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The insecticidal activity of parasiticide residues in dung of cattle treated with a sustained release eprinomectin formulation was examined, and an improved eprinomectin dung residue extraction method is presented. Emergent insect abundance and richness were significantly reduced in all post-treatment intervals (7, 14, 28, 56, 84, 112, and 140 d), relative to pre-treatment. Emergent insect diversity was reduced for between 84 and 112 d post-treatment. Collembola were not affected by residues. Chemical analyses subsequently documented residues of eprinomectin in dung of each collection period post-treatment at levels expected based on previously reported excretion profiles for this product. Cattle subcutaneously injected with this product excreted residues that reduced dung-breeding insect emergence for 5 mo post-treatment. The consequences of these long-term non-target effects to pasture ecosystems are not known.

Natural systems of hybridizing plants are powerful tools with which to assess evolutionary processes between parental species and their associated arthropods. Here we report on these processes in a trispecific hybrid swarm of Populus trees. Using field observations, common garden experiments and genetic markers, we tested the hypothesis that genetic similarities among hosts underlie the distributions of 10 species of gall‐forming arthropods and their ability to adapt to new host genotypes. Key findings: the degree of genetic relatedness among parental species determines whether hybridization is primarily bidirectional or unidirectional; host genotype and genetic similarity strongly affect the distributions of gall‐forming species, individually and as a community. These effects were detected observationally in the wild and experimentally in common gardens; correlations between the diversity of host genotypes and their associated arthropods identify hybrid zones as centres of biodiversity and potential species interactions with important ecological and evolutionary consequences. These findings support both hybrid bridge and evolutionary novelty hypotheses. However, the lack of parallel genetic studies on gall‐forming arthropods limits our ability to define the host of origin with their subsequent shift to other host species or their evolution on hybrids as their final destination.

Agroecosystems are comprised of environmental compartments where associated microbial communities interact with one another. These microbial communities, called microbiomes, inhabit livestock, insects, and plants. Microbiomes are also present in the soil and watersheds. Clarifying the nature and extent of microbial interactions between compartments both at intra-farm and global scales can promote sustainable production systems, healthier animals, increased crop yields, and safer meat products. Early research on microbiomes was hindered by a lack of expertise and the high cost of molecular sequencing. However, these limitations have been largely resolved with advances in and reduced costs of sequencing technologies. In this paper, we summarize sequencing and bioinformatics approaches, and review the crucial roles of diverse microbiomes in livestock, plants and soil, as well as pollinators and pest insects. These crucial roles include nutrient cycling, nutrient acquisition, metabolism of toxins and enhanced host immune function. Additionally, we examine potentially undesirable effects of microbiomes associated with climate change and agri-food production such as their role in the release of greenhouse gases from cattle and their impact on meat safety and spoilage. By increasing the awareness of microbiomes and the growing ease with which they can be studied, we hope to foster a greater adoption of microbiome research. Further understanding of the diverse effects and interactions of microbiomes will advance our efforts to increase agricultural production while reducing its negative environmental footprint, thus making the agroecosystems more sustainable.

▪ Abstract  Residues of veterinary parasiticides in dung of treated livestock have nontarget effects on dung-breeding insects and dung degradation. Here, we review the nature and extent of these effects, examine the potential risks associated with different classes of chemicals, and describe how greater awareness of these nontarget effects has resulted in regulatory changes in the registration of veterinary products.

Hybrid genotypes that arise between plant species frequently have increased susceptibility to arthropod pests and fungal pathogens. This pattern has been attributed to the breakdown of plant defenses ('Hybrid susceptibility' hypothesis) and (or) to extended periods of susceptibility attributed to plant phenologies in zones of species overlap and (or) hybridization ('phenological sink' hypothesis). We examined these hypotheses by assessing the susceptibility of parental and hybrid Populus host genotypes to a leaf spot disease caused by the fungal pathogen Septoria musiva. For this purpose, 214 genotypes were obtained from morphologically pure zones of P. balsamifera and P. deltoides, and from an intervening zone of overlap and hybridization on the drainage of the Red Deer River, Alberta, Canada. Genotypes were identified as P. balsamifera, P. deltoides, or hybrid using a suite of 27 species-specific SNP markers. Initially the genetic structure of the hybrid zone was characterized with 27.7% of trees classified as admixed individuals. To test the hybrid susceptibility hypothesis, a subset of 52 genotypes was inoculated with four isolates of S. musiva. Levels of susceptibility were P. balsamifera > F1 hybrid > P. deltoides. A further 53 genotypes were grown in a common garden to assess the effect of genotype on variation in leaf phenology. Leaf phenology was more variable within the category of hybrid genotypes than within categories of either parental species. Leaf phenology was also more variable for the category of trees originating in the hybrid (P. balsamifera - P. deltoides [hybrid and parental genotypes combined]) zone than in adjacent pure zones of the parental species. The results from the inoculation experiment support the hybrid intermediacy hypothesis. The results from the common garden experiment support the 'phenological sink' hypothesis. These findings have greatly increased our understanding of the epidemiology and ecology of fungal pathogens in plant hybrid zones.

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.

Contrasting life histories distinguish solitary from gregarious parasitoids. Females of solitary species typically lay one egg in a host; when more than one parasitoid is present in the host, larvae will kill their rivals so that only one parasitoid completes development. Females of gregarious species typically lay multiple eggs in the same host with the resultant larvae co-existing to complete development. Here we provide an unusual report of siblicide by larvae of a gregarious parasitoid; i.e., Cotesiavanessae (Reinhard) (Hymenoptera: Braconidae) developing in noctuid caterpillars (Lepidoptera). Siblicidal behaviour has not previously been reported with larvae of gregarious Braconidae. We speculate that this behaviour reflects a trade-off between the finite amount of resources within the host available for larval development, and selection to optimize use of these resources. ‘Flooding’ the host with eggs allows the female to use the finite resources of the host to their fullest extent, regardless of host size. This strategy also may allow the female to overwhelm the host’s immune system to enhance survival of her progeny in otherwise marginal host species. It further may enhance the ability of the female’s progeny to competitively exclude the larvae of conspecific females or larvae of other parasitoid species co-occurring in the host. Siblicide allows for self-regulation of brood size when host resources are insufficient to support egg-to-adult development of all eggs initially laid in the host.

Khapra beetle, Trogoderma granarium Everts, is unusual in two key respects. First, they are among the most cold hardy of stored-product insect pests even though they originate in hot and dry regions of the Indian subcontinent. Second, their larvae can enter into diapause to survive harsh environmental conditions. In the present study, we examined whether these two phenomena are related, i.e., due to cross-tolerance. Cross-tolerance is the tolerance to one ecological stress when induced by a separate stress. To investigate this, khapra beetle larvae were reared at different relative humidities (3, 28, 49, and 79%) in either nondiapausing or diapausing conditions. Then the cold tolerance of larvae was estimated by measuring mortality after different durations at –10°C. For nondiapausing larvae, relative humidity had little effect on cold tolerance with the lethal time to 50% mortality (LT50) occurring between 2 and 4 d. For diapausing larvae, cold tolerance increased with greater desiccation stress with LT50's of 5, 7, 10, and 18 d at 79, 49, 28, and 3% RH, respectively. This suggests that the physiological mechanisms that protect diapausing larvae from desiccation may also increase cold tolerance, even though these insects may rarely be exposed to low temperatures.

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.

Hippoboscid flies (Diptera: Hippoboscidae) include species that are ectoparasites of birds in the Northern Hemisphere, but little is known regarding their taxonomy, parasites, avian host associations, or geographical distribution in North America. In late August of 2013 and 2014, we collected hippoboscid flies from live birds trapped in mist nets as part of a banding study in Cypress Hills Interprovincial Park in southeastern Alberta, Canada. A total of 113 birds comprising 9 species was examined in 2013. Of these, 18 individuals were infested with 1–3 Ornithomya anchineuria Speiser (n = 22 flies; prevalence = 15.9%). Eight of these flies carried 1–8 adult female epidermoptid mites anchored to their ventral, posterior abdomens. Each female was associated with clusters of up to 30 stalked eggs. The first pair of tarsi on adult female mites was highly modified as anchors, indicating permanent attachment through the host cuticle. Morphological traits identified these mites as Myialges cf. borealis Mironov, Skirnisson, Thorarinsdottier and Nielsen. Cytochrome c oxidase subunit 1 (COX1) gene sequences obtained for 2 mites were distinct from those previously reported for species of Myialges, being most similar to Myialges trinotoni Cooreman. The paucity of available gene sequences for Myialges and related genera of epidermoptid mites prevents any further conclusions regarding taxonomy. These findings extend previous reports of O. anchineuria from Pacific and Atlantic coasts of Canada inland to the central migratory flyway of the Northern Great Plains and expand the limited information available for Myialges spp.