Advantages and Limitations of Yellow Sticky Traps as a Pest Control Method in Pollinator-Friendly Rapeseed Agroecosystems: A Pilot Study in Northern Italy

Entomophilous mass-flowering crops such as rapeseed (Brassica napus L.) may especially benefit from Integrated Pest and Pollinator Management (IPPM) programs aimed at protecting the crop while reducing pollinator exposure to harmful pesticides. Yellow sticky trap barriers around field edges might represent an insecticide-free method of controlling immigrating pests. In this pilot study, we set up two experimental plots in a rapeseed agroecosystem in Northern Italy, comparing sticky traps with an insecticide treatment (acetamiprid), considering pest incidence/damage, pollinators/pollination services and yield. Sticky traps were associated with lower numbers of spring-immigrating pests (pollen beetles, weevils) and a lower percentage of seed pod damage. Overall yield was nonetheless higher in the insecticide treatment plot, possibly due to autumn-immigrating pest species which could be controlled by the insecticide but not by the sticky trap barrier (installed in spring). We found no significant effect of the treatments on pollinators or pollination, although plants treated with insecticide showed a higher average pollination deficit. Overall, our pilot study highlighted potential in yellow sticky traps as an IPPM measure, but they showed some limits—implying they would need to be paired with complementary methods, or to be installed earlier to intercept also autumn-immigrating pests.