Generation-dependent life table parameters of the parasitoid wasp Habrobracon hebetor (Hymenoptera: Braconidae)
عنوان دوره: دومین کنگره بین المللی حشره شناسی ایران
نویسندگان
چکیده
Long-term rearing of parasitoids in insectariums may affect their performance in a positive or negative ways. The parasitoid wasp, Habrobracon hebetor Say is one of the most important biological control agents that parasitizes its hosts in both grain storages and field habitats. This parasitoid attacks mainly moths of the family Pyralidae and other pest families from other orders. In this study, the long-term (wild population, 2, 4, 6, 8, 10, 15, and 20th generation) rearing effect on the life table parameters of H. hebetor on Ephestia kuehniella Zeller was determined under laboratory conditions at 27±1ºC, 65±5% RH, and a photoperiod of 16:8 (L: D) hours. According to the results, the 2nd generation had the longest pre-adult development time (12.2 days) compared with the other generations tested. Furthermore, little difference was observed in duration of the adult pre-oviposition period (APOP) among different generations and this duration was 1, 0, 0.14, 0.17, 0, 0, 0.25, and 0 day in the wild population and the 2nd, 4th, 6th, 8th, 10th, 15th, and 20th generations, respectively. However, the shortest total pre-oviposition period (TPOP) was related to the 10th generation (10.62 days) and this period was 12.5, 12.4, 11.0, 10.92, 10.88, 12.08, 11 days in the wild population and the 2nd, 4th, 6th, 8th, 15th, and 20th generations, respectively. In addition, the highest and lowest fecundity were recorded in the 2nd (1304.00 eggs/female) and the wild population (539.88 eggs/female), respectively. The intrinsic rate of increase (r) in the wild population and the 2nd, 4th, 6th, 8th, 10th, 15th, and 20th generations was 0.2591, 0.199, 0.261, 0.261, 0.2936, 0.3273, 0.2597, and 0.2517 day-1, respectively. In addition, the value of the net reproductive rate (R0) was 139.42, 142.45, 193.83, 187.69, 313.03, 436.28, 221.83, and 168.05 offspring/individual and the mean generation time (T) was 19.20, 24.64, 20.06, 19.96, 19.50, 18.52, 20.68, and 19.97 days in above-mentioned generations, respectively. There was significant difference in the sex ratio of H. hebetor in different generations and it was ranged from 16.3% (females/total) in wild population to 60% in the10th generation, but the sex ratio of other generations were included in this range. In conclusion, the rearing of H. hebetor for multiple generations improves its fitness especially until 15th generation, where the performance H. hebetor increased sharply from 2nd to 15th reared generation compared to wild population and other 20th generation.
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