Red fire ants feasting on caiman hatchlings
New research from Argentina suggests red fire ants, Solenopsis invicta, may be feeding on broad-snouted caimans, Caiman latirostris. The red fire ant, native to central South America, has long been known to colonise caiman nests during the breeding season but it’s only now that we are starting to understand the effect they are having.
The ants will invade the caimans nests where the warm, humid conditions allow the insects eggs and larvae to thrive. The ants will be more likely to colonise a caimans nest if conditions elsewhere are unfavourable such as when food is scarce or when there is a lot of rainfall. If rainfall exceeds 200mm at the beginning of the breeding season there is a 50% greater incidence of colonisation.
As well as shelter the nests provide a food source for the ants in the form of newly hatched young. Once the ants have invaded they evict the mother by repeatedly biting her, then once the eggs hatch the ants are able to kill and eat the hatchlings. It’s been found over a quarter of caiman hatchlings in a season can fall prey to these vicious insects.
Overall there is a 43% reduction in nest success through a combination of direct predation and due to the loss of the mothers protection. However, because the broad-snouted caiman and red fire ant have evolved together there is little concern at the moment about a negative impact on population numbers.
The red fire ant could become a concern as it invades new areas. It has gradually been expanding its range north into the US since the mid 20th century and here the invasive species could have devastating effects on reptiles such as turtles and on other animals such as small birds. In Florida as many as 70% of turtle hatchlings can be killed by the invasive red fire ant. The ant has also been classed as an invasive species in Australia since the early 2000s.
Invasive species can quickly dominate particularly when there is no natural predator to keep population numbers in check. It is vital to halt the spread and control populations where the ant has already invaded before they become an even bigger problem.
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