The cracking of CCA- and creosote-treated poles is a serious problem in tropical and sub-tropical regions, due to sharp variations in atmospheric moisture levels and various new timber species being introduced to the market.The cracking occurs when the hardwood doesn’t dry at the same rate as the sapwood. These cracks expose the hardwood, leaving poles vulnerable to attack by the virulent termites found in these climates.However, these cracks can be treated using insecticides that contain fipronil, a highly effective broad-spectrum termiticide and insecticide that is used by pesticide agencies worldwide.As a pesticide, fipronil must be registered and approved in the country of use. The chemical kills termites by blocking crucial challenges in their central nervous systems – the GABA (gamma-aminobutyric acid) and GluCl (glutamate-gated chloride) channels. It does not affect mammals, whose nervous systems do not have these particular channels.Termites cannot detect fipronil, so they carry it back to their mounds and colonies and infect other termites through contact. As a result, the chemical is effective in small doses. It binds to the soil, where it is not mobile, leading to efficacy over a long period of time.To use fipronil, a cavity should be dug into the soil around the affected pole, and five litres of diluted solution poured into the cavity. The solution seeps into the pole, protecting both the pole and the surrounding soil. Treatment should be re-applied every 2.5 years.“Fipronil is a proven product,” says Bertus. “We recommend it to prevent pole damage, as well as to treat cracked poles, in all areas where wooden transmission or utility poles are particularly vulnerable to termites. This makes it an invaluable product in several African countries.