Foraging Behavior of Two Coccinellid Species (Coleoptera: Coccinellidae) Fed on Aphids 1 Mohamed A. Al-Deghairi, 2,3 Nagdy F. Abdel-Baky, 2 Ahmed H. Fouly, 2 and Nabil M. Ghanim 2 J. Agric. Urban Entomol. 30: 12–24 (2014) ABSTRACT Searching rate, mutual interference, and killing power were studied for two predator species, Coccinella undecimpunctata L. and Hippoda- mia tredecimpunctata L. (Coleoptera: Coccinellidae), provided with two prey species, Aphis gossypii (Glover) and Aphis punicae (Shinji) (Hemiptera: Aphididae), under laboratory conditions of 27 6 2uC and 70 6 5% RH. The searching rate of larvae and adult female C. undecimpunctata was higher than that of H. tredecimpunctata. Both C. undecimpunctata and H. tredecimpunctata exhibited higher searching rates when fed on A. gossypii than when fed on A. punicae. Larvae and adults of C. undecimpunctata showed higher searching rates than H. tredecimpunctata on both prey species. Mutual interference values for larval stage of both C. undecimpunctata and H. tredecimpunctata were higher than those for adults. For H. tredecimpunctata feeding on A. gossypii, respective values were 0.148, 0.190, 0.118, 0.070, and 0.069 for 1 st ,2 nd , 3 rd ,4 th larval instars and adults, respectively; while these values were 0.161, 0.167, 0.218, 0.140, and 0.058 on A. punicae, respectively. In conclusion, our laboratory data suggest that C. undecimpunctata might be a more efficient predator of A. gossypii and A. punicae compared with H. tredecimpunctata. KEY WORDS Coccinella undecimpunctata, Hippodamia tredecimpunc- tata, Aphis gossypii, Aphis punicae, mutual interference, killing power Aphids are cosmopolitan plant pests that occur in tropical, subtropical, and warm temperate regions. These pests may become more abundant due to the intensive use of insecticides, which can alter the natural balance between pests and their natural enemies (Cook 1993). The evolution of insecticide resistance and growing concerns of the environmental hazards of frequent insecticide applications have prompted more emphasis on biological control agents of aphids (van Emden & Harrington 2007), especially the use of predators (Sarmento et al. 2007). For example, the predatory gall midge, Aphidoletes aphidomyza Rondani (Diptera: Cecidomyiidae), has been employed successfully for aphid control in cucumber culture (Bennison & Corless 1993). Coccinellid beetles (Coleoptera: Coccinellidae) are an important group of predatory insects with considerable biocontrol potential against aphids and other pests (Srikanth & Lokkundi 1990, Hodek & Honek 1996, Michaud 2012). They 1 Accepted for publication 11 February 2014. 2 Promising Research Center in Biological Control and Agricultural Information, Qassim University, Saudi Arabia. 3 Corresponding author, email: foulyah@yahoo.com 12