Abstract
We investigated prey preference of adult male and female Propylea dissecta (Mulsant) when fed on the aphids, Aphis craccivora and Lipaphis erysimi, which sequester toxic allelochemicals from their host plants. Both the male and female adults of P. dissecta prefer to consume L. erysimi in most mixed diet treatments (cafeteria experiment). This was well supported by significantly high values of the β and C prey preference indices. However, when provided with these aphids separately, the adults showed no significant difference in aphid consumption, regardless of the species of aphid and sex of the adult ladybird. We conclude that host plant allelochemicals/toxicants have a direct effect on prey preference of ladybirds. Host plant toxic constituents can alter the biochemical composition of the most preferred prey and make them the least preferred. Mixing two toxic similar diets can make one diet more suitable than the other.
Highlights
Dietary habits of predaceous ladybirds (Coleoptera: Coccinellidae) have fascinated many workers (Evans and Gunther 2005; Michaud 2005; Provost et al 2006; Honek et al 2008a, b; Sloggett 2008a, b; Hodek and Evans 2012)
C index 0.84 ± 0.03 0.67 ± 0.03 0.69 ± 0.04 0.95 ± 0.06 0.80 ± 0.04 0.78 ± 0.04 t-value t = −3.87; P = 0.004 t = −8.14; P < 0.0001 t = −5.92; P < 0.0001 t = −0.40; P = 0.7 t = −4.23; P < 0.001 t = −4.07; P = 0.003. Both adult male and female P. dissecta consumed more L. erysimi than A. craccivora in almost all mixed diet combinations. This supports our hypothesis that A. craccivora reared on the toxic R. sceleratus will be less preferred when mixed with L. erysimi
It is evident from the preference (β and C) indices that L. erysimi is preferred over the toxic A. craccivora
Summary
Dietary habits of predaceous ladybirds (Coleoptera: Coccinellidae) have fascinated many workers (Evans and Gunther 2005; Michaud 2005; Provost et al 2006; Honek et al 2008a, b; Sloggett 2008a, b; Hodek and Evans 2012). Toxicity of aphids is directly dependent on host plant toxicants or allelochemicals, which are sequestered by aphids (Pratt et al 2008) as a means of defence against predators and may reduce their growth rates (Noriyuki et al 2012). Prey suitability is directly related to the host plants and the same prey could be either nutritious or toxic depending on its host plant. Prey suitability is directly related to the host plants and the same prey could be either nutritious or toxic depending on its host plant. Wu et al (2010) found that the aphid, Aphis gossypii (Glover) reared on five different host plants have different effects on the population parameters of its predator, Hippodamia variegata (Goeze)
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