Eighty-six cases of kleptoparasitism in grey herons, most of which were intraspecific, were observed in northern Spain and southwest France during four winters (1992-1995). Herons more often attacked individually than in groups, but the success was similar in both cases. Robbing success was significantly higher when herons attacked a young bird (44.4%) compared to adults (17.6%). Adult herons were significantly more successful (37.5%) than young herons (10.0%). Handling time had a great effect on the size of the prey item robbed by the herons. Adult herons were more frequently attacked by both young and adult birds. Age- related differences in winter foraging parameters (total time foraging, feeding success and biomass intake) may favour discrimination between victim age classes by kleptoparasites. Adult heron ingested 0.82 g min-1 during the winter season and young heron 0.45 g min-1. For kleptoparasites adult herons seems to be a more profitable species than young. Kleptoparasitism increased the biomass intake of the pirate (62.8 g more than the normal intake of a young heron), probably to compensate for the inefficiency of young birds.
Diaeretiella rapae MacIntosh (Hymenoptera: Aphidiidae) is one of the most common and successful parasitoids of the cabbage aphid. The functional response of D. rapae towards cabbage aphids was examined in laboratory studies at three constant temperatures, 17°C, 25°C and 30°C. D. rapae exhibited a type II functional response at all three temperatures. The search rates were uninfluenced by temperature whereas handling times differed significantly between 17°C and 25°C, and between 17°C and 30°C, but not between 25°C and 30°C. This study is a first-step in the evaluation of the effectiveness of D. rapae as a biocontrol agent of Brevicoryne brassicae at different temperatures., Hamid R.S.Moayeri ... [et al.]., and Obsahuje seznam literarurty
The functional response of Aenasius bambawalei Hayat (Hymenoptera: Encyrtidae) to different population densities of Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) was investigated under laboratory conditions of 65 ± 5% R.H., a photoperiod of 14L : 10D and at temperatures of 25, 30 and 35 ± 1°C. Two, 4, 6, 8, 16, 32 and 64 third instar nymphs of P. solenopsis were exposed to newly emerged mated female parasitoids for 24 h. The parasitoid exhibited a type II functional response at all temperatures. The searching efficiencies (a) and handling times (Th) were 0.1818 h-1 and 5.0012 h at 25°C, 0.1382 h-1 and 3.2807 h at 30°C, and 0.2097 h-1 and 2.3635 h at 35°C, respectively. The maximum attack rates (T/Th) were 4.8, 7.3 and 10.2 nymphs at 25, 30 and 35°C, respectively. This indicates that A. bambawalei is more likely to be an effective biological control agent of P. solenopsis in warm seasons., Razieh Joodaki, Nooshin Zandi-Sohani, Sara Zarghami, Fatemeh Yarahmadi., and Obsahuje bibliografii