Data from: Food absence is a cue for metamorphosis in the solitary bee Megachile rotundata through a conserved physiological mechanism
Data files
May 15, 2026 version files 582.80 KB
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Grula_Metamorphosis_Dryad_1_2026.csv
15.55 KB
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Grula_Metamorphosis_Dryad_2.csv
1.54 KB
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Grula_Metamorphosis_Dryad_3_2026.csv
7.44 KB
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Grula_Metamorphosis_Dryad_4.csv
3 KB
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Grula_Metamorphosis_Dryad_5.csv
481.58 KB
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Grula_Metamorphosis_Dryad_6_2026.csv
69.20 KB
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README.md
4.48 KB
Abstract
The timing of metamorphosis in insects determines adult body size and influences aspects of fitness, including flight performance and fecundity. The regulation of metamorphosis has been well studied in model insects, but determining the cue that initiates the physiological shift toward metamorphosis in other insects has been challenging. In most insects, the critical weight is a cue to initiate metamorphosis. Our goal was to determine the cue for metamorphosis in the solitary bee Megachile rotundata and to characterize the physiological mechanisms initiated by this cue. Larval bees were fed ad libitum (also termed “fed”) or had all food removed (also termed “starved”). We measured the time to initiate metamorphosis, juvenile hormone (JH) titers, and the abundance of transcripts involved in the endocrine response to metamorphosis. We experimentally manipulated JH by topically applying precocene, which interrupts JH production. We found that M. rotundata does not have a critical weight and that starvation through the removal of food triggered the initiation of metamorphosis. Food removal was associated with low JH titers, and the application of precocene mimicked the response to food absence. Food removal decreased transcripts associated with JH production, and increased transcripts involved in ecdysone synthesis and insulin/TOR signaling. Food absence is an ecologically relevant cue for a M. rotundata larva, which is provisioned a finite amount of food and is unable to forage for additional food. Despite having food removal as a cue for metamorphosis, the physiological mechanisms associated with metamorphosis are similar to those found in other insects.
Dataset DOI: 10.5061/dryad.vhhmgqp7m
Description of the data and file structure
This dataset includes physiological data, including developmental weights and timepoints, hormone analysis from HPLC, and gene transcript abundance from Nanostring
Files and variables
File: Grula_Metamorphosis_Dryad_4.csv
Description: Minimum Viable Weight data
Variables
- Plate ID - The location within the 24 well plate where the larvae were being stored
- Treatment - The feeding treatment the larvae were placed in
- Plate_number - the number of the 24 well plate where the larvae were being stored
- Weight_at_Treatment - the weight of the larvae (in grams) prior to being put into treatment
- Date_Treatment - the date the larvae was placed into treatment
- Sept_Survival - This is a binary status of the survival of the larvae 0 = dead, 1 = alive. This number was recorded after all larvae had completed metamorphosis, before they were placed into overwintering storage temperatures
File: Grula_Metamorphosis_Dryad_5.csv
Description: Results of gene transcript abundance from nanostring analysis (Figs. 5-7)
Variables
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sampleID - Larvae sample ID number
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treatment - Feeding Treatment larvae was placed in.
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hours - The time after treatment that the larvae was sampled for transcript expression
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transcript - The name of the Transcript that was measured
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expression - Expression of the transcript
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weight_g_before_extraction - Weight of the larvae (g) before the RNA was extracted.
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webspinning - Webspinning status of the larvae when it was collected for hormone sampling. This is a binary status of webspinning.
1= the larvae was webspinning
0= the larvae was NOT webspinning
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weight_at_treatment - Weight of the larvae (g) prior to being placed into feeding treatment
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nest_number - The ID number of the nest that the larvae came from in the field
File: Grula_Metamorphosis_Dryad_3_2026.csv
Description: Results of developmental timing using precocene treatment (Fig 4C)
Variables
- Treatment - Treatment Larvae was placed in
- Cell_ID - Location of larvae in the 24-well plate prior to treatment
- Date_in - Date larvae was placed into treatment
- Time_in - Time larvae was placed into treatment
- Date_webspin - Time larvae began webspinning
- Hour_webspin - The number of total hours it took for the larvae to begin webspinning after being placed into treatment (Days_to_webspin * 24)
- cells including N/A indicate that no information was available for that individual
File: Grula_Metamorphosis_Dryad_2.csv
Description: JH hormone titer results from HPLC (Fig. 4A & B)
Variables
- ID - Larvae sample ID number
- Concentration - the concentration of JH (pg/ul)
- Treatment - feeding treatment larvae was placed in
- Hour - the hour after treatment that the larvae was sampled for hormone concentration. EI stands for "Early Instar" these were individuals that were sampled before the fifth instar, the results from this can be seen in figure 4B. Early instar larvae results were removed form the analysis in figure 4A.
- webspin - webspinning status of the larvae when it was collected for hormone sampling. This is a binary stat us of webspinning. 1 = the larvae was webspinning; 0 = the larvae was NOT webspinning
File: Grula_Metamorphosis_Dryad_1_2026.csv
Description: Developmental data used for measuring time to webspinning and critical weight. (Figs. 2 & 3)
Variables
- Treatment - Treatment larvae was placed in
- weight_treatment_g - weight of the larvae directly before putting into treatment (in grams)
- Hour_webspinning - the total number of hours it took for the larvae to begin webspinning after being placed into treatment (days_to_webspin *24)
- Year - Year the sample was collected
File: Grula_Metamorphosis_Dryad_6_2026.csv
Description: Used for PCA and clustering analysis. (Figs 8)
Variables
- BeeID - Larvae sample ID number
- Treatment - Feeding treatment larvae was placed in
- Timepoint - the hour after treatment that the larvae was sampled for transcript expression
- weight - weight of the larvae
- "adh" through "usb" - Each transcript has its own column which shows expression