Intraguild predation of the aphid pathogenic fungus Pandora neoaphidis by the invasive coccinellid Harmonia axyridis

Abstract

1. The ladybird Harmonia axyridis is an invasive alien species in many countries and is predicted to have a negative impact on native biodiversity. However, little is known on the status of this aphidophage as an intraguild predator of natural enemies of aphids such as insect‐pathogenic fungi.2. The study assessed the predation of the aphid‐specific pathogenic fungus Pandora neoaphidis by adult and larval H. axyridis collected from the U.K. (an invasive population) and Japan (a native population) relative to that of the ladybird Coccinella septempunctata (native to the U.K.) and the non‐U.K. C. septempunctata subspecies brucki that were either starved or unstarved.3. Overall, predation of uninfected aphids was greater than infected aphids and, when given a choice, a preference for aphids was shown. However, the extent of this preference was dependent on the species and origin of the coccinellid. Harmonia axyridis (U.K.) consumed the greatest quantity of fungal cadavers and showed little preference for uninfected aphids over infected aphids. In contrast, C. septempunctata rarely consumed infected aphids. Life stage had no direct effects on predation but starved coccinellids consumed more uninfected aphids than infected aphids.4. Harmonia axyridis (U.K.) is a stronger intraguild predator of P. neoaphidis cadavers than the native species C. septempunctata and, therefore, may have an impact on the occurrence and persistence of P. neoaphidis. The differences in intraguild predation by H. axyridis collected in the U.K. and those from Japan suggests that individuals that invaded the U.K. could have a different genetic profile to those in its native range.

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

“…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)…”

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

“…Specifically Roy et al (2008b) demonstrated that H. axyridis from a 513 culture derived from Japan were less likely to consume aphid cadavers supporting the 514 beneficial aphid-specific fungal pathogen P. neoaphidis than those derived from the UK. 515 They speculated that H. axyridis obtained from non-native populations were derived from 516 biological control cultures and, through microevolution or founder effects, have been, 517 perhaps unintentionally, selected for extreme polyphagy and an increased tendency 518 towards intraguild predation compared to H. axyridis in its native range (Roderick and 519 Howarth 1999; Hufbauer and Roderick 2005; Roy et al 2008a). It would be extremely 520 interesting to compare the strength and symmetry of intraguild interactions between 521 Japanese, UK and US derived H. axyridis for a wider range of guild members, from both 522 native and non-native ranges to determine if they function differently in relation to all guild 523 members with which they compete.…”

“…As the sporulating aphid cadaver is sessile, it is an easy prey 301 item for generalist predators. In a laboratory study, Roy et al (2008a) assessed the pre-302 dation of aphid cadavers sporulating with Pandora neoaphidis (Remaudière and 303 Hennebert) Humber (Zygomycetes: Entomophthorales) by UK and Japanese-derived…”

Traits related to biological invasion: A note on the applicability of risk assessment tools across taxa

“…For example, the invasive H. axyridis is more likely than the native Coccinella septempunctata (seven-spot ladybird) to consume the cadavers of Pandora neoaphidis fungus-infected aphids (Roy et al 2008a), a form of intraguild predation. Although study of other members of the aphidophagous and coccidophagous guilds is lacking, evidence indicates that H. axyridis may affect the population of P. neoaphidis more negatively than would C. septempunctata, leading to a greater competitive advantage for H. axyridis.…”