Host specificity of Aphelinus species collected from soybean aphid in Asia

Parasitoid‐mediated indirect interactions between unsuitable and suitable hosts generate apparent predation in microcosm and modeling studies

“…We used A . certus in our study because (a) it is known as a parasitoid of soybean aphid, which has been shown to be suitable (Frewin et al., 2010; Heimpel et al., 2010; Hopper & Diers, 2014; Hopper, et al., 2017a; Kaser & Heimpel, 2018) and (b) it is known to attack milkweed aphid despite the low level of suitability of this aphid species (Kaser, 2016). In addition, the potential egg sink caused by the presence of an unsuitable host may be favored by low daily parasitoid fecundity (Heimpel et al., 2003; Kaser et al., 2018), as is the case in A .…”

“…This parasitoid species has a relatively low egg load (see also Hopper et al, 2013;Monticelli et al, 2019a) and our dissections from the choice studies clearly show that eggs that could have been laid into the suitable soybean aphid were instead laid into the unsuitable milkweed aphid. We believe rather that A. certus attacks unsuitable hosts as reflection of the fact that it is a generalist aphid parasitoid (Hopper et al, 2017a). In this case the "mistake" of attacking A. nerii represents the outcome of the classical trade-off faced by generalists: the ability to develop in many host species leads to weak selection for discrimination ability between suitable and unsuitable hosts and thus some unsuitable hosts are inevitably attacked (Asplen et al, 2012).…”

“…We believe rather that A . certus attacks unsuitable hosts as reflection of the fact that it is a generalist aphid parasitoid (Hopper et al., 2017a). In this case the “mistake” of attacking A .…”

“…However, milkweed aphid has been reported to be attacked by various parasitoid species, including Aphelinus abdominalis, Aphidius ervi, Aphidius colemani, Binodoxys communis, Lysiphlebus testaceipes, and Diaeretiella rapae (Benelli et al, 2014;Colvin & Yeargan, 2013;Cortez-Madrigal et al, 2016;Desneux et al, 2009a;Hartbauer, 2010;Helms et al, 2004;Monticelli et al, 2019a;Vaz et al, 2004;Wyckhuys & Heimpel, 2007). We used A. certus in our study because (a) it is known as a parasitoid of soybean aphid, which has been shown to be suitable (Frewin et al, 2010;Heimpel et al, 2010;Hopper & Diers, 2014;Hopper, et al, 2017a;Kaser & Heimpel, 2018) and (b) it is known to attack milkweed aphid despite the low level of suitability of this aphid species (Kaser, 2016). In addition, the potential egg sink caused by the presence of an unsuitable host may be favored by low daily parasitoid fecundity (Heimpel et al, 2003;, as is the case in A. certus (Miksanek & Heimpel, 2020a).…”

“…These dynamics have been shown or hypothesized for a number of host‐parasitoid systems, including lady beetles and their parasitoids (Hoogendoorn & Heimpel, 2002) and stinkbugs or moths and their egg parasitoids (Abram et al., 2014, 2016; Kaser et al., 2018). Aphids and their parasitoids are also likely candidates for egg sink dynamics based on observations from a number of laboratory studies that aphid species of varying suitability are often parasitized by aphid parasitoid species (e.g., Antolin et al., 2006; Carver, 1984; Desneux et al., 2009a,c; Henry et al., 2010; Hopper et al., 2017a,b; Hopper et al., 2013; Mackauer et al., 1996; Ode et al., 2005).…”