Non-Chemical Control of Nymphal Longhorned Tick, Haemaphysalis longicornis Neumann 1901 (Acari: Ixodidae), Using Diatomaceous Earth

Abstract

The longhorned tick (LHT), Haemaphysalis longicornis, is an invasive species of public health and veterinary importance. Having invaded North America, Australia, and New Zealand from East Asia, the LHT also has the potential to inhabit and survive in Africa, South America, and Europe. Synthetic chemicals have been vital in controlling these ticks but at the risk of the development of resistant strains and sometimes affecting non-target species. There is also a popular demand for non-chemical approaches for pest control. The use of diatomaceous earth (DE) derived from fossilized diatoms to control LHTs was not considered. This study examined whether DE could kill nymphal LHTs. When ticks were dipped into DE powder for a few seconds and then incubated at 30 °C and 70% relative humidity, they began dying as early as 2.5 h and were all dead by 9 h. The movement by walking of DE-treated nymphs was significantly higher in the first two hours and then the same as the control up to death. A dose of 5 g DE/m2 spread on pine leaf litter killed all the ticks. SEMs after treatment showed the mineral on large areas of the tick surface. These results indicated that DE has the potential of being used as a novel acaracide for LHTs.