Behavioral and Electroantennographic Responses of Adults of Guava Weevil, Conotrachelus dimidiatus (Coleoptera: Curculionidae), to Synthetic Host-Associated and Conspecific Volatiles

Abstract

Immature guava fruits (Psidium guajava L.) of commercial orchards in Mexico are affected by adults of Conotrachelus dimidiatus (Champion) causing economic losses to producers. The aim of this study was to assess the behavioral and electrophysiological responses of the weevil to selected semiochemicals emitted by the host plant fruit and to conspecifics. Volatile organic compounds isolated from host plant as β-caryophyllene, (S)-(−)-limonene, hexanal, and nonanal significantly attracted adults of both sexes in behavioral bioassays. Electroantennogram recordings showed largest responses to papayanal and grandlure III + IV released by C. dimidiatus and C. nenuphar, respectively. Our results indicate that behavioral and electroantennographic assays using synthetic compounds from host plant volatiles and insect volatile pheromones produce olfactometry and electroantennographic responses in C. dimidiatus. This is the first report of intraspecific chemical communication in this weevil. We discuss the significance of these responses for the natural behavior in guava orchards and their potential use in a pest management strategy.

Profile of Terpenoid Compounds Mediating a Plant‐Herbivore Interaction: Screening by Static Headspace Solid‐Phase Microextraction‐Gas Chromatography/Q‐ToF Mass Spectrometry

“…Concerning the olfactometric response to host plant volatiles and insect volatiles, we recently reported that the most attractive volatile compound for males is β‐caryophyllene, with a similar preference of both sexes for it. In contrast, the emitted GA was preferred by females more than males, and only this C 10 terpenoid elicited a significantly different response of females and males (χ2=4.49, P =0.03) [42] …”

“…We newly reported that the level of significance in electroantennographic responses of female C. dimidiatus to the ten volatile compounds identified in the current work was demonstrated. The guava volatile compound caryophyllene exhibited the highest antennal response (3.86±0.08 mV, F=1067.7, df=1, P =0.44 ⋅ 10 −7 ) followed by GIII+IV (3.46±0.16 mV, F=1226.4, df=1, P =0.31 ⋅ 10 −8 ), whereas P‐OL elicited the lowest response [42] . When comparing the electroantennographic responses of C. dimidiatus and C. psidii [15] toward P‐OL, the mean signal intensity was 0.78 mV±0.07 (F=4.23, df=1, P =0.03) and 1.11 mV, respectively.…”

“…The guava volatile compound caryophyllene exhibited the highest antennal response (3.86 � 0.08 mV, F = 1067.7, df = 1, P = 0.44 • 10 À 7 ) followed by GIII + IV (3.46 � 0.16 mV, F = 1226.4, df = 1, P = 0.31 • 10 À 8 ), whereas P-OL elicited the lowest response. [42] When comparing the electroantennographic responses of C. dimidiatus and C. psidii [15] toward P-OL, the mean signal intensity was 0.78 mV � 0.07 (F = 4.23, df = 1, P = 0.03) and 1.11 mV, respectively.…”

“…In contrast, the emitted GA was preferred by females more than males, and only this C 10 terpenoid elicited a significantly different response of females and males (χ2 = 4.49, P = 0.03). [42]…”

“…Behavioral and electroantennography experiments with standards were performed by the known routines as thoroughly described elsewhere. [42] Figure 5. Scheme of the SHS-SPME setting a) on the guava plantation and b) for groups of insects in glass chambers exclusively for females or males of C. dimidiatus.…”