Genetic diversity, population structure and rapid early detection of the parasitoid Anastatus orientalis (Hymenoptera: Eupelmidae) inside eggs of spotted lanternfly (Hemiptera: Fulgoridae)

Spotted lanternfly, Lycorma delicatula (Hemiptera: Fulgoridae), is a native pest of more than 70 plant species in China. To date, only two parasitoids are well recognised for biological control of this pest, among which, the egg parasitoid Anastatus orientalis (Hymenoptera: Eupelmidae) is known to account for approximately 69% of parasitism observed in the field. Variable emergence timings have been observed in different geographic populations in this parasitoid. To understand the genetic structure among A. orientalis populations we sequenced partial mitochondrial Cytochrome c oxidase subunit I (COI) sequences and the D2 region of the nuclear 28S gene across five regions of China (Beijing, Gansu, Shaanxi, Ningxia, Shandong). We identified 16 COI haplotypes among these populations and the lowest level of haplotype diversity was found in the Ningxia population Hd = 0.583 +/- 0.133). Results from the analysis of molecular variance indicated that most of the genetic variation is present within the populations. Phylogenetic analysis demonstrated a weak geographic structure among the populations. To evaluate parasitism rapidly, we developed a 558-bp species-specific molecular marker which could efficiently detect parasitoids of any developmental stage inside their host eggs. Sensitivity analysis of markers revealed that our assay could detect as low a DNA template concentration as 0.025 pg/mu l. This method provided more rapid and accurate detection of parasitoids compared with regular natural rearing methods.