2012 Collection Campaign

We are well underway with our 2012 collection campaign.  To process the cones and seeds we have been graciously sent by many seed orchards and arboretums, the project has welcomed myself, Ashley Clingen, back for the fall. We have already recieved shipments from:

University of Guelph Arboretum
Chihuahuan Desert Nature Center
University of Wisconsin at Madison Arboretum
Arnold Arboretum of Harvard University
Dorena Genetic Resource Center
Beaver Creek Seed Orchard on the Siuslaw National Forest
Western Forest Products – Saanich Forestry Centre
Mount Newton Seed Orchard
Kalamalka Forestry Centre

We also have many shipments coming in soon from:

Longwood Gardens
Houston Arboretum and Nature Center
Wilbur D. May Arboretum
New York Botanical Garden
North Carolina Botanical Gardens
Holden Arboretum
University of California at Davis Arboretum
Quarryhill Botanical Gardens
Crosby Arboretum
USDA-NRCS Bridger Plant Materials Center
British Columbia Forest Service Tree Seed Centre
Yellowpoint Propagation

Several other arboretums are working to determine whether their accessions are suitable for sampling for our project or whether or not staff will be allocated to the sampling effort.  We thank these seed and cone sources for their support!


Results of the 2011-12 campaign

This post summarizes the results of our 2011-12 campaign.

Let’s start with the visual examination of the cones and berries:

  • As reported earlier, Western Red Cedar (Thuja plicata) cones received from the Saanich Forestry Centre (British Columbia) showed insect damage. Papery cocoons between the scales, in places where the seeds should have been are likely traces of the red cedar cone midge, Mayetiola thujae (Diptera, Cecidomyiidae). This insect is the most serious pest of Western red cedar in BC, Washington and Oregon. Mayetiola larvae feed inside the cones from May through late summer. The cones were collected mid-August. By that time, mature larvae have constructed a cocoon within which they will overwinter. We didn’t get any emergence from these cocoons so we can’t confirm that it was indeed M. thujae.  One bag of cones also contained a metallic green chalcid that resembles Torymus azureus, a parasite of the galling midge Kaltenbachiola rachiphaga in spruce cones. Could this be a parasite of M. thujae?
    The same cones had also holes previously described as “exit holes” but could also be puncture holes from pentatomid feeding, as suggested by our colleague Ward Strong.
  • Other traces of infestation in the form of almost perfectly circular holes (see picture) were found on cones of Juniperus virginiana, J. horizontalis and J. communis from British Columbia (Shorts Creek Canyon), Ontario (Guelph Arboretum) and Northeastern US (Boston, MA). This damage looks like exit holes of a seed chalcid, possibly Eurytoma juniperina. In their review, Chambers et al (1999) listed several insect species affecting Juniperus seed production in Western North America including the chalcidoid wasp Eurytoma juniperina on J. horizontalis. This insect is also found on the Rocky Mountain juniper (J. scopulorum).

J. horizontalis from Guelph showing exit hole

J. communis from Shorts Creek Canyon (BC) showing exit holes

  • Several insects were also found in the bags containing the juniper berries collect by Ward Strong at the Shorts Creek Canyon (BC). The determination of these insects is in progress.

After visual examination, all samples were processed for seed extraction, cleaning and x-raying. In total, more than 51.000 seeds from 34 species sampled in 35 locations over 2 sampling dates were treated last year. Seeds that were identified as potentially infested on the x-rays were picked from the samples and put in rearing in emergence boxes outside in Great Lakes Forestry Centre (Sault Ste Marie, ON) insectarium. Reading x-rays can be challenging, particularly for smaller seeds, so a conservative approach was taken and seeds were picked out even when there was only the smallest indication of a possible infestation. No emergence had occurred by mid-July so we decided to dissect some seeds from each sample to confirm the presence of larvae in the seeds. We will present the results by host species:

  • Chamaecyparis obtusa: infested seeds were found at the Arnold Arboretum (28/345 infested seeds) and the Morris Arboretum (359/1842 infested seeds). Samples from the New York botanical garden were not infested. The dissection of the Arnold and Morris samples confirmed that the seeds were infested. Seeds of C. obtusa are infested by Megastigmus chamaecyparidis  and Megastigmus cryptomeriae in Japan but to our knowledge, these Megastigmus species have never been recorded in North America.
  • Chamaecyparis thyoides: infested seeds (4/250 on x-rays, 3/251 confirmed after dissection) were found in samples collected at the University of North Carolina Botanical Garden. Interestingly, none of the other C. thyoides samples collected at the Atlanta Botanical Gardens (GA), Arnold Arboretum (MA), New York Botanical Garden (NY), Cornell Plantations (NY), and Morris Arboretum (PA) were infested. Dissection confirmed that 3 seeds were infested, the other was empty. Infestation is likely due to Megastigmus thyoides. This chalcid was first found in seeds of C. thyoides collected in 1994 in North Carolina (Turgeon et al., 1997).
  • Cryptomeria japonica: among all the C. japonica seed samples we received from the Arnold Arboretum (MA), Atlanta Botanical Gardens (GA), the UC Davis Arboretum (CA), and the Morris Arboretum at UPenn, the latter was the only one showing some level of infestation (29/413). The presence of larvae in these seeds was confirmed by dissection. Cryptomeria japonica seeds are known to be infested by Megastigmus cryptomeriae in Japan, China and Taiwan but this species has never been recorded in North America.
  • Juniperus communis or horizontalis: only one seed out of 664 collected by Ward Strong at the Shorts Creek Canyon (BC) appeared on the x-rays as being infested. The dissection of this seed confirmed the presence of a larva.

In summary, without being able to attribute any infestation to a species or even a genus at this point, we can confirm that we have found seed infestation in 4 species of Cupressaceae: Chamaecyparis obtusa, Chamaecyparis thyoides, Cryptomieria japonica and Juniperus communis or horizontalis.

Species sampled in 2011

Well, looking back at our 2011 campaign, the list of species that we sampled doesn’t look to bad indeed. We managed to sample 34 species, including 18 native. The list with sampling locations is given below (native species are in bold):

  • Chamaecyparis lawsoniana: Dorena Genetic Resource Center, Canadian National Tree Seed Centre, UC Davis Arboretum, Morris Arboretum
  • Chamaecyparis nookatensis: Arnold Arboretum, Guelph Arboretum, New York Botanical Gardens
  • Chamaecyparis obtusa: Arnold Arboretum, Cornell Plantations, New York Botanical Gardens
  • Chamaecyparis pisifera: Cornell Plantations, Arnold Arboretum, New York Botanical Gardens
  • Chamaecyparis thyoides: New York Botanical Gardens, Cornell Plantations, Arnold Arboretum, North Carolina Botanical Garden
  • Cunninghamia lanceolata: Morris Arboretum
  • Cryptomeria japonica: Arnold Arboretum, UC Davis Arboretum
  • Cupressus arizonica: Arnold Arboretum, UC Davis Arboretum
  • Cupressus bakeri: Arnold Arboretum, UC Davis Arboretum
  • Cupressus forbesii: UC Berkeley
  • Cupressus glabra: Morris Arboretum
  • Cupressus goveniana: UC Davis Arboretum
  • Cupressus macnabiana: UC Berkeley
  • Cupressus sempervirens: UC Davis Arboretum
  • Juniperus bermudiana: Huntington Botanical Gardens
  • Juniperus chinensis: Morris Arboretum,  UW Arboretum, Cornell Plantations, Guelph Arboretum, New York Botanical Garden, Great Lakes Forestry Centre Arboretum
  • Juniperus communis: Canadian National Tree Seed Centre, Morris Arboretum, Arnold Arboretum, Guelph Arboretum, Bluenose Mountain
  • Juniperus horizontalis: Guelph Arboretum, Pancake Bay Provincial Park, Cornell Plantations, New York Botanical Garden
  • Juniperus phoenicea: JC Raulston Arboretum
  • Juniperus rigida: Cornell Plantations, New York Botanical Garden
  • Juniperus sabina: Arnold Arboretum, Guelph Arboretum
  • Juniperus scopulorum: Canadian National Tree Seed Centre, UC Davis Arboretum, Ellison Provincial Park, Guelph Arboretum
  • Juniperus squamata: Cornell Plantations, New York Botanical Garden, Arnold Arboretum, Guelph Arboretum, Morris Arboretum
  • Juniperus virginiana: Canadian National Tree Seed Centre, Arnold Arboretum, North Carolina Botanical Garden, UC Davis Arboretum Guelph Arboretum, New York Botanical Garden
  • Juniperus xpfitzeriana: New York Botanical Garden
  • Platycladus orientalis: Guelph arboretum
  • Sciadopitys verticillata: Arnold Arboretum
  • Sequioadendron giganteum: Arnold Arboretum
  • Sequoia sempervirens: UC Davis Arboretum
  • Taxodium disticum: UC Davis
  • Thuja occidentalis: Canadian National Tree Seed Centre
  • Thuja plicata: Canadian National Tree Seed Centre
  • Thujopsis dolabrata: Arnold Arboretum
  • Xanthrocyparis nootkatensis: Cornell Plantations

Winter update

This is a long overdue update of our operations two seasons ago!

In Oct. and Nov. 2011, we asked several arboreta, seed orchards and botanical gardens to send us seed samples from their Cupressaceae collections. We received samples from the following locations:

  • University of Guelph Arboretum
  • University of Wisconsin – Madison Arboretum
  • Huntington Botanical Gardens
  • University of California Davis Arboretum
  • University of North Carolina Botanical Gardens
  • Morris Arboretum of the University of Pennsylvania
  • Atlanta Botanical Gardens
  • University of California Berkeley Botanical Garden
  • Beaver Creek Seed Orchard (in the Siuslaw National Forest)

Between the two collection campaigns we organized in 2011, we sampled 35 locations as shown on the map below.

Sampling locations 2011

Sampling locations of Cupressaceae seeds (summer and winter 2011)

The rest of the winter was spent extracting, cleaning and x-raying the seeds. The X-rays were developed and read shortly after.

Western Red Cedar and Yellow Cedar cones from Saanich (BC)

Early September, we received from the Saanich Forestry Centre (British Columbia):

  • 5 samples (12 cones per sample harvested at different locations on the tree) of Yellow Cedar (Callitropsis nootkatensis)
  • 5 samples (12 cones per sample harvested at different locations on the tree) of Western Red Cedar (Thuja plicata).
    As visible in the picture below, some cones exhibited exit holes:

    Some cones had also what looks like midge larvae (see picture below), likely Mayetiola thujae, but we’ll have to wait to confirm.

    Finally, we found in one bag of cones a chalcid, metallic green (see picture below – sorry for the poor quality of the picture and subject presentation), quite small (2mm body length). This is possibly a parasitoid of the midge we found in the cones, but again, we’ll have to wait to confirm!

    We will x-ray the seeds from this shipment in the next few weeks.

Thank you Ashley!

Last Friday was Ashley’s last day on this project. She has done an incredible amount of work in the past 4 months. I would like to thank her for her dedication and wish her all the best in her future endeavours.

All future inquiries related to this project will have to be addressed directly to me (Jean-Noel.Candau@nrcan.gc.ca). Replies will probably come slower than you have experienced in the past 4 months!


Translations Needed

During our extensive literature search for Megastigmus infestations of Cupressaceae both in North America and world-wide, we have come across many journal articles that are not in English or French.  These articles have been used in other publications written in either French or English, which means they have been translated for other authors.  If you have translations for any of the following papers, please email Jean-Noel.Candau@nrcan.gc.ca.

Canakcioglu, H. (1959) Studies on insects which are injurious to the turkish forest tree seeds and control of some of the important species. Orman Fakultesi Dergisi, 9(1): 126-165.

Escherich, K. (1938) Die phytophagen Megastigmus-Arten (Chalcididae) als Zerstorer von Nadelholzamen. Zeitschrift fur Angewandte Entomologie 25: 363-380.

Gottsche, A.B. (1976) Motivated preference for yellow in the orientation behaviour of adults of Megastigmus bipunctatus Swederus (Hym., Chalc. Torymidae). Zeitschrift fur Angewandte Entomologie, 82(2): 210-215.

Gottsche, A.B. (1977) Investigations on life-span and egg production of the juniper seed wasp, Megastigmus bipunctatus Swederus (Hym., Chalc., Torymidae). Anzeiger Fur Schadlingskunde Pflanzenschutz Umweltschutz, 50(3): 40-45.

Gottsche, A.B. (1977) Searching behaviour of Megastigmus bipunctatus (Hymenoptera, Chalcididae) leading to food and breeding sites. Entomologia Experimentalis et Applicata, 22(1): 90-106.

Handa, T. (1990) Quality of artificially pollinated seeds of Hinki (Chamaecyparis obtusa) using insect isolation mesh bags and examination of its effect of investment. Bulletin of the Forest Tree Breeding Institute, Kanto, 8: 101-109.

He, J.H. (1984) A new pest of Cryptomeria fortunei Hooibrenk – Megastigmus cryptomeriae Yano. Forest Pest Disease, 4:11-13.

Hoffmeyer, E.B. (1929) Aus Samen gezuchtete Callimomiden. (Callimomidenstudien I). Entomologiske Meddelelser, 16: 323-334.

Hoffmeyer, E.B. (1931) Beitrage zur Kenntnis der danischen Callimomiden, mit Bestimmungstabellen der europaischen Arten (Hym. Chalc.) (Callimomidenstudien 5). Entomologiske Meddelelser 17: 232-285.

Hongyuan, W., Dehai, Z., and Daoyu, C. (1992) A study on forecast of eclosion period of Megastigmus sabinae. Forest Science and Technology, 7: 4-6.

Imon, Y. (1982) Influence of forest-age and seed parasite on sound seed productivity in hinoki stand. Bulletin of the Ehime University Forest, 19: 79-85.

Imon, Y. (1983) Studies on the seed production of a hinoki stand (I) in a 40-year-old plantation. Bulletin of the Ehime University Forest, 20: 71-83.

Jensen, T.S. and Ochsner, P. (1999) Indigenous and introduced seed chalcids in Denmark – with a revised key to the Danish species (Hymenoptera: Torymidae). Entomologiske Meddelelser, 67(2): 47–56.

Jespersen, C. and Lomholdt, C. (1983) De danske Frøhvespe, Megastigmus Dalman, 1820 (Hymenoptera, Chalcidoidea, Torymidae). Entomologiske Meddelelser, 50: 111–118.

Lessmann, D. (1962) Ubersicht der bisher bekannten Megastigmus-Arten und ihrer Wirtspflanzen. Zeitschrift für Angewandte Entomologie, 50: 233–238.

Lessmann, D. (1974) Studies on distribution and bionomics of Megastigmus spermotrophus Wachtl and M. bipunctatus Swederus (Hymenoptera, Chalcidoidea). Zeitschrift fur Angewandte Entomologie, 75(1): 1-42.

Lessmann, D. (1974) The occurrence of Megastigmus spp. and other seed pests in the German Federal Republic. Zeitschrift fur Angewandte Entomologie, 76(2): 160-166.

Mahnovskii, I.K. (1952) Improving the health of the juniper forests of Uzbekistan. Lesnoe Khozyaistvo 5(6): 62-65.

Nuorteva, M. (1967) Uber die zwei Megastigmus-Arten (Hym. Torymidae) der Waxholdersamen (Juniperus communis L.) Annual Entomnologica Fennica, 33(2): 121-124.

Saito, T. and Yamamoto, S. (1985) Note on two new species attacking the cone of Juniperus chinensis. Proceedings of the Kanto-Tosan Plant Protection Society, 32: 219-220.

Sano, N. (1997) Adult emergence season of Megastigmus chamaecyparidis Kamijo (Hymenoptera: Torymidae) infesting seeds of Chamaecyparis obtusa Sieb. et Zucc. Journal of the Japanese Forestry Society, 79(1): 49-52.  

von Tubeuf, C. (1930) Protection against the introduction into Germany of pests of conifers in seeds. Zeitschrift fur Pflanzenkrankheiten, 40(11): 521-526.

Wu, H.Y., Zhang, D.H., and Chen, D.Y. (1992) Studies on the bioecology of Megastigmus sabinae. Scientia Silvae Sinica, 28(4): 367-371.

Xu, Z. and He, J. (1995) Note on species of phytophagous group of Megastigmus (Hymenoptera: Torymidae) from China. Entomotaxonomia, 17(4): 243-253.

Xu, Z., He, J., and Liu, Z. (1998) Description of a new species of Torymidae (Hymenoptera: Chalcidoidea). Entomotaxonomia, 20(4): 297-299.

Yano, M. and Koyama, M. (1918) On the wasps parasitizing the seeds of coniferous trees. Insect World, 22: 322-325, 372-376, 497-503.