Toxicity of the herbicide glufosinate-ammonium to Tetranychus urticae (Acari: Tetranychidae) under laboratory and field conditions
✍ Scribed by Ahn, Young-Joon; Cho, Jum-Rae; Kim, Young-Joon; Yoo, Jai-Ki; Lee, Jeang-Oon
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 216 KB
- Volume
- 51
- Category
- Article
- ISSN
- 1526-498X
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✦ Synopsis
The toxicity of herbicides widely used in apple orchards to the twospotted spider mite (T etranychus urticae) was evaluated in laboratory and Ðeld studies. In a laboratory study with susceptible T . urticae, glufosinate-ammonium was highly e †ective against larvae, protonymphs and adults, but non-toxic to eggs. Its efficacy was much greater than that of the commonly used acaricide azocyclotin. The immatures died within 24 h after treatment, suggesting that the nymphicidal action may be attributable to a direct e †ect rather than an inhibitory action of chitin synthesis. Glufosinate-ammonium showed a positive temperature coefficient of toxicity against T . urticae adults at six temperatures from 10 to 32¡C, being more toxic at higher temperatures. Very low levels of resistance to the herbicide were observed in the seven Ðeld-collected T . urticae populations resistant to various acaricides. Treatment with glufosinate-ammonium did not cause a repellent response from either adults or immature stages of T . urticae. Paraquat dichloride and glyphosate were ine †ective against all stages of T . urticae. In a Ðeld study of a population of T . urticae, glufosinate-ammonium when sprayed to weeds caused signiÐcant decrease in T . urticae population densities in apple trees for nine weeks after treatment, as compared with the control. Thereafter, a single application of standard acaricides to apple foliage greatly reduced population densities, although there was no di †erence in the densities between the glufosinate-ammonium-treated and control plots. Based upon laboratory and Ðeld data, two single treatments with glufosinate-ammonium to weeds in May and a selective acaricide to apple trees in July may be used to prevent damage by T . urticae.