DOI: 10.5061/dryad.37pvmcvrm
title: Data for: Oviposition fluids mediate larval competition

description: Parasitoid wasp larvae engage in intense interspecific competition when
 sharing a host insect, with lethal consequences for the losers. Larval
 parasitoid competition is generally thought to be resolved by physical
 traits, such as enlarged mandibles. Although solitary parasitoid larvae
 are typically superior competitors against gregarious larvae, such
 physical traits are unlikely to be effective against large numbers of
 competitors. Larval competition may instead be mediated by maternal
 factors that increase the survival of offspring facing interspecific
 competition, thus increasing parental fitness. When laying eggs inside a
 host, many female parasitoids also inject oviposition fluids that are
 known to suppress host immune responses, permitting successful offspring
 development. We explored whether the oviposition fluids of two wasp
 species in the genus Cotesia (Cotesia rubecula, a strong
 competitor that almost always wins interspecific competition against a
 weaker competitor, Cotesia glomerata) might also represent
 maternal factors that improve the interspecific competitive ability of
 their offspring. We demonstrate that injections of both venom and calyx
 fluid from C. rubecula can inhibit egg hatching and larval
 development of C. glomerata. Venom from C.
 rubecula decreased C. glomerata egg development
 by 2.7 times, and calyx fluid injections caused deformities in 23% of
 developing C. glomerata. In contrast, reciprocal
 injections of the oviposition fluids from C.
 glomerata did not inhibit the development of C.
 rubecula. Our results show that maternal factors can improve the
 interspecific competitive ability of parasitoid larvae, challenging the
 previous assumptions that larval competition was resolved primarily
 through physical combat or larval secretions.
description: # Data for: Oviposition fluids mediate larval competition
 [https://doi.org/10.5061/dryad.37pvmcvrm](https://doi.org/10.5061/dryad.37pvmcvrm) ## Description of the data and file structure Data set contains details, primarily counts, resulting from dissection of injected *P. rapae* caterpillar hosts. Common abbreviations used: * Cg = Cotesia glomerata * Cr = Cotesia rubecula * Treatment names: cv - calyx + venom, c - calyx only, cr - C. rubecula parasitized, pbs - pbs only, v - venom only * CgL = C. glomerata larva File descriptions (including column headers without clear titles): "CgCV injection data" is dissection data from hosts injected with C. glomerata oviposition fluids and associated controls. Hosts were parasitized by C. rubecula * Trt - injection treatment * Rep - replicate number * Cr present - y/n C. rubecula larva present * Deform/dead - y if C. rubecula does not appear to be developing normally and alive "CrCV injection data" is dissection data from hosts injected with C. rubecula oviposition fluids and parasitized by C. glomerata (and associated controls) * Small eggs - number of underdeveloped C. glomerata eggs * Big eggs - number of C. glomerata eggs that had swelled and begun developing * Film eggs/film larva - respective number of C. glomerata appearing to have film developed as described in manuscript * Encapsulation - yes or no whether there was visible evidence of encapsulation during dissection (primarily melanization) * rubecula - number of C. rubecula larva in this host. Used to confirm Cr parasitism and look for multiparasitism "Cg dissection larval size data" is the dataset associated with C. glomerata immature size data (areas and lengths). Data was obtained using Nikon Elements software using a Nikon SMZ18 microscope with DS-Fi2 camera. Each row is an individual C. glomerata larva or egg with the picture file name (source), treatment, replicate, host ID (caterpillar), Cg larva/egg rep (CgL), stage of development (stage), presence of film or deformities, and length (um) and area (um^2).