title: Host tree species and burn treatment as determinants of preference and suitability for Monochamus scutellatus scutellatus (Coleoptera: Cerambycidae).
abstract: 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.
authors.affiliation: Faculté de foresterie, de géographie et de géomatique, Pavillon Abitibi-Price, 2405 rue de la Terrasse, Bureau 1151, Université Laval, QC, Canada G1V 0A6.
authors.forename: Yannick
authors.initials: Y
authors.lastname: Breton
authors.forename: Christian
authors.initials: C
authors.lastname: Hébert
authors.forename: Jacques
authors.initials: J
authors.lastname: Ibarzabal
authors.forename: Richard
authors.initials: R
authors.lastname: Berthiaume
authors.forename: Eric
authors.initials: E
authors.lastname: Bauce
mesh_terms: D000818:Animals; D001517:Coleoptera / Q000254:growth & development / Q000502:physiology*; D005260:Female; D005390:Fires; D007814:Larva / Q000254:growth & development / Q000502:physiology; D010058:Oviposition; D028222:Picea / Q000254:growth & development*; D028223:Pinus / Q000254:growth & development*; D011156:Population Density; D011792:Quebec