Chemical Cues From Honeydew and Cuticular Extracts of Trialeurodes Vaporariorum Serve as Kairomones for The Parasitoid Encarsia Formosa

Abstract

Kairomones are semiochemicals that are emitted by an organism of different species to the organism receiver which benefits from these chemical substances. Parasitoids find and recognise their hosts through eavesdropping on the kairomones emitted from the by-products or body of the hosts. Hemipteran insect pests feed on plant sap and excrete the digested plant materials as honeydew. Honeydew serves as a nutritional food source for parasitoids and a medium for micro-organisms whose activity induces the release of volatiles exploited by parasitoids for host location. The parasitoid Encarsia formosa preferentially parasitises its host, the greenhouse whitefly, Trialeurodes vaporariorum, on tomato Solanum lycopersicum, but little is known about the chemicals that mediate these interactions. We investigated the olfactory responses of the parasitoid E. formosa to odours from honeydew and nymphs of T. vaporariorum in a Y-tube olfactometer. Arrestment behaviour of the parasitoid to honeydew and nymph extracts, as well as to synthetic hydrocarbons, was also observed in Petri-dish bioassays. We found that T. vaporariorum honeydew volatiles attracted the parasitoid E. formosa but odours from the whitefly nymphs did not. We also found that the parasitoid spent more time searching on areas treated with extracts of honeydew and nymphs than on untreated areas. Gas-chromatography-mass spectrometric analysis revealed that the honeydew volatiles contained compounds such as (Z)-3-hexenol, 3-carene, 3-octanone, α-phellandrene, methyl salicylate, β-ocimene, β-myrcene and (E)-β-caryophyllene which are known to be attractive to E. formosa. The cuticular extracts of the nymphs predominantly contained alkanes, alkenes and esters. Among the alkanes, synthetic of nonacosane arrested the parasitoid. Our findings are discussed in relation to how the parasitoid E. formosa uses these chemicals to locate its host, T. vaporariorum.

Perception and kairomonal response of the coccinellid predator (Harmonia axyridis) to the fall armyworm (Spodoptera frugiperda) sex pheromone

“…Chemical cues play a key role in mediating the interactions between natural enemies and their hosts or prey. The host or prey can release kairomones that differs from the plant background odors, thus providing the most reliable source of chemical information for natural enemies to detect host and prey in the natural environment ( Rodriguez-Saona and Stelinski, 2009 ; Ayelo et al, 2022 ). In this study, we examined and determined the kairomonal effect of S. frugiperda sex pheromone on the coccinellid predator H. axyridis , and the binding properties of H. axyridis OBPs to the components of the sex pheromone.…”

“…Alternatively, sex pheromone may attract natural enemies to the dispensers and reduce their densities in the field, thereby affecting the effectiveness of biological control ( Pekas et al, 2015 ). Knowledge of the kairomonal effects of pheromones on enemies can help to improve lures that recruit and retain natural enemies and to improve the efficiency of biological control of crop pests ( Ayelo et al, 2021 ; Ayelo et al, 2022 ).…”

Exploiting volatile organic compounds in crop protection: A systematic review of 1‐octen‐3‐ol and 3‐octanone

“…Since completion of the search conducted in this systematic review, as of August 2022 a further six records have been identified detailing chemically mediated interactions between 1‐octen‐3‐ol and 3‐octanone and specified target/effectors. Most of these records explored plant sourced interactions with invertebrate target/effectors (Ayelo et al, 2022; Jermakowicz et al, 2022; Liang et al, 2021; Zhuo et al, 2022). The remaining two records explored interactions between invertebrate and fungal sources with invertebrate targets/effectors (Bourdon et al, 2022; Shi et al, 2021).…”

The Susceptibility of Bemisia tabaci Mediterranean (MED) Species to Attack by a Parasitoid Wasp Changes between Two Whitefly Strains with Different Facultative Endosymbiotic Bacteria

“…Parasitoids are able to perceive variations in the host's metabolite profile induced by defensive endosymbionts, including variations in sex pheromones [87] or other volatile compounds [85], cuticular hydrocarbon profiles, and honeydew composition [86]. Parasitoids of whiteflies rely on chemical signals from the host's honeydew and cuticula to recognize their host nymphs [88,89]. Cardinium could alter the host's chemical profile that regulates the foraging behaviour of parasitoids to make B. tabaci MED nymphs less susceptible to parasitization.…”