DOI: 10.5061/dryad.wpzgmsc2t
title: Data from: Nitrogen fertilizer input alters the prey consumption rate of a widespread aphid predator, <em>Harmonia axyridis</em>

description: The sharp rise in synthetic inorganic fertilizer use (notably nitrogen)
 over decades has caused unknown effects on ecosystems and the services
 they provide, such as biocontrol. The present study aimed to test the
 hypothesis that host plant nitrogen input alters the interactions between
 pests and natural enemies, specifically investigating whether aphid
 consumption by Harmonia axyridis differed depending on nitrogen fertilizer
 input. It was hypothesised that H. axyridis would consume fewer aphid
 individuals reared under nitrogen conditions that are optimal for aphid
 fecundity. Observed effects of different nitrogen inputs in Chinese
 cabbage on the aphid Myzus persicae and the predator H. axyridis support
 our hypothesis: at lower nitrogen levels, the fecundity and longevity of
 M. persicae increased in the absence of predators, and the numbers of
 adult aphids H. axyridis consumed to reach temporary satiation and to
 finish the 3rd and 4th instars decreased. In addition, the fitness of H.
 axyridis, indicated by the pupal weight, also reduced at the nitrogen
 treatment favourable for aphid fecundity. These findings revealed the
 mechanisms underlying the long observed amplified changes in biocontrol
 efficacy with different nitrogen inputs in agroecosystems that reducing
 nitrogen for plants increases pest fecundity while reduces predation.
 Therefore, we recommend an economical increase in nitrogen application to
 achieve optimal plant nutrition and enhance biocontrol efficacy of the
 ladybeetles.
description: # Data from: Nitrogen fertilizer input alters the prey consumption rate of
 a widespread aphid predator, *Harmonia axyridis* Dataset DOI:
 [10.5061/dryad.wpzgmsc2t](https://doi.org/10.5061/dryad.wpzgmsc2t) ##
 Description of the data and file structure This dataset comprises three
 csv files. The "aphid_data_fecundity" file contains data on
 aphid fecundity (number of offspring) and longevity across three different
 treatment levels (Low, Medium, High) during the experimental period. The
 "*Harmonia_axyridis*_A" file provides data on temporary
 satiation points (represented by the number of aphids consumed) by
 fourth-instar *Harmonia axyridis* larvae under different nitrogen levels.
 The "*Harmonia_axyridis*_BCDEF.CSV" file describes prey
 consumption, developmental duration, pupation rate, and pupal weight of
 *Harmonia axyridis* from the third instar to pupation under the different
 nitrogen level treatments. # Files and variables ### File:
 aphid_data_fecundity.CSV #### **Description:** Aphid fecundity (number of
 offspring) and longevity cross three different treatment levels (Low,
 Medium, High) during the experimental period. Empty cells represent
 missing data. ### Number of variables: 3 ### Number of cases/rows: 99 (one
 row per trial) #### **Variable List** 'level' (levels):
 Different nitrogen levels (L: 0.4 g/plant, M: 0.8 g/plant, H: 1.6 g/plant
 ) 'fecundity' (individuals): Total lifetime offspring production
 in a *Myzus persicae* 'longevity' (days): Survival time of
 *Myzus persicae* ### File: Harmonia_axyridis_A.CSV #### **Description:** 
 Temporary satiation points (represented by the number of aphids consumed)
 by fourth-instar *Harmonia axyridis* larvae under different nitrogen
 levels. Empty cells represent missing data. #### Number of variables: 2
 #### Number of cases/rows: 90 (one row per trial) #### **Variable List**
 'level' (levels): Different nitrogen levels (L: 0.4 g/plant, M:
 0.8 g/plant, H: 1.6 g/plant) '4th' (individuals): The temporary
 satiation points of 4th instar in *H. axyridis* under different nitrogen
 applications on cabbage ## File: Harmonia_axyridis_BCDEF.CSV ####
 **Description:** Prey consumption, developmental duration, pupation rate,
 and pupal weight of *Harmonia axyridis* from the third instar to pupation
 under the same nitrogen level. Empty cells represent missing data. ####
 Number of variables: 6 #### Number of cases/rows: 45 (one row per trial)
 #### **Variable List** 'level' (levels): Different nitrogen
 levels (L: 0.4 g/plant, M: 0.8 g/plant, H: 1.6 g/plant) '3rd'
 (individuals): Number of adult aphids required to complete the 3rd instar
 in *H. axyridis* under different nitrogen applications on cabbage
 '4th' (individuals): Number of aphids required to complete the
 4th instar in *H. axyridis* 'day' (days): The duration from the
 3rd instar to pupation of *H. axyridis* 'pupal rate' (logical):
 Pupation status of *Harmonia axyridis* (1 = successful pupation, 0 =
 failed pupation) 'pupal' (weight): Pupal weight of *H. axyridis*
 (g)