DOI: 10.5061/dryad.pzgmsbcwx
title: Petri dish effect of hyperparasitoids

description: In nature, resources necessary for reproduction and survival are often
 spatially distributed or scarce. Parasitoid wasps are insects that develop
 as larvae in or on a single invertebrate resource (often another insect),
 while the adults are free living. Parasitoid larvae, exploit hosts for
 reproduction, while adults rely on carbohydrates, e.g. floral nectar, for
 maintenance. Finding these different resources may affect fitness related
 traits such as fecundity and survival. We compared reproduction and
 longevity in a hyperparasitoid wasp, Gelis agilis, utilizing cocoons of
 the primary parasitoid Cotesia glomerata as hosts in microcosm arenas
 consisting of a single Petri dish or two dishes connected by a tube. The
 number of compartments in each dish was varied and provisioning of food
 and hosts was either temporally separated by 48h intervals (single-dish
 microcosms) or spatially separated (two-dish microcosm). In the two
 experimental designs batches of host cocoons were offered to G. agilis
 females and cocoon fate (emergence of an adult primary or hyperparasitoid,
 or precocious death) was recorded. In the single-dish arenas in which
 provisioning of cocoons and food were alternated every 48h, there were no
 consistent effects of arena complexity (i.e., the number of compartment in
 the dishes) on hyperparasitoid longevity and fecundity, or host survival.
 However, when food and hosts were spatially separated in two Petri dishes
 connected by a plastic tube, longevity and fecundity of G. agilis traits
 were reduced, and survival of C. glomerata increased, in particular, when
 the number of compartments was increased. Additional experiments in the
 two-dish arenas in which only food, only cocoons or nothing was offered,
 provided further evidence that finding food is a major factor limiting
 longevity and, concomitantly, fecundity of the hyperparasitoids in more
 complex environments. Our findings are discussed within the contexts of
 habitat heterogeneity and resource-consumer interactions, and refuge
 theory.    
description: # Petri dish effect of hyperparasitoids Female hyperparasitoid (Gelis
 agilis) that had been allowed to host feed for 48 h were released in one
 of the arenas (one female per dish) with four cocoons (Cotesia glomerata)
 and or honey+water for 48h periods. The number of compartments in a dish
 (13.5 cm diameter) was varied. Cocoons and or honey+water were replaced
 every 48h. Cocoons were stored in vials and their fate was recorded (adult
 hyperparasitoid, adult primary parasitoids, or dead cocoon when nothing
 emerged within a month since exposure to the hyperparasitoid).
 **Experiment 1----Single dish experiment alternating cocoons and food
 every 48h** Provisioning of cocoons and honey + plus water were alternated
 every 48h until the female died. Thus, females had access to only hosts
 for 48h, followed by access to only carbohydrates + water for 48h. This
 protocol was repeated until death of the female Single dish arenas with a
 single compartment, 2, 4, 8 or 16
 compartments![](file:///C:/Users/10158/AppData/Local/Temp/msohtmlclip1/01/clip_image002.jpg) Data are stored in data sheet: Exp_1.csv #### Variables in data sheets Mother_ID             unique identification number of the female hyperparasitoid released in the arena Compartment        number of compartments in dish=complexity variable in analysis Rep                replication number (10 or 30 replicates per arena type) Total_cocoon          total number of cocoons offered in a dish throughout the life of a female Sum_G_agilis        total number cocoons producing adult G. agilis offspring Sum_C_glomerata total number cocoons producing adult C. glomerata offspring Sum_dead             total number of cocoons that were recorded as dead Mother_longevity   longevity of the female mother **Experiment 2.1---Two dish experiment offering cocoons in one dish and food in the other** Cocoons were offered in one dish and honey+plus in the other. Dishes were connected by a tube. Cocoons and food were replaced every 48h until the female died. This protocol was repeated until death of the female mother. Thus females had access to hosts and carbohydrates+water continuously, but had to travel from one dish to the other through the connecting tube. Two dish experiment connected by a tube![](file:///C:/Users/10158/AppData/Local/Temp/msohtmlclip1/01/clip_image004.jpg) Data are stored in data sheet: Exp2_1.csv Experiment 2.2 as experiment 2.1 but here only carbohydrates+plus water were offered in one of the dishes until the female died. Data are stored in data aheet: Exp2_2.csv Experiment 2.3 and 2.4 Same arenas as in 2.1 and 2.2 but now females are provided with only cocoons placed in one of the dishes (2.3) or nothing at all (2.4). Longevity of the females was recorded, and data were combined into one data file Exp2_3_and_2_4 with the ‘exp’-column referring to the two experiments