099.8+471.8 individuals/50 cotton plants) were recorded during August in the two seasons, 2003 and 2004, respectively.
1-1-2- Survey and seasonal abundance of predatory species:
Field survey revealed the presence of the coccinellids, Adonia variegate Goeze, Coccinella undecimpunctat L., Hippodamia convergens Guer. and Scymnus spp.; the chrysopid, Chrysoperla cornea (Steph.); the anthocorids, Orius spp.; the staphylinid,
Paederus alfierii Koch; the syrphid, Metasyrphus corollae (F.) and true spiders.
I-1-2-1- Common coccinellid species:
•Adonia variegate was present in cotton fields in a few numbers.
•C. undecimpunctata populations peaked (68 and 41 adults/50 cotton plants) during the 1st and 4th weeks of June in the two seasons 2003 and 2004, respectively. This predatory species represented 26.9 and 29.96 % of the total number of the coccinellids and 15.7 and 12.4 % of the total numbers of predatory species surveyed in the cotton fields in the two seasons, respectively.
•H. convergens populations peaked (79 and 45 adults/50 cotton plants) during the 1 s’ and 4th weeks of June in the two seasons 2003 and 2004, respectively. This predatory species represented 28.32 and 27.98% of the total number of coccinellids and 16.5 and 11.6 % of the totalnumbers of predatory species surveyed in the cotton fields in the two seasons, respectively.
•Scymnus spp. Two population peaks (74 and 50 individuals/50 cotton plants) were recorded during season 2003, the first was during the 1” week of June and the second was during the 3rd week of July. In season 2004, they peaked (50 individual/50 plant) during the 4th week of June. Scymnus spp. represented 44.41 and 41.7 % of the total number of the coccinellids surveyed and 25.8 and 17.8 % of the total numbers of predatory species recorded in the cotton fields in 2002 and 2003 seasons, respectively.
I-1-2-2- Other common predatory species:
•C. cornea: a total seasonal larval counts of 8 and 21 larvae were recorded throughout 2002 and 2003 seasons, respectively.
•Orius spp.: populations peaked (107 and 94 individuals /50 cotton plants) during the 4th week of June in 2003 and 2004, respectively. The total seasonal count of Onus spp. represented 33.1 and 38.3 % of the total counts of predators surveyed in the cotton fields in the two seasons, respectively.
•P. alfierii: adults were found in cotton fields in few numbers throughout 2003 season and peaked (18 indivivals/50 plants) during the 2”d week of July in season 2004.
•M. corollae: was present in cotton fields in a very few numbers.
•True spiders: population peaked (11 and 28 individuals /50 cotton plants) during the 3rd and 2nd weeks of June in the two seasons 2003 and 2004,
respectively.
Generally, the total number of coccinellids counted in the cotton fields throughout the first season(858 adults) exceeded that recorded in 2004 season (504 adults) by about 70.24%.
Also, it could be, generally, stated that the total monthly number of predators recorded in season 2003 was highest during June (838 individuals) followed by July (310 individuals). While the lowest number (46 individuals) was recorded during August. Respective numbers in 2004 cotton season were 700 and 397 individuals in June and July. While the lowest numbers (59 and 62 individuals) were recorded during May and August, respectively.
1-2 Maize
1-2-1- Survey and seasonal abundance of maize aphids:
Three cereal aphid species were surveyed in maize fields; Rhopalosiphum maidis Fitch, R. padi L. and Schizaphis gramthum (Rond.). The highest population of aphids (278.8 and 398.3 individuals/50 maize plants) was recorded in August in the two seasons 2002 and 2003,
respectively. This period is usually synchronized with the maize plant flowering stage.
1-2-2- Survey and seasonal abundances of predatory species:
The two seasons survey revealed the presence of the following species, the coccinellids, A. variegat, C. undecimpunctata, H convergens, Scymuns spp., the staphylind, P. alfierii and true spiders.
1-2-2-1- Common coccinellid species:
Immature stages:
Regardless to the species, coccinellid larvae peaked (86 and 21 individuals/50 maize plants) during
the 1 st and 3s weeks of August 2002 and 2003, respectively.Adult stage:
•C. vicina var isis was found in maize fields by a very few numbers. Adult total counts represented only 0.95 and 0.56 % of the total numbers of coccinellids and 0.48 and 0.32 % of the total numbers of all predatory individuals surveyed on maize plants in the two seasons of the study, respectively.
•A. variegate: was found in a very few number of adults in maize fields, representing 0.95 and 0.93 % of the total numbers of coccinellids and 0.48 and 0.53 % of the total numbers of the predatory species surveyed on maize plants in 2002 and 2003, respectively.
•C. undecimpunctata: maxima numbers of 36 and 57 adults /50 maize plants were counted during the 1st week of August in 2002 and 2003, respectively. Total seasonal adult counts represented 22.3 and 25.8 % of the total numbers of coccinellids and 11.2 and 14.7 % of the total numbers of the predatory species surveyed in the two seasons, respectively.
•H. convergens: was found in very low population on maize plants. Total adult counts represented 1.18 and 0.93 % of the total counts of coccinellid adults and 0.59 & 0.53 % of the total predatory species recorded, respectively.
•Scymnus spp.: were the most abundant predatory species on maize plants. Their population peaked (54 and 95 individual adults/50 maize plants) during the fd week of July 2002 and the 1” week of August 2003. Scymnus spp. adults represented 74.6 and 71.7 % of the total counts of coccinellids and 37.4 and 40.8 % of the total counts of predatory species surveyed in seasons 2002 and 2003, respectively.1-2-2-2- Other common predatory species:
•C cameo: was found in few numbers on maize plants during the two seasons of study.
•Orius spp.: population abundance peaked (51 and 48 adults/50 maize plants) during the 1” and 3’d
weeks of August in seasons 2002 and 2003, respectively.
•P. alfierth populations peaked (28 and 19 adults/50 maize plants) during the 3`d and 4th weeks of July in the two seasons, respectively.
•True spiders: highest abundance (20 and 32 adults/50 maize plants) occurred during the 4th
week of July 2002 and the 4th week of August 2003.
In general, the highest total monthly number of coccinellid adults was recorded during July (200 individuals) followed by August (177 individuals) in the 1’d season. While, in the 2”d season, that was 303 individuals during August followed by 210 individuals during July. Generally, the coccinellids represented 50.1 and 56.9% of the total numbers of the predatory species recorded on maize plants in the two seasons, respectively. 1-3- Faba bean:
1-3-1- Survey and seasonal abundance of aphids:
The legume aphid, Aphis craccivora Koch. was the dominant among all the encountered aphid species on faba bean plants. Two peaks of aphids’ population were recorded, the first (243 indivivals/50 faba bean plants) was detected during the 4th week of December, 2002 and the second, (284 individuals) during the 4th week of January, 2003. Another two peaks of abundance were recorded in season 2003/04, (315 and 534 individuals/50
faba bean plants) during the Pt and 4th weeks of January 2004, respectively.1-4-2- Survey and seasonal abundance of common predatory species:
Field survey in 2002/03 and 2003/04 seasons revealed the presence of the coccinellids; C. undecimpunctata, H. convergens and Scymnus spp; the chrysopid, C. carnea; the anthocorids, Orius spp.; the staphylinid, P. alferii; the syrphid, M. corollae and true spiders.
I-4-2-1- Common coccinellids:
•C. undecimpunctata: adults’ population peaked (41 adults/50 double net strokes) during the 4th week of May, 2003 and (27 adults/50 double, net strokes) in the 4th week of May, 2004. The total seasonal count of C. undicimpunctata adults (143 and 97 adults) represented 33.6 and 27 % of the total coccinellids and 19.7 and 13.8 % of the total predators counted in the two seasons, respectively.
•H. convergens: peaks of adults’ abundance (62 and 64 adults/50 double net strokes) were recorded during the 4th week of May in the two seasons, respectively.
•Scymnus spp.: peaks of 44 and 37 adults/50 double net strokes were found during the 4111 week of May in the two seasons of the study.
1-4-2-2- Other common predatory species:
•C. carnea: population reached a peak of 9 adults/50 double net strokes during the last week of May, 2003, and 11 adults/50 double
strokes/week during the second half of May, 2004.
•Orius spp.: highest monthly adults’ population occurred during May of the two seasons (58 and 42 adults, respectively). The highest peak was detected during the 41h week of May (21 and 23.