Assessment of <em>Drosophila melanogaster</em> pupae killed by heat as hosts for rearing <em>Trichopria drosophilae</em>

Trichopria drosophilae is a globally distributed pupal parasitoid that targets various species within the Drosophilidae family, including the invasive Drosophila suzukii. The mass rearing of T. drosophilae is a critical step in ensuring their successful application for field D. suzukii control. The pupae of D. melanogaster are currently used as a host for the mass rearing of T. drosophilae. After thermal treatment, the period during which pupae remain suitable for parasitism is extended, resulting in increased parasitism efficiency of the parasitoids. However, there have been no reports to date on the parasitism of heat–killed D. melanogaster pupae by T. drosophilae, and the effects of continuous rearing on heat-killed pupae on T. drosophilae remain unknown. To evaluate the utilization efficiency of heat–killed Drosophila pupae by T. drosophilae, we conducted a comprehensive analysis of key biological indicators across the F1, F2, and F3 generations. These included adult longevity, parasitism rate, female offspring production, changes in offspring sex ratio with maternal age, and population life table parameters. Our results showed that T. drosophilae can be continuously reared for multiple generations on heat–killed D. melanogaster pupae. Moreover, the T. drosophilae exhibits an adaptive response to heat–killed hosts, with population parameters declining in the F2 generation and recovering in the F3 generation. Using heat–killed pupae provides an efficient and economically viable method for the mass rearing of T. drosophilae, and offers valuable insights into its potential effectiveness in the field control of D. suzukii.