Tritrophic Interactions

Plant volatile signals can provide important information about the physiological status and genetic identity of the emitter, and nearby plants can use this information to detect competitive neighbours. The novelty of these signals is that plants eavesdropping to volatiles of undamaged neighbours respond with typical competition responses, even before competition takes place, initiating specific growth responses that can increase their competitive capacity. This preparing for future competition mechanism affects the behaviour and abundance of herbivore pests and their natural enemies. Previously, such responses were only known to occur in response to volatiles released by damaged plants. However, volatile interactions occur only in specific combination of species/genotypes, indicating that plants use volatile signals in the detection and adaption only to substantial competitive neighbours.

Some herbivore-induced-plant volatiles (HIPVs) compounds are vital for the functioning of an ecosystem, by triggering multi-trophic interactions for natural enemies, plants and herbivores. However, the effect of these chemicals, which play a crucial role in regulating the multi-trophic interactions between plant-herbivore-entomopathogenic fungi, is still unknown. To fill this scientific gap, we therefore investigated how these chemicals influence the entomopathogenic fungi growth and efficacy. In this study, Lipaphis erysimi induced Arabidopsis thaliana HIPVs were collected using headspace system and detected with GC-MS, and then analyzed the effects of these HIPVs chemicals on Lecanicillium lecanii strain V3450. We found that the HIPVs menthol and methyl salicylate at 1 and 10 nmol·ml −1 improved many performance aspects of the fungus, such as germination, sporulation, appressorial formation as well as its pathogenicity and virulence. These findings are not only important for understanding the multi-trophic interactions in an ecosystem, but also would contribute for developing new and easier procedures for conidial mass production as well as improve the pathogenicity and virulence of entomopathogenic fungi in biological pest management strategies. Herbivore-induced-plant-volatiles (HIPVs) are emitted from plants after infestation by arthropods, and these volatiles are composed by many organic compounds which are involved in plant communication with natural enemies of the insect herbivores, neighboring plants, and different parts of the damaged plant. For instance, green leaf volatiles (GLVs) are comprised of C 6 aldehydes, alcohols as well as esters, and terpenoids 1,2. It was well known that HIPVs play a significant role in attracting natural enemies of herbivores when plants become infested by herbivorous insects. Likewise, Arabidopsis thaliana (L) Heynh (Brassicales: Brassicaceae) attracted more parasitic wasp Cotesia glomerata (Linnaeus) (Hymenoptera: Braconidae), when the plant emitted a high amount of GLVs 3. Recently, it has been reported that (Z)-3-hexenol, a unique compound of GLVs is the most important info-chemical for the natural enemy attraction 4. A blend of six HIPVs compounds, such as beta-myrcene, n-octanal, and alpha-phellandrene, along with other host-nonspecific (E)-beta-ocimene, gamma-terpinene, and linalool played a role in the communication between plant and parasitic wasps Aphidius ervi Haliday (Hymenoptera: Aphidiidae) at a minimal quantity of 0.001 ng to 5 ng 5. In addition, it also reported that predators respond to transgenic plant volatiles, like (E, E)-4, 8,12-trimethyltrideca-1, 3, 7, 11-tetraene, which is produced endogenously 6. Furthermore, plant roots also emit HIPVs to attract natural enemies, such as;

Plant volatile signals can provide important information about the physiological status and genetic identity of the emitter, and nearby plants can use this information to detect competitive neighbours. The novelty of these signals is that plants eavesdropping to volatiles of undamaged neighbours respond with typical competition responses, even before competition takes place, initiating specific growth responses that can increase their competitive capacity. This preparing for future competition mechanism affects the behaviour and abundance of herbivore pests and their natural enemies. Previously, such responses were only known to occur in response to volatiles released by damaged plants. However, volatile interactions occur only in specific combination of species/genotypes, indicating that plants use volatile signals in the detection and adaption only to substantial competitive neighbours.