DOI: 10.5061/dryad.931zcrjtz
title: Ecology of fear: Ontogeny-mediated non-consumptive effects in a parasite-host system

description: Non-consumptive effects (NCEs) arise in the presence of parasites even
 when the infection does not occur and can include changes to host
 behaviour, physiology, or morphology. Using the Drosophila nigrospiracula
 – Macrocheles subbadius fly-mite system, we investigated the impact of
 parasite exposure (sans infection) during the pupal and adult
 pre-reproductive stages. First, we exposed fly pupae to mites—either
 indirectly (caged mites) or directly (free-roaming mites) to test the
 effects of parasite exposure on pupation success. Second, we tested how
 exposing adult female flies to mites prior to reproduction affects
 fecundity during the post-exposure reproductive period. We found that
 direct exposure to mites significantly decreased the rate of successful
 eclosion (development from pupa to adult) compared to unexposed pupae;
 however, the duration of pupation was not significantly affected. The
 indirect exposure did not have a significant effect on either successful
 eclosion or duration of pupation. We also found that indirectly exposed
 (caged mites) females had a significant decrease in the number of
 offspring produced, but only for the first few days post-eclosion,
 suggesting the effect was reversible after mite removal. NCEs arise after
 mite exposure during the pupal and pre-reproductive life stage of
 Drosophila, in the form of decreased eclosion success and fecundity.
 Investigating the NCEs associated with parasite exposure at various life
 stages of the host is important in understanding the ecology of fear and
 its total impact on hosts throughout their entire lifespan, with
 consequences for host ontogeny and population growth.
description: <strong>Pre-reproductive exposure </strong>
 <em>(Data: Offspring.csv)</em>
 Fecundity was measured by aspirating and manually counting all
 F<sub>1</sub> offspring that emerged from each of the 6 serial
 transfer vials. Fecundity analysis was performed using a generalized
 linear mixed effects model with a negative binomial distribution
 (glmer.nb; package <em>lme4</em>). The number of offspring
 ("Offspring") was the dependent variable and exposure
 ("Treatment") was the explanatory variable, with the fly mating
 group ("ID") as a random variable to account for natural
 heterogeneity between each mating group. In total, there were 18 350
 offspring collected from female flies not exposed to mites (n=28) and 17
 102 from those exposed to mites (n = 28).
 <em>(Data: SexRatios.csv)</em> A
 random subsample of 100 flies from each mating group ("ID") was
 sexed and a generalized linear model using the ‘cbind’ formula with
 binomial distribution (glm, family = ”binomial”) was used to analyze the
 effect of "Treatment" (Control = no mites; Exposed = 5 mites in
 a cage) on the number of "Females" versus "Males" out
 of a total of 100 offspring. <em>(Data:
 Weight.csv)</em> A subsample of 20 flies from the
 above-mentioned 100 sampled flies for sexing were weighed to the nearest
 0.01 mg (XP105DR, Mettler Toledo, Columbus), and a generalized linear
 model was used to analyze the effect of "Treatment" on the
 "Weight" of the offspring. Mating group "ID" was
 included as a column, but was not found to be significant for final model
 selection.  <strong>Pupae
 exposure</strong>  <em>(Data:
 Emerged.csv)</em> The effect of indirect (n= 34),
 direct (n= 33), or no mite (n= 36) exposure ("Treatment") on fly
 development was measured by counting the "Total" number of
 emerged adults out of 10 pupae over 7 days. Analysis was performed using a
 generalized linear model with a negative binomial distribution
 (glm.nb). <em>(Data:
 Duration.csv)</em> The effect of indirect (n=
 34), direct (n= 33), or no mite (n= 36) exposure ("Treatment")
 on the "Duration" of pupal development was analyzed using a
 Kruskal-Wallis test (kruskal.test).
description: # Ecology of fear: ontogeny-mediated non-consumptive effects in a
 parasite-host system
 [https://doi.org/10.5061/dryad.931zcrjtz](https://doi.org/10.5061/dryad.931zcrjtz) ## Description of the data and file structure This data set contains measurements of fly fecundity and development. There are five data files in total: Offspring.csv, Weight.csv, SexRatios.csv, Emerged.csv, and Duration.csv. For pre-reproductive female data files (Offspring.csv, Weight.csv, SexRatios.csv), each cell represents a single measurement for a group of 3 female flies. For pupae emergence data (Emerged.csv), each cell represents a measurement out of 10 pupae. In the pupae duration data (Duration.csv), each cell represents a single measurement for a single pupa and NA denotes any pupae that did not successfully emerge within the 7 days (see Methods section of MS).   #### *(Data file: Offspring.csv)* A mating group (henceforth known as "MG"; 3 female flies + 2 male flies) was given an "ID", which allowed us to consider MGs as a random factor in our model to account for heterogeneity. The "Treatment" column designated females as either an "Exposed" group to 5 mites in a cage prior to the completion of egg development, or a "Control" group that was exposed to an empty cage with no mites. Each MG was placed in a vial and every 3-4 days moved to a fresh vial for a total of 6 serial transfers represented by the "Vial" column.  The "Offspring" column is the count of first-generation offspring from the MGs from each of the 6 serial transfer vials.  #### *(Data file: Weight.csv)* As stated above, "ID" and "Treatment" designate the MGs and either exposed or control flies respectively. The "Sex" column has either "Female" or "Male" and the "Weight" column is the measured weight of the first-generation offspring to the nearest 0.01 mg (XP105DR, Mettler Toledo, Columbus). #### *(Data file: SexRatios.csv)* As stated above, "ID", and "Treatment" designate the MGs and either exposed or control flies respectively. The "Female" and "Male" columns represent the count of how many—out of 100 total flies—were either female or male.  #### *(Data file: Emerged.csv)* Each petri dish contained 10 pupae and was given an "ID". The "Treatment" column designated either an "Indirect Exposure" with 5 caged mites, "Direct Exposure" with 5 free-roaming mites, or "Control" without mites. The "Block" column represents replicates that were done on the same day to account for temporal differences. Columns "Day*X*" have the number of adults that successfully emerged *X* days after the pupae were formed. No pupae emerged on Day 1 or 2, therefore no data was recorded 1 or 2 days after the pupae formed. The "Total" column represents the total number of adults that emerged from the 10 pupae in each petri dish.  #### *(Data file: Duration.csv)* As above, each petri dish was given an "ID". The "Treatment" column designated either an "Indirect Exposure" with 5 caged mites, "Direct Exposure" with 5 free-roaming mites, or "Control" without mites. The "Pupa" column represents each individual pupa out of 10 total pupae from one petri dish ("ID"). The "Duration" column is the day the adult emerged from the pupal case and "NA" represents pupae that did not successfully emerge.  ## Sharing/Access information NA ## Code/Software All statistics were completed in RStudio. All packages are made available through the R website. Chosen packages and associated functions are noted within the manuscript.