Harmonia axyridis: What will stop the invader?

Abstract

In recent years Harmonia axyridis (Pallas, 1773) (Coleoptera: Coccinellidae) has become a very popular insect among biological control practitioners and scientists, not only for its potential to be an efficient biological control agent but also because it is considered invasive. Individuals of this species were deliberately introduced into several countries for biological control of different arthropods pests. However the predator itself became an invasive species, affecting the dynamics and composition of several guilds through direct or indirect interactions with established species, including intraguild predation. In this paper we discuss the reasons why the species has a high invasiveness and what are the limits to invasion by this species. It is not clear if the invasiveness of the beetle is linked to its biological, ecological and behavioural abilities, or to other factors such as invasibility and interactions between the invaders, the noninvaders, and the habitat, which may in part explain the reasons of its success and help us to answer the question ''what will stop the invader?'' We also discuss the reason for the absence of the predator in the Azores islands. Despite the intentional introduction of H. axyridis in the Azores and the high number of individuals released, there are no records of this species in the wild, despite recent extensive sampling effort. In this paper we discuss the reasons for the apparent failure or the delay in establishment of the predator. One factor which may hamper the establishment of H. axyridis in some of the Azores islands is the absence of winter

The aphidophagous predator Harmonia axyridis (Coleoptera: Coccinellidae) in Greece, 1994-1999

“…A similar case of a failure in establishment of H. axyridis was observed by Soares et al (2008) at Santa Maria of the Azores islands where more than one hundred thousand third instar larvae were released into several citrus orchards. Although after the releases there were records of individuals that dispersed and fed on citrus, apple trees and bean plants, the exotic predator failed to establish (Soares et al, 2008).…”

“…Although after the releases there were records of individuals that dispersed and fed on citrus, apple trees and bean plants, the exotic predator failed to establish (Soares et al, 2008). According to this study, the released populations failed to establish due to ecological factors such as the maladaptation to the local conditions and functional diversity saturation.…”

“…This has been recently concluded by scientists working on risk assessment of biological control agents (van Lenteren et al, 2008;Roy & Wajnberg, 2008). Finally, scientists should be alerted as H. axyridis has shown a lag phase in its establishment (Soares et al, 2008) and in the future H. axyridis might resurface elsewhere in Greece.…”

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

“…1220 individuals bearing two different allelic forms) conforms to the rule of mosaic dominance heredity, 1221 which states that any portion of the elytra which has black pigment in the homozygote for a given 1222 allele will have black pigment also in the heterozygotes in which that allele is present (Tan 1946). 1223 Interestingly, Michie, Mallard et al (2010) reported that the non-melanic morph succinea 1224 dramatically increases its degree of melanization at cold temperatures, and that there is genetic 1225 variation in reaction norms, with different families responding to temperature in different ways. The 1226 exact genomic architecture and gene content of the multiallelic locus controlling color morph 1227 variation and phenotypic plasticity of the non-melanic morph remains unknown.…”

Photoperiodic control of development and reproduction in Harmonia axyridis (Coleoptera: Coccinellidae)

“…This study has also a practical aim: H. axyridis has been widely used for the biological control of aphids in the field and in greenhouses (Koch, 2003;Roy & Wajnberg, 2008), but recently this predaceous coccinellid has attracted attention because of its unexpected ability to invade natural ecosystems and is now also considered to be an alien invader (Koch & Galvan, 2008;Roy & Wajnberg, 2008;Soares et al, 2008). The photoperiodic reactions of H. axyridis have been studied, but mostly to determine the optimal methods for mass rearing and storage, for example, authors (e.g.…”