Specific bottom–up effects of arbuscular mycorrhizal fungi across a plant–herbivore–parasitoid system

Abstract

The majority of plants are involved in symbioses with arbuscular mycorrhizal fungi (AMF), and these associations are known to have a strong inXuence on the performance of both plants and insect herbivores. Little is known about the impact of AMF on complex trophic chains, although such eVects are conceivable. In a greenhouse study we examined the eVects of two AMF species, Glomus intraradices and G. mosseae on trophic interactions between the grass Phleum pratense, the aphid Rhopalosiphum padi, and the parasitic wasp Aphidius rhopalosiphi. Inoculation with AMF in our study system generally enhanced plant biomass (+5.2%) and decreased aphid population growth (¡47%), but there were no fungal species-speciWc eVects. When plants were infested with G. intraradices, the rate of parasitism in aphids increased by 140% relative to the G. mosseae and control treatment.When plants were associated with AMF, the developmental time of the parasitoids decreased by 4.3% and weight at eclosion increased by 23.8%. There were no clear eVects of AMF on the concentration of nitrogen and phosphorus in plant foliage. Our study demonstrates that the eVects of AMF go beyond a simple amelioration of the plants' nutritional status and involve rather more complex species-speciWc cascading eVects of AMF in the food chain that have a strong impact not only on the performance of plants but also on higher trophic levels, such as herbivores and parasitoids.

The underestimated role of roots in defense against leaf attackers

“…Although this is not entirely consistent with the priming hypothesis based on the perception of an initial mild stress [48], it might nevertheless serve as a starting point to uncover the elusive root-shoot signal emanating from colonized roots. Interestingly, evidence is increasing that arbuscular mycorrhizal fungi (AMF) can have similar effects on aboveground resistance as ISR [69,70] and it has been proposed that the two phenomena share a similar mechanistic basis [24,69]. However, it was recently shown for barrel clover (Medicato truncatula) that root colonization by the AMF Glomus intraradices, unlike ISR, directly induces a variety of defense related genes in the shoot [71].…”

Mycorrhizae Alter Toxin Sequestration and Performance of Two Specialist Herbivores

“…Aphids had the lowest per capita growth rates and individual masses on plants under medium AMF availability, yet had the highest per capita growth rates and masses on plants under high AMF availability (Figure 2). Thus, we found within a single study the range of aphid responses to AMF from the literature, from positive to negative (Pacovsky et al, 1985;Gange and West, 1994;Gange et al, 1999Gange et al, , 2002Gehring and Whitham, 2002;Wurst et al, 2004;Hempel et al, 2009;Koricheva et al, 2009;Abdelkarim et al, 2011;Babikova et al, 2014a;Colella et al, 2014;Grabmaier et al, 2014;Williams et al, 2014;Bennett et al, 2016;Simon et al, 2017;Tomczak and Müller, 2017). Our findings suggest that some of the previously found variation in aphid responses may result from differences in AMF inoculum availability among studies.…”

“…AMF-mediated increases in aphid performance under high AMF availability may also be a consequence of increased vascular bundle size; AMF colonization increases the size of vascular bundles in plants (Krishna et al, 1981), increasing aphid phloem feeding and reproductive success (Simon et al, 2017). Although aphids are often responsive to changes in amino acid content of phloem (Züst and Agrawal, 2016a), we think it unlikely that AMF influenced A. nerii performance by changing phloem soluble sugar or amino acid content because previous studies found no correlations among AMF-mediated changes in aphid performance and foliar or phloem nutrient content (Gange and West, 1994;Hempel et al, 2009;Grabmaier et al, 2014).…”

“…For instance, aphids generally benefit from AMF colonization of their host plants; aphids are more attracted to plants colonized by AMF and have greater body masses, growth rates, and fecundity on host plants colonized by AMF (Gange and West, 1994;Gange et al, 1999Gange et al, , 2002Koricheva et al, 2009;Babikova et al, 2014a,b;Simon et al, 2017). However, aphids have also been found to not respond to AMF colonization of their host plants (Pacovsky et al, 1985;Wurst et al, 2004;Colella et al, 2014;Grabmaier et al, 2014;Williams et al, 2014;Bennett et al, 2016) or to have reduced population growth on plants colonized by AMF (Gehring and Whitham, 2002;Hempel et al, 2009;Abdelkarim et al, 2011). Similarly, while some specialist chewers benefit from AMF colonization of their host plants (Borowicz, 1997;Goverde et al, 2000;, others are unaffected (Laird and Addicott, 2008;Cosme et al, 2011).…”

Peranan Jamur Mikoriza Arbuskular Terhadap Perkembangan Penyakit Daun Keriting Kuning Cabai (The Role of Vesicular Arbuscular Mycorrhiza on Disease Severity of Pepper Yellow Leaf Curl Disease)

“…Vierheilig et al (2008) melaporkan bahwa ada beberapa perubahan fisologi dan biokimiawi yang terjadi pada tanaman yang terinfeksi oleh mikoriza sehingga mampu melindungi tanaman dari infeksi patogen seperti: induksi enzim hidrolitik, akumulasi senyawa fitoaleksin dan kalose, akumulasi asam salisilat. Hempel et al (2009) juga melaporkan bahwa inokulasi JMA mampu menurunkan perkembangan populasi afid yang dapat berperan sebagai serangga vektor karena adanya senyawa fenolik yang dihasilkan oleh tanaman bermikoriza. Gambar 2.…”