Acaricidal effects of diatomaceous earth on Haemaphysalis longicornis under laboratory conditions

Ticks transmit various diseases to humans and animals, posing a significant global threat to public health. The primary method currently employed to control tick infestations is the use of chemical acaricides. However, improper use leads to environmental contamination, residue in meat and milk, and the development of acaricide-resistant ticks. Therefore, alternative tick control methods that are safe for humans, animals, and the environment and that do not induce resistance are urgently needed. Diatomaceous earth (DE), a naturally occurring physical insecticide, has been proven to effectively kill various arthropods without producing resistance or toxic side effects. In the present study, the acaricidal effects of DE on larval, nymphal, and adult stages of Haemaphysalis longicornis ticks were evaluated using sprinkling and immersion methods. In larvae, mortality was first observed 20 min after sprinkling, with a 100% mortality rate by 200 min. Immersion treatment of nymphs with DE resulted in initial mortality observed after 120 min, and the mortality rate reached 100% after 12 h. The initial mortality rate for adult male ticks was 5% after 8 h of treatment, and 5% for adult female ticks after 6 h treatment. By 24 h, the mortality rates for both adult male and female ticks had reached 100%. These findings demonstrate that DE has acaricidal effects on the larval, nymphal, and adult stages of H. longicornis under laboratory conditions. Our study provides a foundation for future field trials to explore DE as a safe and effective alternative to chemical acaricides in tick control methods.