Decreasing worker size diversity does not affect colony performance during laboratory challenges in the ant Temnothorax nylanderi

Winter is a difficult period for animals that live in temperate zones. It can inflict high mortality or induce weight loss with potential consequences on performance during the growing season. Social groups include individuals of various ages and sizes. This diversity may improve the ability of groups to buffer winter disturbances such as starvation or cold temperature. Studies focusing on the buffering role of social traits such as mean size and diversity of group members under winter conditions are mainly performed in the laboratory and investigate the effect of starvation or cold separately. Here, we experimentally decreased worker size diversity and manipulated worker mean size within colonies in order to study the effect on overwintering survival in the ant Temnothorax nylanderi. Colonies were placed under natural conditions during winter. Colony survival was high during winter and similar in all treatments with no effect of worker size diversity and mean worker size. Higher brood survival was positively correlated with colony size (i.e., the number of workers). Our results show that the higher resistance of larger individuals against cold or starvation stresses observed in the laboratory does not directly translate into higher colony survival in the field. We discuss our results in the light of mechanisms that could explain the possible non-adaptive size diversity in social species.

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Effect of temperature and social environment on worker size in the ant Temnothorax nylanderi

Journal of Thermal Biology ◽

10.1016/j.jtherbio.2017.04.013 ◽

2017 ◽

Vol 67 ◽

pp. 22-29 ◽

Cited By ~ 9

Author(s):

Mathieu Molet ◽

Romain Péronnet ◽

Sébastien Couette ◽

Christophe Canovas ◽

Claudie Doums

Keyword(s):

Social Environment ◽

Effect Of Temperature ◽

Worker Size ◽

Temnothorax Nylanderi

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Is diversity in worker body size important for the performance of bumble bee colonies?

10.1101/2020.05.06.079525 ◽

2020 ◽

Author(s):

Jacob G. Holland ◽

Shinnosuke Nakayama ◽

Maurizio Porfiri ◽

Oded Nov ◽

Guy Bloch

Keyword(s):

Body Size ◽

Bombus Terrestris ◽

Bumble Bee ◽

Insect Societies ◽

Physiological Adaptations ◽

Comparable Performance ◽

Colony Performance ◽

Size Diversity ◽

Individual Effort ◽

Bee Colonies

ABSTRACTSpecialization and plasticity are important for many forms of collective behavior, but the interplay between these factors is little understood. In insect societies, workers are often predisposed to specialize in different tasks, sometimes with morphological or physiological adaptations, facilitating a division of labor. Workers may also plastically switch between tasks or vary their effort. The degree to which predisposed specialization limits plasticity is not clear and has not been systematically tested in ecologically relevant contexts. We addressed this question in 20 freely-foraging bumble bee (Bombus terrestris) colonies by continually manipulating colonies to contain either a typically diverse or reduced (“homogeneous”) worker body size distribution, over two trials. Pooling both trials, diverse colonies did better in several indices of colony performance. The importance of body size was further demonstrated by the finding that foragers were larger than nurses even in homogeneous colonies with a very narrow body size range. However, the overall effect of size diversity stemmed mostly from one trial. In the other trial, homogeneous and diverse colonies showed comparable performance. By comparing behavioral profiles based on several thousand observations, we found evidence that workers in homogeneous colonies in this trial rescued colony performance by plastically increasing behavioral specialization and/or individual effort, compared to same-sized individuals in diverse colonies. Our results are consistent with a benefit to colonies of predisposed (size-diverse) specialists under certain conditions, but also suggest that plasticity or effort, can compensate for reduced (size-related) specialization. Thus, we suggest that an intricate interplay between specialization and plasticity is functionally adaptive in bumble bee colonies.

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Body Size and Behavioural Plasticity Interact to Influence the Performance of Free-Foraging Bumble Bee Colonies

Insects ◽

10.3390/insects12030236 ◽

2021 ◽

Vol 12 (3) ◽

pp. 236

Author(s):

Jacob Holland ◽

Shinnosuke Nakayama ◽

Maurizio Porfiri ◽

Oded Nov ◽

Guy Bloch

Keyword(s):

Body Size ◽

Bombus Terrestris ◽

Division Of Labour ◽

Bumble Bee ◽

Behavioural Plasticity ◽

Insect Societies ◽

Comparable Performance ◽

Colony Performance ◽

Size Diversity ◽

Bee Colonies

Specialisation and plasticity are important for many forms of collective behaviour, but the interplay between these factors is little understood. In insect societies, workers are often developmentally primed to specialise in different tasks, sometimes with morphological or physiological adaptations, facilitating a division of labour. Workers may also plastically switch between tasks or vary their effort. The degree to which developmentally primed specialisation limits plasticity is not clear and has not been systematically tested in ecologically relevant contexts. We addressed this question in 20 free-foraging bumble bee (Bombus terrestris) colonies by continually manipulating colonies to contain either a typically diverse, or a reduced (“homogeneous”), worker body size distribution while keeping the same mean body size, over two trials. Pooling both trials, diverse colonies produced a larger comb mass, an index of colony performance. The link between body size and task was further corroborated by the finding that foragers were larger than nurses even in homogeneous colonies with a very narrow body size range. However, the overall effect of size diversity stemmed mostly from one trial. In the other trial, homogeneous and diverse colonies showed comparable performance. By comparing behavioural profiles based on several thousand observations of individuals, we found evidence that workers in homogeneous colonies in this trial rescued colony performance by plastically increasing behavioural specialisation and/or individual effort, compared to same-sized individuals in diverse colonies. Our results are consistent with a benefit to colonies of large and small specialists under certain conditions, but also suggest that plasticity or effort can compensate for reduced (size-related) specialisation. Thus, we suggest that an intricate interplay between specialisation and plasticity is functionally adaptive in bumble bee colonies.

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Multiple processes drive wing size diversity in stick insects

10.1603/ice.2016.94177 ◽

2016 ◽

Author(s):

Yu Zeng

Keyword(s):

Wing Size ◽

Stick Insects ◽

Multiple Processes ◽

Size Diversity

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SIZE-DIVERSITY TRENDS AND FEEDING-STRATEGY DISTRIBUTIONS IN BRACKISH-WATER ICHNOFOSSILS

10.1130/abs/2016am-286466 ◽

2016 ◽

Author(s):

Murray Gingras ◽

◽

Eric R. Timmer ◽

Eric Ditzler ◽

John-Paul Zonneveld ◽

...

Keyword(s):

Brackish Water ◽

Feeding Strategy ◽

Size Diversity

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Plant-based supplement containing B-complex vitamins can improve bee health and increase colony performance

Preventive Veterinary Medicine ◽

10.1016/j.prevetmed.2021.105322 ◽

2021 ◽

Vol 190 ◽

pp. 105322

Author(s):

Nemanja M. Jovanovic ◽

Uros Glavinic ◽

Biljana Delic ◽

Branislav Vejnovic ◽

Nevenka Aleksic ◽

...

Keyword(s):

Bee Health ◽

Colony Performance ◽

B Complex Vitamins

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Impact of “non-lethal” tarsal clipping on bumble bees (Bombus vosnesenskii) may depend on queen stage and worker size

Journal of Insect Conservation ◽

10.1007/s10841-021-00297-9 ◽

2021 ◽

Author(s):

John M. Mola ◽

Clara Stuligross ◽

Maureen L. Page ◽

Danielle Rutkowski ◽

Neal M. Williams

Keyword(s):

Genetic Material ◽

Population Monitoring ◽

First Year ◽

Negative Effects ◽

Worker Size ◽

Monitoring Tools ◽

Individual Survival ◽

Body Sizes ◽

Negative Effect ◽

Worker Caste

Abstract Recent bumble bee declines have prompted the development of novel population monitoring tools, including the use of putatively non-lethal tarsal clipping to obtain genetic material. However, the potential side effects of tarsal clipping have only been tested in the worker caste of a single domesticated species, prompting the need to more broadly test whether tarsal clipping negatively affects sampled individuals. To determine if tarsal clipping reduces queen survivorship and colony establishment, we collected wild queens of Bombus vosnesenskii and clipped tarsi from a single leg of half the individuals. We reared captive queens and estimated survivorship and nest establishment success. We also clipped tarsi of workers from a subset of colonies across a range of body sizes. We found no consistent negative effect of clipping on queen survival. In the first year, clipped nest-searching queens suffered heavy mortality, but there was no effect on foraging queens. The following year, we found no effect of clipping on queen survival or establishment. Clipping did not reduce overall worker survival but reduced survivorship for those in the smallest size quartile. Implications for insect conservation Our findings suggest tarsal clipping does not have consistent negative effects on individual survival. However, our results varied with queen behavioral state, year, and worker size, suggesting differences within and among species and interactions with landscape stressors warrant further study. In the interim, we recommend researchers and conservationists minimize the use of tarsal clipping for sensitive species, populations, or small workers except in cases of exceptional scientific need.

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Polymorphism and division of labour in a socially complex ant: neuromodulation of aggression in the Australian weaver ant, Oecophylla smaragdina

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2015.0704 ◽

2015 ◽

Vol 282 (1811) ◽

pp. 20150704 ◽

Cited By ~ 27

Author(s):

J. Frances Kamhi ◽

Kelley Nunn ◽

Simon K. A. Robson ◽

James F. A. Traniello

Keyword(s):

Social Systems ◽

Division Of Labour ◽

Oecophylla Smaragdina ◽

Minor Worker ◽

Task Specialization ◽

Territorial Defence ◽

Weaver Ant ◽

Eusocial Insects ◽

Worker Size ◽

Pharmacological Manipulations

Complex social structure in eusocial insects can involve worker morphological and behavioural differentiation. Neuroanatomical variation may underscore worker division of labour, but the regulatory mechanisms of size-based task specialization in polymorphic species are unknown. The Australian weaver ant, Oecophylla smaragdina , exhibits worker polyphenism: larger major workers aggressively defend arboreal territories, whereas smaller minors nurse brood. Here, we demonstrate that octopamine (OA) modulates worker size-related aggression in O. smaragdina . We found that the brains of majors had significantly higher titres of OA than those of minors and that OA was positively and specifically correlated with the frequency of aggressive responses to non-nestmates, a key component of territorial defence. Pharmacological manipulations that effectively switched OA action in major and minor worker brains reversed levels of aggression characteristic of each worker size class. Results suggest that altering OA action is sufficient to produce differences in aggression characteristic of size-related social roles. Neuromodulators therefore may generate variation in responsiveness to task-related stimuli associated with worker size differentiation and collateral behavioural specializations, a significant component of division of labour in complex social systems.

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