Cold‐Pressed <scp> <i>Camelina sativa</i> </scp> and <scp> <i>Brassica carinata</i> </scp> Oils as a New Tool for Sustainable Control of <scp> <i>Dendrolimus pini</i> </scp>

ABSTRACT Outbreaks of Dendrolimus pini L. threaten the health and stability of Scots pine forests across Europe, and increasing restrictions on synthetic insecticides underscore the need for effective, environmentally compatible alternatives. Cold‐pressed seed oils from Camelina sativa and Brassica carinata contain diverse bioactive compounds with potential insecticidal properties, yet their efficacy against major forest defoliators remains largely unexplored. This study evaluated the lethal and sublethal effects of 2% oil‐based formulations on D. pini larvae to assess their suitability as plant‐derived bioinsecticides. Both oils significantly reduced larval survival compared with the emulsifier‐treated control. Median survival decreased from 105 days in the control to 38.5 days for the B. carinata formulation and 7.5 days for the C. sativa formulation. Cox regression revealed a more than fivefold increase in mortality risk for C. sativa (hazard ratio: 5.39) and a threefold increase for B. carinata (hazard ratio: 3.07). The B. carinata formulation prolonged the larval stage and markedly reduced pupal mass, length, and width, with the strongest reductions in males. Female fecundity was also reduced, with B. carinata ‐fed females producing 33% fewer eggs than controls. The C. sativa formulation caused very high early larval mortality, preventing most larvae from reaching pupation. Cold‐pressed oils from Camelina sativa and Brassica carinata exhibit potent lethal and sublethal effects on D. pini , impairing survival, growth, development, and reproductive output. These findings highlight their promise as sustainable, plant‐derived bioinsecticides and provide a basis for developing novel, low‐risk tools for forest pest management.