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Origin, behaviour, and genetics of reproductive workers in an invasive ant
Pauline Lenancker
Sugar Research Australia Ltd
Corresponding Author
ORCiD: https://orcid.org/0000-0002-0532-2768
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background: Worker reproduction has an important influence on the social cohesion and efficiency of social insect colonies, but its role in the success of invasive ants has been neglected. We used observations of 233 captive colonies, laboratory experiments, and genetic analyses to investigate the conditions for worker reproduction in the invasive Anoplolepis gracilipes (yellow crazy ant) and its potential cost on interspecific defence. We determined the prevalence of worker production of males and whether it is triggered by queen absence; whether physogastric workers with enlarged abdomens are more likely to be reproductive, how normal workers and physogastric workers compare in their contributions to foraging and defence; and whether worker-produced males and males that could have been queen- or worker-produced differ in their size and heterozygosity.
Results: Sixty-six of our 233 captive colonies produced males, and in 25 of these, some males could only have been produced by workers. Colonies with more workers were more likely to produce males, especially for queenless colonies. The average number of days between the first appearance of eggs and adult males in our colonies was 54.1± 10.2 (mean ± SD, n=20). In our laboratory experiment, queen removal triggered an increase in the proportion of physogastric workers. Physogastric workers were more likely to have yolky oocytes (37-54.9%) than normal workers (2-25.6%), which is an indicator of fertile or trophic egg production. Physogastric workers were less aggressive during interspecific aggression tests and foraged less than normal workers. The head width and wing length of worker-produced males were on average 4.0% and 4.3% greater respectively than those of males of undetermined source. Our microsatellite DNA analyses indicate that 5.5% of worker-produced males and 14.3% of males of undetermined source were heterozygous, which suggests the presence of diploid males and/or genetic mosaics in A. gracilipes.
Conclusions: Our experimental work provides crucial information on worker reproduction in A. gracilipes and its potential cost to colony defence. The ability of A. gracilipes workers to produce males in the absence of queens may also contribute to its success as an invasive species if intranidal mating can take place between virgin queens and worker-produced males.
Keywords
Anoplolepis gracilipes, aggression tests, eusocial insects, haplodiploid, Hymenoptera, Oecophylla smaragdina, oocytes, ovaries, worker conflict, worker reproduction
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This is a list of supplementary files associated with this preprint. Click to download.
- Additionalfile1Tablesv2trackedFinal.pdf
Additional file 1: Table S1. Genotyping results of males, workers, and queens. Table S2. Site coordinates of where colonies were collected Table S3. Additional information on the colonies used in dissections of worker’s ovaries of entire colonies, the queen transfer experiment, and the aggression tests. Table S4 Additional information on the colonies used in the colony observations
- Additionalfile2Figuresprotocolv2trackedFinal.pdf
Additional file 2: Figure S1. Boxplot showing the proportion of normal workers in the queen transfer experiment by colony status and number of days since the start of the experiment until day 120 Figure S2. Forewing of a male A. gracilipes showing which veins were used to measure wing width and wing lengthAppendix S1. Additional information on the genotyping protocol including Table S5 which summarises the characteristic of the microsatellite loci
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CURRENT STATUS: Under Review
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Posted 11 Feb, 2021
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Review #2 received
Received 18 Feb, 2021
Reviewer #2 agreed
On 09 Feb, 2021
Reviewer #1 agreed
On 08 Feb, 2021
Editor assigned
On 06 Feb, 2021
Reviewers invited
Invitations sent on 06 Feb, 2021
Submission checks complete
On 06 Feb, 2021
Editor invited
On 06 Feb, 2021
No comments provided
Review #2 received
Received 20 Dec, 2020
Editorial decision: Major revision
On 20 Dec, 2020
Review #1 received
Received 14 Dec, 2020
Reviewer #2 agreed
On 30 Nov, 2020
Reviewer #1 agreed
On 27 Nov, 2020
Reviewers invited
Invitations sent on 15 Nov, 2020
Editor assigned
On 10 Nov, 2020
Submission checks complete
On 10 Nov, 2020
Editor invited
On 10 Nov, 2020
First submitted
On 09 Nov, 2020
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Subject Areas
Animal Science
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This preprint is under consideration at Frontiers in Zoology. A preprint is a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Learn more about In Review
Research
Origin, behaviour, and genetics of reproductive workers in an invasive ant
Pauline Lenancker
Sugar Research Australia Ltd
Corresponding Author
ORCiD: https://orcid.org/0000-0002-0532-2768
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
Peer Review Timeline
CURRENT STATUS: Under Review
Version 2
Posted 11 Feb, 2021
No community comments so far
Review #2 received
Received 18 Feb, 2021
Reviewer #2 agreed
On 09 Feb, 2021
Reviewer #1 agreed
On 08 Feb, 2021
Editor assigned
On 06 Feb, 2021
Reviewers invited
Invitations sent on 06 Feb, 2021
Submission checks complete
On 06 Feb, 2021
Editor invited
On 06 Feb, 2021
No comments provided
Review #2 received
Received 20 Dec, 2020
Editorial decision: Major revision
On 20 Dec, 2020
Review #1 received
Received 14 Dec, 2020
Reviewer #2 agreed
On 30 Nov, 2020
Reviewer #1 agreed
On 27 Nov, 2020
Reviewers invited
Invitations sent on 15 Nov, 2020
Editor assigned
On 10 Nov, 2020
Submission checks complete
On 10 Nov, 2020
Editor invited
On 10 Nov, 2020
First submitted
On 09 Nov, 2020
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
Animal Science
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background: Worker reproduction has an important influence on the social cohesion and efficiency of social insect colonies, but its role in the success of invasive ants has been neglected. We used observations of 233 captive colonies, laboratory experiments, and genetic analyses to investigate the conditions for worker reproduction in the invasive Anoplolepis gracilipes (yellow crazy ant) and its potential cost on interspecific defence. We determined the prevalence of worker production of males and whether it is triggered by queen absence; whether physogastric workers with enlarged abdomens are more likely to be reproductive, how normal workers and physogastric workers compare in their contributions to foraging and defence; and whether worker-produced males and males that could have been queen- or worker-produced differ in their size and heterozygosity.
Results: Sixty-six of our 233 captive colonies produced males, and in 25 of these, some males could only have been produced by workers. Colonies with more workers were more likely to produce males, especially for queenless colonies. The average number of days between the first appearance of eggs and adult males in our colonies was 54.1± 10.2 (mean ± SD, n=20). In our laboratory experiment, queen removal triggered an increase in the proportion of physogastric workers. Physogastric workers were more likely to have yolky oocytes (37-54.9%) than normal workers (2-25.6%), which is an indicator of fertile or trophic egg production. Physogastric workers were less aggressive during interspecific aggression tests and foraged less than normal workers. The head width and wing length of worker-produced males were on average 4.0% and 4.3% greater respectively than those of males of undetermined source. Our microsatellite DNA analyses indicate that 5.5% of worker-produced males and 14.3% of males of undetermined source were heterozygous, which suggests the presence of diploid males and/or genetic mosaics in A. gracilipes.
Conclusions: Our experimental work provides crucial information on worker reproduction in A. gracilipes and its potential cost to colony defence. The ability of A. gracilipes workers to produce males in the absence of queens may also contribute to its success as an invasive species if intranidal mating can take place between virgin queens and worker-produced males.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5