Chinese oak silkworm Antherae pernyi egg, a suitable factitious host for rearing eupelmid egg parasitoids

Eupelmid egg parasitoids in the genera Anastatus and Mesocomys are important biological control agents for lepidopterous and hemipterous pests worldwide. The egg of Chinese oak silkworm Antheraea pernyi has been widely used for mass rearing of Trichogramma parasitoids. This study evaluated the suitability and optimal use methods of A. pernyi egg as a factitious host for the rearing of six eupelmid egg parasitoids (Anastatus fulloi, Anastatus gansuensis, Anastatus japonicus, Anastatus meilingensis, Mesocomys albitarsis and Mesocomys trabalae). Each parasitoid was tested for its oviposition preference and offspring performance on various differently treated host eggs (extracted from virgin moths or laid naturally by virgin or mated moths, and washed or unwashed prior to the use) in both no-choice and choice tests.

All treated A. pernyi eggs were readily parasitized by the six parasitoids. In general, A. gansuensis and M. trabalae preferred washed over unwashed eggs regardless of the fertilization status of host eggs, A. fulloi and A. meilingensis parasitized more unfertilized than fertilized host eggs, and A. japonicus and M. albitarsis did not show a preference among differently treated host eggs. Host egg treatment did not significantly affect offspring fitness (development time, survival, sex ratio and body size) nor reproductive potential of developed adult females for each parasitoid species, except for M. albitarsis (whose females contained more eggs when reared from unfertilized than fertilized host eggs).

Results suggest that manually extracted, unfertilized and washed A. pernyi eggs are most suitable for mass rearing of these eupelmid egg parasitoids in biological control programs.