N. Kirk Hillier

Factors regulating the bioavailability of methylmercury to breeding rusty blackbirds in northeastern wetlands

Rusty blackbirds are undergoing rapid population decline and have elevated Hg concentrations while breeding in the Acadian ecoregion of North America. Factors regulating the bioavailability of methyl-Hg (MeHg) within this populations habitat were determined using water, invertebrates, and blood from adult rusty blackbirds collected for Hg-speciation, along with additional water column parameters: MeHg and THg, dissolved organic carbon, pH, dissolved oxygen, conductivity, redox potential, and temperature. Both DO(2) and pH were negatively related to biota MeHg, while water MeHg concentrations were positively related. Both invertebrate MeHg concentration and %MeHg increased with trophic level. Invertebrate MeHg concentrations were among the greatest reported when compared with those reported elsewhere for wetlands and waterbodies-often several times greater for similar taxa-while percent MeHg of THg were similar. An environment with high bioavailability of MeHg in combination with a high trophic position best explains elevated Hg concentrations for this species regional population.

Plant Essential Oils Synergize and Antagonize Toxicity of Different Conventional Insecticides against Myzus persicae (Hemiptera: Aphididae).

Plant-derived products can play an important role in pest management programs. Essential oils from Lavandula angustifolia (lavender) and Thymus vulgaris (thyme) and their main constituents, linalool and thymol, respectively, were evaluated for insecticidal activity and synergistic action in combination with insecticides against green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae). The essential oils and their main constituents exerted similar insecticidal activity when aphids were exposed by direct sprays, but were non-toxic by exposure to treated leaf discs. In synergism experiments, the toxicity of imidacloprid was synergized 16- to 20-fold by L. angustifolia and T. vulgaris essential oils, but far less synergism occurred with linalool and thymol, indicating that secondary constituents of the oils were probably responsible for the observed synergism. In contrast to results with imidacloprid, the insecticidal activity of spirotetramat was antagonized by L. angustifolia and T. vulgaris essential oils, and linalool and thymol. Our results demonstrate the potential of plant essential oils as synergists of insecticides, but show that antagonistic action against certain insecticides may occur.

Influence of Hepatozoon parasites on host-seeking and host-choice behaviour of the mosquitoes Culex territans and Culex pipiens.

Graphical abstract Highlights ► We observed behaviour of uninfected mosquitoes and those infected with Hepatozoon parasites. ► We observed mosquito choice of infected and uninfected frogs and snakes. ► Host-seeking behaviour of infected Culex pipiens differed from uninfected mosquitoes. ► We report the first parasite-induced changes in host behaviour in this system.

Susceptibility of selected boreal fruits and berries to the invasive pest Drosophila suzukii (Diptera: Drosophilidae).

BACKGROUND Drosophila suzukii Matsumara has recently emerged as a major invasive pest species in soft-skinned fruits in berries throughout North America and Europe. Its distribution has spread so rapidly that little is known of the extent of fruit susceptibility, particularly in boreal regions. Populations of D. suzukii increase dramatically in late summer in boreal regions, concurrent with fruiting seasons for commercially and culturally significant fruits and berries. We tested fruit preference and susceptibility of lingonberry, blueberry, chokecherry, sea buckthorn and raspberry fruits to D. suzukii. RESULTS Female D. suzukii attempted to oviposit on all fruit types tested. Fruits with lower brix and lower pH levels were preferred in choice tests. Undamaged lingonberries were relatively safe from infestation; however, bruised or frost-damaged fruits were easily penetrated. Sea buckthorn and raspberry fruits were highly preferred. CONCLUSION Although blueberry growers have experienced severe economic crop losses due to D. suzukii, we have found that blueberries were the least preferred of the fruits tested. This suggests that D. suzukii are largely opportunistic and highlights the importance of fruit phenology in fruit susceptibility.

Differential Octopaminergic Modulation of Olfactory Receptor Neuron Responses to Sex Pheromones in Heliothis virescens

Octopamine is an important neuromodulator of neural function in invertebrates. Octopamine increases male moth sensitivity to female sex pheromones, however, relatively little is known as to the role of octopamine in the female olfactory system, nor its possible effects on the reception of non-pheromone odorants. The purpose of this study was to determine relative effects of octopamine on the sensitivity of the peripheral olfactory system in male and female Heliothis virescens. Single sensillum recording was conducted in both sexes following injection with octopamine or Ringer solution, and during odorant stimulation with conspecific female sex pheromone or host plant volatiles. Results indicate that octopamine plays a significant modulatory role in female sex pheromone detection in female moths; and that male and female pheromone detection neurons share distinct pharmacological and physiological similarities in H. virescens despite sexual dimorphism at the antennal level.

Evaluation of repellent and insecticidal properties of a novel granite dust product in crop protection

Inert rock dusts, such as diatomaceous earth, represent effective products for insect pest management. We investigated the properties of a novel granite dust product in different formulations as a repellent and insecticidal agent against two important horticultural crop pests (Plutella xylostella and Trichoplusia ni). Foliar application of granite dust (dry and in aqueous solution) reduced larval feeding damage of P. xylostella and T. ni on cabbage leaves. In the case of P. xylostella, aqueous formulation of granite dust with surfactant had a significant insecticidal effect on larvae. In oviposition bioassays, adult P. xylostella female insects oviposited significantly fewer eggs on cabbage leaves treated with granite dust than on control leaves. Our results demonstrate, for the first time, the potential use of granite dust as a pest management treatment providing repellent and insecticidal activities exceeding other mineral and dust-based pest management products.

Effect of Color and Contrast of Highbush Blueberries to Host-Finding Behavior by Drosophila suzukii (Diptera: Drosophilidae)

Abstract Drosophila suzukii Matsumara (Diptera: Drosophilidae) has become a serious pest in soft-skin fruits and berries, infesting both ripe and ripening fruits. Crop damage in highbush blueberry has been particularly severe. During blueberry fruit development, fruits of various degrees of ripeness are present simultaneously. In addition, foliage color changes as the season progresses. We investigated the influence of blueberry fruit and leaf color on host-finding behavior in D. suzukii. Opposing shifts between reflectance spectra of ripening fruits and senescing leaves increased contrast between ripe fruit and senesced foliage. Developmental changes in contrast between fruit color and leaf color may act as a visual contextual cue in finding suitable host fruits. Opposing shifts in reflectance spectra of ripening fruits and senescing leaves increased the contrast between ripe fruit and senesced foliage.These opposing changes in color may contribute to the attractiveness of blueberry fruit as a late season host for D. suzukii.

Identification of Mompha capella Busck, a Microlepidopteran Predator of an Endangered Plant, Crocanthemum canadense (L.) Britton, in Nova Scotia

Abstract In recent years, a small insect was discovered predating seeds of Crocanthemum canadense (Canada Frostweed or Rockrose), which is an endangered plant with small, localized populations in Nova Scotia. This insect targets primarily chasmogamous flowers (insect-pollinated, open flowers) but not cleistogamous flowers (self-pollinated, closed) of Canada Frostweed. This behavior is of concern because a decrease in the number of seeds produced by outcrossing could cause a decrease in genetic variance within populations at affected sites (e.g., Canadian Forces Base Greenwood, NS). We extracted DNA from larvae collected from chasmogamous flowers and used the mitochondrial cytochrome oxidase subunit I (COI) gene to barcode the DNA. Results from queries showed a 91% match to Mompha (Lepidoptera: Momphidae) species on GenBank, indicating that this insect was a member of the genus Mompha, but that this particular species was not in the database. To further characterize this lepidopteran, we collected and incubated chasmogamous flowers to rear the larvae to adulthood. We identified the reared adults as Mompha capella, a species of Momphidae not previously documented in the Maritime provinces, Canada.

Morphological Comparison of Altica sylvia Malloch, 1919 and Mantura chrysanthemi (KOCH, 1803) (Coleoptera: Chrysomelidae: Galerucinae: Alticini), with a Focus on Sexual Dimorphism

Abstract Altica sylvia Malloch, 1919 and Mantura chrysanthemi (Koch, 1803) co-inhabit natural and commercial stands of lowbush blueberry, Vaccinium angustifolium Aiton (Ericaceae), in eastern Canada and the northeastern United States. Whereas A. sylvia feeds on lowbush blueberry plants, an important crop to the region, M. chrysanthemi feeds on sheep sorrel, Rumex acetosella L. (Polygonaceae), an important weed frequently found in lowbush blueberry fields. This study provides a detailed morphological examination of males and females of these flea beetles to compare species and sex-specific features. Scanning electron microscopy identified key distinguishing features, including internal and external sexual dimorphism of both species.