The lifetime functional response and predation rate of Amblyseius swirskii Athias-Henriot on eggs of the two-spotted spider mite, Tetranychus urticae Koch were determined under laboratory conditions using cucumber leaf discs. Densities of 2, 4, 8, 16, 32, 64 and 128 prey were offered to 3, 4, 5, 6, 7, 12, 17, 22 and 27-day-old A. swirskii individuals. Based on the logistic regression, the functional response of twelve-day-old A. swirskii was type III, while the other ages showed type II. The Rogers model was used to estimate searching efficiency (a) and handling time (Th). The longest handling time (1.387±0.315 h) was observed in the protonymphal stage, while the shortest handling time and highest maximum attack rate (T/Th) were estimated at the age of seven-days (0.396±0.057 h and 60.67 prey/day, respectively). In the functional response experiments, results of the highest prey density used (128 eggs) showed that the highest number of prey consumed by A. swirskii individuals aged twelve and seventeen-days old (35.6 and 43.1 eggs, respectively). It is concluded that A. swirskii could be an efficient biological control agent of T. urticae at the middle-age of its life and at higher prey densities.

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The egg parasitoid, Trichogramma brassicae Bezdenko (Hymenoptera: Trichogrammatidae) is the most important and widely distributed species of Trichogramma in Iran. It attacks eggs of several lepidopterous pests, and is a major biological control agent. Rearing parasitoids is necessary for experimental work, and, potentially, for mass release in the field. Selecting a suitable host is critical for developing a successful rearing method. If other conditions are the same, the rate of population increase will be a suitable indicator of parasitoid performance on different hosts. However, conclusions based on a single generation can be misleading because of the learning ability of parasitoids. Life history parameters of T. brassicae were studied on two hosts easily reared in the laboratory, Anagasta kuehniella Zeller, and Plodia interpunctella Hübner (Lepidoptera: Pyralidae). All the experiments were carried out at 24 ± 1°C, 65±10% RH, and 16:8 L:D photoperiod. Eight parameters including gross and net reproductive rates (GRR and R0 respectively), intrinsic rate of natural increase (rm), finite rate of population increase (λ), intrinsic birth and death rates (b and d respectively), cohort generation time (T), and doubling time (DT) were compared between two hosts for two generations. All parameters showed a highly significant difference (α = 0.01) between hosts. GRR, R0, rm, λ, and b were higher, while d, T, and DT were lower in Anagasta than Plodia. The intrinsic rate of natural increase was 0.2912 and 0.2145 female/female/day and net replacement rate was 45.51 and 19.26 female/female/generation in Anagasta and Plodia respectively. Differences between generations were significant except for rm, λ, and d. The net replacement rate was 28.56 and 39 in the 1st and 2nd generations respectively. These results showed that A. kuehniella was a better host than P. interpunctella. Higher reproduction occurred in the second generation that may be due to increased adaptation to experimental conditions.

This study was carried out on the ability of predatory thrips Scolothrips longicornis Priesner to feed on 2 phytoseiid species and vice versa. Also the effect of predation of Neoseiulus californicus (McGregor) on Typhlodromus bagdasarjani Wainstein and Arutunjan and vice versa was evaluated. The larvae, prepupae, and pupae of thrips and the eggs, larvae, and protonymphs of phytoseiids were selected as intraguild prey. The intraguild predation (IGP) among S. longicornis and 2 phytoseiid species was unidirectional and in favor of phytoseiids, i.e., S. longicornis was not able to feed on larval stages of 2 phytoseiids. However, N. californicus and T. bagdasarjani fed on the 1st instar larvae (1.39 and 0.80 per day), 2nd instar larvae (0.87 and 0.55 per day), prepupae (0.51 and 0.48 per day), and pupae of thrips (0.51 and 0.49 per day, respectively). Both phytoseiids fed on eggs, larvae, and protonymphal stages of each other. Females of N. californicus consumed more phytoseiid larvae (2.49 per day) than T. bagdasarjani, which consumed 1.08 N. californicus larvae per day. When Tetranychus urticae was presented as an extraguild prey, intensity of IGP between 2 species of phytoseiids and on larval stages of S. longicornis reduced significantly. Therefore, it is concluded that (i) IGP existed among the 3 examined species and lack of feeding of S. longicornis on 2 phytoseiid species can be justified by its feeding type (monophagy), (ii) N. californicus was much more prone to IGP than was T. bagdasarjani.