الفهرس 
The effect of Aphis craccivora density on the feeding capacity and development
The population density of the insect predators associated with AphisOnly 14 pages are availabe for public view
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Abstract
The present work was conducted out at Shandweel Agricultural
Research Station to study the effect of releasing of 2nd larval instars of
Coccinella septempunctata L. and chrysoperla carnea Stephens on the
infestation of common bean plants with Aphis craccivora Koch. and its
associated insect predators during two successive seasons (2010 and
2011). The population densities of Aphis craccivora and its associated
insect predators were studied. Also, correlations between aphid and its
associated insect predators was evaluated. In addition, the effect of the
prevailing weather factors of area on the populations of Aphis craccivora
and its associated insect predators were analyzed. Finally, three
laboratory studies were performed: (1) effect of Aphis craccivora density
on daily and total consumption and development of Coccinella
undecimpunctata L., Coccinella septempunctata and chrysoperla carnea
larvae, (2) predation upon Aphis craccivora by Coccinella
undecimpunctata, Coccinella septempunctata and chrysoperla carnea
larvae in the presence and absence of Bemisia tabaci (Genn) and
Empoasca decipiens (Paoli) nymphs, and (3) effect of alate and apterous
Aphis craccivora on the feeding potential of Coccinella undecimpunctata,
Coccinella septempunctata and chrysoperla carnea larvae. The results
could be summarized as follow:
1- Field studies:
1.1- The population densities of Aphis craccivora infesting common
bean plants and its associated insect predators during 2010 and
2011 seasons.
The obtained results revealed that alate, apterous and total number
of A. craccivora formed 2, 1 and 1 peaks, respectively, in both seasons.
Coccinella undecimpunctata eggs, larvae, pupae, adults and total number
maximized 1, 1, 2, 2 and 2 times, respectively, in 2010 season, and 2, 3,
2, 2 and 1 times in 2011 season. The eggs, larvae, pupae, adults and total
number of Ch. carnea formed 2, 2, 1, 3 and 2 peaks, respectively, in 2010
season, and 2, 1, 1, 3 and 2 peaks in 2011 season. The mean of nymphs,
adults and total number of O. spp. were observed to form 1, 1 and 2
peaks, respectively, in 2010 season, and 1, 1, 1 peaks, respectively, in
2011 season. The weekly average number of Scymnus spp. larvae adults
and total number formed 1, 2 and 2 peaks, respectively, during 2010
season, and formed 2, 2 and 2 peaks, respectively, during 2011 season.
The populations of Syrphus corollae (F.) larvae, pupae and total number
peaked one time in 2010 season, and peaked 2, 1 and 1 times,
respectively, in 2011 season.
1.2- The correlations between Aphis craccivora infesting common
bean plants and its associated insect predators.
Highly significant positive correlation values were found between
the numbers of C. undecimpunctata eggs and larvae in side and aphid
numbers on the other side in both seasons of the study. However, the
correlation between aphid and adult numbers was highly significant
positive in 2011 season, only. Concerning, Ch. carnea, significant and
highly significant positive correlation values were found between the
numbers of aphid and lace wing eggs and larvae, respectively, in 2010
season. The correlation between S. spp. larvae and A. craccivora numbers
was found to be highly significant and significant positive in 2010 and
2011 seasons, respectively. No significant correlations were found
between A. craccivora numbers and other insect predators in both seasons.