Morphological analysis revealed that the number of sensilla on the antennae of Bombyx mori females is considerably reduced compared to the abundant sensilla of Bombyx mandarina. In addition, the researchers measured different activity patterns in the brain of the domesticated and the wild silkmoths by using calcium imaging techniques. These patterns were highly variable among individuals of domesticated silkmoths but were largely constant in their wild ancestor group as well as in four other insect species.
Compared to wild moths, domesticated silkmoths seem to have less ability to smell environmental odors with their antennae and to locate host plants due to several millennia in captivity. As oviposition substrate is provided by humans, this ability has become redundant. In the wild, however, selecting an adequate oviposition site is crucial for the survival of the offspring, and thus helps preserve the species.
On the other side, perception of the female-produced attractant bombykol in Bombyx mori males is unabated, although it is not necessary anymore to find the females, as they are presented to the males by the breeders. Probably because bombykol not only attracts males but also triggers mating behavior in the males, it has remained indispensable for reproductive success.
Domestication effects are localized on the sex chromosome
Unlike in mammals, the female ovule determines the sex of the offspring in moths and butterflies. The distinction is made, analogous to the XY chromosomes, between W and Z chromosomes. Males have ZZ, females WZ chromosomes. Because both species, B. mori and B. mandarina, can still be crossbred, the scientists bred
|Contact: Dr. Silke Sachse|
Max Planck Institute for Chemical Ecology