2025, Durak, Roma, Borowiak-Sobkowiak, Beata, Szpyrka, Ewa, Durak, Tomasz, Ciak, Beata, Jedryczka, Małgorzata

Cannabis aphid Phorodon (Diphorodon) cannabis Passerini 1860 is an economically impor­tant pest of oil hemp (Cannabis sativa L.) and is controlled by insecticides. Oil hemp crops are treated with herbicides, which are non-target pesticides for aphids but may also affect aphid populations. Such ecological implications of plant protection products are rarely in­vestigated. The aim of the present research was to better understand plant ‒ aphid ‒ her­bicide interactions, specifically, changes of fatty acids (FAs) in leaves, caused by cannabis aphids and a common herbicide used in hemp fields. Of 21 FAs detected in hemp leaves, aphid feeding significantly increased the amounts of myristic and oleic acids and decreased the content of α-linolenic acid. This effect was found when aphids fed on hemp plants and especially when plants were treated with an herbicide containing quizalofop-P-tefuryl. This compound on its own did not affect the FA composi­tion. In spite of the extremely high increase of myristic acid (7- to 9-fold, depending on the experiment variant), which could cause the repellent effect in hemp plants, the decreased amount of α-linolenic acid, the precursor of jasmonic acid may have helped aphids to ma­nipulate the jasmonate signaling pathway involved in plant defense to herbivory enabling their continued feeding on hemp. This study revealed the importance of FAs in plant de­fense as well as the side effects of non-target plant protection products. Future pest man­agement should take into account the complex interactions between crop plants, their pests and non-target effects of chemicals used in real field situations.