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 > Sericulture: research

The Sericulture section of CRA –API is developing several research fields. In particular the activity is divided into two complementary sectors: sericulture and moriculture.


Within the sericulture sector:
- Preservation, development and genetic improvement of the silkworm strains belonging to the Bombyx mori germplasm bank
- Silkworm rearing on the diet substituting for the mulberry leaf (artificial diet): promotion of the current diet patent, amelioration of the diet formulation also in order to adapt it to the needs of the different strains and to various rearing methods; breeding technologies concerning diet (germ-free and “clean” rearing)
- Economics of the silkworm rearing
- Silkworm pathology
- Relationship between the silkworm and the environment
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Cultural, social, historic and exhibition aspects of sericulture

Within the moriculture sector:
- Preservation, characterization and development of the different mulberry cultivars belonging to Morus sp.p. germplasm bank
- Relationships between the mulberry and the silkworm
- The mulberry for the fruit production
- The mulberry for animal feeding
- The mulberry for biomass production
- Mulberry for pharmaceutics
- Mulberry environmental impact assessment and recovery of marginal abandoned or polluted soils through moriculture





Preservation, enhancement and genetic improvement of the silkworm strains belonging to the Bombyx mori germplasm collection.
The Padua seat preserves a heritage of around 190 silkworm strains (60 of recent attainment and originated from INRA). The strains continuously undergo morphological and production analyses, in order to  maintain original  characters and to make silk production steady. The objective  is reached through reproduction rearing, which is carried out on leaf  in springtime and summer, while on diet all the year long. Strain selection for particular traits is addressed too (polyphagy, disease resistance, phenotypic markers).

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Rearing on the diet substituting for the mulberry leaf: promotion of the current patent, improvement of the diet formulation and adaptation to the needs of the different strains and to the different kinds of productions; rearing technologies related to the diet (“clean” and germ-free rearing).
The  Padua seat patented the formulation of a diet substituting for mulberry leaf in 2004: the diet, in addition to being used in order to preserve the Bombyx mori germplasm bank, by enabling rearing in different periods of the year, makes it easy to study particular ingredients which are added to the artificial food, and which have effects on the silkworm physiology and production. Furthermore, the diet recipe is being constantly updated on the basis of knowledge advances, in order to obtain better performances from the different strains and in order rearing on the leaf substitute resembles as much as possible natural feeding. In particular, the germ-free rearing, which requires no preservatives in the diet, and the combined rearing: diet (first instars).- leaf (last instars) are currently under study.

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Economics of the silkworm rearing
Application of new rearing technologies,  opportunity of mechanization of some phases, change of production targets, from the merely textile to more complex ones, stimulate  the staff of the Padua seat to study profitability of the different rearing techniques, according to the market demand and industry requirements. In this specific field, the Padua seat works in collaboration with the Silk Experiment Station of Milan too, which has research on processes following cocoon production as its own mission, and  with the Silkworm Rearer National Association, which represents cocoon producers’ requirements.

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Silkworm pathology
The study of pathology and of disinfection techniques has ever been a very important research field for our seat. In particular, by applying the diet substituting for the mulberry leaf in practice, new primary concerns have been growing, and pathology research which is currently carried out is concerning microorganisms related to that new rearing method. Furthermore, with a view to respect environment, disinfections techniques consistent with no residuals both in the rearing place and in the final product (silk) have been approached. The seat’s staff is also enabled to carry out analysis to test hereditary diseases in the silkworm eggs which are produced in Padua and distributed to silkworm rearers, privates and laboratories in addition to that sometimes imported.

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Relationship between the silkworm and the environment
The silkworm, like the honey bee, is an environment sentry. Being ever reared in a particularly protected environment for thousands of years and feeding of a tree species which is not treated with pesticides, both for its own resistance, and for the final use, the silkworm has never developed characteristic mechanism of detoxication with regard to environmental pollutants; therefore the insect immediately signals the presence of an environmental contamination, both in case of insecticide treatments, industrials emissions, or other human activity (car exhausts and effects of urban heating). Therefore, the silkworm is very precious to study the action of pollutants on physiology and ecology of Lepidopterans, taking also into account there is no environmental survey net recording about wild Lepidopterans.

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Cultural, social, historic and exhibition aspects of sericulture

Due to the strict link between sericulture and history and cultural evolution of the Italian society in the ‘800 and ‘900, the seat performs an  activity of cultural and historic consultancy, which on one hand is carried out through specific archive and librarian research activities, on the other is in collaboration with the Living Insect Museum, whose relationship with the Padua seat is of symbiosis. In particular, there is a continuous research about new means for communication and teaching, whose activity the didactic kit SETAVIVA, which was established in collaboration with the Experiment Silk Station of Milan, and the video about sericulture, which was established in collaboration with the Living Insect Museum, are examples.  

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Preservation, characterisation and enhancement of the different mulberry cvs belonging to the Morus sp.p. germplasm bank
A collection of 50 cultivars from different mulberry species belongs to the Padua seat.  The various cultivars are studied according to both the silkworm nutrition and other uses (multifunction mulberry). Mulberry cultivars are under characterisation from a morphological, phenological, genetic and chemical point of view, also thanks to the RGV-FAO project.

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Mulberry/silkworm relationships
The cultivars are being characterised  on the basis of their attraction to the silkworm, in relation  both to the leaf nutritional and phenolic content too. Even mulberry ephiphytic and endophytic microflora has been identified in order to find out the link between microflora in the silkworm gut and on the leaf. Nutritional value in the different cultivars has been analysed with the method  of addition to the artificial diet, which permits optimal standardisation of the experiments.

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Mulberry for fruit production
Especially Morus nigra is employed as fruit tree. From the fruits of that species marmalades, jellys, jams, water-ices, cakes, spirits can be obtained. Mulberry fruits can be used as flavours and pigments for ice-creams, giving a blue-violet colour to the food to which are added. In the Centre of Italy and in Sicily M. nigra is cultivated for local use. The main problem in the cultivation for fruit production is the non-homogenous ripening, which makes it difficult to mechanise harvesting. Furthermore, on the basis of our actual knowledge, preservation time is low. Nevertheless, vitamin and antioxidant content of the mulberry fruits make them optimum from a nutritional point of view.

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Mulberry for animal husbandry
The mulberry nutritional value, in particular for ruminant feeding, has been studied in the framework of the GEPRO project. Furthermore, the mulberry field density and design for animal husbandry and  prototypes of harvesting machineries were research subjects.

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Mulberry for bio-mass production
Mulberry utilization in order to produce fuels, especially in marginal soils, is one of the possible applications of moriculture with the aim of integrating the income from sericulture.
 
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Mulberry for pharmaceutics
Mulberry has a long history as a medicinal plant, especially as cardiotonic; due to that property it has been employed since ancient times in Chinese traditional and in ayurvedic (Indian) medicine. Recently mulberry active ingredients have been found to be effective in controlling blood pressure, against arteriosclerosis, diabetes type 2, and virtually against HIV too. In fact mulberry contains two chemicals: astragalin and isoquecetrin, which are metabolised into quercetrin, powerful antioxidant, and which avoids oxidation of LDL cholesterol, so-called “bad cholesterol”, fighting against plaque formation into the arteries (arteriosclerosis). The 1-deoxynojirimycin, a third important chemical, counteracts the alpha-glycosidic enzymes in the stomach, where they break both the starch and carbohydrate molecules, giving place to absorbable glucose. It is estimated that the above mentioned active ingredient hampers to 50% of total sugars to enter into circulation and it reduces usable calories to 35% (positively acting on the body weight). Such a phenomenon reduces the glucose and insulin level into the blood, mostly after meals, by stabilizing carbohydrate level into circulation and therefore contributes to the control of diabetes 2. Anti-HIV action by the same chemical is under experiment testing phase.

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Mulberry environmental impact assessment and recovery of marginal abandoned or polluted soils through moriculture
The interest in mulberry alternative uses is enhanced by the plant’s great adaptability  and, therefore, by its capability of colonization of hilly soils which nowadays are going to be abandoned or degraded.  In fact, the mulberry shows the advantage of being part of the rural national landscape, because of the fact it has been introduced into Italy in a very ancient time.  
Reforestation by using the mulberry in those areas which with difficulty are usable by agriculture (strongly urbanised, hilly, with restriction because of law or operative limits) is a solution with many positive characteristics. A small amount of irrigation is needed only in the Centre-Southern areas, while it is not necessary at all in the Northern regions and mostly in the zone close to the mountains. On purpose-selected mulberry varieties can be employed in salty or in heavy metal-polluted soils.

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