Ephestia kuehniella; HYMENOPTERAN-PARASITES; Venturia canescens; Parasite virus like particle gene, allelic variation; Parthenogenetic strains characterization Venturia canescens; PROTEINS-; OOGENESIS-; Virus like particles production; EGG-; Virus like particles, gene variation; OVARY-; Characteristics; REPRODUCTIVE-PRODUCTIVITY; EMBRYO-DEVELOPMENT; PHENOTYPE-; Parthenogenetic strains differing in virus like particle gene; MOLECULAR-GENETICS; MUTATION-; BIOCHEMICAL-VARIATION; Lepidopteran host; LEPIDOPTERAN-HOSTS; Ephestia kuehniella; Virus like particle gene, allelic variation; Parthenogenetic strains characterization Endoparasitoid wasps rely on maternal protein secretions, including viruses and virus-like particles (VLPs), to overcome host defense reactions. In the ichneumonid Venturia canescens, VLPs are assembled in the nuclei of ovarian calyx gland cells, secreted into the lumen of the gland, and eventually transmitted into the host caterpillar together with the parasitoid egg. One of the genes coding for VLP proteins, termed VLP1, exists in two alleles producing two structurally different proteins. Here we describe the establishment and initial phenotypic characterisation of two parthenogenetic laboratory strains, which differ in VLP1 as well as in other genetic markers. A comparison of calyx tissues from the two strains revealed morphological differences that seem to affect egg movement from the ovarioles into the oviduct. The observed histolocical changes are correlated with differences in egg maturation and embryonic development causine a delay in larval hatching in one of the strains. Under conditions that favour superparasitism, the two strains differ in the number of offspring produced. none