Life history of Spalangia gemina Boucek (Hymenoptera: Pteromalidae), a fast-breeding microhymenopteran pupal parasitoid of muscoid flies

Laboratory studies at 25.5 degrees C and 70-75% r.h. demonstrated that the average daily survival rate for females of the parasitoid Spalangia gemina Boucek (Hymenoptera: Pteromalidae) was 0.907 over a 20-day period, with 50% mortality in 17.3 days. Mean immature developmental time of S.gemina was 22 days and the population growth rate was c. 40-fold per generation. The females successfully parasitized 1-, 2- and 3-day-old pupae of Musca domestica L. and parasitism of 98-100% was obtained at parasitoid to host ratios of 1:0.5-2.5. Parasitism of 81-87% was obtained at parasitoid to host ratios of 1:10. The male to female sex ratio was 1:1.59. S.gemina appears to have advantages over other Spalangia spp., which have immature development times of 28-32 days under comparable conditions, for the biological control of Muscidae.     

Relationship between the bovine major histocompatibility complex (BoLA), erythrocyte markers and susceptibility to mastitis in Icelandic cattle

Summary. Milk and blood samples were obtained from three Icelandic dairy herds. The herds were monitored regularly for mastitis incidence. Cell counts, adenosine triphosphate (ATP) and antitrypsin levels of the milk samples were recorded. In addition, red cell and BoLA typing were performed on the blood. Although cell counts and ATP levels showed significant associations with mastitis, antitrypsin levels did not. Red blood cell antigens N'₂ and S₁ and the lymphocyte antigen detected by the monoclonal antibody M7 were associated with low cell counts, whilst BoLA w6 and w6.1 were associated with high cell counts. BoLA w6.2 and w11 showed significant association with high antitrypsin levels. Only ED116 showed a significant association with mastitis.     

Foliar freezing resistance of Australian alpine plants over the growing season

We assessed the freezing resistance of leaves ex situ of 25 Australian alpine plant species. We compared the freezing resistance of forb, graminoid and shrub species from three alpine summits of different altitudes; from a low altitude site just above treeline, to a fully alpine tundra site. Foliar freezing resistance (LT₅₀) in spring varied from ?5.9°C to ?18.7°C and standardized LT₅₀ values within species were significantly related to site altitude. Additionally, when comparing all the species in the study, freezing resistance was significantly related to site; the LT₅₀ of samples from a low‐altitude summit (1696 m) were significantly lower than those of samples from mid‐ (1805 m) and high‐altitude (1860 m) summits. The LT₅₀ of juvenile foliage did not differ significantly from that of adult foliage. Shrubs were highly resistant to freezing. At the highest summit, we examined the course of seasonal freezing resistance from early summer to early autumn across three alpine plant communities that differed in the time of natural snowmelt; from sheltered (snowpatch) to exposed (open heath). No differences in freezing resistance over the growing season were detected for exposed or sheltered communities and there were no consistent trends indicating frost hardening over the growing season. Overall, the common Australian alpine species we investigated appear well adapted to freezing conditions throughout the snow‐free growing season. We have no evidence to suggest that freezing temperatures soon after snowmelt in spring are especially damaging to the alpine plants at these summits.