10.5061/DRYAD.QNK98SFJG
Millena, Rebecca Jean
0000-0002-5150-7325
American Museum of Natural History
Rosenheim, Jay
University of California, Davis
A Double-Edged Sword: Parental care increases risk of offspring infection
by a maternally-vectored parasite
Dryad
dataset
2022
parental care
vertical transmission
Ammophila
Strepsiptera
Paraxenos lugubris
provisioning
FOS: Natural sciences
University of California Leadership Excellence through Advanced Degrees
(UC LEADS)*
University of California, Davis; Department of Ecology and Environmental
Sciences*
2022-04-20T00:00:00Z
2022-04-20T00:00:00Z
en
https://doi.org/10.5281/zenodo.5828908
2427699 bytes
8
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Parental care can protect offspring from predators but can also create
opportunities for parents to vector parasites to their offspring. We
hypothesized that the risk of infection by maternally-vectored parasites
would increase with the frequency of mother-offspring contact. Ammophila
spp. wasps (Hymenoptera: Sphecidae) build nests in which they rear single
offspring. Ammophila species exhibit varied offspring provisioning
behaviors: some species enter the nest once to provision a single, large
caterpillar, whereas others enter the nest repeatedly to provision with
many smaller caterpillars. We hypothesized that each nest visit increases
the risk of offspring parasitism by Paraxenos lugubris (Strepsiptera:
Xenidae), whose infectious stages ride on the mother wasp (phoresy) to
reach the vulnerable Ammophila offspring. We quantified parasitism risk by
external examination of museum-curated Ammophila specimens—the anterior
portion of P. lugubris protrudes between the adult host’s abdominal
sclerites and reflects infection during the larval stage. As predicted,
Ammophila species that receive larger numbers of provisions incur greater
risks of parasitism, with nest provisioning behavior explaining ca. 90% of
the interspecific variation in mean parasitism. These findings demonstrate
that parental care can augment, rather than reduce, risk of parasite
transmission to offspring.
We gathered records of the provisioning behavior for Californian species
of Ammophila from the literature. Using “Ammophila” and “provisioning” as
terms, we conducted searches via the Web of Science, BIOSIS, and Google
Scholar search engines. We supplemented the published literature with our
own unpublished field observations. When multiple provisioning records
existed for a species, we calculated an average across the studies to
produce a single estimate for the mean prey provisioned. These data were
gathered via examination of all specimens of Ammophila housed in the
Bohart Museum of Entomology, University of California, Davis. Parasitized
Ammophila specimens stored in the Strepsiptera collections were also
included in our dataset. Paraxenos lugubris develops as an endoparasite,
but its anterior end protrudes visibly from the abdomen of its host as it
completes its development, allowing parasitism to be recorded in
museum-preserved specimens. We examined each specimen with a
stereomicroscope and scored for the presence or absence of Paraxenos.
Wasps were scored as parasitized when they had a female Paraxenos still
present in their abdomen, or when they had a male Paraxenos either still
present and enclosed in a pupal casing, or previously-emerged from the
abdomen, leaving behind a still-visible pupal exoskeleton (winged males
emerge from their host to seek out females for mating, whereas the
wingless females never leave their hosts). We also recorded Ammophila wing
length as an index of host size, and the collection date for each
specimen. Our final data set included all 16 species for which established
estimates of mean prey provisioned were available. We scored a total of
8957 specimens collected between 1902 and 2009. All data were recorded in
Excel, and the spreadsheet plus its metadata are available here.
Parasitism data were analyzed with a generalized linear mixed model with
binomial variance and a logistic link function, using the R package
lme4. An additional analysis involving phylogenetic contrasts run with the
R package ape is included as an R script. A third R script contains the
code for each visualized linear analysis. View README.txt for details
about necessary R package versions.
In the document “ammophila_strep_project.csv”, null or 0 values should be
left blank (with the exception of 0 values in columns
"parasitism", "m_strep", and "f_strep"). One
README file is available detailing the package versions used for each of
the R scripts in this collection. Metadata/data description is available
as a tab in the raw data Excel file.