Biological Control of Pests in Forests of Eastern United States

 

 

Winter Moth (Operophtera brumata [L.])

Joseph Elkinton, University of Massachusetts, Amherst (elkinton@ent.umass.edu)

Invaded Range in North American

Three parts of North America have been invaded by winter moth (Operophtera brumata [L.]) (Figure 1) in distinct historical periods: Nova Scotia (Canada) in the 1930s (with later spread to New Brunswick and Prince Edward Island), British Columbia in 1970s (first recognized in 1976) (Embree and Otvos, 1984), and southeastern Massachusetts (USA) in the 1990s (Elkinton- need ref). The focus of this website article is on events in Massachusetts. The biological control program in Massachusetts discussed here seeks to replicate past successful biological control achieved in Canada through the establishment of the tachind Cyzenis albicans (Fallen), one of two agents held to be important in previous work.

Damage

The larvae of winter moth (Figure 1), when populations reach high densities, defoliate various deciduous forest and ornamental tree species, including oak (Quercus spp.) , apple (Malus spp.) and linden (Tilia spp.), among others. In British Columbia, larvae fed on species of Acer, Crataegus, Malus, Prunus, Populus, Quercus (especially Garry oak, Quercus garryana) and Salix. In Massachusetts, tens of thousands of acres of mixed deciduous forest were defoliated in the late 1990s in the southeastern portion of the state (Figure 2- Joe, do you have a map?).

Known Natural Enemies

Based on successful control of winter moth in Nova Scotia (Embree, 1971) in the 1960s and on populations dynamics studies carried out in England (in the native range of the pest) by Varley (1971), the importance of the tachinid C. albicans as a parasitoid of winter moth was well known by the time the biological control programs in British Columbia and Massachusetts were begun. Other parastioids noted in these studies include the ichneumonidsAgrypon flaveolaturm (Gravenhorst) and Cratichneumon culex. Other parasitoids have also been recorded attacking winter moth in Europe (e.g., Sechser, 1970).

Cyzenis albicans (Tachinidae) (Figure 3-Joe, need photo of fly). This tachinid lays large numbers of microtype eggs on winter moth-infested foliage. Eggs hatch after ingestion by late instar winter moth caterpillars. The tachinid maggot penetrates the host salivary gland and waits until the host has dropped to the soil and pupated. The parasitoid then develops, killing the host by mid summer and then overwintering in the host pupal case in the soil.

Agrypon flaveolaturm (Gravenhorst) (Ichneumonidae). This ichneumonid attacks young larval instars, but develops in host pupae. It is believed to be more effective against low density winter moth populations and to become ineffective as pest densities rise (Embree and Otvos, 1984).

Cratichneumon culex (O. F. Mull.) (Ichneumonidae) is a pupal parasitoid found associated with winter moth populations in England by Varley (1971) but this species was never introduced to North America during biological control projects against winter moth.

Biological Control Efforts Against the Pest, Worldwide

Winter moth populations were brought to low densities in Nova Scotia by introductions of C. albicans and A. flaveolaturm (Embree, 1971; Embree and Otvos, 1984). In the post-collapse, low density populations of winter moth, both parasitoids remained present but the collapse from high density was attributed to C. albicans. In British Columbia, (Joe, fill in please something on status in BC)

Current Status of Biological Control Efforts in the United States

In Massachusettes (Joe, fill in history of effort please, include map of infested area in MA)

References Cited

Embree, D. G. 1971. Operophtera brumata (L.), winter moth (Lepidoptera: Geometridae), pp. 167-175. In: Anon. Biological Control Programmes against Insects and Weeds in Canada, 1959-1968. Commonwealth Agricultural Bureaux, Farnham Royal, Slough, UK.

Embree, D. G. and I. S. Otvos. 1984. Operophtera brumata (L.), winter moth (Lepidoptera: Geometridae), pp. 353-357. In: Kelleher, J. S. and M. A. Hulme (eds.). Biological Control Programmes against Insects and Weeds in Canada, 1969-1980. Commonwealth Agricultural Bureaux, Farnham Royal, Slough, UK.

Sechser, B. 1070. The parasite complex of the winter moth (Operophtera brumata L.) (Lep., Geometridae) with particular reference to pupal parasites. Part 1. Zeitschrift für Angewandte Entomologie 66: 1-35.

Varely, G. C. 1971. The effects of natural predators and parasites on winter moth populations in England. Proceedings of the Tall Timbers Conference on Ecological Animal Control by Habitat Management No. 2, Tallahassee, Florida, pp. 103-116.