Research from the University of Florida, USA, has shown that when Formosan subterranean termites are weakened by insecticide bait, a neighbouring colony will invade their territory, only to meet the identical fate. The research finding is key for pest managers in understanding the potential effects of termite baiting.

The study, led by Professor Nan-Yao Su, a faculty member at the University’s Institute of Food and Agricultural Sciences, wanted to determine how quickly subterranean termites would invade another colony’s territory after they die. “Sometimes those areas remain vacant for months; sometimes they invade in days,” said Professor Su, who has worked to help control termite populations in New Orleans, Louisiana, for nearly 20 years.

“What surprised me was that when one colony was weakened by baits – and even before they were killed – it looks like the neighbouring colony can sense this and begins to invade. How do they sense it? We simply don’t know,” he added.

The study, published in the Journal of Economic Entomology, looked at the way colonies of Formosan termites reacted to nearby colonies in which the researchers had established baits. Healthy colonies will defend their territories, and so the scientists wanted to test if termites from a nearby colony would invade a baited colony after the termites had discovered that a chemical had weakened termites from that colony.

“The good news for homeowners is that as soon as the colony is weakened by baits, the neighbouring colony would immediately invade its tunnelling system, discover the baits and consume them,” explained Professor Su. “The results showed that as long as the baits are still present in the bait stations, they will continue to intercept and eliminate incoming colonies.” In the study, the invading termites invaded and eventually died.

The results of the study indicate that bait monitoring systems can potentially have a double impact on subterranean termites, not only eliminating colonies immediately next to a property, but colonies in the surrounding area too.

Although the research was carried out on Coptotermes formosanus, it is quite probable that the same behaviour occurs with Australian Coptotermes species. This would explain the observation from several pest managers that sometimes baiting seems to have controlled the colony, only for termites to reappear in the bait station a couple of weeks later. To counter this behaviour, it certainly makes sense to complete two or three visits after control has been confirmed and maintain bait levels in the station, to pick up activity from any invading colonies.

Reworked extract from: ‘Neighboring termite colonies re-invade, expose themselves to deadly bait’ by Brad Buck. Science Daily, 13 March 2017.