Host plant volatile compounds capable of stimulating Anastrepha fraterculus male sexual competitiveness

BELLIARD, SILVINA A.; BACHMANN GUILLERMO; FERNANDEZ, PATRICIA; HURTADO JUAN; M. TERESA VERA; DF SEGURA

Congreso; 11th INTERNATIONAL sYMPOSIUM ON FRUTI FLIES OF ECONOMIC IMPORTANCE; 2022

Background: In some tephritid fruit flies, exposure to volatile compounds from host plants increases male sexual success. This phenomenon has been proposed as a mean to boost sterile males’ sexual competitiveness in the framework of the sterile insect technique (SIT). Previous studies revealed that males of Anastrepha fraterculus (Diptera: Tephritidae) exposed to volatiles from guava (Psidium guajava) fruit (GF) and guava essential oil (GEO) exhibit intensified courtship behavior and have greater copulatory success relative to unexposed males. Similar results were achieved in these flies through exposure to moradillo (Schinus polygama) essential oil or lemon (Citrus limon) essential oil. The goal of this study was to identify compounds involved in the exacerbate male calling behavior that follows exposure to guava volatiles. Methods: We identified the volatile chemical profiles of GF and GEO through chromatography coupled to mass spectrometry (GC-MS), and compared them with published profiles of moradillo and lemon essential oil. We selected compounds present in all profiles as candidate compounds. Using the electroantennographic detection (EAD) technique, we verified that males are able to detect all the candidate compounds between 0.01μg/μl and 100 μg/μl for each compound. Furthermore, we tested if exposure to each of these compounds stimulates male calling behavior at three doses (1, 10, and 100 g/l). We also tested two mixtures of candidate compounds for their effect on male calling behavior.Results: We selected five candidate compounds: (E)-β-ocimene, (Z)-β-ocimene, limonene, β-caryophyllene, and α-humulene. Mature males’ antennae were able to detect all candidate compounds. We confirmed a stimulating effect on the courtship behavior of males for (E/Z)-β-ocimene and (R)-limonene, whereas β-caryophyllene and α-Humulene did not affect male courtship behavior. For both β-ocimene and (R)-limonene the stimulating effect was dose-dependent. The behavioral response to these semiochemicals was further increased when β-ocimene and (R)-limonene were combined together in an exposure mixture. However, the response was reduced when β-caryophyllene and α-humulene were added to the mixture, which suggests negative interactions between some of the candidate compounds. Conclusion: Our results support the potential of limonene, β-ocimene, or a mixture of both compounds as a stimulating factor capable of enhancing the sexual performance of A. fraterculus males. These compounds have yet to be tested on sterile males in the SIT context. Searching for these compounds in the volatile profiles of other, non-tested sources may help find other resources that can be employed to improve the SIT efficiency