Chemical cues modulating electrophysiological and behavioural responses in the parasitic waspCotesia sesamiae

Abstract

A better understanding of the chemical cues employed by parasitoids to locate their herbivore hosts will contribute towards effective exploitation of parasitoids as biological control agents against damaging crop pests. The current study was conducted to establish key bioactive compounds mediating behavioural response in the parasitic wasp Cotesia sesamiae (Cameron, 1906) (Hymenoptera: Braconidae) by employing electrophysiological techniques and behavioural studies. Electroantennogram (EAG) recording with synthetic equivalents of herbivore-induced plant volatiles (HIPVs) using C. sesamiae confirmed that 13 compounds elicited electrophysiological activity. In an olfactometer bioassay, only (E)-4,8-dimethyl-1,3,7-nonatriene, (E)-β-farnesene, and (E,E)-4,8,-trimethyl-1,3,7-tridecatetraene elicited behavioural responses from the parasitoid when tested individually at a natural dose, while (R)-linalool and (E)-caryophyllene were attractive at the highest test dose. Other EAG-active HIPVs were not attractive either at lower or higher concentrations, suggesting their role as blend components rather than functioning as attractants by themselves. In contrast, nine-component synthetic HIPV blends formulated in the same ratio and concentration as in a natural sample was as attractive as the original headspace sample. By providing further insights into maize–stemborer–parasitoid tritrophic interactions, results from this study will help in selecting crop cultivars emitting appropriate HIPVs to attract natural enemies and perhaps repel damaging crop pests.

An odorant receptor mediates the attractiveness of cis‐jasmone to Campoletis chlorideae, the endoparasitoid of Helicoverpa armigera

“…Odorants in the surrounding environment are detected by olfactory sensilla mainly distributed on the antennae. Electrophysiological studies using electroantennograms (EAGs) and single sensillum recordings revealed that the olfactory sensory neurones in the antennal sensilla of parasitoids respond to certain HIPV components (Dweck et al ., ; Tamiru et al ., ). Odorant receptors (ORs) function with well‐conserved odorant coreceptors (ORcos) in the dendrites of olfactory sensory neurones to determine the sensitivity and specificity of olfactory reception (Larsson et al ., ; Benton et al ., ; Hallem and Carlson, ).…”

Behavioral responses of Anagrus nilaparvatae to common terpenoids, aromatic compounds, and fatty acid derivatives from rice plants

“…Successful location of oviposition sites by parasitoids requires the ability to perceive physical and chemical cues that indicate the presence of resources (Schröder & Hilker, ). It is widely accepted that chemical stimuli, such as infochemicals, are of great value for parasitoid foraging and survival (Tamiru et al., ; Avila et al., ).…”

“…Plants can emit complex blends of volatile chemical compounds from various organs in response to pest attack. These volatiles are commonly used by natural enemies as cues to seek prey and locate hosts (Tan & Liu, ; Tamiru et al., ; Penaflor et al., ). In the study conducted by Lou et al.…”

“…Plants can emit complex blends of volatile chemical compounds from various organs in response to pest attack. These volatiles are commonly used by natural enemies as cues to seek prey and locate hosts (Tan & Liu, 2014;Tamiru et al, 2015;Penaflor et al, 2017). In the study conducted by Lou et al (2005b), rice plants infested by brown planthopper, Nilaparvata lugens (St al) (Hemiptera: Delphacidae), were attractive to the parasitoid A. nilaparvatae.…”

Volatile Semiochemical Mediated Plant Defense in Cereals: A Novel Strategy for Crop Protection

“…Although the volatile profiles display an enormous range of diversity among plant species, different plant taxa exhibited a considerable overlap in production of HIPVs [5,17]. Most HIPVs could fall into the following major categories (in order of decreasing size): terpenoids (e.g., (E)-β-ciemene, (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), (E,E)-α-farnesene), fatty acid derivatives including lipoxygenase pathway products (e.g., hexanal, (Z)-3-hexen-l-ol, (Z)-3-hexenyl acetate), benzenoids/phenylpropanoids (e.g., methyl salicylate, methyl eugenol, indole), C 5 -branched compounds, and various nitrogen-and sulphur-containing compounds (e.g., isothiocyanates or nitriles, respectively) [3,17].…”