Sublethal effects of spiromesifen on life table traits of Tetranychus urticae (Acari: Tetranychidae) and Neoseiulus californicus (Acari: Phytoseiidae)

Abstract

The assessment of long-term negative effects of insecticides on the target and non-target insects can help assess the toxicity and side-effects of pesticides. In this study, the sublethal effects of a low concentration of spiromesifen (LC₂₀) on life-history traits of T. urticae and its phytoseiid predator N. californicus were estimated for two successive generations (F0 and F1). According to the results, adult longevity, oviposition days, fecundity, and life table parameters (r_m, R₀, and T) exhibited significant negative impacts at LC₂₀ compared to the control. Meanwhile, significant effects of the LC₂₀ were found on most parameters of the life table (longevity, fecundity, oviposition days) of N. californicus. Also, spiromesifen had significant negative effects on the population parameters except for the net reproductive rate (R₀) in N. californicus. On the other hand, the parameters of the consumption rate (finite predation rate (ω), stable consumption rate (ψ), and net consumption rate (C₀)) in this predator exhibited significant negative impacts. Therefore, the results suggested that spiromesifen effectively controls the successive generation of T. urticae. Also, this compound adversely affected most parameters of N. califonicus, so it is inappropriate for IPM applications in the presence of this parasitoid.