The Effects of Spirodiclofen on Reproduction of Two-spotted Spider Mite (Tetranychus urticae Koch)

Pesticidi i Fitomedicina

关键词: Tetranychus urticae;    Spirodiclofen;    Reproduction;   

DOI  :  

来源: DOAJ

【 摘 要 】

Laboratory bioassay was conducted to evaluate the effects of spirodiclofen on the survival, fecundity and fertility of two-spotted spider mite (Tetranychus urticae Koch) females treated as 3-days old adults with a series of acaricide concentrations starting with the concentration discriminative for eggs and immatures. After a 24 h exposure, the proportion of females that survived treatment was 0.86 (6 mg/L), 0.71 (12 mg/L), 0.54 (24 mg/L), 0.50 (48 mg/L) and 0.44 (96 mg/L). Over the following five days, the survival rates of females treated with 6 mg/L and 12 mg/L were considerably below the survival rate of untreated females, but they still remained above the survival rates of females treated with other concentrations.Total fecundity/fertility significantly decreased as concentrations of spirodiclofen increased. The highest concentration, 96 mg/L, completely terminated egg-laying, while only two and three females of those surviving the respective concentrations of 48 mg/L and 24 mg/Llaid viable eggs. On the other hand, 60% and 84% of female survivors of treatments with the respective concentrations of 12 mg/L and 6 mg/L laid viable eggs; total fertility of these females was reduced by 58.6 and 45.2%, respectively. On the first day after treatment, thefemales treated with 24 mg/L, 12 mg/L and 6 mg/L laid eggs; viable eggs were laid only by the latter group and the percentage of hatching was barely 3.1% (89% in control). On the second day, the females treated with 48 mg/L also began to lay eggs, but viable eggs were laid only by females treated with 12 mg/L and 6 mg/L (the respective percentages of hatching were 28.5% and 65.3%; 93.9% in control). From the third day onward, viable eggs were laid also by females treated with 48 mg/L, and the difference in hatchability was considerably smaller or disappeared completely. Compared to control, gross fecundity was significantly reduced by all concentrations on the first day only, and gross fertility on the first two days of trial. No significant difference in gross fecundity/fertility was observed further on until the end of the trial between untreated females and those treated with 6 mg/L and 12 mg/L. However, all concentrations significantly reduced net fecundity/fertility throughout the trial, which indicates a considerable impact of the decreased female survival rate on overall reduction in net fertility, especially from the third day onward. Sublethal effects ofspirodiclofen and its impact on T. urticae management are discussed.

【 授权许可】

Unknown