Performance of two <Emphasis Type="Italic">Trichogramma</Emphasis><Emphasis Type="Italic">brassicae</Emphasis> strains under greenhouse and field conditions for biocontrol of the silver Y moth in spinach cultures

The suitability of Trichogramma brassicae Bezd. (Hymenoptera: Trichogrammatidae) to control the silver Y moth, Autographa gamma (L.) (Lepidoptera: Noctuidae) in spinach was investigated under greenhouse and field conditions. Two strains of T. brassicae were selected to study host searching efficiency and dispersal ability of the wasps on spinach. The experiments were conducted with defined release densities. The results show that T. brassicae strain I failed to locate host eggs in all experiments. In contrast, T. brassicae strain II females were able to locate 37% of the exposed egg clusters in the greenhouse within 48 h. Individuals colonised rapidly at least an area of 0.25 m². At distances up to 26 cm to the release point of the T. brassicae females, parasitization rate was 100%. Moreover, under field conditions silver Y moth eggs were exposed two times for 48 h on 12 experimental plots of 100 m² in two spinach fields. During the first exposure interval, i.e. 4 days after mass release of T. brassicae strain II, overall parasitization rates reached 20% on both fields. Furthermore parasitization rates still reached 16 and 19% during the second exposure interval, i.e. 9 days after natural enemy release, indicating a constant Trichogramma activity over time. Parasitization rates were highest in the close vicinity of the release point, i.e. 86%, whereas 6.5 m away the mean parasitization rate decreased to 3%. In conclusion results indicate a high potential of T. brassicae strain II as antagonist of A. gamma. Nevertheless the dispersal ability of T. brassicae strain II was limited, but adjustment of release densities and techniques might compensate this disadvantage.     

Preservation capability of horse semen by the use of two diluents and preservation temperatures

The effect of a skim milk extender and a glycine-containing extender on sperm motility and acrosome morphology of stallion semen was examined. There was no difference concerning acrosome morphology. After 24 hours of preservation motility of the ejaculates diluted with glycine extender was significantly superior to those handled with skim milk extender. Storage at 5 degrees C in all cases gave better results than storage at room temperature. Skim milk extender is an appropriate diluent when the semen is used for al on the day of its collection, whereas the glycine-containing extender offers the possibility to maintain sperm viability beyond 24 hours up to 72 hours.     

A sex chromosome mosaic in male pseudohermaphroditism in a horse

In a 7 months old foal with a male pseudohermaphroditism the cytogenetic investigation revealed a XO/XYY-mosaic with a centric fusion of the Y-chromosomes.     

Minimum health and sexual requirements for breeding stallions

The rules for the minimal requirements in health and genital potency for stallions formulated by GOTZE (1950) are reformulated, taking into consideration the results achieved by KLUG (1982) and KENNEY (1983). A stallion must be free of phenotypic hereditary faults. Furthermore he has to be in general and genital health and must be fit in both, potentia coeundi and generandi. The figures are based on the examination of thoroughbred and so called "warmblood" stallions. However, they can be adapted to other breeds like draughthorses and ponys.     

Application of the ‘fast’-method to a long term interregional air pollution model

The Fourier Amplitude Sensitivity Test (FAST) is applied to an interregional Air Pollution Model which simulates SO₂/SO₄-concentrations and -depositions as an annual average. The results are discussed and problems connected with the application of the FAST-method are reported.     

Relation of Soil Water Movement and Sulfide Concentration to Spartina alterniflora Production in a Georgia Salt Marsh

It is proposed that differences in plant height and productivity of the salt-marsh cordgrass Spartina alterniflora are the result of a dynamic interaction among tidal water movement, dissolved iron and sulfide concentrations in marsh soils, and bacterial sulfate reduction. Tidal water movement regulates the input of iron into marsh soils and the drainage of sulfide-containing interstitial water, and thereby controls the concentration of dissolved sulfide formed as a result of bacterial sulfate reduction. Near tidal creeks, where water movement and plant height and production are greatest, sulfide concentrations are lowest; in more elevated regions of marsh, where water movement andplant production are least, sulfide concentrations are highest. Plant height and productivity may be limited by the effects of sulfide on nutrient uptake.     

Advances in synchronizing estrus and ovulations in the mare: A mini review

Synchronization of estrus (SE) in mares has been achieved, but not of ovulation (SO). Progestins followed by PGF_2a are useful for SE only. In the two studies reviewed here, SE and SO were attempted by using CIDR-B, an intravaginal (itv) progesterone (1.9 g) releasing device, alone (study 1) or accompanied by estradiol (10 mg) given also itv (study 2). In both studies, Ovuplant™ (OT), an implant containing 2.1 mg of the GnRH analog deslorelin was used for the control of ovulation. Eighty cycling Hanoverian mares, 40 each in studies 1 and 2, received CIDR-B itv for 12 days, with PGF_2a given once at CIDR-B removal. In study 1, 15 mares each received OT when the lead follicle had reached 40 mm (A) or on Day 3 of estrus (B); 10 controls received no OT (C). In study 2, E2 was used in addition on Day 0 (CIDR-B insertion) (10 mares; group II), or on Days 0 and 7 (10; group III) or not (20; groups I and IV). Mares in groups I to III received OT as in study 1 (A); group IV (10) remained untreated. Ovaries were examined and blood samples were taken in studies 1 and 2 from all mares in 1, 2 or 4-day intervals, respectively, and concentrations of FSH, LH, progesterone and estradiol were determined by RIA. In study 1, CIDR-B treatment achieved SE, but not SO as shown by a wide spread of days on which follicles were reaching 40 mm; OT treatment assured ovulations in 48 hours in 93.3% of treated mares vs. 44.4% in controls (P<0.05. In study 2, SE was achieved and SO, but only when estradiol was given once (itv) on Day 0 (group II) but not twice on Days 0 and 7 (group III). In both studies, CIDR-B prevented estrus but stimulated follicle growth: 8 mares in study 1 ovulated with CIDR-Bs in place and 2 in trial 2, respectively. Only when estradiol was used together with CIDR-B, follicle growth was retarded (group II) or suppressed (group III: P<0.05 vs. groups I and IV). The pregnancy rate in study 2 from a single breeding at the first estrus was 52.8% with no significant differences between groups. FSH rose until Day 4 or 8 and had dropped sharply at Day 12; after CIDR-B removal FSH rose most quickly in group II, study 2. LH declined slightly until Day 12 and rose thereafter, reaching peak levels by Day 18 or 20, respectively. In both studies, estradiol had dropped slightly by Day 4 but increase steadily thereafter until ovulation had occurred. Preovulatory rise and postovulatory drop was seen earlier in group II, study 2. Values for progesterone had risen uniformly by Day 4, had declined slowly by Day 12 and precipitously in response to PGF_2a by Day 14. Treatment of cyclic mares with CIDR-B for 12 days, followed by PGF_2a at the day of CIDR-B removal and by Ovuplant™ a deslorelin implant when a follicle had reached 40 mm, resulted in synchronization of estrus. Adding to this scheme a single dose of estradiol (10 mg, intravaginal) on Day 0 resulted also in synchronization of ovulation.