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Forest protection against eastern spruce budworm, Choristoneura fumiferana (Clemens), relies on aerial applications of Bacillus thuringiensis (Btk). However, Btk prescriptions have been developed for balsam fir (Abies balsamea (L.) Mill.) stands, generating uncertainty as to the relevance of this protection approach on white spruce (Picea glauca (Moench) Voss). The main goal of this study was to evaluate the efficacy of three Btk application treatments (early application, late application, and double application) for protecting white spruce and balsam fir in mixed stands. Our results show that all Btk treatments tested kept defoliation under the 50% threshold on balsam fir (27.7 to 38.1% less defoliation than in controls). In contrast, differences in defoliation among treatments were not significant for white spruce. Larval mortality was significantly lower on white spruce than on balsam fir. The low efficacy of Btk treatments on white spruce may be explained by its shoot phenology (most bud caps were still present during the early application), and its foliar chemistry, which could decrease Btk efficacy. Consequently, many larvae may survive simply because Btk spores do not reach them, or because they may consume sublethal doses. We recommend maintaining the current strategy in mixed stands, as it provides a good protection for balsam fir. Further research is needed to determine the causes of the low efficacy of Btk treatments on white spruce. [ABSTRACT FROM AUTHOR]

This study aimed to characterize the vertical distribution of longhorned beetle larvae in burned trees of the eastern Canadian boreal forest. Black spruce (Picea mariana (Mill.) Britton, Sterns & Poggenb.) and jack pine (Pinus banksiana Lamb.) trees burned at three severity levels were cut, and 30 cm boles were collected from the ground up to a height of 9.45 m. Boles were debarked and dissected to collect insect larvae. Results show that the three most abundant longhorned beetle species were vertically segregated among burned jack pine and black spruce trees, but the section having the highest timber value was heavily infested by woodborer larvae. Larval density distribution of Monochamus scutellatus scutellatus (Say) and of Acmaeops proteus proteus (Kirby) could be linked with bark thickness, which also depends on fire severity. Lightly burned stands of black spruce were the most heavily infested and should be salvaged only if they are easily accessible and can thus be rapidly harvested and processed at the mill. More severely burned stands should be salvaged later as they will be less affected by woodborers, as should jack pine, which is lightly infested compared with black spruce. The ecological role of stumps should be further investigated because they could still have an ecological value after salvage logging as Arhopalus foveicollis (Haldeman) uses them specifically. Key words: Cerambycidae, vertical distribution, boreal forest, bark thickness, fire severity. Cette etude visait a caracteriser la repartition verticale des larves de longicornes dans des arbres brules de la foret boreale de l'est du Canada. Des epinettes noires (Picea mariana (Mill.) Britton, Sterns & Poggenb.) et des pins gris (Pinus banksiana Lamb.) brules atrois degres de severite ontete coupes etdesbuches de 30cmontete recoltees, apartirdu soljusqu'aune hauteur de 9.45 m. Les buches ont ete ecorcees et dissequees pour recolter les larves d'insectes. Les resultats revelent que les trois especes les plus abondantes de longicornes montraient une segregation verticale sur le pin gris et l'epinette noire brules, mais que la section ayant la plus grande valeur commerciale etait fortement infestee par des larves de longicorne. La densite larvaire de Monochamus scutellatus scutellatus (Say) et celle d'Acmaeops proteus proteus (Kirby) pourraient etre liees a l'epaisseur de l'ecorce, qui depend elle aussi de la severite du feu. Les peuplements d'epinette noire legerement brules etaient les plus infestes et devraient etre recuperes seulement s'ils sont faciles d'acces et peuvent ainsi etre rapidement recuperes et traites a l'usine. Les peuplements plus gravement brules devraient etre recuperes plus tard, car ils sont moins affectes par les longicornes, de meme que le pin gris qui est moins infeste que l'epinette noire. Le role ecologique des souches devrait etre etudie davantage car elles pourraient conserver une valeur ecologique meme apres la coupe de recuperation puisque Arhopalus foveicollis (Haldeman) les utilisent specifiquement. Mots-cles: Cerambycidae, repartition verticale, foret boreale, epaisseur de l'ecorce, severite du feu., Introduction Wildfire is considered a dominant natural disturbance in the Canadian boreal forest (Nappi et al. 2011). Between 2000 and 2010, an average of 1784 590 ha of forest has [...]

We investigated the early responses of bark and wood boring beetles to an extensive supply of balsam fir (Abies balsamea) trees, stressed or recently killed during an outbreak of the hemlock looper (Lambdina fiscellaria) in Quebec, Canada.The present study aimed to (i) examine beetle assemblages across all levels of defoliation and (ii) assess the relative influences of defoliation, tree mortality, stand structure and spatial context on beetle assemblages.We used three types of traps in each of 36 plots: multidirectional flight interception traps measured adult beetle flight activity within stands, trunk window traps measured visitation rates at trees and emergence traps measured beetle colonization of trees.Flight traps in nondefoliated plots allowed characterization of 'pre‐outbreak' beetle assemblages, which were not discernable in emergence traps because few insects colonize heathy trees. 'Pre‐outbreak' assemblages, characterized by a mix of polyphagous beetle species (e.g. Evodinus monticola, Dryocoetes autographus), shifted to those dominated by Trypodendron lineatum after extensive defoliation. Two Pissodes species colonized heavily defoliated trees but not dead ones.Defoliation level, conifer basal area, basal area of dead balsam firs and the extent of recently logged areas around sampling plots were positively correlated with the abundance of T. lineatum. [ABSTRACT FROM AUTHOR]

After fire, the whitespotted sawyer, Monochamus scutellatus scutellatus (Say) (Coleoptera: Cerambycidae), is considered one of the most damaging xylophagous insects by forest industries in the eastern boreal forest of North America. Although this species is often considered opportunistic because it dwells on various stressed host trees, it can be found in very high abundance after forest fire and, consequently, it has been suspected of being a pyrophilous species or fire-associated species. The aim of this study was first to determine whether the whitespotted sawyer lays eggs preferentially on burned rather than unburned hosts, and second, to determine its preference between black spruce (Picea mariana [Mill.] B.S.P.) and jack pine (Pinus banksiana Lamb.) for oviposition. Host suitability also was estimated to determine if whitespotted sawyer females make optimal choices to maximize offspring development. To determine host suitability, we used the abundance distribution of larval instars as a proxy of larval development quickness and we compared weight and head-capsule width of larvae of different larval instars as measures of insect growth in each type of log. Based on the frequency of oviposition behavior, females showed no preference for either burned or unburned black spruce logs, and both were equally suitable for larval development. Furthermore, females laid more eggs on black spruce than on jack pine, but host suitability was not statistically affected. Nevertheless, larvae had mostly reached the fourth instar on black spruce, whereas those on jack pine were mostly at the third instar, suggesting faster development on black spruce. [ABSTRACT FROM AUTHOR]

The article presents the study on the cost effectiveness of bacterial insecticide Bacillus thuringienses ssp. Kurstaki (Btk) on the defoliation of spruce budworm (SBW) Choristoneura fumiferana on balsam fir trees. The study has evaluated the growth loss and mortality to find out their contributions on the total losses in each tree treatment category. The result reveals that Btk is able to reduce growth loss impacts caused by SBW. It further concludes that Btk treatments has economic advantage.

The Asian ladybird beetle, Harmonia axyridis, an introduced species that is established in Quebec since 1994, rapidly became an entomological problem because it aggregates in buildings during fall and winter. The reason most often invoked to explain this behaviour is a weak resistance of the species to winter coldness. To determine cold resistance of the Asian ladybird beetle, a study including various cold temperatures and exposure times was carried out. Groups of 50 beetles were placed in Petri dishes and exposed to different temperatures (5, 0, −5, −10 and −20°C) for different periods of time (2, 6, 12 and 18 weeks). Results indicate that survival is strongly influenced by temperature but also by exposure duration. Furthermore, no Asian ladybird beetle survived at −20°, even for only one day of exposure. [ABSTRACT FROM AUTHOR]

Studies changes in hemlock looper pupal distribution through a three-year outbreak cycle on Anticosti Island, Quebec. Distribution in pre-outbreak conditions; Pupal density; Preferred location for hemlock looper pupation.

A major outbreak of the hemlock looper, Lambdina fiscellaria (Guenée), predicted for 1997 on the Gaspé Peninsula in Quebec, collapsed due to egg parasitism by Telenomus spp. Only 3,857 ha of balsam–spruce forest were defoliated from the forecasted 130,000-ha outbreak area. This represents only 3% of the anticipated outbreak area. We present data that indicate highly efficient natural control by Telenomus spp. The L. fiscellaria population also collapsed due to egg parasitism by Telenomus spp. on Anticosti Island in the same year. In the past, L. fiscellaria egg parasitism has usually been estimated from egg samples collected in the fall or early spring surveys and was based mostly on the eggs’ black coloration. However, our observations indicate that entirely black and opaque eggs result from parasitism by Trichogramma spp., those attacked by Telenomus spp. varying from translucent to dark brown but always showing a single dark spot on the chorion. Moreover, our data on seasonal egg parasitism showed important and rapid increases in parasitism by Telenomus spp. in late spring. Therefore, similar unexplained L. fiscellaria outbreak collapses that occurred in the past might have also been caused by egg parasitism by Telenomus spp. There are several species in the Telenomus complex attacking L. fiscellaria and the most abundant one might be a “keystone species” in the population dynamics of this defoliator. The spring activity of Telenomus spp. may lead to errors when forecasting L. fiscellaria populations based only on fall egg surveys. [ABSTRACT FROM PUBLISHER]