Survey for Winter Moth (Lepidoptera: Geometridae) in Northeastern North America with Pheromone-Baited Traps and Hybridization with the Native Bruce Spanworm (Lepidoptera: Geometridae)

Abstract

We used pheromone-baited traps to survey the distribution of winter moth, Operophtera brumata (L.) (Lepidoptera: Geometridae), a new invasive defoliator from Europe in eastern New England. The traps also attracted Bruce spanworm, Operophtera bruceata (Hulst) (Lepidoptera: Geometridae), native to North America. We distinguished between the two species by examining male genitalia and sequencing the mitochondrial cytochrome oxidase subunit 1 (COI) gene, the DNA barcoding region. In 2005, we recovered winter moths at sites stretching from eastern Long Island, southeastern Connecticut, all of Rhode Island, eastern Massachusetts, coastal New Hampshire, and southern coastal Maine. At sites further west and north we captured only Bruce spanworm. In 2006, we confirmed that both winter moth and Bruce spanworm are present in Nova Scotia and in coastal Maine, but only Bruce spanworm was recovered in coastal New Brunswick, Canada; Pennsylvania; Vermont; or Quebec City, Canada. In 2007, we collected Bruce spanworm, but no winter moths, in New Brunswick and the interior areas of Maine, New Hampshire, and New York. Winter moth and Brace spanworm differed in the COI sequence by 7.45% of their nucleotides. The prevalence of intermediate genitalia in the zone of overlap suggested that hybridization between the two species may be occurring. To confirm the presence of hybrids, we sequenced the nuclear gene, glucose-6phosphate dehydrogenase (G6PD). We identified six nucleotides that routinely distinguished winter moth and Bruce spanworm, of which three were always diagnostic. We showed that eggs produced by hybridizing the two species in the laboratory contained copies of both species at these six sites. We found that most of the moths collected in the field with intermediate genitalia had winter moth CO1 and G6PD sequences and thus were not hybrids (or at least F1 hybrids). We found three hybrids out of 158 moths with intermediate genitalia in the region where both species were caught. We conclude that hybrids occur in nature, but are not as common as previously reported. Introgression of genes between the two species may still be significant.

Variation in Captures of Adult Winter Moths (Operophtera brumata) in Coastal Maine Over Two Years

“…2, page 7) and Gwiazdowski et al (2013), Bruce spanworm is ubiquitous, except perhaps in areas where winter moth is now predominant. Elkinton et al (2010 confirm that winter moth and Bruce spanworm hybridize to some extent, so gene flow is occurring between the two species. The extent and implications (Tenow 1972, Jepsen et al 2008.…”

“…Like winter moth, it is extremely polyphagous and is an occasional pest in apple orchards (Ives 1984). As shown by the survey conducted by Elkinton et al (2010), (Fig. 2, page 7) and Gwiazdowski et al (2013), Bruce spanworm is ubiquitous, except perhaps in areas where winter moth is now predominant.…”

“…In all of these introductions, casual observers initially mistook the infestation for that of native geometrid defoliators, such as the fall cankerworm (A. pometaria Harr). Elkinton et al (2010) completed a survey for winter moths with pheromone-baited traps in the northeastern United States and adjacent areas of Canada (Fig. 2) showing that winter moth occurs from Long Island, New York, through southeast Connecticut, most of Rhode Island, eastern Massachusetts and coastal areas of New Hampshire and Maine.…”

Invasion of Winter Moth in New England: Effects of Defoliation and Site Quality on Tree Mortality

“…Winter moth was the dominant defoliator in, or in close proximity (4.8 km) to, our study sites since this species was first incorporated into ADS beginning in 2004 and was responsible for 100% of the defoliation events within 4.8 km of our study sites from 2008-2010 [54]. It is likely that winter moth was also active within our study area prior to 2004, as winter moth was confirmed in 2003 to be responsible for a prolonged outbreak of defoliation in eastern Massachusetts in the 1990s and early 2000s [10]. However, it is important to note that other Quercus defoliators (including gypsy moth and forest tent caterpillar) were active from 2000-2007 [54], and that, in some years, multiple defoliators were present within the study region and could have overlapped in our study sites with winter moth.…”

“…The tree species composition and climate of eastern North America offer suitable habitat for winter moth [10,29]. Eastern Massachusetts represents the oldest and best documented case of winter moth infestation in the eastern United States.…”