جستجوی مقالات مرتبط با کلیدواژه « کرم ابریشم » در نشریات گروه « گیاهپزشکی »

ISSR molecular marker, in order to isolate the Iranian native Bombyx mori silkworm breeds were used. Extracted DNA by using phenol-chloroform was performed. The qualitative and quantitative measurements of extracted DNA and its dilution, was obtained from the bands on 1.5% agarose gel and they marked and analyzed. The results showed that the observed bands were between 200-1000 bp and the most bands were observed corresponding to Harati-yellow with 32 bands and Khorasani-lemon had their lowest with 25 bands. Second Primers were the highest number of bands with 43 bands and thefourth primer had the lowest number of bands with 30 bands. Cluster analysis of races, placed them in three main groups. The first groups consisted of Gilani-orange, Harati-yellow and Khorasani-pink, Khorasani-lemon and Baghdadi races placed in seprate groups. In cluster analysis, Gilani-orange showed the most similar to Herati-yellow and this two races with khorasani-pink were the first group. The most genetic similarity were between Gilani-orange and Herati–yellow and the most genetic distance was obtained between Baghdadi and other four races. It is concluded that, ISSR marker can seperate differentraces of silkworm with different origin very well.there fore to approve the it is suitalle to use more than more than 30 primer for 14 silkworm individuals with 2n= 28 is better.

The effects of mulberry leaves enrichment with Asparagine amino acid biological parameters and economic characters of silkworm Bombyx mori L. were studied in Natanz, Iran. Different concentration of Asparagine treatments including 10, 100, 500 and 1000 mg/ml diluted by distilled water. Normal leaves and treated with distilled water were used as controls. Silkworm larvae fed on enriched mulberry leaves, once a day. All biological and economic parameters were measured by using standard techniques in sericulture. Results showed that enrichment of mulberry leaves with Asparagine had not significant effects on biological parameters and economic characters in treatment groups compared with controls. According to the results of this investigation, mulberry leaves enriched with Asparagine amino acid could not increase silk production, therefore the mentioned concentrations are not recommend in Natanz of Isfahan province.

In this study, the genetic parameters and economic weights of some important economic traits in six Iranian commercial varieties (110, 107, 101433, Xinhong1, Koming1 and Y) of the silkworm were estimated and selection indices for these traits constructed. Individual recording of cocoon weight, shell weight and shell ratio were carried out during six generations. Heritabilities and genetic correlation between traits were estimated by restricted maximum likelihood method. The heritability of cocoon weight and shell weight were higher than that of shell ratio. Genetic improvement of cocoon weight and shell weight were high in the line 101433 due to higher heritability and genetic correlation between them. Therefore, the restriction of genetic gain of cocoon weight in this line is expected to cause a severe decrease in improvement of shell weight, and subsequently a decrease of selection efficiency. The genetic improvement of cocoon shell percentage increased in restricted indices due to low genetic correlation with cocoon weight, and selection accuracy in these indices decreased significantly compared to other indices. Considering the difference in genetic parameters and economic values of traits in commercial lines of the silkworm, it would be necessary to define a separate breeding goal and selection strategy in each line.

Different responses of silkworm larvae under various rearing climate condition would help to obtain better economic performance of some silkworm varities in specific climate conditions. The effect of 4 rearing climate conditions including 1) standard 2) high temperature and humidity, 3) high temperature and low humidity and 4) temperature fluctuation were investigated on the performances of six different silkworm hybrids including 151×152, 151×110-32, 151×154,103×104, 31×32 and 107×110. All hybrids showed better performances for larval, pupa and total vitality under standard conditions compared with the other rearing environments. There was no significant difference for the good cocoon percentage between the hybrids of 151×152, 151×154 and 107×110 under standard temperature fluctuating and warm/dry climate condition. The hybrid of 151×110-32 at standard condition and the hybrids of 103×104 and 31×32 at standard and warm/dry conditions produced higher values of good cocoons. For all hybrids, the larval mortality increased by growth of temperature and humidity. Meanwhile the pupal mortality rose with increasing of temperature either in dry or humid condition. The highest productivity (weight of total and good cocoon per 10000 larvae) within all treated hybrids obtained under standard and temperature fluctuation of temperature left no adverse effect on single cocoon weight for hybrids of 151×110-32, 31×32 and 107×110, while significantly increased the cocoon weight for hybrid of 103×104. The obtained results provide high temperature and humidity, high temperature and low humidity, and temperature fluctuation decreased production level. Furthermore, 103×104 hybrid is suitable for regions with temperature fluctuation. Also 103×104 and 31×32 hybrids are suitable for regions with high temperature and humidity, and high temperature and low humidity.

The biological effects on silkworm larvae fed on mulberry leaves contaminated with 0.5 and 1 mg/ml carbendazim were analyzed in different periods. The fungicide was sprayed on trees with 0, 1, 2, 4 and 8 days intervals before the first feeding of second instar larvae. Carbendazim decreased the larval weight and the highest reduction was 4.5% decrease compared to control. One mg/ml of fungicide used immediately after treatment caused a significant decrease in female cocoon characteristics such as cocoon weight, pupa weight and shell weight by 8.4, 8.5 and 7.8, respectively. The rate of hatching had also decreased in some treatments. Economical traits of male insects and the number of laid eggs by females were not affected. In total, the mean of cocoon shell percentage in both sexes did not have any difference with control. Feeding from the leaves contaminated with carbendazim residue did not have significant effects on larval mortality and utilization of the leaves sprayed by this fungicide two days after application is recommended.