Abbas Ali Gheisari,
Volume 2, Issue 4 (1-1999)
Abstract
This study aims to determine the effects of storage period and egg weight on albumen pH and hatchability of hatching eggs. For this purpose, the eggs produced by native breeder hens (28 - 31 weeks of age) were used in a completely randomized design with a 3 × 8 factorial arrangement. The main factors were 3 egg weight ranges (46 - 49, 50 - 52 and 53 - 56) and 8 storage periods (1, 3, 6, 9, 12, 15, 18 and 21 days). Temperature and relative humidity of storage room was 16 ± 1.5 °C and 75 - 85%, respectively. Storage period had significant effects on albumen pH (P < 0.001), hatchability (P < 0.001), chick weight (P < 0.001), chick weight as a percentage of egg weight (p < 0.01) and late embryonic mortality (15 - 21 days of incubation) (P < 0.05). As the storage period increased from one to twenty-one days, hatchability of fertile eggs decreased from 89.4% to 42.7%, albumen pH, chick weight, chick weight as a percentage of egg weight and late embryonic mortality also increased from 9.25, 34.8 gr, 67.5% and 5.19% to 9.49, 35.9 gr, 70.1% and 42.7%, respectively. Egg weight of hatching eggs also was significantly related to hatchability (P < 0.05), chick weight (P < 0.001), chick weight as a percentage of egg weight (P < 0.01) and late embryonic mortality (P < 0.05). Heavy eggs (53 - 56 gr) had lower hatchability than medium and small weight groups (64.2% Vs. 68 and 69.5%, respectively). As the weight of hatching eggs increased, chick weight (p < 0.001), chick weight as a percentage of egg weight (P < 0.01) and late embryonic mortality (P < 0.05) also increased. The results indicate that, under the conditions of this experiment (16 ± l.5 °C and 75-85% relative humidity), highest hatchability can be obtained with eggs of medium weight range and storage periods of less than three or four days.
B. Hatami, H. Ghahari,
Volume 5, Issue 3 (10-2001)
Abstract
Regarding the importance and high potential of
Encarsia formosa Gahan (Hymenoptera: Aphelinidae) for control of the greenhouse whitefly,
Trialeurodes vaporariorum Westwood (Homoptera: Aleyrodidae), the effect of different diets and storage of the parasitoid at low temperatures on its longevity and efficiency was studied. The average longevity of the parasitoid on different diets including honey-syrup 15%, honey-syrup 10%, sucrose syrup 15%, honeydew of whitefly were significantly different at 1% from distilled water and control (without water and food) treatments.
Change in honey-syrup concentration at a range of 5% did not affect the longevity of the parasitoid. The honeydew and sucrose-syrup treatments were not significantly different. This was probably due to the relative similarity of food quality of these two diets. Storage of host parasitized nymphs containing pupae of 1-2 days-old of E. formosa at 8±1°C affected the emergence rate and efficiency of adult parasitoids.
Four treatments including the pupae of parasitoids in 4th nymphal instars of the greenhouse whitefly were stored at 8±1°C for 5, 15, 25 and 35 days. Control treatment included pupae of parasitoid that were held at room temperature, 24±4°C. Host nymphs were parasitized by the parasitoids emerging from all treatments. The average parasitized nymphs by parasitoids emerging from 5, 15 days and control treatments were not significantly different at 1 %.
