DOI: 10.5061/dryad.dncjsxkxh
title: Immature Sirex noctilio woodwasp size and sex dataset

description: Resource quality can have direct or indirect effects on female oviposition
 choice, offspring growth and survival, and ultimately on body size and sex
 ratio. We examined these patterns in Sirex noctilio Fabricus, the globally
 invasive European pine woodwasp, in South African Pinus patula
 plantations. We studied how tree position as well as natural variation in
 biotic and abiotic factors influenced sex-specific density, larval size,
 tunnel length, male proportion, and survival across development. Twenty
 infested trees divided into top, middle, and bottom sections were sampled
 at three time points during larval development. We measured moisture
 content, bluestain fungal colonization, and co-occurring insect density
 and counted, measured, and sexed all immature wasps. A subset of larval
 tunnels was measured to assess tunnel length and resource use efficiency
 (tunnel length as a function of immature wasp size).  Wasp
 density increased from the bottoms to the tops of trees for both males and
 females. However, the largest individuals and the longest tunnels were
 found in bottom sections. Male bias was strong (~10:1) and likewise
 differed among sections, with the highest proportion in the middle and top
 sections. Sex ratios became more strongly male biased due to high female
 mortality, especially in top and middle sections. Biotic and abiotic
 factors such as colonization by Diplodia sapinea, weevil (Pissodes sp.)
 density, and wood moisture explained modest residual variation in our
 primary mixed effects models (0-22%). These findings contribute to a more
 comprehensive understanding of sex-specific resource quality for S.
 noctilio and of how variation in key biotic and abiotic factors can
 influence body size, sex ratio, and survival in this economically
 important woodwasp.
description: Trees were felled and three logs
 (top middle, and bottom) collected from two <em>P. patula</em>
 pulp plantations in Mpumalanga, South Africa where moderate to high
 densities of <em>S. noctilio</em>-infested trees were known to
 be present. To locate trees infested by <em>S. noctilio</em>,
 we used the symptoms known to correlate with infestation, specifically the
 presence of resin drops and yellow or red foliage color (Talbot 1977,
 Dodds et al. 2010). At three time points throughout the <em>S.
 noctilio</em> larval life cycle, ten random <em>S.
 noctilio-</em>infested <em>P. patula</em> trees were
 selected from each of the two sites. In the sampled area, wasp adults
 emerge and lay eggs from late October/early November and sampling dates
 were selected to represent the early (March 2012), late (September 2012),
 and mid (June 2013) developmental stages. Since the mid-development larval
 stage was taken from a different larval cohort, only the early and late
 stages were used to estimate sex-specific patterns in survival and size
 distribution. Each main stem was visually divided into thirds and a 90 cm
 section was cut from the approximate middle of each third to represent the
 bottom, middle and top of each tree. Trees that showed no evidence of
 active tunneling on the cross-sectional face (top or bottom) of at least
 one cut log section were discarded and a new tree selected. Diameters of
 the top and bottom of each log were measured and wood volume calculated
 using mean log diameter, assuming a perfect cylinder. Four moisture
 measurements from each log were taken immediately after felling using a
 Delmhorst RDM-3 moisture probe (species setting: <em>P. radiata
 </em>[<em>P. patula </em>was<em> </em>not
 available]) and averaged to represent log moisture. To prevent wasp
 development prior to log dissection, logs were stored at 4°C at the
 Forestry and Agricultural Biotechnology Institute (FABI), University of
 Pretoria. Tunnel sampling and larval
 extraction Using a hand-operated hydraulic
 MAC-AFRIC™ 10-ton hydraulic log splitter, logs were carefully split into
 small fragments (~200 mm long by 5 mm wide) to extract all <em>S.
 noctilio</em> larvae and pupae. Up to eight randomly selected
 tunnels per log were meticulously traced back to their origin at the
 phloem-xylem interface and measured for length and maximum width. Only
 tunnels within the middle two thirds of log length (60 cm) were selected
 for measurement to exclude tunnels that continued outside the sampled area
 and so could not be fully measured. Tunnels were measured as they were
 uncovered during splitting using digital calipers; lengths were summed
 across split fragments to provide a total length for each selected
 gallery. All measured tunnels were separated by at least 10 cm throughout
 their length. All larvae and pupae were removed from the log, counted,
 measured, and sexed. Larval sex was determined by the presence of
 hypopleural organs in cuticular folds on either side of female larvae
 between the first and second abdominal segments (Gilmour 1965). Also
 called mycetangia (reflecting their function in collection and storage of
 arthrospores of the fungal symbiont, <em>A. areolatum</em>)
 these organs are absent in the first instar. Since all larvae encountered
 in this study were second instar or greater, this did not represent a
 source of error. Pupal sex was determined by the presence or absence of an
 ovipositor, visible through the pupal skin. Measurements included length
 (from the tip of the head capsule to the tip of the tail spine at the end
 of the abdomen), head capsule width, and wet and dry body mass. In
 addition, ten larvae per log section were randomly selected and dissected
 to confirm the presence or absence of the parasitic nematode,
 <em>Deladenus siricidicola</em> (Bedding and Akhurst 1974)
 used as a biocontrol agent in South Africa and elsewhere. Lastly, the
 number of dead larvae as well as identity and abundance of other insects
 in the log sections were recorded.
description: GarnasEcolEvol_dryad_allImmatures.csv           Variable Description Notes larvalindex unique number for each immature wasp extracted  1-5794 samplingDate Date of sampling relative to S. noctilio life cycle (1Early, 2Middle, 3Late) In the sampled area, wasp adults emerge and lay eggs from late October/early November and sampling dates were selected to represent the early (March 2012), late (September 2012), and mid (June 2013) developmental stages.  site E or H, Pinus patula pulp plantations in central South Africa   uniqueTreeIndex Unique code for each tree   Log_position B (bottom), M (middle), T (top)   uniqueLogIndex Unique code for each tree   sex Male or female (m or f) Handful of missing values due to lost or squished immature larvae_pupae Larvae or pupae (L or P) Handful of missing values due to lost or squished immature headwidth_mm Head capsule width to the nearest 10th mm Handful of missing values due to lost or squished immature length_mm Length of immature from the head to the tip of the last abdominal segment in mm Handful of missing values due to lost or squished immature mass_mg Wet mass of the immature to the nearest 10th of a mg Handful of missing values due to lost or squished immature tunnelLength Reconstructed tunnel length in mm Only measured for up to 8 immatures per log (many missing values by design) tunnelWidth Maximum tunnel width Only measured for up to 8 immatures per log (many missing values by design) tunnelVolume Tunnel volume Calculated at 1/3*tunnelLength*pi*(tunneWidth/2)^2       GarnasEcolEvol_dryad_allLogs.csv           Variable Description Notes logindex unique code for each log concatenates site, tree #, log position, and sampling date larval_stage Date of sampling relative to S. noctilio life cycle (1Early, 2Middle, 3Late) In the sampled area, wasp adults emerge and lay eggs from late October/early November and sampling dates were selected to represent the early (March 2012), late (September 2012), and mid (June 2013) developmental stages.  site E or H, Pinus patula pulp plantations in central South Africa   position B (bottom), M (middle), T (top)   treeindex Unique code for each tree   log_diam Diameter of each log  in cm log length Length of log sample 45 or 90 cm (some logs were subsampled but all densities were reported as per decimeter or standardized to a 90 cm section wood_vol Wood volume =(log_diam)^2)*pi*log_length moisture_ Percent moisture Mean of three measurements (Delmhorst RDM-3 moisture probe (species setting: P. radiata [P. patula was not available])  deadlarvae_per90cm Dead S. noctilio immatures standardized to a 90 cm log   pissodesper90cmlog Pissodes spp. (standardized to a 90 cm log)   bstain_crosssectional Cross-sectional area of bluestain mean of top and bottom cut face measurements   Note:  27 logs did not have S. noctilio and will not have rows corresponding to these logs in the "Immatures" table.