ویژگی های رفتاری مگس پارازیتوئید Compsilura concinnata (Diptera: Tachinidae) روی دوگونه میزبان در شرایط آزمایشگاهی

Dipteran parasitoids constitute approximately 20% of the total number of insect parasitoid species. Despite the high potential of the Tachinidae parasitoids, their role in biological control programs has not been fully considered. Compsilura concinnata (Meigen) is one of the most important tachinid species, which is a larval, gregarious, and endoparasitoid with a wide host range. In the current research, two experiments were performed to investigate the foraging behavior of C. concinnata (host location and acceptance) on two key pest species, including the small white butterfly Pieris rapae (L.)(Lepidoptera: Pieridae) and the tobacco caterpillar Spodoptera litura (Fabricius)(Lepidoptera: Noctuidae) under a standard growth chamber condition (26±1°C, 65±5% RH, and 16:8L:D photoperiod). The first experiment was a two-choice test, including (a) a last instar larva of P. rapae and (b) a last instar larva of S. litura, which were exposed simultaneously to a mated-7-day-old female parasitoid in a ventilated Plexiglas cage (45×35×35cm). Two parameters, including the number of females which chose each target and the total duration of time (min) spent by each female in the cage until larviposition were recorded. The experiment was conducted with 40 females of C. concinnata. The second experiment included four treatments: P. rapae larvae (a)exposed or (b)not exposed to C. concinnata and S. litura larvae (c)exposed or (b)not exposed to C. concinnata. Each treatment consisted of 20 host larvae and four replications were considered per treatment. The larvae were singly exposed to the female and removed when attacked two times by the parasitoid. The duration (min) needed to larviposition on each host larva was recorded. The host larvae (parasitized and unparasitized) were daily monitored until death or the formation of parasitoid and pest pupae. Two indices, including Degree of Infestation (DI) and Success rate of Parasitism (SP) were scored. In the first experiment, there was no significant difference between the two host species in the target host selection and the time (min) spent by the female parasitoid to larviposition. The percentage of female choice and the required time to larviposition for P. rapae and S. litura were 60 and 40% and 3.75±0.29 and 4.25±0.38 min, respectively. In the second experiment, the time to have two C. concinnata larvae deposited on the host larva showed a significant difference. This value was calculated for P. rapae and S. litura as 5.14±0.10 and 5.68±0.10min, respectively. The females spent a significantly longer time to larviposition S. litura compared to P. rapae. The DI values showed a significant difference and were estimated as 93±1.4 and 91.8±1.5% for the mentioned host species, respectively. However, the SP values were 100% for the two host species. The current results reveal the potential of C. concinnata in biological control programs of P. rapae and S. litura.