ABSTRACT
O bicho-da-seda, Bombyx mori L. (Lepidoptera: Bombycidae), é o inseto produtor de casulos de seda, destinados à fiação industrial têxtil, para posterior produção de tecidos de seda. Os filamentos de seda, expelidos pelas glândulas sericígenas do inseto, se solidificam ao entrar em contato com o ar. A sericicultura abrange a criação das lagartas de B. mori e a cultura da amoreira, principal fonte de alimentação da lagarta. Com o objetivo de avaliar a influência da alimentação na morfologia da glândula sericígena de lagartas de B. mori, realizou-se experimento em que foram fornecidos aos insetos quatro cultivares de amoreira, sendo estes a variedade Korin e os híbridos comerciais FM86, SK4 e IZ40. Os dados obtidos revelaram que, quanto ao peso da glândula sericígena, as lagartas alimentadas com SK4 e Korin apresentaram maior peso quando comparadas com os cultivares FM86 e IZ40. O híbrido SK4 revelou diferença significativa no comprimento da glândula posterior. Porém, os dados gerais apresentaram um certo equilíbrio entre os cultivares, perdendo em alguns aspectos e superando outros, quando comparados entre si.
El gusano de seda, Bombyx mori L. (Lepidoptera: Bombycidae), es el insecto productor de los capullos de seda, destinado a la hilatura industrial textil, para posterior producción de tejidos de seda. Los filamentos de seda, expulsados por las glándulas sericígenas del insecto, se solidifican al ponerse en contacto con el aire. La sericicultura abarca la creación de lagartas de B. mori y el cultivo de la morera, principal fuente de alimentación de la lagarta. Con el fin de evaluar la influencia de la alimentación en la morfología de la glándula sericígena de lagartas de B. mori, se realizó experimento en que fueron suministrados a los insectos cuatro cultivares de morera, siendo estos la variedad Korin y los híbridos comerciales FM86, SK4 y IZ40. Los datos obtenidos revelaron que, cuanto al peso de la glándula sericígena, las lagartas alimentadas con SK4 y Korin presentaron mayor peso en comparación con los cultivares FM86 y IZ40. El híbrido SK4 reveló diferencia significativa a lo largo de la glándula posterior. Sin embargo, los datos generales muestran un cierto equilibrio entre los cultivares, perdiendo en algunos aspectos y superando en otros, cuando comparados entre ellos.
The silkworm, Bombyx mori L. (Lepidoptera:Bombycidae), is the insect that produces cocoons of silk - the more important raw material for the silk industry. Silk filaments, which are expelled by the insects silk-producing gland, become solid in contact with air. Silk culture encloses the creation of silkworm and mulberry plant growing its major source of food. With the objective of evaluating the influence of feeding in the morphology of the silk-producing gland of the B. mori worms, an experiment was conducted with four mulberry cultivars: Korin , FM86, SK4 e IZ40. The results revealed that with respect to wight of the silk-producing gland, the silkworms fed with SK4 and Korin presented higher weight when compared to the FM86 and IZ40 cultivars. SK4 presented significant difference with respect to the posterior gland length. However, general data presented certain balance among the cultivars when compared mutually.
Subject(s)
Animals , Bombyx/anatomy & histology , Animal Nutrition Sciences , Morus , SilkABSTRACT
Estradiol-17beta (E2) at the dose of 1 microg/g caused an increase in cell area, lumen area and the total (cell + lumen) area of posterior silk gland (PSG) in Bombyx mori indicating that exogenously applied estradiol-17beta has a regulatory influence on silk gland activity. A dose-dependent variation in trehalase activity of PSG was found on the 5th day after topical administration of estradiol on 1st and 2nd day of the fifth larval instar. Of all the doses of E2 used, 1 microg/g dose had maximum stimulatory effect on trehalase activity. Co-administration of each of a specific receptor antagonist for estradiol, the ICI-182780 and a protein biosynthetic blocker, cycloheximide with E2 suppressed the E2-induced increase in silk gland activity. The results suggest some specific metabolic action of E2 on silk gland and offer a promising way for future investigations regarding the physiological significance of vertebrate steroids in insects.
Subject(s)
Animals , Bombyx/anatomy & histology , Estradiol/pharmacology , Larva/drug effects , Trehalase/metabolismABSTRACT
Lepidopteran insects present a complex organization of appendages which develop by various mechanisms. In the mulberry silkworm, Bombyx mori a pair of meso- and meta-thoracic discs located on either side in the larvae gives rise to the corresponding fore- and hind-wings of the adult. These discs do not experience massive cell rearrangements during metamorphosis and display the adult wing vein pattern. We have analysed wing development in B. mori by two approaches, viz., expression of patterning genes in larval wing discs, and regulatory capacities of larval discs following explantation or perturbation. Expression of Nubbin is seen all over the presumptive wing blade domains unlike in Drosophila, where it is confined to the hinge and the wing pouch. Excision of meso- and meta-thoracic discs during the larval stages resulted in emergence of adult moths lacking the corresponding wings without any loss of thoracic tissues suggesting independent origin of wing and thoracic primordia. The expression of wingless and distal-less along the dorsal/ventral margin in wing discs correlated well with their expression profile in adult Drosophila wings. Partially excised wing discs did not show in situ regeneration or duplication suggesting their early differentiation. The presence of adult wing vein patterns discernible in larval wing discs and the patterns of marker gene expression as well as the inability of these discs to regulate growth suggested that wing differentiation is achieved early in B. mori. The timings of morphogenetic events are different and the wing discs behave like presumptive wing buds opening out as wing blades in B. mori unlike evagination of only the pouch region as wing blades seen in Drosophila.