Abstract

Predatory mites have a salient role in biological control of pests. Intraguild predation (IGP) is a common phenomenon among arthropods sharing the same extraguild (EG) prey and contains elements of competition and predation, whereby the competitors can kill each other. The exotic predatory mite Amblyseius swirskii Athias-Henriot is used as a biological control agent against thrips and whiteflies in some greenhouses in Iran. Typhlodromus bagdasarjani Wainstein and Arutunjan is a native predatory mite and is considered as appropriate candidate for controlling spider mites. They may co-occur in ecosystems and act as food competitors, interrupting biological control success of each other. There is no evidence concerning interaction between the two predatory mites. Therefore, we investigated the predation preference of the female predatory mites when having choice between larvae of the other predatory mite species (IG prey) with and without extraguild (EG) prey, Tetranychus urticae Koch. Adult females of each predatory species were individually placed into Petri dish arenas and were provided with adequate larvae of IG with/without T. urticae over 5 consecutive days. The arenas were checked over a period of 8 h for the first attack and the first choice on IG or EG prey. Predation rates were recorded every 24 h. Each treatment was replicated 17–18 times. In the absence of EG prey, T. bagdasarjani and A. swirskii females attacked the larvae of each other in 162±33.5 and 8.68 ±1.6 minutes, respectively, which were significantly different. The daily IG predation rates of T. bagdasarjani females were 1.39 ± 0.1 A. swirskii larvae. However A. swirskii females killed 9.5±0.4 T. bagdasarjani larvae daily. In the presence of EG prey, attack time of T. bagdasarjani females on IG and EG prey were 60 and 25 ± 0.7 minutes, while the time for A. swirskii females to attack both IG (4.3 ± 0.2) and EG prey (13.9 ± 6.2) were far shorter than that of T. bagdasarjani females. Most T. bagdasarjani females (16 out of 17 replicates) preferred to attack EG prey at first and also consumed more EG than IG prey daily (3.5± 0.2 vs.0.34 ± 0.7). A. swirskii females consumed significantly more IG (8.8± 0.34) than EG (5.8 ± 0.28) prey daily. In conclusion, based on the preliminary results, presence of EG prey had not significant effect on reducing the intense of IGP, resembling that IGP between A. swirskii and T. bagdasarjani is against T. bagdasarjani. However, further experiments are needed to evaluate the IGP interaction between the two species by detail.