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3 Brown, P.M.J. & Roy, H.E. (2017) Native ladybird decline caused by the invasive harlequin ladybird Harmonia axyridis: evidence from a long-term field study. Thus, I decline in percentage abundance does not necessarily indicate a negative effect of the invader on the abundance of the native species i , as is often claimed (Alyokhin & Sewell, 2004; Grez I et al i ., 2016; Brown & Roy, 2017, etc.). It is seductive to say that an invader in reducing the abundance of native predators lowers the biocontrol potential of the whole guild (Soares I et al i ., 2008; Brown I et al i ., 2011; Roy I et al i ., 2012). [Extracted from the article]

Modelling of empirical data on the abundance of host-specific, tree-dwelling aphids indicates that their abundance is determined by the effect of the abundance of their host plants on the realised annual population growth rate ( I R i ) of the aphids (Dixon & Kindlmann, [7]). Viewed in this way it is not just the abundance of the host plant of aphids that determines the abundance of aphids (Dixon & Kindlmann, [7]) but also their potential annual population growth rate ( I r i SB p sb ) and subsequently their realised population growth rate ( I R i ). The most striking and consistent feature of rare aphid species is that the period suitable for their development and reproduction is shorter than for the common species and, consequently, the potential yearly rate of increase of these rare species is lower. [Extracted from the article]