11/2/2022 0 Comments Unity in strength storyo![]() ![]() The researchers also carried out a survival experiment, to see how pathogen load 24 hours after exposure correlates with death from disease. "In a colony, not all animals have to be protected-but the most valuable individuals should survive," Keller explains. The queen, the only individual that reproduces, and the nurses, young worker ants that can still contribute many hours of work to the colony, received less of the pathogen. The analyses also showed that the colony protects especially valuable animals. Detected ants are highlighted with a dot and identity number, and physically interacting ants are connected with a yellow line.[Credit: Created by Nathalie Stroeymeyt using VirtualDub (/) and the VirtualAnts4 plugin (written by Danielle Mersch and Alessandro Crespi) Automated tracking of a Lasius niger ant colony. "The pathogen is distributed on many shoulders, and the ants' immune systems can deal very well with this lower pathogen level, which provides a form of immune memory," says Cremer. In addition, more ants received a low dose, which Cremer and her group previously showed to not cause disease but instead be protective in the face of future infections-similar to variolation in humans. Only few individuals received a high pathogen dose, which could cause disease. This allows researchers to draw conclusion about how much of the DNA, and by inference how much of the fungal spores, were present in the beginning.īecause the ants changed how they interact, spores transfer patterns also changed. qPCR monitors how a targeted DNA molecule is amplified during the so-called polymerase chain reaction. Using a highly sensitive qPCR method established in the Cremer group, the researchers could quantify exactly how many spores an individual ant carried on its body. ![]() This is a response by the whole colony-also animals who are not themselves treated with spores change their behavior." Laurent Keller adds: "This is the first scientific study that shows that an animal society is able to actively change its organization to reduce the spread of disease." Foragers interact more with foragers, and nurses more with nurses. "The ants change how they interact and who they interact with," explains Sylvia Cremer, "The cliques among ants become even stronger, and contact between cliques is reduced. Comparing the ant colonies before and after pathogen exposure showed that the ants quickly detect the presence of the fungal spores and change their behavior to strengthen already existing defenses. Credit: Timothée Brütschġ0 percent of the worker ants (all foragers) were then exposed to fungal spores which spread easily through contact. ![]() The scientists tagged thousands of ants in total to quantify all interactions between individuals and understand how colonies can protect themselves from disease. The researchers showed that the ants' subdivision into groups acts prophylactically and reduces the risk that disease spreads. ![]() Infrared cameras took an image of the colonies every half second, and so the researchers could follow and measure the movement and position of each individual, and their social interactions. In a first experiment, they placed digital markers on 2,266 garden ants. The researchers used a "barcode" system developed in the Keller group to follow the interactions between ants, especially to observe their behavior when disease spreads. These forager ants are more exposed to pathogens. While young worker ants, so-called "nurses," look after the valuable brood at the center of the colony, older worker ants become foragers that collect food outside the nest. Ants do not interact randomly with other colony members, but are organized in sub-groups according to their age and the tasks they carry out. To protect their colonies, ants have developed disease defense mechanisms, including adaptations to their social organization. High population density, as well as frequent and close contacts between individuals, contribute to a rapid spread of diseases. ![]()
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