Intraguild predation involving Harmonia axyridis: a review of current knowledge and future perspectives

Abstract

9 Abstract As an effective generalist predator of aphids and other hemipteran pests 10 H. axyridis has been a successful biological control agent. However, the very functional 11 traits that have contributed to its success in this regard also implicate it as an intraguild 12 predator that poses a significant risk not only to the diversity of other natural enemies of 13 Hemiptera (and their associated ecosystem services), but to biodiversity more widely. In 14 this paper we will specifically review the existing data on intraguild predation involving 15 H. axyridis, and consider the strength and symmetry of such interactions both within its 16 native guild and within exotic guilds where it has established as an invasive alien. We will 17 use these studies to interpret the observed population declines in predator diversity in the 18 field, predict species at risk in regions not yet invaded and consider implications for 19 resulting ecosystem services. We will also indicate gaps in our knowledge that require 20 further study in order to identify opportunities for mitigation.21 Keywords Coccinellidae Á Harmonia axyridis Á Aphidophagous guild Á 22 Intraguild predation Á Predators Á Parasitoids Á Pathogens Á Ecosystem services 23 Introduction 24 Terrestrial ecosystems support a diversity of species that are directly and indirectly linked 25 to each other within food webs that span multiple trophic levels. Natural enemy species (in 26 the context of this paper we will collectively call these 'predators' as they all have a trophic 27 relationship with their hosts/prey) contribute to the population regulation of species in both

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

“…The wide diet breadth and recognition that H. axyridis is a top predator (Pell et al 2008) Chilocorus stigma (Say) (Colunga-Garcia, Gage 1998), followed more recently by a decline in 265…”

“…Such 307 interactions between drivers of change are undoubtedly important in population dynamics, and the 308 negative effects of H. axyridis are likely to be the result of a complex range of interactions and 309 processes including resource competition and intra-guild predation (IGP) (Majerus et al 2006). 310 The majority of research examining interactions between H. axyridis and other aphidophagous 321 species has focused on direct interference competition on other ladybirds, proposing that decline is 322 due to strong asymmetric IGP of eggs and larvae in favour of H. axyridis (Pell et al 2008 to the eggs of native species (Smith, Gardiner 2013). However, out of 342 attacks, video surveillance 328 illustrated that only two were attributable to alien ladybirds (H. axyridis feeding on conspecific eggs).…”

“…There has been less research on the interactions between H. axyridis and species within the 347 aphidophagous guild beyond ladybirds (Pell et al 2008 (Roy et al 2008a) whereas most other aphid 354 predators avoid consumption of infected aphids (Roy et al 1998)…”

Detecting arthropod intraguild predation in the field

“…Brown et al (2011) showed evidence of a decline in the abundance of Adalia bipunctata (L.) (Coleoptera: Coccinellidae) in England and there has been a drop in frequency of A. bipunctata and Adalia decempunctata (L.) (Coleoptera: Coccinellidae) in Belgium (Adriaens et al 2010). Studies on intraguild interactions between H. axyridis and other aphid predators have been conducted under controlled conditions in laboratories and reveal predation of these other species by H. axyridis (Pell et al 2008). Although these laboratory bioassays enhance our understanding of possible IGP among aphidophagous species, it remains unclear whether the success of H. axyridis in the field can be attributed to a direct (e.g.…”

Aspectos biológicos de Harmonia axyridis alimentada com duas espécies de presas e predação intraguilda com Eriopis connexa

“…Avaliações sobre a sua competição com outros coccinelídeos, em laboratório, foram realizadas por Kajita et al (2000), Cottrell (2005), Pell et al (2008) e , que verificaram que sua atuação foi dominante em relação à Adalia bipunctata (L.), Coleomegilla maculata De Geer, Olla v-nigrum (Mulsant) e Propylaea japonica Thunberg, em razão do maior tamanho e da presença de estruturas protetoras como os espinhos dorsais ao longo do corpo das larvas.…”