Dynamic changes in virus-induced volatiles in cotton modulate the orientation and oviposition behavior of the whitefly Bemisia tabaci

Abstract

Manipulation of insect vector behavior by virus-induced plant volatiles is well known. But how the viral disease progression alters the plant volatiles and its effect on vector behavior remains less explored. Our studies tracked changes in volatile profile in progressive infection stages of cotton leaf curl virus (CLCuV) infected plants and their effect on B. tabaci behavior. Significant differences in virus titers were noticed between progressive infection stages showing distinct symptoms. Whiteflies initially settled on CLCuV infected plants, but their preference was shifted to healthy plants over time. GC-MS analysis revealed subtle quantitative/qualitative changes in volatile organic compounds (VOCs) between the healthy and selected CLCuV infection stages. VOCs such as hexanal, (E)-2-hexen-1-ol, (+)-α-pinene, (−)-β-pinene, (Z)-3-hexen-1-ol, (+)-sylvestrene, and (1S,2E,6E, 10R)-3,7,11,11-tetramethylbicycloundeca-2,6-diene (Bicyclogermacrene) were associated with the infection stage showing upward curling of leaves; (E)-2-hexen-1-ol, β-myrcene, β-ocimene, and copaene were associated with the infection stage showing downward curling. Validation studies with eight synthetic VOCs indicated that γ-terpinene elicited attraction to B. tabaci (Olfactometric Preference Index (OPI) = 1.65), while β-ocimene exhibited strong repellence (OPI = 0.64) and oviposition reduction (66.01%–92.55%). Our studies have demonstrated that progression of CLCuV disease in cotton was associated with dynamic changes in volatile profile which influences the behavioural responses of whitefly, B.tabaci. Results have shown that VOCs such as (+)-α-pinene, (−)-β-pinene γ-Terpinene, α-guaiene; 4- hydroxy- 4 methyl-2- pentanone and β-ocimene emitted from Begomovirus infected plants could be the driving force for early attraction and later repellence/oviposition deterrence of B. tabaci on virus-infected plants. The findings of this study offer scope for the management of whitefly, B. tabaci through semiochemicals.

Mycoviruses Increase the Attractiveness of Fusarium graminearum for Fungivores and Suppress Production of the Mycotoxin Deoxynivalenol

“…Does the stimulation of VOC emission by mycoviruses possess an ecological function? Plant viruses modulate the attractiveness of their hosts to animal vectors, increasing their chance of propagation [ 58 , 59 ]. The dissemination of mycoviruses by fungivores has been demonstrated in a single case [ 16 ].…”

Variations in the expression of odorant binding and chemosensory proteins in the developmental stages of whitefly Bemisia tabaci Asia II-1

“…Our results are in concordance with the findings of He et al 14 who reported that these compounds enhance whiteflies’ ability to locate host plants. Furthermore, α-pinene had been implicated in eliciting a positive response from virus-infested plants to B. tabaci facilitating the rapid transmission of cucumber mosaic virus 47 , tomato leaf curl virus 48 and cotton leaf curl virus 49 . Myrcene bound strongly to both OBP8 and CSP4 (− 4.8 kcal/mol), while β-ocimene showed moderate affinities to OBP8 (− 4.8 kcal/mol) and CSP4 (− 4.3 kcal/mol).…”

Small Talk: On the Possible Role of Trans-Kingdom Small RNAs during Plant–Virus–Vector Tritrophic Communication

“…Plants infected with a virus are preferred by the insect vector over healthy plants. This preference/early attraction relates to a combination of disease symptomatology (for example, yellowing of the leaves attracts insects) and changed volatile emission spectra [ 72 ]. Then, viruliferous insect vectors prefer healthy plants over virus-infected plants.…”