Asymmetric larval interactions between introduced and indigenous ladybirds in North America

Abstract

Understanding the mechanisms that result in the success of introduced species will contribute to predicting future invasions and managing invaded systems. We examined interactions between larvae of two predatory ladybird species recently introduced to North America, Coccinella septempunctata (CS) and Harmonia axyridis (HA), and two indigenous ladybirds, Coccinella transversoguttata (CT) and Hippodamia convergens (HC). By pairing young and old larvae in the laboratory at low and high levels of aphid availability, we assessed the degree of asymmetry in intraguild predation (IGP), the strength of competitive effects on growth and development of larvae escaping predation, and the nature of attack and escape behavior among the species. Interactions were generally asymmetric, with larvae of introduced species acting most frequently as intraguild predators and larvae of indigenous species serving most frequently as intraguild prey (the two Coccinella spp., however, preyed on each other at similar rates). Because they were especially aggressive and because other larvae were least successful in escaping their attacks, larvae of HA had stronger negative effects on larvae of the two indigenous species than did larvae of CS. Such negative effects, expressed most strongly when aphid availability was low, were especially adverse for the smaller of the two indigenous species, HC. In general, older larvae interacted with each other more strongly than young larvae did, and older larvae had especially strong negative effects on young larvae when interactions occurred between age classes. Our results suggest that HA more than CS may represent a threat to indigenous ladybirds as an intraguild predator, and that IGP in turn may play a stronger role for HA than for C. septempunctata in promoting the successful invasion of North America.

The harlequin ladybird, Harmonia axyridis: global perspectives on invasion history and ecology

“…Studies to date have failed to show that H. 365 axyridis negatively affects native North American ladybirds through exploitative competition among 366 larvae (Hoogendoorn, Heimpel 2004;Yasuda et al 2004), however, field and microcosm studies 367 reveal reduced fitness in the predatory bug Anthocoris nemoralis (F.) (Hemiptera: Anthocoridae) due 368 to competition with H. axyridis . Evans (2004) proposed that following the 369 introduction of alien competitors (specifically C. septempunctata), native species abandoned 370 croplands due to increased competition for shared prey.…”

Predators and parasitoids of the harlequin ladybird, Harmonia axyridis, in its native range and invaded areas

“…Yasuda and Ohnuma 1999;Yasuda et al 2004;Pell et al 2008;Ware and Majerus 2008;Raak-van den Berg et al 2012), little data is available on H. axyridis as an intraguild prey. Indeed, in experiments testing the outcomes of intraguild interactions involving H. axyridis, it usually appears superior to other aphidophagous predators (Yasuda and Ohnuma 1999;Yasuda et al 2004;Ware and Majerus 2008;Raak-van den Berg et al 2012; Katsanis et al 2013). A few exceptions include larvae of the ladybird Anatis ocellata (L.) Katsanis et al 2013) and of the lacewings Chrysoperla carnea (Stephens) (Nedvȇd et al 2010(Nedvȇd et al , 2013 and C. rufilabris (Burmeister) (Michaud and Grant 2003).…”

Invasions by Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) in the Western Hemisphere: implications for South America

“…First, as with many other exotics, H. axyridis may threaten native organisms. For example, densities of native predators seem to have decreased as the abundance of H. axyridis increased (Colunga- Garcia & Gage 1998, Brown & Miller 1998, Michaud 2002b, Alyokhin & Sewell 2004, Saini 2004, which may be partly due to intraguild predation (e.g., Cottrell & Yeargan 1998, Michaud 2002b, Cottrell 2004, Yasuda et al 2004. In addition, H. axyridis may impact populations of the monarch butterfly, Danaus plexippus (Koch et al 2004c, in press b).…”