Three species of cecidomyiid midges (Diptera: Cecidomyiidae) cause significant yield losses on wheat in Europe: Sitodiplosis mosellana (Géhin), Contarinia tritici (Kirby) and Haplodiplosis marginata (von Roser). Eggs and young larvae may be parasitised by a complex of hymenopteran parasitoids belonging to the Pteromalidae and Platygastridae families which contributes to natural pest control. We have developed molecular tools for detecting and identifying seven parasitoid species previously encountered in Belgium inside individual wheat midge larvae. Barcode DNA sequences from COI, 18S and 28S genes were obtained from the midges and parasitoid species. Each of the three genes allowed all the species to be distinguished although 18S was the only one displaying a barcoding gap, both between parasitoids and midges, and at the species level. Based on the 18S gene, we developed a TaqMan assay to assess parasitism in midge larvae, regardless of the midge and parasitoid species. Next, two group-specific PCR primer pairs were generated, allowing the separate amplification of midge DNA or parasitoid DNA in parasitised individuals and subsequent identification by Sanger sequencing. Finally, species-specific primers were designed to identify six parasitoid species by simple PCR amplification. These tools were successfully applied to assess the parasitism rate of S. mosellana larvae in seven Belgian fields.
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Pachacamac is a major precolumbian site located on Peru’s Central Coast. Covering approximately 6 km2, the site was occupied for over a thousand years before the Spanish conquest in the early sixteenth century. In 2012, the Ychsma Project discovered a unique Late Intermediate period (AD 900–1470) multiple burial (“Cx4”) made of two funerary chambers with a vegetal roof structure, containing over 110 intact and fragmentary deceased together with numerous grave goods. More than 60% of the individuals are subadults whose sex cannot be assigned using osteological observation. Among the adults, 23 females and 20 males were identified, and the sex of the remaining four individuals couldn’t be assigned with certainty. We aim to fully understand the sociobiology of the Cx4 population, including biological sex, using a combined bioarchaeology and molecular archaeology approach. Despite significant human modern contamination and low amounts of endogenous ancient DNA, our results show that sex could be assigned genetically in >70% of the cases, including subadults. Sex identification of infants, children and adolescents is crucial to fully understand this complex context and its funerary recruitment, and to perform an integrated and holistic analysis of all associated data.
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