Mulberry whitefly (Pealius mori) interference with silkworm (Bombyx mori) nymphal development

The mulberry whitefly (Pealius mori Takashashi) is increasingly causing concern in agriculture as the distribution of this pest expands. In Egypt, the recent invasion and population expansion of the mulberry whitefly has caused particular concern in the sericulture industry. The silkworm (Bombyx mori L.), also called mulberry silkworm or Chinese silkworm, is the most important source for natural silk production. A study was conducted to examine interference by the mulberry whitefly on the population development of the silkworm. White mulberry (Morus alba L.) leaves were obtained from trees maintained in the field which had different levels of natural infestation of whiteflies (P. mori), and these were fed to silkworms in the laboratory. Regardless of instar, all silkworm caterpillars that fed and developed on white mulberry leaves that were moderately whitefly-infested (350–450 nymphs per leaf) or heavily whitefly-infested (1650–1750 nymphs per leaf) failed to molt to the next instar or failed to pupate. By comparison, 88–95% of the caterpillars that were fed non-infested mulberry leaves molted and pupated. This study demonstrates that infestation of mulberry by P. mori can have a significant negative impact on the development of silkworms. These results have high economic implications for the sericulture industry.