Distribution of alfalfa weevil (Coleoptera: Curculionidae) and its parasitoids on the Canadian Prairies, with a key to described species of NearcticBathyplectes(Hymenoptera: Ichneumonidae)

Abstract

AbstractThis study recorded distribution and size of alfalfa weevil (Hypera postica(Gyllenhal); Coleoptera: Curculionidae) populations in Saskatchewan, Canada, from 2001 to 2014. The spread of alfalfa weevil across the province, originally southwest to southeast, was northward and westward during this time. By 2014, only northwestern and west central areas remained relatively alfalfa weevil free. From a minor pest in 2001, the alfalfa weevil increased to be the principal insect pest of alfalfa (Medicago sativaLinnaeus; Fabaceae) in 2014. The parasitoidBathyplectes curculionis(Thomson) (Hymenoptera: Ichneumonidae) had a similar distribution. Other parasitoids collected includedOomyzus incertus(Ratzeburg) (Hymenoptera: Eulophidae) andMicroctonus colesiDrea (Hymenoptera: Braconidae). Conservation of these parasitoids is an important step in maximising their effectiveness as alfalfa weevil biocontrol agents. Molecular sequencing of the DNA barcoding region of specimens identified morphologically asB. curculionisindicated moderately high levels of sequence divergence among specimens (up to 5.8%); however, interspecific genetic variation between other species ofBathyplectesFörster was also high. Therefore, we conclude thatB. curculioniswas the onlyBathyplectesspecies collected in our study. An illustrated key to the described species ofBathyplectesin North America is provided, as well as DNA barcodes of most species, including five distinct barcodes in theBathyplectes curculionis–B. exiguus(Gravenhorst) species complex.