ATP assay for determining the viability of the two-spotted spider mite (Tetranychus urticae Koch) and the European red mite (Panonychus ulmi (Koch)) (Acari: Tetranychidae) during diapause

Abstract

A bioluminescent adenosine triphosphate (ATP) assay for determining viability in adult females of the two-spotted spider mite, Tetranychus urticae, and eggs of the European red mite, Panonychus ulmi, (both diapause and non-diapause state), was investigated. ATP contents in living and dead individual mites (adult females or eggs) were measured. The mites of the lethal treatment group were killed by freezing at −35°C. Mean (±SD) ATP contents for non-diapause and diapause T. urticae female adults were 34.39±5.14 pmol and 26.40±2.67 pmol, respectively. Corresponding values for non-diapause and diapause P. ulmi eggs were 1.12±0.19 pmol and 0.87±0.16 pmol, respectively. ATP contents in living mites in diapause were therefore approximately 77% of those in non-diapause mites. A wide variance in the ATP contents (0.00–0.94 pmol) was found in individual P. ulmi diapause eggs at 2 and 4 h after treatment; therefore, their mean ATP contents did not show a rapid decrease. We speculated that some P. ulmi diapause eggs survived for several hours after treatment by cold hardiness, maintaining metabolic activities until death. However, with the exception of P. ulmi diapause eggs, ATP contents in both mite species rapidly decreased at 2 h after treatment. At 24 h after treatment, ATP contents in both mite species had decreased significantly to 0.4–2.7% of the pre-treatment values, regardless of whether they were in a non-diapause or diapause state. Thus, based on our findings with T. urticae adult females and P. ulmi eggs, the ATP bioluminescence assay could be applicable to the determination of pest viability, regardless of their diapause state.