North American Distribution of Coccinella septempunctata (Coleoptera: Coccinellidae) and Its Mass Appearance in Coastal Delaware

Abstract

The Palearctic sevenspotted ladybeetle, Coccinella septempunctata L., well established in North America, has now spread through parts of five Canadian provinces and 34 contiguous eastern states of the United States. In southern coastal Delaware in June 1984, a mass appearance of C. septempunctata occurred where wind systems brought masses of these beetles into the area from unknown sources and dropped them into the seawater. Large numbers then washed up on beaches, and some surviving beetles annoyed vacationers and even bit some people. We speculate on the original establishment of this insect in North America. Presenting evidence previously overlooked, we add to speculation that early intentional releases led to establishment of this predator in North America. However, accidental importation on transoceanic ships cannot be ruled out.

Use of Eelgrass, <em>Zostera marina</em>, Wrack by Three Species of Ladybird Beetles (Coleoptera: Coccinellidae) in Prince Edward Island

“…Davis and Gray (1966) also reported another ladybird beetle, Naemia serriata, from a salt marsh in North Carolina. The mass occurrences of C. septempunctata that we found are different from that in Delaware in which numerous dead and some living individuals were washed ashore following deposition in the ocean and association with seaweed wrack (Schaefer et al 1987). The North Carolina mass occurrence is similar to that reported by Schaefer et al, and involved mass mortality and shore deposition (Nalepa et al 1998).…”

“…Although terrestrial, both C. septempunctata and Propylea quatuordecimpunctata have previously been found in coastal habitats including salt marshes in Connecticut, North Carolina and Delaware (Schaefer et al 1987;Pupedis 1997;Nalepa et al 1998). Davis and Gray (1966) also reported another ladybird beetle, Naemia serriata, from a salt marsh in North Carolina.…”

Fates of Rare Species under Siege from Invasion: Persistence of Coccinella novemnotata Herbst in Western North America alongside an Invasive Congener

“…The highly successful initial establishment of this species in North America was a cause for widespread concern over potential adverse effects on native lady beetles in general (Schaefer et al, 1987;Ehler, 1990;Ruesink et al, 1995;Simberloff and Stiling, 1996;Obrycki et al, 2000). Indeed, it appears that in Utah the dominance of C. septempunctata in alfalfa fields has led, often through reduced availability of aphid prey, to reduced numbers of native lady beetles exploiting this habitat (Evans, 2004).…”

“…Another introduced species of much concern is Coccinella septempunctata L. This Eurasian species became established in North America in the 1970s and 1980s (Angalet et al, 1979;Obrycki et al, 2000) and soon thereafter came to be regarded as invasive and a likely threat to native North American lady beetles (Schaefer et al, 1987;Ehler, 1990;Elliott et al, 1996). Wheeler and Hoebeke (1995) carefully and thoroughly reviewed the case of Coccinella novemnotata Herbst, detailing that this species (once common throughout North America; Gordon, 1985) declined precipitously in its abundance in northeastern North America in the 1980s and early 1990s at the same time that the ecologically very similar, introduced C. septempunctata was rapidly increasing to very high numbers.…”

Gene Flow in the Exotic Colonizing LadybeetleHarmonia axyridisin North America

“…This is the second recent instance of a surprising, explosive colonization of North America by ladybeetles. The first such was the exotic Coccinella septempunctata L., which spread rapidly over the United States after first being detected in 1973, despite extensive earlier releases of cultured beetles (Schaefer et al, 1987).…”