DOI: 10.5285/54b722a7-7cda-4817-86a5-b96ad0bb4ae7
title: Population count data from a resource degradation and temperature variation population dynamics experiment in the Plodia-Venturia host-parasitoid interaction

description: This dataset contains information on population counts in experimental populations of Plodia interpunctella (Pyralidae; Hübner) and the parasitoid wasp Venturia canescens (Ichneumonidae; Gravenhorst).

The data was collected from a multi-generation microcosm experiment carried out to characterise the combined effects of daily stochastic temperature fluctuations and resource degradation on population responses in the Plodia-Venturia host-parasitoid trophic interaction. The population count data include the weekly total numbers of dead adult hosts and parasitoids and the numbers of live early (L1-L3) and late (L4-L5) host instars and of host and parasitoid pupae in half sections of diet removed weekly and replaced by fresh diet (half sections are a 12th of experimental population boxes). The temperature time series data include the date and daily temperature in the fluctuating temperatures treatment.
description: The Plodia-Venturia microcosm experiment used hosts from laboratory stock cultures and parasitoids from a laboratory parthenogenetic thelytokous (asexual) strain, which were kept on non-degraded host resource at constant 28 deg C in incubators with a 16:8h light cycle. Daily temperature variation and host resource degradation (also referred as 'diet' in datasets) were manipulated in a full factorial design. Two temperature treatments in each resource degradation treatment were compared. Both temperature treatments were characterized by a mean temperature of 26°C, which did not vary in the constant ('CST') treatment and varied randomly between 22.3 and 30.2°C every 24h in the variable (‘VAR’) treatment (26°C ± 1.5°C SD, AR(1) = 0.02, 95% CI [-0.10, 0.14].

A  gradient of resource degradation was created from none to high by replacing 0, 25, 50 and 75 % of wheat germ in the host’s diet with methyl cellulose, an indigestible bulking agent with no nutritional value. The microcosm experiment started on day 1 of the temperature time series and was carried out for 262 days.

Three replicates of 'host alone' (Pi) and 'host-parasitoid' (PiVc) microcosms were set up in each temperature by resource treatment, giving a total of 48 (3 × 2 × 2 × 4) microcosms. Each microcosm was established with fifteen male and fifteen female fifth instar larvae randomly selected from host stock cultures in 175 x 116 x 60 mm plastic containers filled with 83 grammes of the assigned resource. All microcosms were kept at constant 26°C until all 30 host larvae had pupated, after which they were maintained under their assigned temperature treatment (week 1 of the experiment). Microcosms were left undisturbed until adult hosts emerged, mated and the first cohort of their offspring had reached the adult stage on week 8. Thereafter, for the remainder of the experiment, one sixth of the resource was replenished sequentially during weekly monitoring by replacing the oldest section with fresh resource of the same treatment. In PiVc microcosms, the second host cohort was left to develop until fourth and fifth instars were present in all treatments (on week 13). Two newly emerged adult parasitoids randomly selected from stock cultures were then added to each microcosm. Each week from week 9 to 37, dead adults were removed from each microcosm and counted, giving a measure of live host and parasitoid abundance from the previous week. Host early (L1-L3) and late (L4-L5) instars and pupae and parasitoid pupae were counted in half of each section of old diet (half section a or b) removed weekly from microcosms (counted in a 12th of each experimental population boxe). More details of the material and methods can be found in the Supplementary information.