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<p>Biological control, which relies on natural enemies to suppress insect pest populations, is a cornerstone of sustainable agriculture. However, its efficacy depends on plant-mediated interactions that influence predator and parasitoid behaviour. Prohydrojasmon (PDJ), a jasmonate analogue, primes plant defences against herbivores, but its effects on tritrophic interactions remain understudied. Here, we investigated how PDJ treatment of <i>Brassica juncea</i> L. (Brassicaceae) alters the behaviour and efficacy of three aphid parasitoids (<i>Diaeretiella rapae</i>, <i>Aphidius gifuensis</i>, <i>Aphidius colemani</i>) and two predators (<i>Coccinella septempunctata</i>, <i>Harmonia axyridis</i>) at 24 h (PDJ<sub>24</sub>) and 48 h (PDJ<sub>48</sub>) post-treatment. Using parasitoid landing assays, foraging trials, parasitism rate evaluations, olfactometer bioassays, predator preference tests, and volatile profiling, we assessed PDJ’s temporal impact on tritrophic dynamics. Results showed that PDJ<sub>48</sub> increased foraging duration and parasitism rates in <i>D. rapae</i> (at 24 h and 48 h) and <i>A. gifuensis</i> (48 h only), while <i>A. colemani</i> remained unaffected. PDJ<sub>48</sub> also enhanced <i>H. axyridis</i> settlement and aphid consumption, with predators showing no preference for PDJ<sub>24</sub>-treated plants. Olfactometer assays revealed stronger attraction of <i>D. rapae</i> and <i>A. gifuensis</i> to PDJ<sub>48</sub>-induced volatiles, aligning with delayed landing responses (24 h for <i>D. rapae</i>; 48 h for <i>A. colemani</i>) and prolonged foraging. PDJ<sub>48</sub> increased parasitoid retention on treated plants, suggesting improved host-location cues, whereas <i>C. septempunctata</i> exhibited no preference. These findings demonstrate that PDJ application at 48 h post-treatment enhances tritrophic interactions by synchronising plant defence induction with natural enemy recruitment, while PDJ<sub>24</sub> effects were transient or absent. Our study underscores PDJ’s potential as a sustainable tool to synergise plant resistance and biological control, offering a timed application strategy for integrated pest management in <i>Brassica</i> crops.</p>

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Prohydrojasmon treatment enhances aphid (Brevicoryne brassicae) biological control by improving the performance of key natural enemies in Brassica juncea

  • 期刊论文

  • 发表日期：

    2026年5月13日

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  • Jamin Ali,
  • Adil Tonğa,
  • Sohail Abbas,
  • Khalid Ali Khan,
  • Hamed A. Ghramh,
  • Mohammad Mahamood,
  • Vol Oberemok,
  • Rizhao Chen

摘要

Biological control, which relies on natural enemies to suppress insect pest populations, is a cornerstone of sustainable agriculture. However, its efficacy depends on plant-mediated interactions that influence predator and parasitoid behaviour. Prohydrojasmon (PDJ), a jasmonate analogue, primes plant defences against herbivores, but its effects on tritrophic interactions remain understudied. Here, we investigated how PDJ treatment of Brassica juncea L. (Brassicaceae) alters the behaviour and efficacy of three aphid parasitoids (Diaeretiella rapae, Aphidius gifuensis, Aphidius colemani) and two predators (Coccinella septempunctata, Harmonia axyridis) at 24 h (PDJ24) and 48 h (PDJ48) post-treatment. Using parasitoid landing assays, foraging trials, parasitism rate evaluations, olfactometer bioassays, predator preference tests, and volatile profiling, we assessed PDJ’s temporal impact on tritrophic dynamics. Results showed that PDJ48 increased foraging duration and parasitism rates in D. rapae (at 24 h and 48 h) and A. gifuensis (48 h only), while A. colemani remained unaffected. PDJ48 also enhanced H. axyridis settlement and aphid consumption, with predators showing no preference for PDJ24-treated plants. Olfactometer assays revealed stronger attraction of D. rapae and A. gifuensis to PDJ48-induced volatiles, aligning with delayed landing responses (24 h for D. rapae; 48 h for A. colemani) and prolonged foraging. PDJ48 increased parasitoid retention on treated plants, suggesting improved host-location cues, whereas C. septempunctata exhibited no preference. These findings demonstrate that PDJ application at 48 h post-treatment enhances tritrophic interactions by synchronising plant defence induction with natural enemy recruitment, while PDJ24 effects were transient or absent. Our study underscores PDJ’s potential as a sustainable tool to synergise plant resistance and biological control, offering a timed application strategy for integrated pest management in Brassica crops.