Showing 5 results for Parasitoid
R. Ebadi, A. Jozeyan,
Volume 5, Issue 1 (4-2001)
Abstract
In order to study the parasitoid flies of Sunn pest in Isfahan, this research was conducted during the years 1997-1998. The results indicated that the dominant species of parasitoid fly is Phasia subcoleoptrata L. This species has two generations per year and over winters as pupae in soil under the shrubs of aestivation and hibernation places of Sunn pest and remains there until the following spring. The adults of the first generation of this parasitoid emerge from the pupae before the Sunn pest migrate to the grain fields and parasitize on the Sunn pest at the time of migration. About 6-8 days after the flies lay eggs in the body of Sunn pests, parasitoid larvae hatch from the eggs and grow in the body of their host. Larval period of parasitoid lasts about 15-20 days and then they fall on to the soil and pupate. In the laboratory, the length of pupal period for males and females is 17 and 18.5 days, respectively, for the first generation. Flies of the second generation of the parasitoid parasitize the fifth nymphal instar and the new adults of the Sunn pest.
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 %.
A. Jozyan, R. Ebadi,
Volume 5, Issue 4 (1-2002)
Abstract
In order to study the efficacy of Sunn pests' parasitoid flies, four overwintering sites of Sunn pest in Isfahan, including mountains of Kolahghazy, Panjeh, Jozdan and Sacepid were selected and from each site four different elevations were designated as sampling sites. During 1997, at least 6 and, in 1998, three samples were taken at each sampling site. In spring 1998, four wheat and barley fields were selected from Mahyar, Zeyar, Shahinshahr and Lavark regions and from each field eight samples were taken. In order to observe the larvae of parasitoids and to determine their efficiency, 100 Sunn pests were dissected from each sampling unit of aestivation, overwintering, wheat and barley fields.
The parasitism of prevalent species (Phasia subcoleoptrata L.) in spring 1998 was 15.39% for the 1st generation and 1.5% in 1997 and 3.5% in 1998 for the second generation of the pest. All other parasitoid species parasitized less than 1% of the pest population. In some regions, such as Lavark and Zeyar, chemical application against nymphs of Sunn pest were accomplished in spring 1998 at the peak of adult activity of parasitoids' 2nd generation. This application had negative effects on the population of parasitoids but in Shahinshahr where chemical application was accomplished at pupal stage of parasitoid, it did not have any direct adverse effects on the population of dominant parasitoid.
A. A. Talebi, E. Rakhshani, S. E. Sadeghi, Y. Fathipour,
Volume 6, Issue 3 (10-2002)
Abstract
Fertility, developmental time and adult longevity of walnut aphid, Chromaphis juglandicola (Kalt.) and its parasitoid wasp, Trioxys pallidus (Hal.) were studied under controlled conditions with a constant temperature of 26±2oC, relative humidity of 60±5%, and 16:8 (L:D) photoperiod. Populations of walnut aphid and parasitoid wasp were reared on walnut seedling in a growth chamber. The mean developmental period, daily fertility rate, and progeny sex ratio were combined to construct demographic life tables. From these tables, intrinsic natural rate of increase (rm), net reproductive rate (R0) and mean generation time (Tc) were calculated. The net reproductive rate (female offsprings per female per generation) and intrinsic rate of natural increase values were 34.69 and 0.278 in walnut aphid and 53.85 and 0.385 in parasitoid, respectively. The mean generation time was 12.75 days in walnut aphid and 10.35 days in parasitoid. Values of rw (weekly multiplication of the females) indicates that T. pallidus is able to multiply 14.81 times per week, whereas the population of walnut aphid multiplies by only 7.001 times in the same period. The population of parasitoids doubled within 1.8 days while the aphid took 2.49 days. Mean pre-imaginal period was 9.14±0.34 days for male and 9.16±0.12 days for female parasitoids on a mixture of different nymphal stages of host. In walnut aphid it was 9.30±0.10 days. The pre-imaginal periods of parasitoid decreases as the aphid host ages. Longevity of adult male and female was 6.17±0.22 and 6.87±0.23 days, respectively, and 12.24±0.94 days for walnut aphid.
H. M. Takalloozadeh, K. Kamali, A. Talebi, Y. Fathipour,
Volume 7, Issue 4 (1-2004)
Abstract
The host-stage preferences of alfalfa black aphid, Aphis craccivora, by parasitoid wasp, Lysiphlebus fabarum, were studied under two trials under growth chamber conditions (55±5 %, R. H., L:D 14:10 H. and Tem. 20 ±2° C ). In the first trial, all stages of aphid in equal ratios, and in the second trial, variable ratios of 5:15, 15:15 and 15:5 of 3rd and 4th instar nymphs were used for parasitisation. The objective was to identify the most preferred stage of aphid for parasitism by Lysiphlebus fabarum. The results showed that 3rd instar nymphs of alfalfa black aphid were the most preferred stage with 38.75% of parasitism. Whereas 4th instar nymphs and adults had 23.75% and 21.25% parasitism, respectively. The first instar nymphs were not parasitized at all. In the second trial with variable ratios of 3rd and 4th instars of alfalfa black aphid, parasitism of 3rd instar in ratios 25, 50 and 75 percent of total population were 35.9, 55.74 and 79.6%, respectively, while those for 4th instar nymphs were 20.36, 44.26 and 64.09%, respectively. So there was a positive preference for 3rd instar and a negative preference for 4th instar nymphs.
