Abstract
Social insect colonies function cohesively due, in part, to altruistic behaviors performed towards related individuals. These colonies can be affected by parasites in two distinct ways, either at the level of the individual or the entire colony. As such, colonies of social insects can experience conflict with infected individuals reducing the cohesiveness that typifies them. Parasites of social insects therefore offer us a framework to study conflicts within social insect colonies in addition to the traditionally viewed conflicts afforded by groups of low genetic relatedness due to multiple mating for example. In our study, we use the behavior manipulating fungal pathogen, Ophiocordyceps kimflemingiae (= unilateralis) and its host, Camponotus castaneus, to ask if colony members are able to detect infected individuals. Such detection would be optimal for the colony since infected workers die near foraging trails where the fungus develops its external structures and releases spores that infect other colony members. To determine if C. castaneus workers can detect these future threats, we used continuous-time point observations coupled with longer continuous observations to discern any discrimination towards infected individuals. After observing 1,240 hours of video footage we found that infected individuals are not removed from the colony and continuously received food during the course of fungal infection. We also calculated the distances between workers and the nest entrance in a total of 35,691 data points to find infected workers spent more time near the entrance of the nest. Taken together, these results suggest healthy individuals do not detect the parasite inside their nestmates. The colony’s inability to detect infected individuals allows O. kimflemingiae to develop within the colony, while receiving food and protection from natural enemies, which could damage or kill its ant host before the parasite has completed its development.
| Original language | English |
|---|---|
| Article number | e0193536 |
| Journal | PLoS One |
| Volume | 13 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - Feb 2018 |
| Externally published | Yes |
Bibliographical note
Funding Information:Emilia Solá Gracia was supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE1255832. Charissa de Bekker was supported by a Marie Curie Actions International Outgoing Fellowship [IOF 299501]. This work was funded by NSF grant 1414296 as part of the joint NSF-NIH-USDA [NIH-NSF-USDA, USDA-NSF-NIH] Ecology and Evolution of Infectious Diseases program (DPH/EMH) and NSF grants IOS-1558062 (DPH). We thank undergraduate students Emily Wilson, Caterina Abate, and Abby Koenig from the Hughes Laboratory for their support throughout the course of the experiment. We thank Kezia Manlove and James Russell for their input on the analysis and data collection which helped this project considerably. Furthermore, we would like to thank our anonymous reviewers for their constructive criticism and input. Any opinions, findings, conclusions, or recommendations expressed in this material are solely those of the authors(s) and do not necessarily reflect the views of the National Science Foundation.
Publisher Copyright:
© 2018 Solá Gracia et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding
Emilia Solá Gracia was supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE1255832. Charissa de Bekker was supported by a Marie Curie Actions International Outgoing Fellowship [IOF 299501]. This work was funded by NSF grant 1414296 as part of the joint NSF-NIH-USDA [NIH-NSF-USDA, USDA-NSF-NIH] Ecology and Evolution of Infectious Diseases program (DPH/EMH) and NSF grants IOS-1558062 (DPH). We thank undergraduate students Emily Wilson, Caterina Abate, and Abby Koenig from the Hughes Laboratory for their support throughout the course of the experiment. We thank Kezia Manlove and James Russell for their input on the analysis and data collection which helped this project considerably. Furthermore, we would like to thank our anonymous reviewers for their constructive criticism and input. Any opinions, findings, conclusions, or recommendations expressed in this material are solely those of the authors(s) and do not necessarily reflect the views of the National Science Foundation.