DNA barcoding and the taxonomy of Microgastrinae wasps (Hymenoptera, Braconidae): impacts after 8 years and nearly 20 000 sequences.

Microgastrine wasps are among the most species-rich and numerous parasitoids of caterpillars (Lepidoptera). They are often host-specific and thus are extensively used in biological control efforts and figure prominently in trophic webs. However, their extraordinary diversity coupled with the occurrence of many cryptic species produces a significant taxonomic impediment. We present and release the results of 8 years (2004-2011) of DNA barcoding microgastrine wasps. Currently they are the best represented group of parasitoid Hymenoptera in the Barcode of Life Data System (BOLD), a massive barcode storage and analysis data management site for the International Barcoding of Life (iBOL) program. There are records from more than 20 000 specimens from 75 countries, including 50 genera (90% of the known total) and more than 1700 species (as indicated by Barcode Index Numbers and 2% MOTU). We briefly discuss the importance of this DNA data set and its collateral information for future research in: (1) discovery of cryptic species and description of new taxa; (2) estimating species numbers in biodiversity inventories; (3) clarification of generic boundaries; (4) biological control programmes; (5) molecular studies of host-parasitoid biology and ecology; (6) evaluation of shifts in species distribution and phenology; and (7) fostering collaboration at national, regional and world levels. The integration of DNA barcoding with traditional morphology-based taxonomy, host records, and other data has substantially improved the accuracy of microgastrine wasp identifications and will significantly accelerate further studies on this group of parasitoids.

Native range assessment of classical biological control agents: impact of inundative releases as pre-introduction evaluation.

Diadromus pulchellus Wesmael (Hymenoptera: Ichneumonidae) is a pupal parasitoid under consideration for introduction into Canada for the control of the invasive leek moth, Acrolepiopsis assectella (Zeller) (Lepidoptera: Acrolepiidae). Since study of the parasitoid outside of quarantine was not permitted in Canada at the time of this project, we assessed its efficacy via field trials in its native range in central Europe. This was done by simulating introductory releases that would eventually take place in Canada when a permit for release is obtained. In 2007 and 2008, experimental leek plots were artificially infested with pest larvae to mimic the higher pest densities common in Canada. Based on a preliminary experiment showing that leek moth pupae were suitable for parasitism up to 5-6 days after pupation, D. pulchellus adults were mass-released into the field plots when the first host cocoons were observed. The laboratory-reared agents reproduced successfully in all trials and radically reduced leek moth survival. Taking into account background parasitism caused by naturally occurring D. pulchellus, the released agents parasitized at least 15.8%, 43.9%, 48.1% and 58.8% of the available hosts in the four release trials. When this significant contribution to leek moth mortality is added to previously published life tables, in which pupal parasitism was absent, the total pupal mortality increases from 60.1% to 76.7%. This study demonstrates how field trials involving environmental manipulation in an agent's native range can yield predictions of the agent's field efficacy once introduced into a novel area.

Comparative life tables of leek moth, Acrolepiopsis assectella (Zeller) (Lepidoptera: Acrolepiidae), in its native range.

Leek moth, Acrolepiopsis assectella (Zeller) (Lepidoptera: Acrolepiidae), is an invasive alien species in eastern Canada, the larvae of which mine the green tissues of Allium spp. This study was designed to construct and analyse life tables for leek moth within its native range. Stage-specific mortality rates were estimated for the third leek moth generation at three sites in Switzerland from 2004 to 2006 to identify some of the principle factors that inhibit leek moth population growth in areas of low pest density. The contribution of natural enemies to leek moth mortality was measured by comparing mortality on caged and uncaged leeks. Total pre-imaginal mortality on uncaged plants was 99.6%, 99.1% and 96.4% in 2004, 2005 and 2006, respectively. Variation in mortality was greater among years than among sites. Total larval mortality was greater than that in the eggs and pupae. This was due largely to the high mortality (up to 83.3%) of neonates during the brief period between egg hatch and establishment of the feeding mine. Leek moth pupal mortality was significantly greater on uncaged than on caged leeks, indicating an impact by natural enemies, and this pattern was consistent over all three years of study. In contrast, the other life stages did not show consistently higher mortality rates on uncaged plants. This observation suggests that the pupal stage may be particularly vulnerable to natural enemies and, therefore, may be the best target for classical biological control in Canada.

A review of the species of Mesopolobus (Chalcidoidea: Pteromalidae) associated with Ceutorhynchus (Coleoptera: Curculionidae) host-species of European origin.

Four species of Mesopolobus Westwood were reared as parasitoids of Ceutorhynchinae hosts in Europe during surveys in 2000-2004. An illustrated key is given to differentiate the four species, M. gemellus Baur & Muller sp. n., M. incultus (Walker), M. morys (Walker) and M. trasullus (Walker), plus M. moryoides Gibson, a parasitoid of the cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham), in North America. Pteromalus clavicornis Walker is recognized as a junior synonym of M. incultus syn. n., and Pteromalus berecynthos Walker (also a junior synonym of M. incultus) is considered a correct original spelling. For Disema pallipes Förster (a junior synonym of Mesopolobus morys), a lectotype is designated. Mesopolobus morys is for the first time accurately associated with the seed weevil Ceutorhynchus turbatus (Schultze), a potential agent for classical biological control, of hoary cress, Lepidium draba L. (Brassicaceae), in North America. Mesopolobus gemellus is associated with another seed weevil, Ceutorhynchus typhae (=C. floralis) (Herbst), in pods of shepherd's purse, Capsella bursa-pastoris (L.) Medik. (Brassicaceae). Implications of the host-parasitoid associations are discussed relative to the introduction of species to North America for classical biological control of the cabbage seedpod weevil.

Controlling Lygus plant bugs (Heteroptera: Miridae) with European Peristenus relictus (Hymenoptera: Braconidae) in Canada--risky or not?

The European Peristenus relictus Loan (syn. P. stygicus) has been considered for biological control of Lygus plant bugs native to Canada. Laboratory and field studies were conducted in the area of origin to evaluate the host specificity of P. relictus. Laboratory choice and no-choice tests demonstrated that P. relictus attacked all non-target species offered (fundamental host range). However, closely related non-target mirids (tribe Mirini) were generally well accepted by P. relictus, while hosts from the tribe Stenodemini were less frequently attacked and less suitable for parasitoid development. To validate the laboratory results, a thorough examination of the parasitoid complex of common mirids in Europe was conducted to determine which non-target species may serve as alternative hosts for P. relictus in a natural situation (ecological host range). When comparing both approaches, the fundamental host range of P. relictus matched its ecological host range. In addition to three Lygus species, the ecological host range of P. relictus in the area of Schleswig-Holstein, northern Germany, contains at least 16 non-target species, including hosts belonging to the subfamilies Mirinae, Phylinae and Bryocorinae. A broad ecological and fundamental host range suggests that P. relictus is a generalist; however, P. relictus was not the primary contributor to parasitism of most non-target hosts studied. Although P. relictus is assumed to be of minor importance for regulating non-target populations in the area of investigation, the results of the present study indicate that P. relictus has the potential to use non-target host populations for reproduction.

Meteorological factors influencing host-seeking activity of female Simulium luggeri (Diptera: Simuliidae).

The influence of selected meteorological variables on host-seeking activity of parous and nulliparous female Simulium luggeri at cattle bait was studied in central Saskatchewan. Variability in the pattern of diurnal host-seeking probably was attributable to the secondary influence of meteorological parameters on endogenous rhythms that are primarily stimulated by illumination. Although some differences occurred, nulliparous and parous female S. luggeri activity was similarly influenced by the meteorological factors measured. The most important limiting factors were wind speeds greater than 15 km/h, followed by temperatures less than 20 degrees C. When values were outside of these thresholds, saturation deficit, cloud cover, barometric pressure, and illumination became influential. Parous S. luggeri appeared to be more tolerant of dry conditions than nulliparous individuals. Seasonal differences, site location (exposed versus protected), and varied interactions among environmental factors contributed to the inconsistent relationships among meteorological variables and black fly host-seeking activity.

Evaluation of a "cow-type" silhouette trap with and without CO2 bait for monitoring populations of adult Simulium luggeri (Diptera: Simuliidae).

A "cow-type" silhouette trap with "head" and "body" collecting chambers was evaluated for use in monitoring adult populations of Simulium luggeri in Saskatchewan. Ninety-five percent of the black flies taken were S. luggeri. Other species collected included S. vittatum, S. meridionale, S. venustum and S. decorum. Traps baited with CO2 collected significantly more (P less than 0.01) S. luggeri than unbaited traps. The "body" collecting chamber took significantly more (P less than 0.01) S. luggeri than the "head" collecting chamber.