Evaluation of fatty acids for spatial repellency against the two-spotted spider mite, Tetranychus urticae: Laboratory and greenhouse bioassays

Monday, November 11, 2024

11:18 AM – 11:30 AM MST

Location: Phoenix Convention Center, 126 A, PCC

Presenting Author(s)

JO

Ji Hye Oh

Gyeongsang National University, Kyongsang-namdo, Republic of Korea

Co-Author(s)

RK

Ryeo Eun Kim

Gyeongsang National University
Jinjusi, Kyongsang-namdo, Republic of Korea
DK

Dong Hee Kim

Gyeongsang National University
Jinjusi, Kyongsang-namdo, Republic of Korea
EJ

Eun Su Jang

Undergraduate research assistant
Gyeongsang National University
Jinju-si, Kyongsang-namdo, Republic of Korea
HK

Hyeon Gu Kim

Gyeongsang National University
Jinjusi, Kyongsang-namdo, Republic of Korea
SP

Seo Yeon Park

Gyeongsang National University
Jinjusi, Kyongsang-namdo, Republic of Korea
DY

Da Hyeon Yu

Gyeongsang National University
Jinju City, Kyongsang-namdo, Republic of Korea
Sang-Bin Lee

Postdoctoral research associate
University of California
Fairfield, California
GR

Gwang hyun Roh

Gyeongsang National University
Jinjusi, Kyongsang-namdo, Republic of Korea

The two-spotted spider mite, Tetranychus urticae Koch, is one of the most important agricultural pests. T. urticae rapidly develops resistance to acaricides due to its short life cycle and continuous exposure to these chemicals. Therefore, new resources to alternate pesticides are needed to achieve sustainable management of T. urticae. Fatty acids have been studied spatial repellency, oviposition deterrence, antifeedant activity, and toxicity against various pests, but their spatial repellency effects on T. urticae have yet to be investigated.

In this study, we evaluated the spatial repellency of fifteen fatty acids against T. urticae in the laboratory and greenhouse using two-choice and no-choice bioassays. In laboratory two-choice tests, nine of 15 fatty acids showed significant spatial repellency against female adult mites at a 20 mg dose. Among them, six fatty acids demonstrated significant repellency at a 2 mg dose, while none were effective at a 0.2 mg dose. The individual of the six compounds did not exhibit significant repellency compared to the repellency of the six-compound blend. Among these, three medium-chain fatty acids (C8:0, C9:0, and C10:0) demonstrated predominant repellent activity (over 90%) that persisted for at least three days in laboratory no-choice tests.

In greenhouse tests, we observed fewer T. urticae on strawberry seedlings treated lure with 2 mg and 20 mg doses of C8:0, C9:0, and C10:0 compared to those treated lure with a solvent control. Given their efficacy, cost-effectiveness, and natural origin, these fatty acids can be used as potential agents for the sustainable management of T. urticae.