Assumed effects of invasive intraguild predators and how to avoid the snowball effect of unsupported expectations

Invasive intraguild predators: Evidence of their effects, not assumptions

“…On the contrary, we tend to agree with the general point made by Kindlmann et al (2021) that H. axyridis may increase biological control function in some ecosystems, at least in the short term. At the end of their paper, in the section ‘Predatory effectiveness in regulating the abundance of their prey’, Kindlmann et al (2021) indicate that there is increasing evidence that predators may not strongly regulate pests in nature. In this regard, we suggest looking at a recent review about the role of non‐native ladybirds introduced for biological control, including H. axyridis (Rondoni et al, 2021).…”

“…Another facet of the criticism of Kindlmann et al (2021) involves the existence and effects of intraguild predation (IGP). In their section 'Intraguild predation as a causative factor ' Kindlmann et al (2021) start from the premise that IGP intensity is difficult to determine and is rare in ladybird guilds (Kindlmann & Houdková, 2006).…”

“…Another facet of the criticism of Kindlmann et al (2021) involves the existence and effects of intraguild predation (IGP). In their section 'Intraguild predation as a causative factor ' Kindlmann et al (2021) start from the premise that IGP intensity is difficult to determine and is rare in ladybird guilds (Kindlmann & Houdková, 2006). We concede that rigorous assessments of IGP intensity are not easy, but there is evidence from a range of studies that IGP takes place in field and laboratory situations and may be common.…”

“…Furthermore, there are advantages of using multiple approaches, for example, by combining citizen science data with standardised sampling designs but sometimes over shorter periods of time (as presented in Roy et al, 2012; Grez et al, 2016). Kindlmann et al (2021) also criticised the work of Grez et al (2016) for concluding from a short‐time series an adverse impact of H. axyridis on the abundance of native species. On the contrary, these authors did not conclude this, and actually indicated that ‘there was no significant relationship ( R 2 = 0.524, p = 0.167; fig.…”

Cannibalism and intraguild predation between endemic and introduced coccidophagous lady beetles (Coleoptera: Coccinellidae)

“…Other factors such as weather conditions, habitat size, food availability, presence of other natural enemies etc. may impose disadvantages on native species (Kindlmann et al 2017(Kindlmann et al , 2020Li et al 2021) or alter the dynamics of what we observed under controlled conditions. This is the first report to confirm these interactions between C. montrouzieri and T. notata; hence, it is essential to review the possible success or failure for the biological control of mealybugs where both of these lady beetle species occur simultaneously.…”