Plant defences and spider-mite web affect host plant choice and performance of the whitefly Bemisia tabaci

Abstract

Herbivores select host plants depending on plant quality and the presence of predators and competitors. Competing herbivores change host plant quantity through consumption, but they can also change plant quality through induction of plant defences, and this affects the performance of herbivores that arrive later on the plant. Some herbivores, such as the spider mite Tetranychus evansi, do not induce, but suppress plant defences, and later-arriving herbivores can profit from this suppression. It has been suggested that the dense web produced by this spider mite serves to prevent other herbivores to settle on the plant and benefit from the suppressed defences. Here, we confirmed this by studying the preference and performance of the whitefly Bemisia tabaci, a generalist herbivorous pest. To disentangle the effects through changes in plant defences from the effects of spider-mite web, we included treatments with a strain of the closely-related web-producing spider mite T. urticae, which induces plant defences. Whiteflies did perform worse on plants with defences induced by T. urticae, but, in contrast to other herbivores, did not perform better on plants with defences suppressed by T. evansi. Moreover, the web of both spider mites reduced the juvenile survival of whiteflies, and whiteflies avoided plants that were covered with web. Hence, whitefly performance was not only affected by plant quality and induced plant defences, but also through the web produced by spider mites, which thus serves to protect against potential competitors, especially when these could profit from the suppression of plant defences by the mites.

Higher‐order species interactions cause time‐dependent niche and fitness differences: Experimental evidence in plant‐feeding arthropods

“…1 < $$$ {\mathcal{N}}_i\Big) $$$. For example, some herbivores do not induce but suppress plant defence, allowing other herbivores to profit from this suppression (Dias et al., 2023; Godinho et al., 2016). Others change the nutritional composition, alter plant architecture or physically damage plant tissue, which improves the suitability and accessibility of the plant for other species (Paz‐Neto et al., 2022; Tscharntke, 1989).…”

Can Macrolophus pygmaeus (Hemiptera: Miridae) Mitigate the Damage Caused to Plants by Bemisia tabaci (Hemiptera: Aleyrodidae)?

“…Insect pests can trigger the production of deterrents or toxic secondary metabolites that reduce the suitability of plant tissues for further insect colonization and may compromise the ability of the plant to activate certain resistance-related pathways [ 58 , 59 , 60 ]. This could be the case with B. tabaci , which induces the activation of salicylic acid (SA) [ 61 , 62 ], a phytohormone able to suppress the activation of jasmonic acid (JA) [ 53 , 63 ]. However, the latter phytohormone can be induced by mirid insect activities (e.g., oviposition by adult females and feeding by M. pygmaeus nymphs) [ 54 ] and functions in the mediation of plant responses.…”

Understanding the joint evolution of dispersal and host specialisation using phytophagous arthropods as a model group

“…Interspecific competition has long been established as an important factor shaping resource use, leading to ecological or reproductive character displacement (Brown & Wilson, 1956). The performance of herbivores on different host plants is indeed affected by the presence of interspecific competitors, either negatively (Magalhães et al ., 2007 c ), positively (Xu, Ma & Liu, 2014), or in both directions (Dias et al ., 2022). This factor is also predicted to affect dispersal in different ways (Case & Taper, 2000), and is known to affect the dispersal of phytophagous arthropods (Denno & Roderick, 1992) and thus the choice and distribution of herbivores at different scales (Nakadai et al ., 2018; Denno et al ., 2000; Godinho et al ., 2020; Fragata et al ., 2022).…”