Stethorus gilvifrons (Mulsant), Orius albidipennis (Reuter) and Scolothrips longicornis Priesner are the key predators of Tetranychus urticae in Egypt. In this study, the intraguild predation (IGP) and cannibalism of adult females of these predators were studied under laboratory conditions. Data revealed that in the absence of extra guild prey (T. urticae), the adult females of IG predator S. gilvifrons consumed more larvae or nymphs of IG prey species than IG predators of O. albidipennis or S. longicornis. Females of S. gilvifrons showed significantly a higher predation rate on heterospecific young and old nymph instars of O. albidipennis than on S. longicornis. Interactions of adults S. gilvifrons and larvae or nymphs of O. albidipennis or S. longicornis were highly asymmetric or unidirectional predation always being the IG predator. S. gilvifrons had stronger intraguild predator than O. albidipennis or S. longicornis. Intraguild predation could be considered mutual between O. albidipennis and S. longicornis but there is neither predation nor egg deposition occurred on young or old larvae of S. gilvifrons. The IG predator O. albidipennis showed higher predation rate on S. longicornis than on conspecific nymphs. Whereas, S. longicornis showed high predation rate on conspecific larvae. Females of S. gilvifrons provided with conspecific or heterospecific young and old larvae or nymphs were able to lay eggs when fed on S. gilvifrons, O. albidipennis and S. longicornis. Also, O. albidipennis and S. longicornis laid eggs when fed on conspecific or heterospecific young and old larvae or nymphs except when fed on larvae of S. gilvifrons as IG prey. Obviously, the presence of T. urticae led to significant decrease in IGP.
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