Henri Goulet

Towards Insecticide Free Apple Orchards: Flowering Plants to Attract Beneficial Arthropods

Tanacetum vulgare, Chrysanthemum maximum, Aster tongolensis and Achillea millefolium were planted to attract and retain predacious and parasitoid arthropods in a Quebec apple orchard. The plants covered one-third of the surface of the experimental block and provided nectar, pollen and refuge for beneficial arthropods. The parasitoid fauna increased several-fold during the study. The most important index of pest management in this study was the quality of the fruit at harvest and it attained 90.8% (clean fruit) in the fifth year of the study. The technique cannot be readily adopted into an orchard that is in full production because it would require several years to build up the beneficial arthropod fauna to an effective bio-control force. During that period, pesticides would not be applied and losses in yield would be commercially unacceptable. Habitat management should be used as a template for biological control of orchard pests over which other bio-control techniques can be superimposed to further increase the quality of the yield at harvest.

A poorly known high-latitude parasitoid wasp community: unexpected diversity and dramatic changes through time.

Climate change will have profound and unanticipated effects on species distributions. The pace and nature of this change is largely unstudied, especially for the most diverse elements of terrestrial communities – the arthropods – here we have only limited knowledge concerning the taxonomy and the ecology of these groups. Because Arctic ecosystems have already experienced significant increases in temperature over the past half century, shifts in community structure may already be in progress. Here we utilise collections of a particularly hyperdiverse insect group – parasitoid wasps (Hymenoptera; Braconidae; Microgastrinae) – at Churchill, Manitoba, Canada in the early and mid-twentieth century to compare the composition of the contemporary community to that present 50–70 years ago. Morphological and DNA barcoding results revealed the presence of 79 species of microgastrine wasps in collections from Churchill, but we estimate that 20% of the local fauna awaits detection. Species composition and diversity between the two time periods differ significantly; species that were most common in historic collections were not found in contemporary collections and vice versa. Using barcodes we compared these collections to others from across North America; contemporary Churchill species are most affiliated with more south-western collections, while historic collections were more affiliated with eastern collections. The past five decades has clearly seen a dramatic change of species composition within the area studied coincident with rising temperature.

DNA barcoding reveals diversity of Hymenoptera and the dominance of parasitoids in a sub-arctic environment.

BackgroundInsect diversity typically declines with increasing latitude, but previous studies have shown conflicting latitude-richness gradients for some hymenopteran parasitoids. However, historical estimates of insect diversity and species richness can be difficult to confirm or compare, because they may be based upon dissimilar methods. As a proxy for species identification, we used DNA barcoding to identify molecular operational taxonomic units (MOTUs) for 7870 Hymenoptera specimens collected near Churchill, Manitoba, from 2004 through 2010.ResultsWe resolved 1630 MOTUs for this collection, of which 75% (1228) were ichneumonoids (Ichneumonidae + Braconidae) and 91% (1484) were parasitoids. We estimate the total number of Hymenoptera MOTUs in this region at 2624-2840.ConclusionsThe diversity of parasitoids in this sub-Arctic environment implies a high diversity of potential host species throughout the same range. We discuss these results in the contexts of resolving interspecific interactions that may include cryptic species, and developing reproducible methods to estimate and compare species richness across sites and between surveys, especially when morphological specialists are not available to identify every specimen.

Establishment of Peristenus digoneutis and P. relictus (Hymenoptera: Braconidae) in California for the control of Lygus spp. (Heteroptera: Miridae)

Abstract Lygus hesperus Knight is native to the western United States and is a perennial pest of numerous crops in California. It is responsible for triggering the early season application of insecticides on cotton, Gossypium hirsutum L., and strawberries, Fragaria L. Despite several surveys conducted in alfalfa (Medicago sativa L.) grown in central California, nymphal parasitoids associated with L. hesperus and L. elisus have not been found. Two exotic parasitoids were released into California beginning in 1998. Peristenus relictus (Ruhte), formerly P. stygicus Loan, and P. digoneutis Loan were collected from several locations in southern Europe and released at up to six locations over a 6-year period. At the original release site in Sacramento, a 0.25-ha plot of alfalfa, parasitism by P. digoneutis and P. relictus combined increased from zero to 90%, 3 years after the last releases were made. Parasitoids have been recovered from vacant fields of weedy annuals within 2 km of this site. Recoveries at more southerly release sites in central California have been poor.

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.

The diversity and biogeography of the Coleoptera of Churchill: insights from DNA barcoding

BackgroundColeoptera is the most diverse order of insects (>300,000 described species), but its richness diminishes at increasing latitudes (e.g., ca. 7400 species recorded in Canada), particularly of phytophagous and detritivorous species. However, incomplete sampling of northern habitats and a lack of taxonomic study of some families limits our understanding of biodiversity patterns in the Coleoptera. We conducted an intensive biodiversity survey from 2006–2010 at Churchill, Manitoba, Canada in order to quantify beetle species diversity in this model region, and to prepare a barcode library of beetles for sub-arctic biodiversity and ecological research. We employed DNA barcoding to provide estimates of provisional species diversity, including for families currently lacking taxonomic expertise, and to examine the guild structure, habitat distribution, and biogeography of beetles in the Churchill region.ResultsWe obtained DNA barcodes from 3203 specimens representing 302 species or provisional species (the latter quantitatively defined on the basis of Molecular Operational Taxonomic Units, MOTUs) in 31 families of Coleoptera. Of the 184 taxa identified to the level of a Linnaean species name, 170 (92.4%) corresponded to a single MOTU, four (2.2%) represented closely related sibling species pairs within a single MOTU, and ten (5.4%) were divided into two or more MOTUs suggestive of cryptic species. The most diverse families were the Dytiscidae (63 spp.), Staphylinidae (54 spp.), and Carabidae (52 spp.), although the accumulation curve for Staphylinidae suggests that considerable additional diversity remains to be sampled in this family. Most of the species present are predatory, with phytophagous, mycophagous, and saprophagous guilds being represented by fewer species. Most named species of Carabidae and Dytiscidae showed a significant bias toward open habitats (wet or dry). Forest habitats, particularly dry boreal forest, although limited in extent in the region, were undersampled.ConclusionsWe present an updated species list for this region as well as a species-level DNA barcode reference library. This resource will facilitate future work, such as biomonitoring and the study of the ecology and distribution of larvae.

Weevil (Coleoptera: Curculionoidea) Diversity and Abundance in Two Quebec Vineyards

Abstract The wine-making region of southern Quebec in Canada experiences growing conditions that are unique in northeastern North America. After an outbreak of insect pests in 1996, a study of insect groups that may include potential pests or beneficial species was initiated. This article reports on the weevil diversity and abundance during three consecutive years of sampling (1997–1999) in two vineyards. All weevils were collected using pitfall and flight intercept traps. In total, 3,176 specimens were collected, representing 73 species in three families of Curculionoidea. The family Curculionidae was the most species rich, especially the subfamilies Ceutorhynchinae, Curculioninae, and Entiminae. Four of the species recorded are known to feed on the genus Vitis (Vitaceae) in North America: Madarellus undulatus (Say), Barypeithes pellucidus (Boheman), Otiorhynchus ovatus (L.), and Otiorhynchus sulcatus (F.). Of these, O. sulcatus is thought to represent the greatest potential threat based on adult abundance at one of the sites and the negative impact of this species in other wine-making regions in North America. Four species [Ceutorhynchus oregonensis Dietz, Pelenomus waltoni (Boheman), Rhinoncus perpendicularis (Reiche), and Sphenophorus minimus Hart] are recorded in Quebec for the first time. A significant number of weevils collected during this study are adventive species associated with agroecosystems of northeastern North America.

Diversity and Seasonal Activity of Ground Beetles (Coleoptera: Carabidae) in Two Vineyards of Southern Quebec, Canada

Abstract From 1997 to 1999, 11,435 specimens of ground beetles representing 124 species were captured in pitfall traps at two commercial vineyards in southern Quebec, Canada. Taking into account only the species breeding or likely breeding in the two vineyards, the carabid diversity was similar over the 3-yr period in both sites. The number of species was similar (51 and 54) in both vineyards, but the most common species were ranked differently in a position that was consistent over the 3-yr period. Chlaenius sericeus (Forster) and Clivina fossor (L.) occurred mainly on the clay loam vineyard, and Amara latior (Kirby) and Harpalus herbivagus Say on the gravel and sand loam vineyard. The Shannon diversity and evenness indexes were greater at the gravel and sand loam vineyard. Two recently introduced European species, Harpalus rufipes (Duftschmid) and Pterostichus vernalis (Panzer), became more prevalent between 1997 and 1999 and are likely to affect the rank position at each site. Diversity at the clay loam vineyard was equal to another unsprayed and annually cultivated site on clay in the ecozone. It shared with the unsprayed site a similar number of species for an equal sample size, Shannon and evenness indexes, and for most species, ranking of the most commonly trapped species.

Native braconid parasitism of the Tarnished plant bug (Hemiptera: Miridae) in Southern Ontario

Abstract Three agricultural regions in southern Ontario (London, Niagara and Guelph) were sampled weekly from May to September for Lygus spp. and their parasitoids in 1998, 1999 and only one region in 2000. Alfalfa was the primary crop sampled, including both “clean” and weedy alfalfa fields. Lygus lineolaris (Palisot de Beauvois) accounted for 99% of all Lygus spp. collected by sweepnet. Lygus lineolaris had two generations (mid-June and late July) on alfalfa with a partial third generation in early September which contributes to the over-wintering adults. In 1998 and 2000, an early first generation peak of Lygus nymphs was observed in mid-May on the weeds, chickweed and shepherds purse. Overall rates of parasitism (from dissections) for native parasitoids were consistent from year to year and the means of the three regions in each growing season were below 11%. Both nymphs and adult Lygus were parasitized, with the highly mobile adults being a potential means of dispersing the parasitoids. In general weedy fields were more highly parasitized than fields of weed-free alfalfa. Six species of native braconid parasitoids were collected from L. lineolaris in southern Ontario (in decreasing order of occurrence): Peristenus pallipes (Curtis), Peristenus pseudopallipes (Loan), Leiophron lygivorus (Loan), L. solidaginis Loan, L. uniformis (Gahan), and Leiophron sp. near brevipetiolatus Loan. The large populations of Lygus and the low percent baseline parasitism in southern Ontario, particularly of second generation Lygus, support the need for introduction of a multivoltine parasitoid species in this region.

Biological assessment of Macrocentrus linearis and Apanteles polychrosidis (Hymenoptera: Braconidae) as parasitoids of the obliquebanded leafroller, Choristoneura rosaceana (Lepidoptera: Tortricidae)

Abstract The biologies of two endoparasitoids of the obliquebanded leafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae) from organically managed apple orchards in the southern interior of British Columbia, Canada were studied in the laboratory. Macrocentrus linearis (Nees) (Hymenoptera: Braconidae) oviposited into first through fourth instar obliquebanded leafrollers. A sympatric leafroller species found in this area of British Columbia, the three-lined leafroller, Pandemis limitata (Robinson) (Lepidoptera: Tortricidae) was not accepted as an alternate host species by M. linearis. When provided with honey-water and held under fall and summer orchard temperatures, M. linearis females survived significantly longer under fall than summer temperatures ( =28.3±2.4 and 20.2±2.5 days, respectively) but parasitized a similar number of obliquebanded leafroller larvae ( =12.2±5.0 and 24.4±9.2 larvae, respectively). A mean of 20.6±4.9 larvae emerged per parasitized obliquebanded leafroller in the hosts fifth or sixth instar. Obliquebanded leafroller larvae parasitized by M. linearis consumed significantly more diet than unparasitized hosts from fifth instar to pupation, suggesting that M. linearis may not reduce host feeding damage to fruit except through the ultimate reduction of host populations. Apanteles polychrosidis Viereck (Hymenoptera: Braconidae) parasitized the first through third instars of both the obliquebanded and three-lined leafrollers. When provided with honey-water and held at temperatures typical of either fall or summer in orchards, A. polychrosidis females survived significantly longer ( =46.6±3.1 and 26.4±2.5 days, respectively) and parasitized significantly more obliquebanded leafrollers under fall than summer temperatures ( =61.5±7.2 and 18.4±5.3 total larvae, respectively). A single A. polychrosidis larva emerges from a third or fourth instar leafroller host. Consequently, parasitized obliquebanded leafroller larvae consumed significantly less diet than unparasitized larvae from fourth instar to pupation. Attributes of both parasitoids are compared with those of another common obliquebanded leafroller parasitoid, Apophua simplicipes (Cresson) (Hymenoptera: Ichneumonidae).