الفهرس 
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Abstract
Objectives: 1- Examine interspecific egg predation among different predator species and the egg toxicity effect of two ladybeetles on the incidence of predation between these species. 2- Study the interactions between predators in different larval densities to determine the influence of predator larval density on the incidence of IGP between predators. 3- Test the effect of EG prey availability on IGP. 4- Measure the intensity of IGP by the IG predator on the IG prey and the resulting impact on the EG prey population dynamics on field. 5- Determine the nontarget effects of predators in the field to have focused on possible impacts on other predator species in agricultural systems. Methods and Results: ІІ. Laboratory experiments: 1- Examination of IGP on egg and the role of surface chemicals in two aphidophagous coccinellids species, C. undecimpunctata and C. visina isis . 2- Evaluation of the interspecific interactions between larval instars of different predator species: A. IGP between different larval instars of C. undecimpunctata and C. visina isis B. IGP between different larval instars of C. carnea and C. undecimpunctata . C. IGP between different larval instars of E. nigromaculatus and M. corollae . D. IGP between different larval instars of C. carnea and M. corollae . E. IGP between the same instars of C. carnea and R. cardinalis larvae. F. IGP between larval instars of different aphidophagous predators, C. carnea , C. undecimpunctata, C. visina isis and M. corollae. 3- Estimation of IGP on pupae of different aphidophagous predator species. II. Field experiments: Series of field experiments were carried out to measure the intensity of IGP by the IG predator on the IG prey between various intars of two predator species and the resulting impact on the EG prey population dynamics. Conclusion: 1- Surface alkanes on the eggs of aphidophagous ladybeetles seem to be deterrents to heterospecific neonates coccinellids. Thus, this surface chemical appears to reduce IGP between them. 2- Percentage of IGP various predator species increased particularly in the absence of EG prey. 3- IGP was strongly density dependent and both predators may negatively affect each other and reduce their controlling of insect pest populations. 4- The predatory guild of aphid consisted of diverse species, therefore differences in their size, age, prey specificity, feeding strategies ,mobility, speed of searching, aggressiveness, morphological, chemical, behavioral defensive and priority effects were recorded for their possible effect on intraguild interaction. 5- IGP among natural enemies can influence biological control efforts.