<p><strong>Spirotetramat toxicity to immatures and sublethal effects on fecundity of female adults of </strong><strong><em>Tetranychus urticae </em></strong><strong>Koch*</strong></p>

Abstract

Acute toxicity of spirotetramat to immatures and its sublethal effects on adult females of two-spotted spider mite, Tetranychus urticae Koch, were investigated in laboratory bioassays, at 27 ± 2°C, 50–80% RH and 16/8 L/D photoperiod.Acute toxicity was tested by successive treatments of eggs, larvae, protonymphs and deutonymphs on bean leaf discs, and mortality was evaluated based on the number of mites reaching the adult stage. Concentration-mortality data were subjected to probit analysis and the following LC50 data were computed: 0.10 mg/l (larvae), 0.17 mg/L (protonymphs) and 0.15 mg/L (deutonymphs). The acaricidal effect after the treatment of eggs was not the result of spirotetramat toxicity to this developmental stage, but rather of its residual activity on hatched larvae (LC50=0.62 mg/L). Sublethal effects were evaluated after the treatment of pre-ovipositing adult females on leaf discs using the concentrations of 2 mg/L, 20 mg/L and 200 mg/L.After 18–20 hours of exposure on treated discs, females showing no visible symptoms of poisoning were transferred to untreated leaf discs and re-transferred to new discs at 48 h intervals over ten days. Based on the number of eggs laid and survival rate of females, gross fecundity and net fecundity were calculated. At the end of the tenth day, the survival rate was 0.72 in untreated and 0.40, 0.27 and 0.05 in females treated at the concentrations mentioned above. Compared with the control mites, gross fecundity was reduced by 9% (2 mg/L), 29% (20 mg/L) and 93% (200 mg/L), while net fecundity decreased by 40%(2 mg/L), 67%(20 mg/L) and 98%(200 mg/L). The results indicate that spirotetramat exerts similar effects on spider mites as do the acaricides spirodiclofen and spiromesifen.

Toxicity and Biochemical Effects of Spirotetramat and its Binary Mixtures with Nanosilica against Aphis gossypii Glover, Bemisia tabaci Gennadius and the Earthworm, Eisenia fetida

“…Gong et al (2016) and Ramalakshmi et al (2020) revealed that spirotetramat was highly effective on the A. gossypii fecundity and increased the total CarE activity dramatically. At the same pace, the insecticidal effect of spirotetramat was confirmed against other insects, cotton mealybug, Phenacoccus solenopsis (Rezk et al, 2019 andSequeira et al, 2020), Tetranychus urticae Koch (Marcic et al, 2011 andSaryazdi et al, 2013). Fiaz et al (2018) found that combined application of spirotetramat along with Isaria fumosorosea formulation has shown a significant synergistic effect against Diaphorina citri infestation.…”

Susceptibility to Acaricides and the Frequencies of Point Mutations in Etoxazole- and Pyridaben-Resistant Strains and Field Populations of the Two-Spotted Spider Mite, Tetranychus urticae (Acari: Tetranychidae)

“…Pyflubumide is classified in the new subgroup 25B (carboxanilide) in the IRAC (Insecticide Resistance Action Committee) MoA classification as a novel inhibitor of mitochondrial complex II on the respiratory chain and has a similar mechanism to cyenopyrafen and cyflumetofen, so resistance to this compound may have developed via the same factors [ 39 , 40 ]. Spirodiclofen, spiromesifen, and spirotetramat have sterility effects on adult females and ovicidal effects on eggs but do not have a control effect on adults [ 41 ]. Therefore, abamectin, acequinocyl, bifenazate, and fluxametamide will be effective in controlling adults that have developed resistance to etoxazole and pyridaben.…”