Summary The highly invasive spotted wing Drosophila Drosophila suzukii is a key pest of soft fruit and berries in Europe and North America, and development of control techniques is an urgent research challenge. Drosophila suzukii is widely associated with the yeast Hanseniaspora uvarum. Yeasts are symbionts of drosophilid flies and communicate with insects through volatile metabolites for spore dispersal. Accordingly, yeasts and behaviour‐modifying chemicals produced by yeasts are prospective tools for environmentally sound insect management. We first bioassayed flight attraction, feeding and oviposition of D. suzukii females in response to H. uvarum yeast and blueberries, which are a preferred host fruit. We then investigated the combined effect of yeast and insecticide on adult female oviposition behaviour and mortality towards the development of a yeast‐based control method. Following mating, attraction of female flies to blueberry and yeast odour cues was strongly enhanced. Yeast feeding significantly increased in mated females, while yeast did not increase oviposition on blueberries. This observation suggests that mated flies become attracted to yeast for feeding and to fruit for egg laying. A combined feeding–oviposition assay demonstrated different roles and interference between yeast and fruit stimuli: during the day after mating, females laid fewer eggs when yeast was available. The post‐mating yeast‐feeding response is an opportunity for the development of an attract‐and‐kill technique for population control of D. suzukii. Exposing flies to a blend of yeast and insecticide reduced oviposition and greatly enhanced adult fly mortality compared with an insecticide treatment alone. Synthesis and applications. Mated females are the key life stage for Drosophila suzukii population control. Egg‐laying females perforate fruit skin and fungal infestations ensue, even when eggs and larvae are killed off by insecticide sprays. Behaviour‐modifying chemicals, including yeast metabolites, enable environmentally safe insect management via manipulation of olfactory‐mediated reproductive behaviour. Our results highlight that yeast and yeast semiochemicals hold potential for D. suzukii management and that response modulation to olfactory stimuli following mating is a vital element for the development of D. suzukii control methods. Yeast feeding is enhanced in mated D. suzukii females, and this change in post‐mating behaviour can be exploited by an attract‐and‐kill strategy, combining a fly‐associated yeast with an insecticide. Furthermore, using the D. suzukii yeast mutualist, H. uvarum, may reduce non‐target effects and increase species specificity, which further contributes to the development of an efficient and safe control method.
A new species, Contarinia brassicola Sinclair (Diptera: Cecidomyiidae), which induces flower galls on canola (Brassica napus Linnaeus and Brassica rapa Linnaeus (Brassicaceae)), is described from Saskatchewan and Alberta, Canada. Larvae develop in the flowers of canola, which causes swelling and prevents opening, pod formation, and seed set. Mature larvae exit the galls, fall to the soil, and form cocoons. Depending on conditions, larvae will either pupate and eclose in the same calendar year or enter facultative diapause and emerge the following year. At least two generations of C. brassicola occur each year. Adults emerge from overwintering cocoons in the spring and lay eggs on developing canola flower buds. The galls produced by C. brassicola were previously attributed to the swede midge, Contarinia nasturtii (Kieffer) in Saskatchewan; here, we compare and list several characters to differentiate the two species.
The goals of pheromone-mediated mating disruption are to interfere with mate finding, suppress insect population growth, and prevent crop damage. In addition to prevention of mating, pheromone treatment can also result in a delay of mating so that the fitness and subsequent population dynamics of the target insect pest are impacted. Females have a limited time to mate, mature eggs, and find suitable oviposition hosts, and a delay in mating can have large consequences on female fitness. As a result, delayed mating could be considered an indirect method by which mating disruption works to control pest populations. We perform a metaanalysis on 24 experimental studies to assess the consequences of delayed mating on female moth fecundity, egg fertility, adult longevity, and pre-oviposition period. Our goal is to determine whether the effect of delayed mating on female moth fitness is influenced by the following explanatory variables: moth family, voltinism, larval diet breadth, adult dispersal capacity, female mating strategy, and egg development strategy. Across species, the effect of delayed mating on female moths significantly decreases fecundity, fertility, and pre-oviposition period and increases female longevity. The effect of delayed mating on female fitness is only marginally affected by the explanatory variables tested. We discuss the observed patterns and argue that delayed mating can be an important method by which population regulation is achieved through pheromonemediated mating disruption. Finally, we highlight areas where future research could add to the growing body of knowledge on mating disruption-imposed delayed mating of female moths.
Coleophora deauratella Leinig and Zeller (Lepidoptera: Coleophoridae) is an invasive pest of red clover, Trifolium pratense L. (Fabeles: Fabaceae), grown for seed in Canada. A pheromone-based monitoring program to determine the presence and seasonal activity of adult C. deauratella would be a valuable tool for growers because larvae are difficult to sample due to their internal feeding behavior. We conducted field experiments to evaluate several pheromone-baited trap characteristics, including pheromone lure substrate, trap type, trap color, lure longevity, trap height, and field position. The type of substrate that pheromone was released from and lure age did not affect trap capture of male C. deauratella. Moth capture in nonsaturating green Unitraps was significantly higher than Diamond or Wing traps when inspected at 2-wk intervals. Multi-colored Unitraps caught significantly more male C. deauratella than Diamond, and Wing traps when inspected at weekly intervals. Trap color did not influence C. deauratella capture, but by-catch of bumblebees, Bombus spp., was greatest in yellow and white colored Unitraps. Traps placed 35 cm above the soil surface captured more male C. deauratella than those placed at 1 m above or at ground level regardless of trap position within the field. Green Unitraps baited with either gray or red rubber septa lures placed 35 cm above the soil surface and 5 m from the field edge should be used to monitor C. deauratella. These characteristics optimize pheromone-baited trap performance and reduce by-catch of beneficial insects, and should be incorporated into a C. deauratella pheromone-monitoring program.
We identified species of mites phoretically associated with mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae: Scolytinae), collected from bolts of lodgepole pine, Pinus contorta Douglas ex Louden (Pinaceae), and pheromone-baited traps in northwestern Alberta, Canada. Mite load and species composition were compared between beetle sexes and with beetle emergence time and estimated body size. The vast majority of mites associated with D. ponderosae in Alberta belonged to three species: Proctolaelaps subcorticalis Lindquist (Acari: Mesostigmata: Melicharidae), Histiogaster arborsignis Woodring (Acari: Astigmatina: Acaridae), and Tarsonemus ips Lindquist (Acari: Prostigmata: Tarsonemidae). There was no difference in mite loads on male and female beetles recovered from bolts in the laboratory and those from pheromone-baited traps in the field. More mites were found on larger beetles in the laboratory, but only T. ips showed this pattern on field-trapped beetles. There was no relationship between total mite load or load by mite species and beetle emergence time in the laboratory, but total mite load on field-trapped beetles decreased over the collecting season (10 June – 3 September 2009) at five collection locations (Grovedale, Blueberry Mountain, Hythe, Evergreen Park, and Glenleslie). This study is the first to document the assemblage of phoretic mites on D. ponderosae in Alberta and will help to direct future research on their interactions.
Sex pheromone-mediated mating disruption using pheromone puffer dispensers was evaluated to control Coleophora deauratella (Lepidoptera: Coleophoridae) at three red clover seed production fields in Alberta, Canada. The objectives of the study were to determine aspects of the biology of C. deauratella which may affect successful mating disruption, evaluate the ability of aerosol-emitting pheromone puffers to reduce male moth catch in small-plot trials, and evaluate the ability of puffers to reduce male capture in traps, larval numbers and damage in large-plot trials. The median longevity of male and female C. deauratella was 6 d in the laboratory where males emerged in larger numbers earlier than females (protandry). Male response to pheromone peaked at sunrise; thus, puffers were programmed to dispense pheromone throughout this time period. Small-plot (0.25 ha) mating disruption trials indicated that pheromone released from puffers could reduce male C. deauratella orientation to traps by 60.7 ± 18.6% compared with that in untreated control plots. Reduction of male orientation to traps in large-plot (5 ha) trials over the course of the season was also successful (93.7 ± 1.6%). However, there was no corresponding decrease in larval numbers or increase in seed yield in pheromone-treated plots. Challenges of mating disruption of C. deauratella appear to be immigration of mated females combined with high population densities.
The red clover casebearer, Coleophora deauratella Lienig & Zeller (Lepidoptera: Coleophoridae), is an invasive pest of Trifolium species (Fabaceae) in Canada. We identified candidate sex pheromone components from female pheromone gland extracts using coupled gas chromatographic–electroantennographic analysis detection. Three compounds elicited an electrophysiological response from antennae and were identified as: (Z)‐7‐dodecenyl acetate, (Z)‐5‐dodecenyl acetate, and (Z)‐7‐dodecen‐1‐ol. Field tests of the candidate pheromone components revealed that males were attracted to a binary mixture of (Z)‐7‐dodecenyl acetate and (Z)‐5‐dodecenyl acetate. Male moth trap capture was greatest in traps baited with lures containing 100:10 or 100:20 ratios of these pheromone components, respectively. Trap capture was reduced when (Z)‐5‐dodecenyl acetate was present below 10 or above 20% of (Z)‐7‐dodecenyl acetate. Equal numbers of male moths were captured in traps baited with 10, 100, and 1 000 μg of the attractive binary mixture. These findings allow for the development of a pheromone‐based monitoring system for this invasive pest of clover in Canada.
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