Fatty Acid Composition of Novel Host Jack Pine Do Not Prevent Host Acceptance and Colonization by the Invasive Mountain Pine Beetle and Its Symbiotic Fungus

Abstract

Fatty acids are major components of plant lipids and can affect growth and development of insect herbivores. Despite a large literature examining the roles of fatty acids in conifers, relatively few studies have tested the effects of fatty acids on insect herbivores and their microbial symbionts. Particularly, whether fatty acids can affect the suitability of conifers for insect herbivores has never been studied before. Thus, we evaluated if composition of fatty acids impede or facilitate colonization of jack pine (Pinus banksiana) by the invasive mountain pine beetle (Dendroctonus ponderosae) and its symbiotic fungus (Grosmannia clavigera). This is the first study to examine the effects of tree fatty acids on any bark beetle species and its symbiotic fungus. In a novel bioassay, we found that plant tissues (hosts and non-host) amended with synthetic fatty acids at concentrations representative of jack pine were compatible with beetle larvae. Likewise, G. clavigera grew in media amended with lipid fractions or synthetic fatty acids at concentrations present in jack pine. In contrast, fatty acids and lipid composition of a non-host were not suitable for the beetle larvae or the fungus. Apparently, concentrations of individual, rather than total, fatty acids determined the suitability of jack pine. Furthermore, sampling of host and non-host tree species across Canada demonstrated that the composition of jack pine fatty acids was similar to the different populations of beetle’s historical hosts. These results demonstrate that fatty acids composition compatible with insect herbivores and their microbial symbionts can be important factor defining host suitability to invasive insects.

Phytochemicals as mediators for host range expansion of a native invasive forest insect herbivore

“…Among terpenes, monoterpenes are the most studied because of their importance to MPB behavior (Erbilgin et al ., ) and to host resistance (Boone et al ., ; Erbilgin et al ., ). Conifers also contain other classes of compounds, such as fatty acids, that can be toxic to MPB (Ishangulyyeva et al ., ).…”

“…Recently, Ishangulyyeva et al . () have shown that G. clavigera grows similarly in media amended with fatty acids at concentrations present in jack or lodgepole pine phloem. Furthermore, samplings of different jack and lodgepole pine populations in various places in western Canada indicated that the composition of fatty acids was similar between the two species, suggesting that the composition of jack pine fatty acids is compatible with MPB and its fungal symbionts.…”

“…Finally, Ishangulyyeva et al . () evaluated whether the fatty acid profile of jack pine impedes host colonization by MPB and G. clavigera (Tables , ). Fatty acids are major components of plant lipids that can be synthesized into derivatives such as jasmonic acid used in plant defenses against insect herbivores.…”

“…() (data only from Alberta); Ishangulyyeva et al . () (data only from Alberta); Lusebrink et al . ().…”

Aphid Antifeedant Fatty Acids from an Endophytic Fungus <em>Trichoderma</em> sp. EFI671

“…Fatty acids are major components of plant lipids, can affect growth and development of insect herbivores and influence host suitability to invasive insects [43]. Additionally, the insecticidal and antifeedant action of fatty acids and esters has been described.…”