DOI: 10.5061/dryad.37pvmcvz8
title: Microbial symbiont performance under thermal stress does not predict vector competence

description: Insect-microbe symbioses are critical to host development, immunity, and
 ecological interactions, including pathogen vectoring. The squash bug
 Anasa tristis is an agricultural pest and vector of Serratia ureilytica,
 the agent of Cucurbit Yellow Vine Disease. This insect hosts an
 environmentally acquired Caballeronia symbiont that aids development and
 suppresses pathogen load. While different Caballeronia strains appear
 functionally equivalent under benign conditions, they differ in thermal
 tolerance. It is unknown whether host thermal stress influences
 symbiont-mediated suppression of S. ureilytica. We evaluated whether
 elevated temperature affects the ability of different symbiont strains to
 influence pathogen titer and host performance. We measured development,
 adult weight, survival, and S. ureilytica counts in A. tristis reared with
 different symbiont strains from 24–36ºC. Thermal stress affected host
 performance in a strain-dependent manner, with some symbionts conferring
 greater survival at high temperatures. Surprisingly, pathogen suppression
 did not vary with symbiont strain or host rearing temperature. These
 results suggest that while symbiont identity modulates host performance
 under thermal stress, these effects do not alter pathogen load or
 transmission potential. Instead, the symbiont may initiate some host
 immune responses. This work underscores the context-dependent nature of
 symbiont-pathogen interactions and the importance of disentangling
 environmental effects on vector competence.
description: # Microbial symbiont performance under thermal stress does not predict
 vector competence ## Description of the data and file structure This
 README file describes the data packages and code accompanying the above
 publication. ### Files and variables #### File: Adult_weight_data.csv
 **Description:** Fresh weight of adult A. tristis across three temperature
 treatments, colonized by one of four Caballeronia isolates or reared
 aposymbiotically, and either exposed to Serratia or not. Each row
 represents a single insect. ##### Variables * BoxID: The cage in which an
 insect was reared. * BugID: Unique identification letter for each insect
 in a box. Letter was provided upon collection at adulthood. * Date: The
 date the insect was collected from its rearing cage. * Strain: Identity of
 the Caballeronia a host was infected with. * Serratia: Does not have
 Serratia (0) or has Serratia (1). * Temp: The temperature in Celsius at
 which the insects were reared. * Weight(mg): Fresh weight in mg upon
 eclosion to adulthood. * Sex: Male (M), female (F), unidentified (X). *
 Status: Collected as a live adult (L), alive but failed to molt (F), died
 before collection (D). * Notes: Any notes about the individual. NA if
 there were no notes. #### File: Strain_growth_curves_data.csv
 **Description:** Serratia thermal growth curves subjected to five
 temperature treatments. Every row represents the maximum growth slope for
 one replicate per strain. ##### Variables * sid: Identity of the Serratia
 isolate. * rep: replicate number for the specified strain. * temp: The
 temperature in Celsius at which the strain was grown. * well: The plate
 well the culture was grown in. * slope: Maximum growth slope. * slope_lwr:
 Lower limit of the growth slope. * slope_upr: Upper limit of the growth
 slope. * intercept: Intercept of the growth curve region. * rsq: R-squared
 value of the growth curve region. * ln_od: Natural log of the optical
 density of the maximum growth curve region. #### File:
 Serratia_Colony_Counts.csv **Description:** Serratia CFU/mL per A. tristis
 whole bug homogenate. Insects were subjected to three temperature
 treatments and provided with Serratia after Caballeronia infections. Every
 row represents one insect. ##### Variables * Date: The date the plate was
 counted (48 h after plating). * PlateID: The specific ID for the insect
 dilution plate. * Strain: Identity of the Caballeronia a host was infected
 with. * temperature: The temperature in Celsius at which the insects were
 reared. * timepoint: Days post 48 h Serratia infection. * iteration: The
 iteration of the plating experiment. * cfu/ml_count: Serratia titer in CFU
 (colony forming units) per mL. * has_Serratia?: Whether the insect had
 Serratia (cfu/ml_count &gt; 0) #### File: Mortality_data.csv
 **Description:** Host survival of A. tristis across three temperature
 treatments, colonized by one of four Caballeronia isolates or reared
 aposymbiotically, and either exposed to Serratia or not. Every row
 represents survival for each cage. ##### Variables * boxid: The cage in
 which an insect was reared. * strain: Identity of the Caballeronia a host
 was infected with. * serratia: Does not have Serratia (0) or has Serratia
 (1). * temp: The temperature in Celsius at which the insects were reared.
 * live3: The number of live third instars. * dead3: The number of dead
 third instars. * live4: The number of live fourth instars. * dead4: The
 number of dead fourth instars. * live5: The number of live fifth instars.
 * dead5: The number of dead fifth instars. * live6 : The number of live
 adults. Insects were collected and removed from the cages at this point. *
 totallive: Total number of insects alive in the cage. Includes adult
 insects that were removed during observations. * totaldead: Total number
 of insects that died in the cage. Includes all insects that died over the
 course of all observations. * totalbugs: Total number of insects in the
 cage. Includes adults and dead insects that were removed when found during
 daily observations. #### File: Development_time_data.csv **Description:**
 Development times of A. tristis across three temperature treatments,
 colonized by one of four Caballeronia isolates or reared aposymbiotically,
 and either exposed to Serratia or not.. Every row represents one daily
 data collection for each cage. ##### Variables * boxid: The cage in which
 an insect was reared. * date: The date of data collection * strain:
 Identity of the Caballeronia a host was infected with. * serratia: Does
 not have Serratia (0) or has Serratia (1). * temp: The temperature in
 Celsius at which the insects were reared. * live3: The number of live
 third instars. * dead3: The number of dead third instars. * live4: The
 number of live fourth instars. * dead4: The number of dead fourth instars.
 * live5: The number of live fifth instars. * dead5: The number of dead
 fifth instars. * live6 : The number of live adults. Insects were collected
 and removed from the cages at this point. * Notes: Any notes about the
 cage. Start indicates initial observation for cage, retire indicates final
 observation, NA if there were no notes. * totallive: Total number of
 insects alive in the cage. Includes adult insects that were removed during
 observations. * totaldead: Total number of insects that died in the cage.
 Includes all insects that died over the course of all observations. *
 totalbugs: Total number of insects in the cage. Includes adults and dead
 insects that were removed when found during daily observations. #### File:
 Code.r **Description:** R code used to generate the figures and analyze
 data. Also it fits linear mixed‐effects models to insect weight data
 across temperatures and strains, then generates predicted values with
 confidence intervals.