Published online by Cambridge University Press: 31 May 2012
Leptoglossus occidentalis Heidemann (Hemiptera: Coreidae) is considered to be an important cone and seed pest in seed orchards in British Columbia; however, no impact studies have been done in Canada. Surveys to determine the distribution of L. occidentalis were conducted over a 3-year period in three coastal seed orchards of Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, and over a 2-year period in two seed orchards of lodgepole pine, Pinus contorta var. latifolia Engelmann. Leptoglossus occidentalis was found to distribute itself in patches, coinciding with a clonal preference. Seed losses were assessed for 2 years in the coastal Douglas-fir orchards and for 1 year in one lodgepole pine orchard. The percentages of partially filled seed that could have been caused by feeding of L. occidentalis or by a number of other factors were < 5% in coastal Douglas-fir for both 1992 and 1993 and ~14% in lodgepole pine in 1993. Apparently because populations of L. occidentalis were low, there was no correlation between the percentage of partially filled seed and number of insects per tree. Except in unusual circumstances, management measures in Canada are judged not to be necessary as populations of L. occidentalis are consistently below the calculated threshold levels required to cause ≥5% loss in seed production.
Leptoglossus occidentalis Heidemann (Hemiptère : Coreidae) est considéré être un important ravageur des cônes et des graines des vergers à graines de la Colombie-Britannique; aucune étude d’impact n’a cependant été effectuée au Canada. Des vergers ont été étudiés sur une période de 3 ans afin de déterminer la distribution de L. occidentalis dans trois vergers à graines de la variété côtière du Douglas taxifolié, Pseudotsuga menziesii (Mirb.) Franco, et sur une période de 2 ans dans deux vergers à graines du pin tordu, Pinus contorta var. latifolia Engelmann. Les auteurs ont trouvé que L. occidentalis se distribue en groupes, correspondant à une préférence clonale. Les pertes en graines ont été évaluées pendant 2 ans dans les vergers à graines du Douglas taxifolié et pendant 1 an dans un verger de pin tordu. Les pourcentages de graines partiellement remplies qui pourraient être attribués à l’activité trophique de L. occidentalis ou à d’autres facteurs étaient < 5% pour le douglas taxifolié en 1992 et en 1993, et ~14% pour le pin tordu en 1993. Aucune corrélation n’a été trouvée entre le pourcentage de graines partiellement remplies et le nombre d’insectes par arbre, apparemment dû au fait que les populations de L. occidentalis étaient faibles. De plus, des mesures particulières de gestion ne sont pas jugées nécessaires au Canada, sauf dans des circonstances inhabituelles, puisque les populations de L. occidentalis sont sans exception sous les seuils requis pour causer des pertes de production de graines ≥5%.
[Traduit par la Rédaction]
To send this article to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Find out more about the Kindle Personal Document Service.
To save this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you used this feature, you will be asked to authorise Cambridge Core to connect with your Dropbox account. Find out more about saving content to Dropbox.
To save this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you used this feature, you will be asked to authorise Cambridge Core to connect with your Google Drive account. Find out more about saving content to Google Drive.