Abstract
Harmonia axyridis (Pallas) has been introduced either intentionally or accidentally in different areas outside its native range, where it is often regarded as invasive. Dinocampus coccinellae (Schrank) has been recorded to parasitize H. axyridis in the field, both in the native and introduced areas, Italy included. The percent of parasitism found in our field investigation was low (four percent). The effect of exposure time of H. axyridis to D. coccinellae and the impact of parasitization on host longevity, oviposition capacity and egg fertility were evaluated in the laboratory. The acceptance and suitability of H. axyridis as host for D. coccinellae were then studied, in comparison with the native coccinellid Adalia bipunctata (L.), which shares the same ecological niche. The effects of parasitization on female longevity and reproduction capacity in the exotic vs. the indigenous lady beetle were also investigated. The overall results showed that D. coccinellae negatively affected the fitness of H. axyridis, more than that of A. bipunctata. The parasitoid may thus play a marginal role in controlling the populations of the Asian lady beetle, without representing a threat to A. bipunctata.
Highlights
The multicolored Asian lady beetle Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), an active predator of aphid and coccid pests originating from Asia [1], was introduced, either intentionally or accidentally, in different areas outside its native range, including NorthAmerica, South America, Europe and a few regions of Africa [2]
Samples of H. axyridis and other coccinellid species, namely Coccinella septempunctata L., A. bipunctata and Hippodamia variegata Goeze, were field collected in the area surrounding the Department of Agricultural Sciences of the University of Bologna (DipSA) (Emilia-Romagna region, Italy, 44◦ 480 39” N, 11◦ 370 84” E)
Dinocampus coccinellae was the only parasitoid species obtained from the field-collected specimens
Summary
The multicolored Asian lady beetle Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), an active predator of aphid and coccid pests originating from Asia [1], was introduced, either intentionally (as a biocontrol agent) or accidentally, in different areas outside its native range, including NorthAmerica, South America, Europe and a few regions of Africa [2]. The multicolored Asian lady beetle Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), an active predator of aphid and coccid pests originating from Asia [1], was introduced, either intentionally (as a biocontrol agent) or accidentally, in different areas outside its native range, including North. Recorded parasitoids of H. axyridis in native areas include the phorid fly Phalacrotophora philaxyridis (Disney) [10], tachinid fly Medina luctuosa (Meigen) and braconid wasp Dinocampus coccinellae (Schrank) [11]. In the new areas some native parasitoids, such as the tachind Strongygaster triangulifera (Loew) in North America [12,13] and different phorid species in Europe [14,15], have been reported to attack H. axyridis. Dinocampus coccinellae, a cosmopolitan parasitoid of adult coccinellids, is the only hymenopterous species reported to date to parasitize H. axyridis both in native and introduced environments. Females usually reproduce by thelytokous parthenogenesis [16] and oviposit
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