Our findings revealed that EPN‐infected insect cadavers emit a characteristic blend of volatile compounds with bioactivity in plants and insects. More specifically, we examined the influence of odours emitted by entomopathogenic nematodes (EPNs), a natural enemy of insect herbivores, on the performance and behaviour of their insect prey and the defence responses of nearby plants. Here, we investigated plant and insect responses to chemical cues from below‐ground natural enemies and explored the ecological significance of these cues for multitrophic interactions.
Prey animals often avoid predator odours to improve survival, and previous research has documented enhanced plant resistance following contact with below‐ground natural enemies, though the ecological basis was unknown. It is increasingly clear, however, that below‐ground cues and those produced by organisms at higher trophic levels also have ecological importance. Previous studies of chemically mediated multitrophic interactions have typically focused on responses to cues from plants or herbivores above‐ground. Here we suggest that the method selected to measure resistance should depend on the longevity of the crop (or culture) and the generation time of the herbivore.Ĭhemical cues are essential for many ecological interactions. Choosing an appropriate measure for plant resistance is essential for engineering future varieties for improved plant production security, with less dependence on chemical pesticides. However, measuring resistance is seldom straightforward, and many different approaches are being used, thus affecting biological interpretations. As many national and intergovernmental bodies have firmly endorsed Integrated Pest Management as the new paradigm for plant protection, the importance of resistant varieties is becoming even more important.
Plant resistance is pivotal in preventing crop yield loss to herbivores, and, thus, it is important to breed for (Hill et al., 2012). Plant resistance is normally defined as the heritable ability of plants to escape attacking enemies, partially or fully, thus minimizing the amount of damage experienced by the plant (Painter, 1951 Mitchell et al., 2016). The present findings suggest that we must consider the risk‐spreading hypothesis in cases where preference and performance are not positively correlated, particularly in specialist herbivores that can feed on a diversity of congener plants and may attempt to expand their exploits to other solanaceae species. Glycoalkaloids such as solanine and chaconine were detected in similar amounts in preferred and non‐preferred hosts, but there was significantly more limonene in the headspace of S. Chemical plant defenses, in general, did not correlate with performance or preference, but some plant volatiles may have played a role in resolving female choice. Adults laid more eggs on Solanum immite Dunal plants, which were poor hosts for larval development, feeding, and survival, compared to the other three Solanum species.Ĥ. It was found that larval performance was mismatched with adult oviposition preferences. Larval feeding, development, oviposition, plant glycoalkaloids, and headspace volatiles in the four plant species were analysed to examine the extent of variation, which might explain performance–preference differences.ģ. In the present study, the hypothesis of preference–performance was tested by offering solanaceous specialist Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae) larvae and adult females four plant congeners that ranged in suitability.Ģ. Maternal preference is a dynamic process and interactions between preference and performance are fundamental for understanding evolutionary ecology and host association in insect–plant interactions.