Termite Foraging Behaviour

The latest research into termite foraging behaviour looks into the role of the each caste and answers questions about preferential food sources and transportation methods. 

Latest termite foraging research

The effect of soil moisture on termite tunnelling behaviour

A key preventative measure to minimise termite attacks on buildings is to keep the soil around buildings as dry as possible. But how dry does it have to be to prevent termites tunnelling?

Researchers in the US assessed the foraging behaviour of two subterranean termites, Coptotermes formosanus and Reticulitermes flavipes.1 They looked at their tunnelling behaviour and survival rate in sand with varying moisture levels from 0% to 30%. Interestingly, even though they are quite different termites in terms of their nesting and foraging behaviour, there was no significant difference in the response between the species. At 0% moisture, the termites did not tunnel and did not survive. At 1%, the termites started tunnelling, but had died by the end of the 28-day study period. At levels between 5-30% moisture, the termites readily tunnelled with no difference in the tunnelling activity or survivorship between the different moisture levels.

The results reinforce the understanding that dry soils are a great way to minimise soil activity, but they do need to be very dry. Moisture levels as low as 5% would appear to be sufficient to allow active tunnelling (at least in these species). At the other end of the scale, termites appear to tolerate very wet soils too.

Termites avoid food marked with alarm pheromone

When foraging for food, for most animals, there is a risk vs reward trade-off. Namely, as the size of a food resource increases, animals may be prepared to take a bigger risk (increased chance of injury or death) to obtain it. This behaviour is not well understood in eusocial insects,
especially in termites. For the first time, researchers have investigated whether this foraging behaviour exists in termites by looking at Nasutitermes corniger.2

They evaluated combinations of differing quantities of food and intensity of pheromone alarm signal (with the varying intensity indicating differing levels of risk). Their results showed that termites avoid a food source if even a small amount of alarm pheromone is present, irrespective of the size of the food resource. This study would indicate that, for this species of termite at least, there isn’t a trade-off; these termites simply do not take any risks, avoiding a resource when an alarm signal is released. For pest managers involved in baiting, this emphasises the need to avoid disturbing feeding sites or bait placements, as this could result in an alarm signal being released and the termites avoiding the area.

Different termites have different tunnel foraging patterns

It has been observed in both Asia and the US that success with using in-ground bait stations for the management of the Asian subterranean termite, Coptotermes gestroi, is somewhat hit and miss. Indeed, in some studies, none of the in-ground stations were found by C. gestroi.
Considering the widespread use of in-ground baits to control C. gestroi, this is clearly an issue. But since in-ground bait stations have proven successful in the management of other Coptotermes species, the question is, why aren’t C. gestroi finding the bait stations?

Researchers in the US compared the foraging patterns of C. gestroi with C. formosanus, which regularly finds in-ground bait stations.3 The study demonstrated that C. gestroi produced longer primary tunnels and shorter secondary tunnels with minimal branching, whereas C. formosanus produced highly branched tunnels.

Termite tunnelling patterns
Coptotermes gestroi (A) and Coptotermes formosanus (B) have very different foraging patterns

The result being that in these studies, C. formosanus found significantly more feeding sites than C. gestroi. Whilst this observation could certainly explain why in-ground stations are not often found in the field, the researchers stressed the need for further research, as tunnelling patterns may vary by location (soil conditions, food source density) and also by age of the colony.

References

1 Richardson, S. and Sun, Q. (2023). Effects of soil moisture on tunneling, survivorship, and food consumption of the Formosan and eastern subterranean termites (Blattodea: Rhinotermitidae). Environmental Entomology. 52(4), pp. 539–545. https://doi.org/10.1093/ee/nvad049

2 Silva A.N.F et al. (2024). Food quantity and the intensity of the alarm signal combine to modulate the resource selection in a termite species. Behavioral Ecology, 35(1). https://doi.org/10.1093/beheco/arad086

3 Su, N. and Lee, S. (2023). A comparison of tunnel geometry between the Formosan subterranean termite and the Asian subterranean termite (Blattodea: Rhinotermitidae). Pest Management Science. 79(10), pp.3999–4003. https://doi.org/10.1002/ps.7594.

Further reading:

General information on termites

Termite predator avoidance:

How termites use sound to avoid predators?

Termites can hear ants coming!

How do termite hear predators?

Termite food choice:

How do termites decide which food source to exploit?

Termite cannibalism in starving colonies

Termites damage to plastic cables

Termite tunneling:

How do termites tunnel?

Division of labour during termite tunneling

Termites as structural engineers – How they stop homes collapsing as they feed.

Termite mud tubes:

Strange examples of termite attack

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