Tarsonemus bakeri Mite Bioassay, 2020

Tarsonemus bakeri can be found on citrus fruit at the time of harvest and can be a species of export concern. We conducted laboratory experiments in Apr 2020 to determine the effects of eight registered miticides and a surfactant (BreakThru S240) on T. bakeri. Mites from a laboratory colony were reared on Alternaria fungus and molasses on detached mature orange leaves. For each treatment, a 250 ml diluted solution was prepared using the label rate of the miticide or surfactant in 100 gpa and sprayed from an 8-oz spray bottle for 2–3 s onto an orange leaf pre-infested with 25 adult T. bakeri (Table 1).The experimental design was an RCB with five replications, and blocking was based on time as one leaf/wk was prepared for each treatment. Treated leaves were held in a room maintained at 22 ± 2°C for 7 d, and mortality was assessed by observing mites under a stereoscope. Mites showing the ability to move one body length upon prodding were counted as live. Percentage mortality data was arcsine (square root (x)) transformed and means were compared using the Fisher’s Protected LSD test after one-way ANOVA analysis after testing for an NS block effect. Non-transformed means are reported in Table 1.

All treatments caused significant mortality of T. bakeri compared with the water control (Table 1). Five treatments, namely, Agri-Mek SC, Magister SC, Nealta, Nexter SC, and Fujimite SC resulted in significantly higher mortalities than Onager Optek, Breakthru S240, Kanemite 15 SC, and Cinnerate (Table 1).¹

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