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Aphis gossypii Glover (Hemiptera: Aphididae) is an important cucumber pest especially in greenhouse. The efficacy of simultaneous release of generalist predator, Orius albidipennis Reuter (Hemiptera: Anthocoridae) and a specialist parasitic wasp, Aphidius colemani Viereck (Hymenoptera: Braconidae), was evaluated in laboratory conditions against the pest. For this purpose, investigations were carried out on preference of the predator between parasitized and non-parasitized aphids. In addition, production of volatile infochemicals between the natural enemies (NEs) was studied by olfactometry trials. In another part of this research, systemic production of volatile synomone by the infested cucumber plants for attraction of each NE was examined by the olfactometry tests. Results revealed that O. albidipennis had no obvious preference to either the parasitized or non-parasitized aphids, while both NEs were significantly attracted to volatiles emitted from infested host plants. Our findings revealed that each of the NEs avoided odors which indicated the presence of another intraguild competitor. The documented facts from the entire study reveal that the NEs are good biocontrol agents against A. gossypii on cucumber, but their avoidance from each other makes simultaneous release of the predator and parasitic wasps unsuitable for biological control of this aphid.
 
 
 

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In this study, the effect of three temperatures was investigated on the functional response of Orius laevigatus to Aphis gossypii in climatic chambers at 20, 25, and 30 ± 1 °C, 60 ± 5% RH, and 16:8 h photoperiod. Different densities of first and second instar nymphs of A. gossypii (2, 4, 8, 16, 32, and 64) on cucumber leaf discs (6 cm in diameter) were separately offered to male and female predators. After 24 h, the number of consumed preys was recorded. Ten replicates per each aphid density were used. Based on the results, predator male and female exhibited types II, III, II and III, II, III functional responses at 20, 25 and 30 °C, respectively. Handling times (T_h) for males were 0.7798, 0.9177 and 0.4476 h and for females were 0.6874, 0.3921 and 0.2831 h at 20, 25 and 30 °C, respectively. Using the indicator variable method, pairwise comparisons of handling times of both males and females were significantly different. The theoretical maximum predation rate (T/T_h) of both males and females were obtained at 30 °C. The results revealed that O. laevigatus is more likely to be an effective biocontrol agent of A. gossypii at higher temperatures around 30 °C. However, additional studies under natural conditions are needed to provide further details of the predator-prey interactions.