Natural mortality of gypsy moth [Lymantria dispar (L.) (Lepidoptera: Lymantriidae)] eggs, larvae, and pupae was examined at several locations along a gradient of infestation in Ontario, Canada. Most mortality of eggs was the result of exposure to winter weather. This mortality was mitigated in egg masses located near ground level where they benefited from snow cover. At least six species of parasitoids were found attacking gypsy moth larvae and pupae. The most common species were present in the same rank order of abundance at all sites. Identified pathogens were also present in most sites but their relative abundance varied greatly. The mycopathogen Entomophaga maimaiga Humber, Shimazu & Soper (Zygomycetes: Entomophthorales) was found at all sites and usually was responsible for the highest levels of observed, single-source mortality at the site.
Can. Ent. 124: 189-199 (1992) Genetic divergence among populations of cone beetles, Conophrhorus banksianae McPherson, C. coniperda (Schwarz), and C. resinosae Hopkins, was assessed by isozyme electrophoretic data. All but one of the eight loci examined were polymorphic, and one locus (Pgi) was sex-linked for C. coniperda. Genotype frequencies generally met Hardy-Weinberg expectations, and fixation index (Fs3 values indicated low-tomoderate genetic differences among conspecific populations. Fixed allele differences were detected at two loci, Pgi and Dia-2, which separated C. resinosae from C. coniperda, and thus confirmed their specific status established previously by morphological, karyological, and other biochemical characters. Electrophoretic data strongly suggested C. coniperda does not attack red pine cones, and C. resinosae does not attack white pine cones. No diagnostic loci were found to separate C. resinosae from C. banksianae. Phenetic clustering and pairwise comparisons of genetic distance coefficients indicated very little genetic divergence between C. resinosae and C. banksianae. These data were interpreted as failing to reject the null hypothesis that C. resinosae and C. banksianae are one species, an interpretation consistent with available taxonomic evidence from ecological, karyological, and other biochemical characters. de Groot, P., G.T. Harvey et P.M. Roden. 1992. Divergence gtnttique chez les scolytes des pines de I'Est nord-amkricain Conophthorus (Coleoptera: Scolytidae). Can. Ent. 124: 18%199. Resume L'Clectrophorkse des isoenzymes a perrnis d'Ctudier la divergence gCnCtique au sein des populations de scolytes des pins, Conophthorus banksianae McPherson, C. coniperda (Schwarz) et C. resinosae Hopkins. Les huit locus examinks, a l'exception d'un seul, se sont avCrCs polymorphes et l'un de ces locus (Pgi) est liC aux chromosomes sexuels chez C. coniperda. Les frkquences gCnotypiques sont gCnCralement conforrnes au modkle Hardy-Weinberg et la valeur des indices de fixation (F,,) indique l'existence de diffkrences gtnCtiques peu ou modCrCment importantes entre des populations conspCcifiques. Des diffkrences entre les allkles fixes ont Ct C perques a deux locus, Pgi et Dia-2, qui sCparent C. resinosae et C. coniperda, confirmant ainsi le statut spCcifique de ces taxons Ctabli selon des caractCristiques morphologiques et karyologiques et selon d'autres caractkres biochimiques. Les donnCes obtenues a 1'Clectrophorkse indiquent que C. coniperda n'attaque pas les c8nes du pin rouge et que C. resinosae n'attaque pas les c8nes du pin blanc. Nous n'avons pas trouvC de locus permettant de sCparer C. resinosae et C. banksianae. L'analyse de groupements phCnttiques et la comparaison deux a deux des coefficients de distance gCnCtiques indiquent qu'il y a trks peu de divergence gCnCtique entre C. resinosae et C. banksianae. Ces donntes ne permettent pas de rejeter I'hypothkse nulle selon laquelle C. resinosae et C. banksianae foment une seule espkce; cette interprktation est en accord avec les preuves t...
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