Early adaptation to an unusual host in the bean weevil Zabrotes subfasciatus is associated with changes in body size and reproductive physiology
Data files
Oct 07, 2025 version files 89.25 KB
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Corpos.csv
61.27 KB
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gonadas.csv
8.39 KB
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README.md
14.46 KB
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reservas.csv
640 B
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Vg_levels.csv
2.19 KB
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VgR_levels.csv
2.31 KB
Abstract
Host shifts can present unique challenges and exert selective pressures that influence the evolutionary trajectory of phytophagous insect species. In Bruchinae beetles, which are highly specialized feeders on Fabaceae plants, host shifts are often linked to changes in life-history traits and are typically accompanied by reduced fitness. Since fitness is closely tied to reproductive success, morphophysiological traits such as body size, gonadal development, and the expression of vitellogenic genes may serve as indicators of how well a population adapts to a novel host. To test this hypothesis, we conducted a short-term selection experiment (12 generations) involving the use of an atypical host, Cicer arietinum (chickpea), by the bean weevil Zabrotes subfasciatus (Boheman 1833) (Chrysomelidae: Bruchinae: Amblycerini). We estimated eight body measures, assessed the development of ovaries and testes, and quantified the expression of vitellogenin (vg) and vitellogenin receptor (vgR) genes in the fat body and ovary of newly emerged individuals (within 24 hours) from both selected populations. Our results reveal that the adaptation involves an increase in body size (e.g., the length of the abdomen not covered by elytra in females), which correlates with higher oocyte storage in the oviducts. This morphological change was coupled with a reduction in the size of the germarium in selected females and a decrease in vgR transcription levels. These findings provide valuable insight into the initial phases of phytophagous insect adaptation to an unconventional host, illustrating how such adaptations are accompanied by significant morphophysiological changes that affect crucial life-history traits and ultimately lead to a decline in fitness.
Dataset DOI: 10.5061/dryad.qbzkh18w6
Description of the data and file structure
Body measures: For measurement, individuals were positioned in dorsal and lateral views under a stereomicroscope (Zeiss - Stemi 305) and photographed using a 5 MP camera (ZEISS Axiocam 105 color) at 30x magnification. Scale bars were added to the photographs using the ZEN program (Zeiss, version 3.8) and analyzed with Photoshop software (version 25.3.1) (Adobe Inc., 2024) using the measurement tool. The defined scale was 341 pixels to 500 µm. The measurements analysed for males and females were: body length, body width, body thickness, elytra length, abdomen length, length of the abdomen not covered by elytra, pronotum length, and pronotum width.
Gonad measures: Ovaries and testicles went through the DAPI-phallodin staining protocol. Slides were mounted in 80% glycerol and examined under a fluorescence microscope (Nis-Element C2 - Nikon), through which photographs were taken at 40x magnification. The images obtained after the fluorescence protocol were analyzed using Photoshop software (version 25.3.1) (Adobe Inc., 2024) at a scale of 83 pixels to 100 µm. To assess the degree of activation, several parameters were recorded for each ovary: Average area of the last oocyte in the ovarioles, measured in each sampled ovary; germarium length, measured from its end to the dark dividing line visible in the fluorescence protocol; percentage of calyces with reserved oocytes, indicated by the enlarged size and visible curves of the oocytes. For the testicles, an average area was calculated based on the area of each testiole.
Transcript levels determination by RT-qPCR: Total RNA was extracted using TRIzol® (Ambion) from pools (six pools each, n= 6) of three whole bodies and five pairs of ovaries sampled from individuals of the parental population (F0) and from the F3, F7, and F11 generations of selection. These samples included individuals reared on both chickpeas and beans. Relative gene expression levels were calculated using the 2-ΔΔCT method with efficiency correction, using a control sample for calibration (Livak and Schmittgen, 2001; Applied Biosystems User Bulletin #2).
Files and variables
File: gonadas.csv
Description: This file holds the data from the analysis of the beetles' gonads. For females, the parameters include the average area of the last oocyte, the length of the germarium, and the percentage of calyces with reserved oocytes. For males, the file contains the average area of each testiole. The data was collected from 5 females and 5 males per population, from individuals that emerged within 24 hours. A column named "Adicional" contains values for the F0 generation to facilitate calculations in R. N/A values in this file indicate cells where a measurement was not applicable.
Variables
- Adicional: Used to analyse additional block (F0) in the ExpDes R package. (categorical interpretation)
- Geracao: Generation (categorical interpretation)
- Semente: Seed / Grain (categorical interpretation)
- Populacao: Population (categorical interpretation)
- AUO: Last oocyte area (μm2)
- NOO: Number of oocytes per ovariole (count)
- CGO: Germarium length (μm)
- ATT: Area of testioles (μm2)
Categorical Interpretation Keys:
- Adicional: Used to analyse aditional block (F0) in ExpDes R package. The only value is F0.
- Geracao (Generation): This column represents the generation of the beetle in the short-term selection experiment. Values:
- 1: Represents the F1 generation
- 2: Represents the F2 generation
- 3: Represents the F3 generation
- 8: Represents the F8 generation
- 12: Represents the F12 generation
- Semente (Seed): This column specifies the type of seed, or host, on which the beetles developed. Values:
- F: Represents common bean (Phaseolus vulgaris), the beetle's usual host.
- GB: Represents chickpea (Cicer arietinum), the unusual and less preferred host.
- Populacao (Population): This column indicates the replicate group within the experiment. Three replicate groups were used for each seed type. Values:
- 1: Replicate 1
- 2: Replicate 2
- 3: Replicate 3
File: Corpos.csv
Description: This file contains the raw data from the body size measurements of the beetles. The dataset includes eight different body measurements taken from 10 females and 10 males from each population. The data were collected from the parental generation (F0) and the selection generations F1, F2, F3, F8, and F12, for both the bean and chickpea populations. A column named "Adicional" contains values for the F0 generation to facilitate calculations in R. N/A values in this file indicate cells where a measurement was not applicable.
Variables
- Adicional: Used to analyse additional block (F0) in the ExpDes R package. (categorical interpretation)
- Geracao: Generation (categorical interpretation)
- Semente: Seed / Grain (categorical interpretation)
- Populacao: Population (categorical interpretation)
- CCF: Body length of females (μm)
- CPF: Pronotum length of females (μm)
- LPF: Pronotum width of females (μm)
- CEF: Elytra length of females (μm)
- LCF: Body width of females (μm)
- ANF: Not covered abdomen of females (μm)
- CAF: Adomen length of females (μm)
- ECF: Body thickness of females (μm)
- CCM: Body length of males (μm)
- CPM: Pronotum length of males (μm)
- LPM: Pronotum width of males (μm)
- CEM: Elytra length of males (μm)
- LCM: Body width of males (μm)
- ANM: Not covered abdomen of males (μm)
- CAM: Adomen length of males (μm)
- ECM: Body thickness of males (μm)
Categorical Interpretation Keys:
- Adicional: Used to analyse aditional block (F0) in ExpDes R package. The only value is F0.
- Geracao (Generation): This column represents the generation of the beetle in the short-term selection experiment. Values:
- 1: Represents the F1 generation
- 2: Represents the F2 generation
- 3: Represents the F3 generation
- 8: Represents the F8 generation
- 12: Represents the F12 generation
- Semente (Seed): This column specifies the type of seed, or host, on which the beetles developed. Values:
- F: Represents common bean (Phaseolus vulgaris), the beetle's usual host.
- GB: Represents chickpea (Cicer arietinum), the unusual and less preferred host.
- Populacao (Population): This column indicates the replicate group within the experiment. Three replicate groups were used for each seed type. Values:
- 1: Replicate 1
- 2: Replicate 2
- 3: Replicate 3
File: reservas.csv
Description: This file provides data on the storage of oocytes within female ovaries. The dataset includes two main metrics related to this physiological change, which is a key indicator of reproductive fitness. One column contains the percentage of oocytes reserved, based on an average of 5 gonads, which reflects the overall level of oocyte retention. The other column contains data on the percentage of calyces with reserved oocytes, based on an average of 10 calyces (2 per ovary), providing a more granular look at oocyte storage. The data was collected from 5 females per population, from individuals that emerged within 24 hours. A column named "Adicional" contains values for the F0 generation to facilitate calculations in R. N/A values in this file indicate cells where a measurement was not applicable.
Variables
- Adicional: Used to analyse additional block (F0) in the ExpDes R package. (categorical interpretation)
- Geracao: Generation (categorical interpretation)
- Semente: Seed / Grain (categorical interpretation)
- Populacao: Population (categorical interpretation)
- GOO: Gonads with oocytes (in %)
- CCO: Calyces with oocytes (in %)
Categorical Interpretation Keys:
- Adicional: Used to analyse additional block (F0) in the ExpDes R package. The only value is F0.
- Geracao (Generation): This column represents the generation of the beetle in the short-term selection experiment. Values:
- 1: Represents the F1 generation
- 2: Represents the F2 generation
- 3: Represents the F3 generation
- 8: Represents the F8 generation
- 12: Represents the F12 generation
- Semente (Seed): This column specifies the type of seed, or host, on which the beetles developed. Values:
- F: Represents common bean (Phaseolus vulgaris), the beetle's usual host.
- GB: Represents chickpea (Cicer arietinum), the unusual and less preferred host.
- Populacao (Population): This column indicates the replicate group within the experiment. Three replicate groups were used for each seed type. Values:
- 1: Replicate 1
- 2: Replicate 2
- 3: Replicate 3
File: Vg_levels.csv
Description: This file contains the mRNA levels of the vitellogenin (vg) gene, as determined by RT-qPCR. The measurements were performed on pools of three whole bodies from the F0 (parental) generation and the F3, F7, and F11 selection generations. The data includes individuals from both the chickpea and bean populations. N/A values in this file indicate cells where resulting values were not applicable.
Variables
- Tube: the analysed replicate sample (categorical interpretation)
- RPL32: Cycle threshold (CT) for the reference gene RPL32 (CT values)
- Vg: Cycle threshold (CT) for the gene of interest Vg (CT values)
- DCt: Delta CT method (subtract reference gene's CT from gene of interest's CT, unitless)
- DDCt: Comparative CT method (subtract the control sample's Delta CT from the experimental sample's Delta CT, unitless)
- 2^-(DDCt): Fold change (Raise two to the power of negative DDCT, unitless)
- Group: Sample group analysed for the statistics that follow (categorical interpretation)
- Mean: Mean for the analysed group (unitless)
- SD: Standard deviation for the analysed group (unitless)
- SEM: Standard error of mean for the analysed group (unitless)
Categorical Interpretation Keys:
- Tube (Replicate Sample): This column identifies the specific sample tube analyzed for gene expression. The values combine a grain abbreviation, the generation, and a replicate number to uniquely identify each sample. It has the format [Grain Abbreviation] [Generation] [Replicate Number]. Values:
- Grain Abbreviation:
- F: Common bean (Phaseolus vulgaris)
- GB: Chickpea (Cicer arietinum)
- Generation:
- 0F: Parental generation (F0)
- 3F: 3rd generation of selection (F3)
- 7F: 7th generation of selection (F7)
- 11F: 11th generation of selection (F11)
- Replicate Number: A number from 1 to 4 indicating the biological replicate pool.
- Grain Abbreviation:
- Group (sample group): This column groups the analyzed tubes that share the same grain type and generation. It is used to analyze the expression patterns across different conditions. It has the format [Grain Abbreviation] [Generation]. Values:
- Grain Abbreviation:
- F: Common bean (Phaseolus vulgaris)
- GB: Chickpea (Cicer arietinum)
- Generation:
- 0F: Parental generation (F0)
- 3F: 3rd generation of selection (F3)
- 7F: 7th generation of selection (F7)
- 11F: 11th generation of selection (F11)
- Grain Abbreviation:
File: VgR_levels.csv
Description: This file contains the mRNA levels of the vitellogenin receptor (vgR) gene, as determined by RT-qPCR. The samples used for this analysis were pools of five pairs of ovaries from individuals in the parental (F0) generation and the F3, F7, and F11 selection generations. The data includes individuals from both the chickpea and bean populations. A column named "adicional" contains values for the F0 generation to facilitate calculations in R. N/A values in this file indicate cells where resulting values were not applicable.
Variables
- Tube: the analysed replicate sample (categorical interpretation)
- RPL32: Cycle threshold (CT) for the reference gene RPL32 (CT values)
- VgR: Cycle threshold (CT) for the gene of interest VgR (CT values)
- DCt: Delta CT method (subtract reference gene's CT from gene of interest's CT, unitless)
- DDCt: Comparative CT method (subtract the control sample's Delta CT from the experimental sample's Delta CT, unitless)
- 2^-(DDCt): Fold change (Raise two to the power of negative DDCT, unitless)
- Group: Sample group analysed for the statistics that follow (categorical interpretation)
- Mean: Mean for the analysed group (unitless)
- SD: Standard deviation for the analysed group (unitless)
- SEM: Standard error of mean for the analysed group (unitless)
Categorical Interpretation Keys:
- Tube (Replicate Sample): This column identifies the specific sample tube analyzed for gene expression. The values combine a grain abbreviation, the generation, the "ov" that indicates the samples were obtained from ovaries, and a replicate number to uniquely identify each sample. It has the format [Grain Abbreviation] [Generation] ["ov"] [Replicate Number]. Values:
- Grain Abbreviation:
- F: Common bean (Phaseolus vulgaris)
- GB: Chickpea (Cicer arietinum)
- Generation:
- 0: Parental generation (F0)
- 3: 3rd generation of selection (F3)
- 7: 7th generation of selection (F7)
- 11: 11th generation of selection (F11)
- Replicate Number: A number from 1 to 4 indicating the biological replicate pool.
- Grain Abbreviation:
- Group (sample group): This column groups the analyzed tubes that share the same grain type and generation. It is used to analyze the expression patterns across different conditions. It has the format [Grain Abbreviation] [Generation]. Values:
- Grain Abbreviation:
- F: Common bean (Phaseolus vulgaris)
- GB: Chickpea (Cicer arietinum)
- Generation:
- 0F: Parental generation (F0)
- 3F: 3rd generation of selection (F3)
- 7F: 7th generation of selection (F7)
- 11F: 11th generation of selection (F11)
- Grain Abbreviation:
Code/software
Although we used Microsoft Excel to open the archives, LibreOffice Calc is also an option.
Access information
Data was derived from the following sources: