Acaricide resistance in the african red mite, Eutetranychus africanus (Tucker), infesting tangerine in Thailand
2026 - Volume: 66 Issue: Suppl pages: 197
https://doi.org/10.24349/mmcb-bmf9
ICA 2026 - XVII International Congress of Acarology, 20-24 July 2026, Montpellier
Keywords
Acaricide resistance
Tangerine pest
Citrus
Bioassay
Resistance management
Amblyseius swirskii
Phytoseiidae
Abstract
The African red mite (Eutetranychus africanus Tucker) is one of the most damaging pest mites of citrus in Thailand, frequently causing leaf discoloration, reduced vigor, and yield loss. Continuous and repeated use of acaricides such as pyridaben, propargite, and amitraz has raised concerns about resistance development in field populations. This study aimed to evaluate the resistance levels of E. africanus populations collected from major tangerine-growing areas in Thailand and to provide evidence-based recommendations for acaricide resistance management. E. africanus collected from the different locations were reared to the F2 generation and tested for resistance using the leaf dipping technique. The experiments were conducted at the Laboratory of Mite and Spider Research Group, Department of Agriculture. Leaves of Erythrina fusca Lour were dipped into different concentrations of each acaricide, and 20 adult female mites were transferred onto each treated leaf per replicate. Each concentration was tested with at least six replicates. Mortality was recorded 72 hours after treatment. LC50 values were estimated using probit analysis, and resistance factors (RF) were determined by dividing the LC50 of each field population by the lowest LC50 recorded across all populations. E. africanus populations of from Chiang Mai, Kamphaeng Phet, Chumphon, and Bangkok exhibited different levels of resistance to the tested acaricides. RF values ranged from 1.00- 589.55-fold for pyridaben, 1.00-101.93- fold for propargite, and 1.00- 4.72-fold for amitraz. The E. africanus from Khlong Khlung District, Kamphaeng Phet Province, exhibited a very high resistance level to pyridaben (RF = 589.55 fold), while the population from Fang District, Chiang Mai Province, showed high resistance to pyridaben (RF = 55.22 fold) and very high resistance to propargite (RF = 101.93 fold). All E. africanus populations exhibited low resistance levels to amitraz. Therefore, to effectively manage E. africanus populations in citrus and delay the development of resistance, acaricides with high resistance levels in specific areas should be avoided, and acaricide rotation programs should be implemented.
Comments
Please read and follow the
instructions
to post any comment or correction.