Several broadleaf crops on the Canadian prairies suffer economic damage by Lygus bugs (Hemiptera: Miridae), populations of which are suppressed by parasitoids in the genus Peristenus (Hymenoptera: Braconidae). We used three different methods to assess levels of this parasitism for different instars of Lygus collected in southern Alberta, Canada. Screening Lygus for Peristenus DNA using a molecular polymerase chain reaction (PCR) method identified levels of parasitism ranging from 35 (second and third instars) to 47 (fifth instars) per cent. With dissection, parasitoids were recovered from 13 (second instars) to 44 (fifth instars) per cent of Lygus. For Lygus collected in the field and reared in the lab, Peristenus emerged from about 22 per cent of individuals. Our results show that use of PCR or dissection for fifth-instar larvae provides comparable estimates of parasitism. For earlier instars, PCR identifies levels of parasitism undetected using dissection – that is, 2.7-fold more for second instars in the present study. For the purposes of pest management and conservation biological control, dissection can provide adequate estimates of parasitism to inform a decision to reduce insecticides to protect Peristenus parasitoids.

Starting in the 1960s, the flea beetle Longitarsus jacobaeae (Waterhouse) (Coleoptera: Chrysomelidae) has been imported and relocated to North America for the control of the weed tansy ragwort, Jacobaea vulgaris (Asteraceae). Some Longitarsus species are morphologically almost indistinguishable, leading to questions regarding the taxonomic identity of the beetles released. Here, we present the results of a molecular study that addresses these questions and updates a list of the releases of Longitarsus within Canada. Our findings confirm the suspected release of the cryptic species L. flavicornis concurrent with releases of L. jacobaeae at sites in British Columbia, Canada, in the 1970s. However, we find no evidence for the continued presence of L. flavicornis at historical release sites in British Columbia nor in Nova Scotia, Canada, where it might potentially have been redistributed. We confirm the presence of L. gracilis Kutschera in Nova Scotia and British Columbia, the latter population likely established from a 2005 release of Longitarsus from Nova Scotia. To our knowledge, this study provides the first published confirmation of L. gracilis in Canada. Finally, we provide evidence that what were recognised in earlier work as three separate taxa (L. succineus (Foudras), L. near noricus, and Longitarsus sp.) are likely all L. succineus.

Aphodius fimetarius (Linnaeus, 1758) (Coleoptera: Scarabaeidae: Aphodiinae: Aphodiini) sensu lato is a taxon of probable European origin common in cattle dung across North America. This species has recently been recognised as a species complex composed of A. fimetarius and Aphodius pedellus (De Geer, 1774), with overlapping distributions in North America. A previous report that only A. pedellus is present in Canada was based on examination of specimens almost solely from the United States of America. In the present study, we examined the morphology of specimens (n = 2091) from localities across Canada. In combination with DNA barcoding, our results confirm that only A. pedellus is present in Canada. Results of similarity analysis confirm reduced genetic diversity among North American specimens of A. pedellus, consistent with the hypothesis that this species was introduced onto the continent during European settlement.

The insect commensal microbiota consists of prokaryotes and eukaryotes. We explored the effect of diet and the persistence of the gut microbiota across generations in Drosophila suzukii (Matsumura) (Diptera: Drosophilidae). We transferred subsets of a single population of D. suzukii to different fruit-based diets (blueberry (Vaccinium Linnaeus; Ericaceae), raspberry (Rubus Linnaeus; Rosaceae), and strawberry (Fragaria × ananassa Duchesne; Rosaceae)) for three generations and then returned them to a common, banana-based, diet. We used 16S rDNA (Bacteria) and ITS (internal transcribed spacer; Fungi) sequencing of female endosymbiont-free flies to identify the microbiota. We identified 2700 bacterial and 350 fungal operational taxonomic units (OTUs); there was no correlation between the number of bacterial and fungal OTUs in a sample. Bacterial communities were dominated by Proteobacteria (especially Acetobacteraceae); Ascomycota dominated the fungal communities. Species diversity of both bacteria and fungi differed among diets, but there were no differences in species-level diversity when these D. suzukii were returned to a control diet. A principle coordinates analysis revealed no differences in the bacterial or fungal community in the first generation on fruit diets, but that the communities diverged over the next two generations; neither fungal and bacterial communities converged after one generation on control food. We conclude that diet changes the D. suzukii microbiota, and that these changes persist for more than one generation.

Cutworms (Lepidoptera: Noctuidae) constitute an important insect pest complex that causes damage to a variety of crops across western Canada and particularly in canola (Brassica napus Linnaeus; Brassicaceae) crops in recent years. However, individual cutworms are very difficult to identify to species based on morphology alone, particularly at the larval stage. Problems with pest identification can lead to difficulties in recommending appropriate management strategies for specific cutworm infestations. In the current study we have developed and applied a single-step multiplex polymerase chain reaction assay, based on the rRNA ITS2 genomic sequence, which can be used to identify, to the species level, individuals of the following five key cutworm species: Agrotis orthogonia Morrison, Euxoa auxiliaris (Grote), Euxoa ochrogaster (Guenée), Feltia jaculifera (Guenée), and Lacinipolia renigera (Stephens). This molecular identification tool will be a valuable asset in agronomic and ecological studies of cutworm infestations in the canola cropping system across western Canada and potentially could be used as a timely identification tool for determining pest infestations to the species level during outbreaks.

Fluctuating asymmetries (FAs) are small random deviations between left- and right-side measurements of normally symmetrical traits in a given organism. Changes in FA have frequently been proposed as biomarkers for organisms exposed to stress during development and may have value for detecting low levels of chemical residues or other stressors in the environment. We tested this hypothesis in three replicated laboratory experiments and failed to find any effect of chemical residues (ivermectin) in cattle dung on levels of FAs (wing and leg traits) for the dung-breeding fly Scathophaga stercoraria L. (Diptera: Scathophagidae). In trying to resolve this discrepancy with previous reports, we found that many studies failed to replicate measurements of FA traits within an experiment, which increases the likelihood of spurious positive results. Furthermore, experiments were rarely replicated either within or between studies, so the repeatability of positive results has usually gone untested. These issues have been raised by others, but are still not being adequately addressed. Discussions regarding the value of FAs as biomarkers will not advance until this is done.