Plant‐mediated Facilitation to Conspecifics and Heterospecifics by Two Phloem‐feeding Maize Pests: the Influence of Insect Identity and Order of Arrival

1. Herbivory by insects leads to changes in both primary and secondary plant metabolism, ultimately impacting subsequent interactions. Some phloem-feeding insects have developed mechanisms to suppress herbivore-induced plant defences and manipulate the quality of host phloem sap, thereby facilitating their establishment on the host plant. Based on evidence that the specialized phloem-feeding insects, Dalbulus maidis and Rhopalosiphum maidis, can suppress herbivore-induced defences in maize, we hypothesized that infestation by either of these pests in maize would facilitate the colonization and establishment of subsequent conspecific and heterospecific individuals. We conducted a series of behavioural assays with these insects in both laboratory and greenhouse settings. 2. The corn leafhopper D. maidis preferred previously infested plants as hosts, but it did not discriminate between conspecific- or heterospecific-infested plants for colonization. However, when selecting a host for oviposition, it preferred depositing eggs on conspecific-infested plants, which were the hosts that the offspring performed better compared to both non-infested and heterospecific-infested plants. 3. The corn aphid R. maidis also preferred previously infested plants over non-infested plants as hosts. However, the aphid preferred heterospecific-infested over conspecific-infested plants, even though heterospecific-infested plants were hosts of lower quality to aphids. Aphids performed better on conspecific-infested plants, followed by heterospecific-infested plants, when compared to non-infested plants. 4. Our results confirm that previous colonization by the specialized phloem-feeding insects facilitates subsequent infestations by conspecifics and heterospecifics. However, the facilitation for heterospecifics was asymmetric, as colonization by D. maidis facilitated infestations by R. maidis more than the reverse sequence of infestation.