Characteristic of newly created F1 tetrahybrids of the silkworm Bombyx mori L. by basic biological traits reared with artificial diet

Radostina Guncheva, Panomir Tsenov and Yolanda Vasileva

Abstract: The aim of this paper was characteristic of newly created F1 tetrahybrids of the silkworm Bombyx mori L. reared with artificial diet throughout the larval stage on basic biological traits, which are essential for determining their receptivity to the food. The study was conducted during 2019-2020 at the Training Experimental Station of the Sericulture section of the Faculty of Agriculture at Trakia University. Object of the study were the tetrachybrid forms of the silkworm (Bombyx mori L.) Vraca63 x Line22/Nig2 x Merefa6 (1st experimental group) and Nig2 x Merefa6/Vratsa63 x Line22 (2nd experimental group). The new, but already established in practice tetrahybrid I1 x VB1/N2 x HB2 was used for the control. Silkworms were reared with artificial diet containing 30% powder of dried mulberry leaf produced at Scientific Center on Sericulture – Vratsa and prepared by methods, developed by the manufacturer. The receptivity of the analyzed hybrids to artificial diet was determined based on the results of the survival rate and duration of the larval development during the first and the last instars of larval stage. The results obtained showed that the studied tetrachybrids are characterized by very high survival rate (> 90%) and relatively short duration of development (average 291 and 293 hours for the first and 309 and 308 hours for the last instars of larval stage, respectively for the individuals from the 1st and 2nd experimental group), in some cases even exceeding, though insignificant, the control. Analysis of variance of effects of hybrid on the duration of larval development shown that the influence is a highly significant (p ≤ 0.001) during the first instars. The established tendencies give grounds to consider that the newly created tetrahybrids have very good receptivity and have a high biological potential of the parental forms, allowing their improvement through the methods of selection and their establishment as specialized for rearing with artificial diet.

Keywords: artificial diet; Bombyx mori L.; duration of larval development; hybrids; receptivity; survival

Date published: 2022-10-17