North American Host Utilization

Research Issue

Literature on the pheromones, microbial control, and general biology and biological control of the nun moth exists.  However, there is little useful information that addresses the problems that would be encountered should the nun moth be introduced into North America.  To predict the risk of successful establishment in various North American forest ecosystems and the potential damage to those systems, knowledge of the nun moth's ability to survive and develop on various North American host plants is required.  Field observations in Eurasia have shown that nun moths can feed and thrive on the foliage of many trees, both coniferous and deciduous.  Two species it prefers and most often damages in Europe are Norway spruce (Picea abies) and Scots pine (Pinus sylvestris).  Sliwa (1987) provides an extensive list of the intensity of natural feeding of nun moth larvae on trees and shrubs in Poland during the 1978-1984 outbreak.  Laboratory investigations of nun moth preferences and utilization of Eurasian host plants provide limited and contradictory information.  Most of the host plant work done on nun moths has concentrated on the relationships between bud burst on the main hosts, Norway spruce and Scots pine, and hatching of nun moth larvae.  This work has shown that host phenology is just as important as host preference in determining the survival and successful development of nun moth larvae.  For example, when larvae hatch before foliage bud burst the presence of male flowers or buds is critical to larval survival and growth.

Our Research 

The survival and development of L. monacha larvae during their first 14 d on 26 North American and eight introduced Eurasian host plants was compared. Larvae on 11 of the hosts used for the 14-d study were allowed to complete their development on those hosts.  The host plants used were from a broad range of tree genera, representing the major forest types present in North America and included many of the major species of economic importance.  Species from Eurasia provided a basis for comparison with the results of European research and provided information on exotic hosts commonly grown in urban areas of North America. 

Expected Outcomes

Provide knowledge of the nun moth's ability to survive and develop on various North American hosts (both native and introduced) that is needed to determine the risk of successful establishment in various North American forest ecosystems and the potential damage to those systems should nun moth be introduced.

Research Results

Species in the genera Betula, Quercus, Pyrus, Abies, and Picea and Pinus sylvestris (with male cones) were suitable for Lymantria monacha (L.) (nun moth) growth and development.  Species from the tree families Aceraceae, Magnoliaceae, Moraceae, Oleaceae, Salicaceae, Tiliaceae and Cupressaceae were unsuitable for nun moth survival and development.  Other species of trees tested were of marginal suitability for nun moth growth and development.  The phenological state of the trees had a major impact on establishment, survival and development of nun moth on many of the tree species tested.  Several of the deciduous tree species that are suitable for nun moth also are suitable for Lymantria dispar (L.) (gypsy moth) and Lymantria mathura Moore (pink gypsy moth).  Nun moth establishment in North America would be catastrophic because of the large number of economically important tree species it can utilize and the ability of mated females to fly and colonize new areas. 
In a separate study, nun moth were found to be capable of completing their development from egg to adult on Pinus radiata. This suggests an accidental introduction of L. monacha to New Zealand, even more so than L. dispar, could have a serious impact on P. radiataplantations. 

Keena MA. 2003. Survival and development of Lymantria monacha (Lepidoptera:Lymantriidae) on North American and introduced Eurasian tree species. J. Econ. Entomol. 96(1): 43-52. 

Withers TM; Keena MA. 2001. Lymantria monacha (nun moth) and L. dispar (gypsy moth) survival and development on improved Pinus radiata. New Zealand Journal of Forestry Science 31(1): 66-77. 

Notes on Eurasian Hosts

In coniferous trees in Eurasia, newly hatched Lymantria monacha larvae usually move to the crowns and start feeding on young soft needles.  When young soft needles are absent, they may feed on buds and male cones until leaf bud break.  Feeding on males cones in Pinus species is often a essential to larval survival since they usually hatch before leaf bud break.  When larvae feed on open male cones of pine they often cover themselves in the pollen so they appear yellow and black.  While feeding on Pinus, Abies, Picea and Larixneedles the larvae are very destructive, they first cut the upper half off then eat the remaining part.  This results in a buildup of both frass and damaged needles at the base of coniferous trees where they are feeding.  In deciduous trees they perforate the young leaves initially then later consume all leaf tissues except the non-edible veins.  Approximately 600-1,000 larvae are sufficient to completely defoliate a P. sylvestris tree and in outbreaks there may be up to 20,000 larvae per tree. 

Primary Hosts (outbreaks occur on these)
Common name	Scientific Name	Geograpic location
Japanese Fir	Abies firma	Japan, Russian Far East Sakhalin
Cajander Larch	Larix cajanderi	South Eastern Siberia
Japanese Larch	Larix leptolepis	Japan
Norway Spruce	Picea abies	Europe
Yeddo Spruce	Picea ajanensis	Russian Far East
Korean Pine	Pinus koraiensis	Russian Far East, Sakhalin
Scots Pine	Pinus sylvestris	Europe

Chinese Hosts (quality not specified)
Common name	Scientific Name
Faber’s Fir	Abies fabri
Manchurian Fir	Abies nephrolepis
Fortune’s Keteleeria	Keteleeria fortunei
Dragon Spruce	Picea asperata
Chinese White Pine	Pinus armandii
Japanese Red Pine	Pinus densiflora
Chinese Douglas Fir	Pseudotsuga sinensis
Chinese Juniper	Juniperus chinensis
Chinese Hemlock	Tsuga chinensis
Heartleaf Hornbeam	Carpinus cordata
South Chinese Beech	Fagus longipetiolata
Chinese Aspen	Populus davidiana
Pencil Willow	Salix humboldtiana
Oriental White Oak	Quercus aliena
Korean Oak	Quercus glandulifera
Korean Mountain-Ash	Sorbus alnifolia
Tuft Leaved Lime	Tilia tuan
Siberian Elm	Ulmus pumila
Large Fruited Elm	Ulmus macrocarpa
Asian Hazel	Corylus heterophylla
Paradise Apple	Malus pumila
Apricot	Prunus armeniaca

Good Hosts (used frequently)
Common name	Scientific Name
White Fir	Abies alba
European Larch	Larix decidua
Dahurian Larch	Larix gmelinii
Yezo Spruce	Picea jezoensis
Sitka Spruce	Picea sitchensis
Lodgepole Pine	Pinus contorta
Douglas Fir	Pseudotsuga menziesii
Erman’s Birch	Betula ermanii
European White Birch	Betula pendula
European Beech	Fagus sylvaticus
English Oak	Quercus robur
Sessile Oak,	Quercus sessilis
Whortleberry	Vaccinium myrtillus
Apple	Malus domestica

Occasional Hosts (used occasionally)
Common name	Scientific Name
Colorado Spruce	Picea pungens
Jack Pine	Pinus banksiana
Austrian Pine	Pinus nigra
White Pine	Pinus strobes
Common Juniper	Juniperus communis
Norway Maple	Acer platanoides
European Hornbeam	Carpinus betulus
European Ash	Fraxinus excelsior
Lombardy Poplar	Populus nigra
Northern Red Oak	Quercus rubra
European Rowan	Sorbus aucuparia
Small-leaved Linden	Tilia cordata
Large-leaved Linden	Tilia platyphyllos
European White Elm	Ulmus laevis
Hazelnut	Corylus avellana
Spindle Tree	Evonymus europeus
Glossy Buckthorn	Frangula alnus
European Raspberry	Rubus idaeus
Pear	Pyrus domestica

 

Research Participants

Principal Investigators

• Melody Keena, USDA Forest Service- Northern Research Station Research Entomologist
• Toni Withers, New Zealand Forest Research Institute

For further details log on website :
https://www.nrs.fs.fed.us/disturbance/invasive_species/nun_moth/risk_detection_spread/host_utilization/