Isozyme patterns for esterase and polyphenol oxidase were determined for diploid isolates of the six Armillaria intersterility groups collected in British Columbia. Factor analysis of digitized isozyme banding patterns separated A. bulbosa, A. ostoyae, and groups V and IX of Anderson and Ullrich. Results suggest that isozyme patterns may be used to identify subgroups within intersterility groups and to identify closely related intersterility groups.

The Canadian Entomologist 130: 27 -54 (1998) The Agabus semivittatus-group is revised. The group, which is restricted to temperate Northtatus new species in Texas. Agabus stagninus and A. flavovittatus hybridize in southeastern Pennsylvania. The placement o f Agabus texanus Sharp as a junior synonym o f A. semivittatus is confirmed. A lectotype is designated for Agabus spilotus LeConte (=A. semivittatus). A neotype is designated for A. stagninus. A key to species is presented and, for each species, the following information is provided: description; illustrations o f taxonomically important characters; morphological measurements on selected population samples; notes on relationships, variation, and ecology; and a map o f collection localities. A cladistic analysis o f the relationships o f the group within Agabus indicated that the americanus-, spinipes-, and confusus-groups belong to the same clade as the semivittatus-group and that the seriatus-group is sister to this clade. Within the semivittatus-group, there are three well-defined subgroups as follows: A. semivittatus; A. johannis and A. astrictovittatus; and A. stagninus, A. flavovittatus, and A. texovittatus. Larson, D.J., et R.W. Wolfe. 1998. Rivision du genre nord-amiricain Agabus (Coleoptera : Dytiscidae) : le groupe semivittatus. The Canadian Entomologist 130 : 27-54. Le groupe Agabus semivittatus a fait l'objet d'une revision. Ce groupe, restreint a la zone temptree nord-amkricaine, compte six esptces: A. semivittatus LeConte, presque transcontinental, A. johannis Fall, dans la peninsule de Floride, A. astricovittatus, nouvelle espece, repartie le long de la c6te atlantique du New York au nord de la Floride et a l'Alabama, A. stagninus (Say), aussi sur la c6te atlantique du New York la Floride et le long de la c6te du Golfe jusqu'a la Louisiane, A. flavovittatus, nouvelle espece, largement repandue a l'est des Grandes Plaines, du sud de I'Ontario au Mississippi et a la partie est du Texas, mais pas sur la c6te atlantique, enfin A. texovittatus, nouvelle espkce, du Texas. I1 y a hybridation entre Agabus stagninus et A. flavovittatus dans le sud-est de la Pennsylvanie. Nous confirmons ici qu'Agabus texanus Sharp est bien un synonyme recent d'A. semivittatus. Des lectotypes ont kt6 designes pour A. spilotus LeConte (=A. semivittatus). Un nkotype d'A. stagninus a Bt B choisi. On trouvera ici une clk des espkces et, pour chaque espece, les informations suivantes: description, illustration des caracteres diagnostiques, mesures morphologiques d'kchantillons choisis de la population, notes sur les liens de parent6, sur la variation et sur l'kcologie, enfin une carte des sites de rkcolte. L'analyse cladistique de la position du groupe au sein du genre 28 THE CANADUN ENTOMOLOGIST JanuaryFebruary 1998 Agabus a rCvtle que les groupes americanus, spinipes et confusus appartiennent au meme clade que le groupe semivittatus, et que le groupe seriatus est le groupe soeur de ce clade. Au sein du groupe semivittatus, il existe trois sous-groupes bien dkfinis : (1) A. se...

The survival of two Canadian isolates of the pinewood nematode, Bursaphelenchus xylophilus, in coniferous wood chips under different temperatures, relative humidities and time intervals was investigated in vitro. The nature of the survival mechanism was examined and it was shown that the nematode's prolonged survival in the chips depended on its dispersal third larval stage. The possibility of PWN‐infested wood chips spreading PWN‐induced pine‐wilt disease to forests is discussed.

Feeding on leaders of resistant Sitka spruce trees, Picea sitchensis (Bong.) Carr., Led to ovarian regression in white pine weevils, Pissodes strobi Peck., that contained already mature eggs at the time of caging on leaders. Such feeding also led to inhibition or a virtual blockage of ovarian development in weevils that did not contain already mature eggs at the time of caging. Ovarian maturation in such weevils was restored by application of juvenile hormone to female weevils. Effects of three levels of resistance were consistent within the experiments and with the field performance of the tested clones. These results indicate that the effects of resistance were postingestive, i.e., resistance was a form of antibiosis. How antibiosis can cause the weevils to concentrate oviposition on susceptible trees is discussed. Results also provide a means of selecting and ranking resistance of individual spruce trees for tree breeding and reforestation.