DOI: 10.5061/dryad.wdbrv163c
title: <em>Epichloë</em> endophytes impair performance and preference of <em>Rhopalosiphum padi</em> by disrupting aphid feeding behaviour in tall fescue

description: Mutualistic symbioses between plants and fungi are widespread in nature
 and are increasingly being adopted in agroecosystems to enhance economic
 and environmental sustainability. Temperate forage grasses often associate
 with Epichloë endophytic fungi that, by hindering herbivore performance,
 confer protection against insect damage, aphids in particular. However,
 despite the well-known impacts of endophytes on aphid preference and
 performance, there is scant information on how such effects are caused by
 alterations in feeding behaviour. The main objective here was to explore
 interactions between a grass plant, its fungal endophyte, and aphids,
 focusing on using the Electrical Penetration Graph technique to understand
 in detail the various aspects of aphid feeding behavior. Experiments were
 conducted in a greenhouse with tall fescue cultivars INIA Aurora and INIA
 Fortuna, grown with (+) or without (-) the AR584-Epichloë strain of
 Epichloë coenophiala, and exposed to bird-cherry oat aphids, Rhopalosiphum
 padi. Aphid performance was evaluated in antibiosis tests (no choice), at
 both population and individual levels, and preference in antixenosis
 (choice) tests. Aphid feeding behaviour was studied using the Electrical
 Penetration Graph technique in both seedlings and adult plants. Daily
 fecundity and aphid population growth were both lower on endophytic
 plants, indicating a preference for endophyte-free plants. Aphids
 exhibited impaired feeding behaviour on endophytic plants, with shorter
 phloem activities. Similar patterns were observed in seedlings. These
 results demonstrate that endophytes negatively affect aphid phloem sap
 ingestion, explaining the subsequent insecticidal and antifeedant effects,
 and that these can explain the ulterior insecticidal and antifeedant
 consequences.
description: All data from both the no-choice (antibiosis) and choice
 (antixenosis) experiments, including aphid population and individual
 responses, were analysed using mixed model ANOVA (PROC MIXED, SAS 2009).
 Normality assumptions were assessed using the Shapiro-Wilk test statistic
 (PROC UNIVARIATE, SAS 2009). The models examined the main effects of
 cultivar (four populations and five individuals), with individual
 seedlings or plants treated as random factors. Pairwise comparisons
 between cultivars were conducted using least-squares means (LS MEANS
 statement), with means separated using an adjusted Tukey method for
 multiple comparisons (α = 0.05). Mean differences were compared using the
 least-squares mean difference (LSD) from an adjusted Fisher’s protected
 LSD method for multiple comparisons (α = 0.05). Additionally, a Pearson
 rank correlation coefficient test was used to analyse the relationship
 between plant dry mass and plant height, specifically in plants inoculated
 with aphids or those that remained aphid-free during the aphid population
 experiment. Results from EPG measurements did not
 exhibit a normal distribution (Table 3, variables 1–8, 10–11, 13–22).
 Therefore, Mann–Whitney U rank sum tests were employed to assess
 differences in aphid feeding behaviour between plants with different
 endophytic status. Fisher’s exact test was used to evaluate disparities in
 the proportions of individuals engaging in specific types of activity
 between plants with different endophytic status (Table 3, variables 9, 12,
 15, 23, and 24). Significance levels were adjusted for multiple testing
 using the false discovery rate (FDR) correction method at α = 0.05
 (Benjamini and Hochberg 1995). A comprehensive description of the FDR
 procedure is provided in Benjamini et al. (2001). All statistical analyses
 for these experiments were conducted using InfoStat Professional v2011p
 software (Di Rienzo et al. 2013).
description: # *Epichloë* endophytes impair performance and preference of
 *Rhopalosiphum padi* by disrupting aphid feeding behaviour in tall fescue
 Dataset DOI:
 [10.5061/dryad.wdbrv163c](https://doi.org/10.5061/dryad.wdbrv163c) ##
 Description of the data and file structure ### **Figure 1: Population
 Experiments** * **Fig. 1A** — from file: `ANTIBIOSIS POP` * **Fig. 1B** —
 from file: `ANTIXENSOSIS` * These contain **population-level data** for
 antibiosis and antixenosis, respectively. --- ### **Figure 1: Individual
 Experiments** * **Fig. 1C** — from file: `ANTIBIOSIS IND` * **Fig. 1D** —
 from file: `ANTIXENSOSIS IND` * These contain **individual-level data**
 for the same traits. --- ### **EPG Data** * File: `EPG DATA SET` * This
 file includes **all variables related to EPG (Electrical Penetration
 Graph)** recordings — likely insect feeding behavior variables. ### Files
 and variables #### File: ANTIBIOSIS_IND.csv **Description:** these contain
 **individual-level data** for the antibiosis (no-cice) exp. #####
 Variables * POT: experimental unit * VAR: pant variety * DAYTA: days to
 adult  * NYMPHS/D: average number of nymphs deposited #### File: EPG_.csv
 **Description:** This file includes **all variables related to EPG
 (Electrical Penetration Graph)** recordings — likely insect feeding
 behavior variables. ##### Variables * Origin: posoition within EPG *
 plant: endophytic status of plant * Exp_time: days  * n_Np: number of non
 probing periods | EPG-TABLE NAME | EXPLANATION | | :-------------- |
 :-------------------------------------------------------------------------------- | | n\_Np | number of non probing periods | | a\_Np | average non probing (period duration)  | | m\_Np | median non probing (period duration) | | s\_Np | sum of non probing  | | n\_Pr | number of probes | | n\_bPr | number of brief probes (probes &lt; 180 s) | | a\_Pr | average probe | | m\_Pr | median  probe | | s\_Pr | sum of probing  | | n\_C | number of C periods | | a\_C | average C; with pd without E1e, F and G  | | m\_C | median C | | s\_C | sum of  C  | | n\_F | number of F | | a\_F | average F | | m\_F | median F | | s\_F | sum of  F | | n\_G | number of  G | | a\_G | average G | | m\_G | median G  | | s\_G | sum of G  | | t\_1G | time to the first G (after first penetration) | | nPr\_1G | number of probes before the first G | | n\_E1e | number of E1 extracellular (E1e) periods | | a\_E1e | average E1e | | m\_E1e | median E1e | | s\_E1e | sum of  E1e | | n\_sgE1 | number of single E1 (without E2) periods | | a\_sgE1 | average single E1 | | m\_sgE1 | median single E1 | | s\_sgE1 | sum of single E1 | | mx\_sgE1 | maximum duration of a single E1 period | | n\_frE1 | number of fractions of E1;: E1followed/preceded by E2 | | a\_frE1 | average fraction of E1   | | m\_frE1 | median fraction of E1  | | s\_frE1 | sum of fractions of E1  | | mx\_frE1 | maximum duration of a fraction of E1  | | n\_E1 | number of all E1 periods (sgE1 + frE1) | | a\_E1 | average E1  | | m\_E1 | median E1 (sgE1 and E1fr) | | s\_E1 | sum of E1 (sgE1 and E1) | | mx\_E1 | maximum E1 period (either sgE1 or frE1) | | n\_E12 | number of E12 phloem periods i.e. with both, E1 and E2 | | a\_E12 | average E12  | | m\_E12 | median E12 (with both E1 and/or E2) | | s\_E12 | sum of E12 | | mx\_E12 | maximum E12, phloem phase with E1 and/or E2  | | n\_E2 | number of E2 periods | | a\_E2 | average E2  | | m\_E2 | median E2  | | s\_E2 | sum of E2 | | mx\_E2 | maximum E2 period | | n\_sE2 | number of sustained E2 (sustained E2, i.e. E2 longer than 10 min) | | a\_sE2 | mean duration of sE2 | | m\_sgE2 | median duration of sE2 | | s\_sE2 | sum of duration of sE2 | | t\_1Pr | time to 1st probe (in recording; = d\_1Np)  | | d\_1Pr | duration of 1st probe | | t\_1E | time to 1st E (always E1; from the 1st probe) | | t\_C\_1E\_1Pr | time to 1st E within the 1st probe with E | | at\_C\_1E\_Pr | average time to 1st E within probes | | mn\_C\_1E\_Pr | minimum time to 1st E within probes | | n\_bPr\_1E | number of brief probes &lt; 3 min before 1st E | | n\_Pr\_1E | number of probes before the 1st E  | | t\_1E12 | time to 1st E12 | | t\_1E2 | time to 1st E2 | | t\_1sE2 | time to 1st sE2 (E2 &gt; 10 min) | | n\_Pr\_1E2 | number of probes to the 1st E2 (=E2 in 1stE12)  | | n\_Pr\_1sE2 | number of probes before 1st sE2 | | nPr\_1sE2 | number of probes after 1st sE2 | | n\_E2\_1sE2 | number of E2 before the 1st sE2 | | t\_1E1\_1E2 | time from the 1st E1 to 1st E2 | | t\_1E1\_1sE2 | time from the 1st E1 to 1st sustainable E2 | | s\_E1\_1sE2 | sum of E1 before 1st sE2 | | s\_E2\_1sE2 | sum of E2 before 1st sE2 | | a\_E2\_1sE2 | mean duration of E2 periods before the 1st sE2 | | rel\_E2\_C | SE ingestion/pathway ratio as %  | | rel\_E1\_allE | E1 index:duration E1/ allE as % | | n\_frE1\_n\_E12 | phloem phase fractioning | | rel\_E2\_1E2 | E2 index: % (all time of E2 / Time to the start of 1st E2 from first penetration) | | n\_pd | number of pd | | a\_pd | average duration of pd | | m\_pd | median duration of pd | | s\_pd | sum of pd | | a\_pd\_II\_1 | average pd2\_1 duration | | m\_pd\_II\_1 | median pd2\_1 duration | | s\_pd\_II\_1 | sum of pd2\_1 periods | | a\_pd\_II\_2 | average pd2\_2 duration | | m\_pd\_II\_2 | median pd2\_2 duration | | s\_pd\_II\_2 | sum of pd2\_2 periods | | a\_pd\_II\_3 | average pd2\_3 duration | | m\_pd\_II\_3 | median pd2\_3 duration | | s\_pd\_II\_3 | sum of pd2\_3 periods | | t\_1pd | time to 1st pd (from start of 1st probe) | | t\_1pd\_1pr | time to 1st pd in 1st probe with a pd | | at\_1pd\_Pr | average time to 1st pd in all probes with a pd | | mt\_1pd\_Pr | median time to 1st pd in all probes with a pd | | mnt\_1pd\_1Pr | min. time to 1st pd in 1st probe | | n\_pd\_minC | no. pd per min C  | | n\_pd\_minC\_pd | no. pd per min C , only C\_phases with pd | | n\_pd\_1Pr | no. pd in 1st probe | | rel\_Prob\_pd | relation of probes with pd | | n\_Pr\_1pd | number of probes before 1st pd  | | d\_1pd | duration of the first pd | | d\_2pd | duration of the second pd | | d\_pd5 | mean duration of the first 5 pd | | s\_pdII-3\_5pd | sum of subphase 3 of the first 5 pd | 
 
 #### File: ANTIXENOSIS_POP.csv **Description:** These contain
 **population-level data** for antixenosis (chocie) exp  ##### Variables *
 CUAD: square  * VAR: variety * DATE : calendar date * ALATE: # alate aphid
 form  * APTEROUS: # apterous aphid form  * NYMPHS :# nymphs aphid form  *
 TOTAL : sum of aphids * HEIGHT: plant height in cm * TILLER: tiller number
 * TEF: tiller weight (mg) * SCORE: damage score * DRY.W: plant dry weight
 (mg) #### File: ANTXENOSIS_IND.csv **Description:** These contain
 **individual-level data** for the antibiosis (choice) exp.  #####
 Variables * DATE: DATE * CUP: experimental unit  * VAR1/VAR2: varietes
 within the capsule (1 and 2; fig 1 D) * VAR1: variety 1 ; fig 1 D * VAR2:
 variety 2 ; fig 1 D